|  |  |  | | | | | pubmed: "regenerative medici... | | | | | | | | | | | | | | | | | | | Characterization of the chemotactic and mitogenic response of SMCs to PDGF-BB and FGF-2 in fibrin hydrogels. J Biomed Mater Res A. 2010 Sep 1;94(3):988-96 Authors: Ucuzian AA, Brewster LP, East AT, Pang Y, Gassman AA, Greisler HP The delivery of growth factors to cellularize biocompatible scaffolds like fibrin is a commonly used strategy in tissue engineering. We characterized smooth muscle cells (SMC) proliferation and chemotaxis in response to PDGF-BB and FGF-2, alone and in combination, in 2D culture and in 3D fibrin hydrogels. While both growth factors induced an equipotent mitogenic response in 2D culture, only FGF-2 was significantly mitogenic for SMCs in 3D culture. Only PDGF-BB was significantly chemotactic in a modified Boyden chamber assay. In a 3D assay of matrix invasion, both growth factors induced an invasive response into the fibrin hydrogel in both proliferating and nonproliferating, mitomycin C (MMC) treated cells. The invasive response was less attenuated by the inhibition of proliferation in PDGF-BB stimulated cells compared with FGF-2 stimulated cells. We conclude that SMCs cultured in fibrin hydrogels have a more robust chemotactic response to PDGF-BB compared with FGF-2, and that the response to FGF-2 is more dependent on cell proliferation. Delivery of both growth factors together potentiates the chemotactic, but not mitogenic response to either growth factor alone. (c) 2010 Wiley Periodicals, Inc. J Biomed Mater Res Part A, 2010. PMID: 20730936 [PubMed - in process] | | | | | | | | | | | | | | | | | | | | | | | | | Modification of polymer networks with bone sialoprotein promotes cell attachment and spreading. J Biomed Mater Res A. 2010 Sep 1;94(3):945-52 Authors: Chan WD, Goldberg HA, Hunter GK, Dixon SJ, Rizkalla AS Biomaterials used for tissue engineering scaffolds act as temporary substrates, on which cells deposit newly synthesized extracellular matrix. In cartilage tissue engineering, polycaprolactone/poly(2-hydroxyethyl methacrylate) (PCL/pHEMA) polymer blends have been used as scaffold materials, but their use in osseous tissue engineering has been more limited. The objective of this study was to evaluate modification of PCL/pHEMA surfaces with bone sialoprotein (BSP), an extracellular matrix protein important in regulating osseous tissue formation. Modification of surfaces with BSP significantly enhanced osteoblastic cell attachment and spreading, without compromising proliferation. Thus, BSP-immobilization may be a useful strategy for optimizing scaffolds for skeletal tissue engineering. (c) 2010 Wiley Periodicals, Inc. J Biomed Mater Res Part A, 2010. PMID: 20730931 [PubMed - in process] | | | | | | | | | | | | | | | | | | | | | | | | | Topographical analyses of proliferation and differentiation of osteoblasts in micro- and macropores of apatite-fiber scaffold. J Biomed Mater Res A. 2010 Sep 1;94(3):937-44 Authors: Honda M, Fujimi TJ, Izumi S, Izawa K, Aizawa M, Morisue H, Tsuchiya T, Kanzawa N A variety of calcium phosphates have been used for bone tissue-engineering applications. We developed porous hydroxyapatite (HAp) ceramics by firing green compacts consisting of spherical carbon beads and HAp fiber. The apatite-fiber scaffold (AFS) forms a three-dimensional network of fibers with two different pore sizes (micro- and macropores). In this study, we investigated cell distribution and fine cell structure in AFS by confocal laser scanning microscopy. Osteoblastic cells were permeated homogenously throughout the scaffold under static culture conditions and grew three-dimensionally in macropores of AFS. Cells penetrated into micropores when they were capable of cell-cell formations. Cell proliferation and differentiation were also evaluated by biochemical and molecular biological approaches. The expression levels of early-phase osteogenic genes in AFS increased immediately, and those of middle-phase genes were maintained during the 2-week study period. Furthermore, the expression of late-phase markers increased gradually during the incubation period. These data indicate that macropores provide sufficient space for cell growth and proliferation and that micropores facilitate cell differentiation via cell-cell networks. This study provides evidence for the effectiveness of three-dimensional culture systems comprising AFS, which mimics the microenvironment of bone cells. (c) 2010 Wiley Periodicals, Inc. J Biomed Mater Res Part A, 2010. PMID: 20730930 [PubMed - in process] | | | | | | | | | | | | | | | | | | | | | | | | | Application of different strain regimes in two-dimensional and three-dimensional adipose tissue-derived stem cell cultures induces osteogenesis: Implications for bone tissue engineering. J Biomed Mater Res A. 2010 Sep 1;94(3):927-36 Authors: Diederichs S, Böhm S, Peterbauer A, Kasper C, Scheper T, van Griensven M Mechanical strain has become an important tool in tissue engineering for progenitor cell differentiation. Furthermore, it is used to enhance the mechanical properties of engineered tissue constructs. Although strain amplitude and frequency are well investigated and optimal values are known; application of various strain schemes regarding duration and repetition are not described in literature. In this study, we therefore applied singular and repetitive cyclic strain (1 Hz, 5%) of 15 min short-time strain and longer strain durations up to 8 h. Additionally, a gradually increasing strain scheme starting with short-time strain and consecutive elongated strain periods was applied. The cultivation surface was planar silicone on one hand and a three-dimensionally structured collagen I mesh on the other hand. Adipose tissue-derived mesenchymal stem cells and an osteogenic model cell line (MG-63) were exposed to these strain regimes and post-strain cell viability, osteogenic marker gene expression, and matrix mineralization were investigated. Upregulation of alkaline phosphatase, osteocalcin, osteopontin, and BMP-2/4 revealed that even short-time strain can enhance osteogenic differentiation. Elongation and repetition of strain, however, resulted in a decline of the observed short-time strain effects, which we interpret as positively induced cellular adaptation to the mechanically active surroundings. With regard to cellular adaptation, the gradually increasing strain scheme was especially advantageous. (c) 2010 Wiley Periodicals, Inc. J Biomed Mater Res Part A, 2010. PMID: 20730929 [PubMed - in process] | | | | | | | | | | | | | | | | | | | | | | | | | Comparative assessment of structural and biological properties of biomimetically coated hydroxyapatite on alumina (alpha-Al(2)O(3)) and titanium (Ti-6Al-4V) alloy substrates. J Biomed Mater Res A. 2010 Sep 1;94(3):913-26 Authors: Kapoor R, Sistla PG, Kumar JM, Raj TA, Srinivas G, Chakraborty J, Sinha MK, Basu D, Pande G Previous reports have shown the use of hydroxyapatite (HAp) and related calcium phosphate coatings on metal and nonmetal substrates for preparing tissue-engineering scaffolds, especially for osteogenic differentiation. These studies have revealed that the structural properties of coated substrates are dependent significantly on the method and conditions used for coating and also whether the substrates had been modified prior to the coating. In this article, we have done a comparative evaluation of the structural features of the HAp coatings, prepared by using simulated body fluid (SBF) at 25 degrees C for various time periods, on a nonporous metal substrate titanium-aluminium-vanadium (Ti-6Al-4V) alloy and a bioinert ceramic substrate alpha-alumina (alpha-Al(2)O(3)), with and without their prior treatment with the globular protein bovine serum albumin (BSA). Our analysis of these substrates by scanning electron microscopy (SEM), X-ray diffraction (XRD), and Fourier-transform infrared (FTIR) spectrometry showed significant and consistent differences in the quantitative and qualitative properties of the coatings. Interestingly, the bioactivity of these substrates in terms of supporting in vitro cell adhesion and spreading, and in vivo effects of implanted substrates, showed a predictable pattern, thus indicating that some coated substrates prepared under our conditions could be more suitable for biological/biomedical applications. (c) 2010 Wiley Periodicals, Inc. J Biomed Mater Res Part A, 2010. PMID: 20730928 [PubMed - in process] | | | | | | | | | | | | | | | | | | | | | | | | | Nanostructured bladder tissue replacements. Wiley Interdiscip Rev Nanomed Nanobiotechnol. 2010 Aug 20; Authors: Chun YW, Lim H, Webster TJ, Haberstroh KM The interaction between cells or tissues and natural or synthetic materials which mimic the natural biological environment has been a matter of great interest in tissue engineering. In particular, surface properties of biomaterials (regardless of whether they are natural or synthetic) have been optimized using nanotechnology to improve interactions with cells for regenerative medicine applications. Specifically, in vivo and in vitro studies have demonstrated greater bladder tissue growth on polymeric surfaces with nanoscale to submicron surface features. Improved bladder cell responses on nanostructured polymers have been correlated to unique nanomaterial surface features leading to greater surface energy which influences initial protein interactions. Moreover, coupled with the observed greater in vitro and in vivo bladder cell adhesion as well as proliferation on nanostructured compared to conventional synthetic polymers, decreased calcium stone formation has also been measured. In this article, the importance of nanostructured biomaterial surface features for bladder tissue replacements are reviewed with thoughts on future directions for this emerging field. Copyright (c) 2010 John Wiley & Sons, Inc.For further resources related to this article, please visit the WIREs website. PMID: 20730887 [PubMed - as supplied by publisher] | | | | | | | | | | | | | | | | | | | | | | | | | Electrically active nanomaterials as improved neural tissue regeneration scaffolds. Wiley Interdiscip Rev Nanomed Nanobiotechnol. 2010 Aug 20; Authors: Seil JT, Webster TJ Numerous biomaterials have provided promising results toward improving the function of injured nervous system tissue. However, significant hurdles, such as delayed or incomplete tissue regeneration, remain toward full functional recovery of nervous system tissue. Because of this continual need for better nervous system biomaterials, more recent approaches to design the next generation of tissue engineering scaffolds for the nervous system have incorporated nanotechnology, or more specifically, nanoscale surface feature dimensions which mimic natural neural tissue. Compared to conventional materials with micron-scale surface dimensions, nanomaterials have exhibited an ability to enhance desirable neural cell activity while minimizing unwanted cell activity, such as reactive astrocyte activity in the central nervous system. The complexity of neural tissue injury and the presence of inhibitory cues as well as the absence of stimulatory cues may require multifaceted treatment approaches with customized biomaterials that nanotechnology can provide. Combinations of stimulatory cues may be used to incorporate nanoscale topographical and chemical or electrical cues in the same scaffold to provide an environment for tissue regeneration that is superior to inert scaffolds. Ongoing research in the field of electrically active nanomaterials includes the fabrication of composite materials with nanoscale, piezoelectric zinc oxide particles embedded into a polymer matrix. Zinc oxide, when mechanically deformed through ultrasound, for example, can theoretically provide an electrical stimulus, a known stimulatory cue for neural tissue regeneration. The combination of nanoscale surface dimensions and electrical activity may provide an enhanced neural tissue regeneration environment; such multifaceted nanotechnology approaches deserve further attention in the neural tissue regeneration field. Copyright (c) 2010 John Wiley & Sons, Inc.For further resources related to this article, please visit the WIREs website. PMID: 20730786 [PubMed - as supplied by publisher] | | | | | | | | | | | | | | | | | | | | | | | | | Microplate-reader compatible perfusion microbioreactor array for modular tissue culture and cytotoxicity assays. Biotechnol Prog. 2010 Jul;26(4):1135-44 Authors: Wen Y, Zhang X, Yang ST One important application of tissue engineering is to provide novel in vitro models for cell-based assays. Perfusion microbioreactor array provides a useful tool for microscale tissue culture in parallel. However, high-throughput data generation has been a challenge. In this study, a 4 x 4 array of perfusion microbioreactors was developed for plate-reader compatible, time-series quantification of cell proliferation, and cytotoxicity assays. The device was built through multilayer soft lithography. Low-cost nonwoven polyethylene terephthalate fibrous matrices were integrated as modular tissue culture scaffolds. Human colon cancer HT-29 cells with stable expression of enhanced green fluorescent protein were cultured in the device with continuous perfusion and reached a cell density over 5 x 10(7) cells/mL. The microbioreactor array was used to test a chemotherapeutic drug 5-FU for its effect on HT-29 cells in continuous perfusion 3D culture. Compared with conventional 2D cytotoxicity assay, significant drug resistance was observed in the 3D perfusion culture. (c) 2010 American Institute of Chemical Engineers Biotechnol. Prog., 2010. PMID: 20730768 [PubMed - in process] | | | | | | | | | | | | | | | | | | | | | | | | | Pathology and Current Treatment of Neurodegenerative Sphingolipidoses. Neuromolecular Med. 2010 Aug 22; Authors: Eckhardt M Sphingolipidoses constitute a large subgroup of lysosomal storage disorders (LSDs). Many of them are associated with a progressive neurodegeneration. As is the case for LSDs in general, most sphingolipidoses are caused by deficiencies in lysosomal hydrolases. However, accumulation of sphingolipids can also result from deficiencies in proteins involved in the transport or posttranslational modification of lysosomal enzymes, transport of lipids, or lysosomal membrane proteins required for transport of lysosomal degradation end products. The accumulation of sphingolipids in the lysosome together with secondary changes in the concentration and localization of other lipids may cause trafficking defects of membrane lipids and proteins, affect calcium homeostasis, induce the unfolded protein response, activate apoptotic cascades, and affect various signal transduction pathways. To what extent, however, these changes contribute to the pathogenesis of the diseases is not fully understood. Currently, there is no cure for sphingolipidoses. Therapies like enzyme replacement, pharmacological chaperone, and substrate reduction therapy, which have been shown to be efficient in non-neuronopathic LSDs, are currently evaluated in clinical trials of neuronopathic sphingolipidoses. In the future, neural stem cell therapy and gene therapy may become an option for these disorders. PMID: 20730629 [PubMed - as supplied by publisher] | | | | | | | | | | | | | | | | | | | | | | | | | Translating tissue-engineered tracheal replacement from bench to bedside. Cell Mol Life Sci. 2010 Aug 21; Authors: Kalathur M, Baiguera S, Macchiarini P There are a variety of airway diseases with different clinical settings, which may extend from a surgical approach to total organ replacement. Tissue engineering involves modifying cells or tissues in order to repair, regenerate, or replace tissue in the body and seems to be a promising approach for airway replacement. The successful implantation of stem-cell-based tissue-engineered trachea in a young woman with end-stage post-tuberculosis left main bronchus collapse serves as a prototype for the airway tissue-engineered-based approach. The trachea indeed could represent a perfect model system to investigate the translational aspects of tissue engineering, largely due to its low-oxygen needs. This review highlights the anatomy of the airways, the various disease conditions that cause damage to the airways, elaborates on the essential components of the tissue-engineering approach, and discusses the success of the revolutionary trachea transplantation approach. PMID: 20730554 [PubMed - as supplied by publisher] | | | | | | | | | | | | | | | | | | | | | | | | | Fate mapping of human embryonic stem cells by teratoma formation. J Vis Exp. 2010;(42): Authors: Ritner C, Bernstein HS Human embryonic stem cells (hESCs) have an unlimited capacity for self-renewal, and the ability to differentiate into cells derived from all three embryonic germ layers (1). Directed differentiation of hESCs into specific cell types has generated much interest in the field of regenerative medicine (e.g., (2-5)), and methods for determining the in vivo fate of selected or manipulated hESCs are essential to this endeavor. We have adapted a highly efficient teratoma formation assay for this purpose. A small number of specifically selected hESCs is mixed with undifferentiated wild type hESCs and Phaseolus vulgaris lectin to form a cell pellet. This is grafted beneath the kidney capsule in an immunodeficient mouse. As few as 2.5 x 10(5) hESCs are needed to form a 16 cm(3) teratoma within 8-12 weeks. The fate of the originally selected hESCs can then be determined by immunohistochemistry. This method provides a valuable tool for characterizing tissue-specific reagents for cell-based therapy. PMID: 20729802 [PubMed - in process] | | | | | | | | | | | | | | | | | | | | | | | | | Stochastic Resonance Stimulation for Upper Limb Rehabilitation Poststroke. Am J Phys Med Rehabil. 2010 Sep;89(9):697-705 Authors: Stein J, Hughes R, Dʼandrea S, Therrien B, Niemi J, Krebs K, Langone L, Harry J Stein J, Hughes R, D'Andrea S, Therrien B, Niemi J, Krebs K, Langone L, Harry J: Stochastic resonance stimulation for upper limb rehabilitation poststroke. OBJECTIVES:: Previous studies have shown that subthreshold electrical or mechanical noise can reduce the sensory threshold and impart short-term improvements in sensorimotor function. We undertook this study to examine the effects of combined subsensory electrical and vibratory stimulation in conjunction with exercise training on long-term motor performance. DESIGN:: Thirty subjects were recruited from adult community-dwelling stroke survivors with residual hemiparesis. Subjects were screened for residual motor ability using a functional task, and those who functioned below this level were excluded. All subjects had a history of a single unilateral ischemic or hemorrhagic stroke at least 6 mos before study entry and were not actively receiving occupational or physical therapy. Subjects were stratified by baseline upper extremity Fugl-Meyer (UEFM) (more impaired [28-35] and less impaired [36-55]) and were randomized to one of two groups: treatment (stochastic resonance stimulation [plus over minus sign] exercise: 15 subjects) and control (sham stimulation [plus over minus sign] exercise: 15 subjects). RESULTS:: No significant difference was found between the stochastic resonance treatment and control group in the UEFM or in any of the secondary measures. The combined group showed modest improvements in UEFM from baseline to completion of therapy (mean improvement, 2.6 points) (P = 0.004); however, these improvements declined by 1-mo follow-up to 1.5 points (P = 0.055). No change in sensory function was detectable. CONCLUSIONS:: Stochastic resonance therapy combined with occupational therapy was no more effective than occupational therapy alone in restoring sensorimotor performance. Other stochastic resonance stimulation montages or protocols might prove more effective. PMID: 20729650 [PubMed - as supplied by publisher] | | | | | | | | | | | | | | | | | | | | | | | | | Rem2 GTPase controls proliferation and apoptosis of neurons during embryo development. Cell Cycle. 2010 Sep 11;9(17) Authors: Edel MJ, Boué S, Menchon C, Sánchez-Danés A, Belmonte JC We have recently found that Rem2 GTPase, highly expressed in human embryonic stem cells (hESC), maintains the cell cycle and controls proper differentiation towards ectoderm, suggesting a role in neuronal development. We describe here the use of the zebrafish (Danio rerio) model to determine the physiological significance of Rem2 during embryogenesis. We show that Rem2 RNA is highly expressed in zebrafish embryos up to 2 hours of development followed by a decrease in expression until 48 hours when afterwards Rem2 is switched on again until 5 days. In situ expression analysis reveals that Rem2 is expressed exclusively in the tectum of the brain and eye of the zebrafish. Rem2 morpholino demonstrates impaired embryo development resulting in loss of neural tissue. We show that the mechanism of action of Rem2 is to control apoptosis and proliferation, peaking at 36 hours of development. Rem2 is down-regulated under general differentiation conditions of hESC and is lower expressed in most differentiated cells; however, it is upregulated with neuronal development. This suggests that Rem2 is critical for neuronal development during embryogenesis by regulating proliferation and apoptosis. We propose a model in which Rem2 GTPase is a key regulator maintaining pluripotency during early stages of embryogenesis and survival of neurons during later embryonic development. PMID: 20729629 [PubMed - as supplied by publisher] | | | | | | | | | | | | | | | | | | | | | | | | | The effects of processing methods upon mechanical and biologic properties of porcine dermal extracellular matrix scaffolds. Biomaterials. 2010 Aug 20; Authors: Reing JE, Brown BN, Daly KA, Freund JM, Gilbert TW, Hsiong SX, Huber A, Kullas KE, Tottey S, Wolf MT, Badylak SF Biologic materials from various species and tissues are commonly used as surgical meshes or scaffolds for tissue reconstruction. Extracellular matrix (ECM) represents the secreted product of the cells comprising each tissue and organ, and therefore provides a unique biologic material for selected regenerative medicine applications. Minimal disruption of ECM ultrastructure and content during tissue processing is typically desirable. The objective of this study was to systematically evaluate effects of commonly used tissue processing steps upon porcine dermal ECM scaffold composition, mechanical properties, and cytocompatibility. Processing steps evaluated included liming and hot water sanitation, trypsin/SDS/TritonX-100 decellularization, and trypsin/TritonX-100 decellularization. Liming decreased the growth factor and glycosaminoglycan content, the mechanical strength, and the ability of the ECM to support in vitro cell growth (p </= 0.05 for all). Hot water sanitation treatment decreased only the growth factor content of the ECM (p </= 0.05). Trypsin/SDS/TritonX-100 decellularization decreased the growth factor content and the ability of the ECM to support in vitro cell growth (p </= 0.05 for both). Trypsin/Triton X-100 decellularization also decreased the growth factor content of the ECM but increased the ability of the ECM to support in vitro cell growth (p </= 0.05 for both). We conclude that processing steps evaluated in the present study affect content, mechanical strength, and/or cytocompatibility of the resultant porcine dermal ECM, and therefore care must be taken in choosing appropriate processing steps to maintain the beneficial effects of ECM in biologic scaffolds. PMID: 20728934 [PubMed - as supplied by publisher] | | | | | | | | | | | | | | | | | | | | | | | | | The epigenetic mechanism of mechanically induced osteogenic differentiation. J Biomech. 2010 Aug 20; Authors: Arnsdorf EJ, Tummala P, Castillo AB, Zhang F, Jacobs CR Epigenetic regulation of gene expression occurs due to alterations in chromatin proteins that do not change DNA sequence, but alter the chromatin architecture and the accessibility of genes, resulting in changes to gene expression that are preserved during cell division. Through this process genes are switched on or off in a more durable fashion than other transient mechanisms of gene regulation, such as transcription factors. Thus, epigenetics is central to cellular differentiation and stem cell linage commitment. One such mechanism is DNA methylation, which is associated with gene silencing and is involved in a cell's progression towards a specific fate. Mechanical signals are a crucial regulator of stem cell behavior and important in tissue differentiation; however, there has been no demonstration of a mechanism whereby mechanics can affect gene regulation at the epigenetic level. In this study, we identified candidate DNA methylation sites in the promoter regions of three osteogenic genes from bone marrow derived mesenchymal stem cells (MSCs). We demonstrate that mechanical stimulation alters their epigenetic state by reducing DNA methylation and show an associated increase in expression. We contrast these results with biochemically induced differentiation and distinguish expression changes associated with durable epigenetic regulation from those likely to be due to transient changes in regulation. This is an important advance in stem cell mechanobiology as it is the first demonstration of a mechanism by which the mechanical micro-environment is able to induce epigenetic changes that control osteogenic cell fate, and that can be passed to daughter cells. This is a first step to understanding that will be vital to successful bone tissue engineering and regenerative medicine, where continued expression of a desired long-term phenotype is crucial. PMID: 20728889 [PubMed - as supplied by publisher] | | | | | | | | | | | | | | | | | | | | | | | | | Dynamic culture enhances stem cell infiltration and modulates extracellular matrix production on aligned electrospun nanofibrous scaffolds. Acta Biomater. 2010 Aug 19; Authors: Nerurkar NL, Sen S, Baker BM, Elliott DM, Mauck RL Electrospun nanofibrous scaffolds have become widely investigated for tissue engineering applications, owing to their ability to replicate the scale and organization of many fiber-reinforced soft tissues such as the knee meniscus, the annulus fibrosus of the intervertebral disc, tendon, and cartilage. However, due to their small pore size and dense packing of fibers, cellular ingress into electrospun scaffolds is limited. Progress in the application of electrospun scaffolds has therefore been hampered, as limited cell infiltration results in heterogeneous deposition of extracellular matrix and mechanical properties that remain below native benchmarks. In the present study, dynamic culture conditions dramatically improved the infiltration of mesenchymal stem cells into aligned nanofibrous scaffolds. While dynamic culture resulted in a reduction of glycosaminoglycan content, removal from dynamic culture to free swelling conditions after 6 weeks resulted recovery of glycosaminoglycan content. Dynamic culture significantly increased collagen content, and collagen was more uniformly distributed throughout the scaffold thickness. While mechanical function was assessed and tensile modulus increased with culture duration, dynamic culture did not result in any additional improvement beyond free swelling culture. Transient dynamic (6 weeks dynamic followed by 6 weeks free swelling) culture significantly enhanced cell infiltration while permitting GAG accumulation. In this study, we demonstrated that a simple modification to standard in vitro culture conditions effectively improves cellular ingress into electrospun scaffolds, resolving a challenge which has until now limited the utility of these materials for various tissue engineering applications. PMID: 20728589 [PubMed - as supplied by publisher] | | | | | | | | | | | | | | | | | | | | | | | | | Differentiation of monocytes on a degradable, polar-hydrophobic-ionic polyurethane: 2-dimensional films versus 3-dimensional scaffolds. Acta Biomater. 2010 Aug 19; Authors: McBane JE, Ebadi D, Sharifpoor S, Labow RS, Santerre JP A degradable, polar, hydrophobic, ionic, (D-PHI) polyurethane, with physical properties comparable to those of peripheral arterial vascular tissue, was evaluated for monocyte interactions with two different physical forms: 2-dimensional films and 3-dimensional porous scaffolds. Monocytes, isolated from human whole blood, were seeded onto D-PHI films and scaffolds, and differentiated to monocyte-derived macrophages (MDM) for up to 28 days. The effect of surface structure on the MDM phenotype was assessed by assaying: cell attachment (DNA), activation (intracellular protein expression, esterase and acid phosphatase (AP) activity) as well as pro- and anti-inflammatory cytokines (TNF-alpha and IL-10, respectively). The cells on scaffolds exhibited an initial peak in total protein synthesized per DNA at 3 days; however, both substrates generated similar protein levels per DNA at all other time points. While scaffolds generated more esterase and AP per cell than for films, the cells on films expressed significantly more of these two proteins relative to their total protein produced. At day 7 (acute phase of monocyte activation), cells on films were significantly more activated than monocytes on the scaffolds as assessed by cell morphology and TNF-alpha and IL-10 levels. Histological analysis of scaffolds showed that cells were able to migrate throughout the 3-dimensional matrix. By inducing a low inflammatory, more wound healing phenotype monocyte, the negative effects of the foreign body reaction in vivo may be controlled in a manner possible to direct the vascular tissue cells into the appropriate functional phenotypes necessary for successful tissue engineering. PMID: 20728587 [PubMed - as supplied by publisher] | | | | | | | | | | | | | | | | | | | | | | | | | Osteogenic Differentiation of Human Mesenchymal Stem Cells Synergistically Enhanced by Biomimetic Peptide Amphiphiles Combined with Conditioned Media. Acta Biomater. 2010 Aug 19; Authors: Anderson JM, Vines JB, Patterson JL, Chen H, Javed A, Jun HW An attractive strategy for bone tissue engineering is the use of extracellular matrix (ECM) analogous biomaterials capable of governing biological response based on synthetic cell-ECM interactions. In this study, peptide amphiphiles (PAs) were investigated as an ECM-mimicking biomaterial to provide an instructive microenvironment for human mesenchymal stem cells (hMSCs) in an effort to guide osteogenic differentiation. PAs were biologically functionalized with ECM isolated ligand sequences (i.e. RGDS, DGEA), and the osteoinductive potential was studied with or without conditioned media, containing the supplemental factors of dexamethasone, beta-glycerol phosphate, and ascorbic acid. It was hypothesized that the ligand-functionalized PAs would synergistically enhance osteogenic differentiation in combination with conditioned media. Concurrently, comparative evaluations independent of osteogenic supplements investigated the differentiating potential of the functionalized PA scaffolds as promoted exclusively by the inscribed ligand signals, thus offering the potential for therapeutic effectiveness under physiological conditions. Osteoinductivity was assessed by histochemical staining for alkaline phosphatase (ALP) and quantitative real-time PCR analysis of key osteogenic markers. Both of the ligand-functionalized PAs were found to synergistically enhance the level of visualized ALP activity and osteogenic gene expression compared to the control surfaces lacking biofunctionality. Guided osteoinduction was also observed without supplemental aid on the PA scaffolds, but at a delayed response and not to the same phenotypic levels. Thus, the biomimetic PAs foster a symbiotic enhancement of osteogenic differentiation, demonstrating the potential of ligand functionalized biomaterials for future bone tissue repair. PMID: 20728586 [PubMed - as supplied by publisher] | | | | | | | | | | | | | | | | | | | | | | | | | Surface modification of electrospun PLLA nanofibers by plasma treatment and cationized gelatin immobilization for cartilage tissue engineering. Acta Biomater. 2010 Aug 19; Authors: Chen JP, Su CH Electrospun poly(lactic acid) (PLLA) nanofibers (NFs) were modified with cationized gelatin (CG) to improve their compatibility with chondrocytes and to show in vitro and in vivo the potential applications of CG-grafted PLLA nanofibrous membranes (CG-PLLA NFMs) as a cartilage tissue engineering scaffold. PLLA NFs were first treated with oxygen plasma to introduce -COOH groups on the surface, followed by covalent grafting of CG molecules on fiber surface, using water-soluble carbodiimide as the coupling agent. The effects of CG grafting and properties of NFMs were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), thermogravimetric analysis (TGA), atomic force microscope (AFM), X-ray photoelectron spectra (XPS), and Fourier transform infrared spectroscopy (FTIR). In vitro studies indicated CG-PLLA NFMs could enhance viability, proliferation, and differentiation of rabbit articular chondrocytes compared with pristine PLLA NFMs. SEM observations of the cell-scaffold construct confirmed the tight attachment of chondrocytes to CG-PLLA NFs and in-growth of cells into the interior of the membrane with proper maintenance of cell morphology. Improved cell differentiation in CG-PLLA NFMs was confirmed by enhanced glycoaminoglycan and collagen secretion, histology analysis, and reverse transcription-polymerase chain reaction (RT-PCR) studies, where cells were able to maintain the expression of characteristic markers (collagen II, aggregan, and SOX 9) of chondrocytes. Subcutaneous implantation of the cell-scaffold constructs with autologous chondrocytes also confirmed the formation of ectopic cartilage tissues in 28 days by histology examinations and immunostaining. PMID: 20728584 [PubMed - as supplied by publisher] | | | | | | | | | | | | | | | | | | | | | | | | | Human cord blood stem cells and the journey to a cure for type 1 diabetes. Autoimmun Rev. 2010 Aug 19; Authors: Zhao Y, Mazzone T Umbilical cord blood contains several types of stem cells that are of interest to a wide range of disciplines in regenerative medicine. The translational potential to the clinical applications of cord blood stem cells has increased enormously in recent years, mainly because of its advantages including no risk to the donor, no ethical issues, low risk of graft-versus-host disease (GVHD) and rapid availability. Type 1 diabetes (T1D) is an autoimmune disease caused by an autoimmune destruction of pancreatic islet beta cells. Understanding the nature and function of cord blood stem cells is an exciting challenge that might set the stage for new approaches to the treatment of T1D. Here, we review progress in this field and draw conclusions for the development of future therapeutics in T1D. New insights are provided on a unique type of cord blood-derived multipotent stem cells (CB-SC), including the molecular mechanisms underlying immune modulation by CB-SC, protection of beta-cell mass, and promotion of islet beta-cell neogenesis. PMID: 20728583 [PubMed - as supplied by publisher] | | | | | | | | | | | | | | | | | | | | | | | | | Human anterior cruciate ligament fibroblasts from immature patients have a stronger in vitro response to platelet concentrates than those from mature individuals. Knee. 2010 Aug 19; Authors: Magarian EM, Vavken P, Murray MM A number of recently published studies have established a substantial age dependence of the response of ACL fibroblasts to stimulation by platelet-rich plasma (PRP). Further in-depth research of this age dependence revealed negative effects on both histological and biomechanical results in a large animal model. However, while it has been postulated that this association could affect potential human applications negatively too it remains to be proven that the same effects occur in human cells. Thus it was the objective of this study to search for age dependence in human fibroblasts before further human experiments are done. Human fibroblasts were obtained from 10 immature and adolescent patients, based on a-priori power calculations, and cultured in a collagen-PRP composite. Three parameters that are pivotal for defect remodeling and wound healing-cell migration, cell proliferation, and scaffold contraction-were chosen as endpoints. Both migration and proliferation were significantly higher in immature cells, but no differences were seen in wound contraction. The former findings suggest that immature patients respond more favorably to treatment with PRP, which consequently might translate into better results in ACL tissue engineering. PMID: 20728363 [PubMed - as supplied by publisher] | | | | | | | | | | | | | | | | | | | | | | | | | The improvement of fibroblast growth on hydrophobic biopolyesters by coating with polyhydroxyalkanoate granule binding protein PhaP fused with cell adhesion motif RGD. Biomaterials. 2010 Aug 19; Authors: Dong Y, Li P, Chen CB, Wang ZH, Ma P, Chen GQ Polyhydroxyalkanoates (PHA), a family of biopolyesters, have been studied as tissue engineering biomaterials due to their adjustable mechanical properties, biodegradability and tissue compatibility. Amphiphilic PHA granule binding protein PhaP has been shown to be able to bind to hydrophobic surfaces of polymers, especially PHA, via strong hydrophobic interaction. Genes of PhaP and RGD peptides, which are a cell adhesion motif recognized by many cell surface receptors, were successfully expressed and obtained as a pure fusion protein PhaP-RGD in Escherichia coli DH5alpha. When films of poly(3-hydroxybutyrate-co-3-hydroxy- hexanoate) (PHBHHx), poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) and polylactic acid (PLA) were coated with PhaP-RGD, their surface hydrophilicities were all increased compared with their corresponding naked (non-coated) films, respectively. Among the three biopolyesters, PHBHHx demonstrated the strongest affinity to PhaP. In vitro study showed that mouse fibroblasts L929 and mouse embryonic fibroblasts NIH/3T3 attached better and grew faster on all three PhaP-RGD coated films compared with their related behaviors on PhaP coated and non-coated films, respectively. Both fibroblasts attached and grew very well on PhaP-RGD coated PHBHHx, PHBV and PLA, even in their serum-free medium, while the non-coated and PhaP coated biopolyesters poorly supported the cell growth if the two fibroblasts were incubated in their serum free medium. These results indicated that PhaP-RGD could be used as a coating material to improve cell growth on hydrophobic biopolyesters for implant tissue engineering purposes. PMID: 20728212 [PubMed - as supplied by publisher] | | | | | | | | | | | | | | | | | | | | | | | | | MSCs: Biological characteristics, clinical applications and their outstanding concerns. Ageing Res Rev. 2010 Aug 18; Authors: Si YL, Zhao YL, Hao HJ, Fu XB, Han WD Mesenchymal stem cells (MSCs) are multi-potent adult stem cells harboring multi-lineage differentiation potential and immunosuppressive properties that make MSCs an ideal candidate cell type for immunomodulation and regenerative medicine. Currently, MSC-related researches and clinical trials have evoked exciting promise in a variety of disorders and tissue regeneration. However, it must be recognized that several critical potential problems have also emerged from current clinical trials, for example: (1) the indefinite association between the phenotypic characteristics and the biological functions of MSCs; (2) the lack of clinical data to support the long-term safety of MSCs; (3) the need for further clarification of multiple mechanisms of MSC transplant actions in vivo; and (4) the lack of comparability of MSC transplant efficacy. Therefore, MSC-based therapies could not yet be considered a routine treatment in the clinic. Based on these, we proposed that large-scale and multi-center clinical trials of MSC-based therapies should be initiated under strict supervision. These interventions might help to establish a new clinical paradigm to turn MSC transplantation into a routine therapy for at least some diseases in the near future. PMID: 20727988 [PubMed - as supplied by publisher] | | | | | | | | | | | | | | | | | | | | | | | | | Female Human iPSCs Retain an Inactive X Chromosome. Cell Stem Cell. 2010 Aug 18; Authors: Tchieu J, Kuoy E, Chin MH, Trinh H, Patterson M, Sherman SP, Aimiuwu O, Lindgren A, Hakimian S, Zack JA, Clark AT, Pyle AD, Lowry WE, Plath K Generating induced pluripotent stem cells (iPSCs) requires massive epigenome reorganization. It is unclear whether reprogramming of female human cells reactivates the inactive X chromosome (Xi), as in mouse. Here we establish that human (h)iPSCs derived from several female fibroblasts under standard culture conditions carry an Xi. Despite the lack of reactivation, the Xi undergoes defined chromatin changes, and expansion of hiPSCs can lead to partial loss of XIST RNA. These results indicate that hiPSCs are epigenetically dynamic and do not display a pristine state of X inactivation with two active Xs as found in some female human embryonic stem cell lines. Furthermore, whereas fibroblasts are mosaic for the Xi, hiPSCs are clonal. This nonrandom pattern of X chromosome inactivation in female hiPSCs, which is maintained upon differentiation, has critical implications for clinical applications and disease modeling, and could be exploited for a unique form of gene therapy for X-linked diseases. PMID: 20727844 [PubMed - as supplied by publisher] | | | | | | | | | | | | | | | | | | | | | | | | | High density gene expression microarrays and gene ontology analysis for identifying processes in implanted tissue engineering constructs. Biomaterials. 2010 Aug 18; Authors: Lammers G, Gilissen C, Nillesen ST, Uijtdewilligen PJ, Wismans RG, Veltman JA, Daamen WF, van Kuppevelt TH The in vivo performance of tissue-engineered constructs is often based on generally accepted read-out parameters, like (immuno)histology. In this study, high-density gene expression microarrays and gene ontology (GO) analysis were used as a read-out tool to identify the biological processes occurring after implantation of an acellular collagen-based skin construct using a rat full-thickness wound model. A freely-available program (DAVID) was used to identify up/downregulated biological processes (GO-terms) and results were compared to wound healing/regeneration without a construct. The entire process from RNA isolation to biological interpretation is explained step-by-step. Conventional (immuno)histology was used to validate the biological processes identified and indicate that microarray analysis may provide a valuable, fast and unbiased tool to evaluate the in vivo performance of tissue-engineered constructs. However, challenges remain e.g. with regards to the development of specific GO-terms and annotation of the (rat) genome. PMID: 20727583 [PubMed - as supplied by publisher] | | | | | | | | | | | | | | | | | | | | | | | | | Chronic label-free volumetric photoacoustic microscopy of melanoma cells in three-dimensional porous Scaffolds. Biomaterials. 2010 Aug 18; Authors: Zhang Y, Cai X, Choi SW, Kim C, Wang LV, Xia Y Visualizing cells in three-dimensional (3D) scaffolds has been one of the major challenges in tissue engineering. Most current imaging modalities either suffer from poor penetration depth or require exogenous contrast agents. Here, we demonstrate photoacoustic microscopy (PAM) of the spatial distribution and temporal proliferation of cells inside three-dimensional porous scaffolds with thicknesses over 1 mm. Specifically, we evaluated the effects of seeding and culture methods on the spatial distribution of melanoma cells. Spatial distribution of the cells in the scaffold was well-resolved in PAM images. Moreover, the number of cells in the scaffold was quantitatively measured from the as-obtained volumetric information. The cell proliferation profile obtained from PAM correlated well with what was obtained using the traditional 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay. PMID: 20727581 [PubMed - as supplied by publisher] | | | | | | | | | | | | | | | | | | | | | | | | | Adrenomedullin reduces expression of adhesion molecules on lymphatic endothelial cells. Regul Pept. 2010 Aug 17; Authors: Jin D, Otani K, Yamahara K, Ikeda T, Nagaya N, Kangawa K We recently reported that lymphatic endothelial cells (LECs) express the adrenomedullin (AM) receptor and proliferation of LECs can be induced by AM. In this study, we analyzed changes in gene expression induced by treatment with exogenous AM in LECs. We found that AM profoundly suppressed expression of cell adhesion and inflammatory response genes, such as intercellular adhesion molecule-1 (ICAM-1), vascular adhesion molecule-1 (VCAM-1), endothelial adhesion molecule-1 (E-selectin), interleukin-8, TNF-alpha induced proteins and chemokine ligands. QRT-PCR and flow cytometry analysis confirmed that both cell surface expression and gene expression of TNF-alpha-induced ICAM-1 and VCAM-l were decreased in LECs after exposure to AM. Treatment of LECs with a cell permeable cyclic adenosine monophosphate (cAMP) analog, 8-Br-cAMP, mimicked the suppressive effect of AM on the expression of adhesion molecules. Moreover, both AM and 8-Br-cAMP suppressed TNF-alpha-induced NF-kappaB activation in LECs. In conclusion, the results of the present study indicate that AM reduces adhesion molecule expression on LECs via a cAMP/NF-kappaB mediated pathway, suggesting a role for AM in the immune and inflammatory response. PMID: 20727374 [PubMed - as supplied by publisher] | | | | | | | | | | | | | | | | | | | | | | | | | Novel strategies in tendon and ligament tissue engineering: Advanced biomaterials and regeneration motifs. Sports Med Arthrosc Rehabil Ther Technol. 2010 Aug 20;2(1):20 Authors: Kuo CK, Marturano JE, Tuan RS ABSTRACT: Tendon and ligaments have poor healing capacity and when injured often require surgical intervention. Tissue replacement via autografts and allografts are non-ideal strategies that can lead to future problems. As an alternative, scaffold-based tissue engineering strategies are being pursued. In this review, we describe design considerations and major recent advancements of scaffolds for tendon/ligament engineering. Specifically, we outline native tendon/ligament characteristics critical for design parameters and outcome measures, and introduce synthetic and naturally-derived biomaterials used in tendon/ligament scaffolds. We will describe applications of these biomaterials in advanced tendon/ligament engineering strategies including the utility of scaffold functionalization, cyclic strain, growth factors, and interface considerations. The goal of this review is to compile and interpret the important findings of recent tendon/ligament engineering research in an effort towards the advancement of regenerative strategies. PMID: 20727171 [PubMed - as supplied by publisher] | | | | | | | | | | | | | | | | | | | | | | | | | CHALLENGES IN TISSUE ENGINEERING AND REGENERATIVE MEDICINE PRODUCT COMMERCIALIZATION: BUILDING AN INDUSTRY. Tissue Eng Part A. 2010 Aug 22; Authors: Hellman KB, Johnson PC, Bertram T, Tawil BJ CHALLENGES IN TISSUE ENGINEERING AND REGENERATIVE MEDICINE PRODUCT COMMERCIALIZATION: BUILDING AN INDUSTRY. PMID: 20726818 [PubMed - as supplied by publisher] | | | | | | | | | | | | | | | | | | | | | | | | | Isolation and Characterization of Multi-Potent Stem Cells from Human Orbital Fat Tissues. Tissue Eng Part A. 2010 Aug 22; Authors: Ho JH, Ma WH, Tseng TC, Chen YF, Chen MH, Lee OK Loss of corneal epithelial cells results in visual problems. Stem cells isolated from the limbal area of the ocular surface are able to replenish lost corneal epithelial cells. However, destruction of the healthy limbus tissue is inevitable. Theoretically, orbital fat should be an excellent source to isolate stem cells for regenerating ocular tissues as the orbital connective tissues share the same embryonic origin with the ocular proper in early organogenesis. The purpose of this study is to isolate stem cells from the human orbital fat and to explore their differentiation potentials into epithelial cells. It was found that spindle-shaped, fibroblast-like cells with extensive proliferation potentials could be isolated from orbital fat tissues. These orbital fat-derived stem cells (OFSCs) possessed multi-lineage differentiation potential to become osteoblasts, chondrocytes and adipocytes. Upon mix-culture with corneal epithelial cells, OFSCs changed their morphology to round, polygonal epithelial-like cells. Loss of CD105 expression and increased expression of epithelial cell markers including epithelial specific antigen and zonal occludin-1 were found upon mix-culture with corneal epithelial cells. Moreover, corneal epithelial differentiation was evidenced by the expression of CK-19 and CK-3 after mix-culture with corneal epithelial cells while human adipose-derived stem cells from subcutaneous fat were unable to differentiate into corneal epithelial cells under the same induction condition. We further found that direct contact with corneal epithelial cells was essential for OFSCs to commit to corneal epithelial cells. Taken together, orbital fat tissues are a novel source for multi-potent stem cells which possess the potential to differentiate into corneal epithelial lineage. OFSCs are therefore a potential candidate for cell therapy and tissue engineering of corneal epithelium. PMID: 20726817 [PubMed - as supplied by publisher] | | | | | | | | | | | | | | | | | | | | | | | | | Hurdles In Tissue Engineering/Regenerative Medicine Product Commercialization A Survey Of North American Academia And Industry. Tissue Eng Part A. 2010 Aug 22; Authors: Johnson PC, Bertram T, Tawil BJ, Hellman KB The TERMIS-NA Industry Committee was formed in February 2009 to address the common roadblocks (i.e., 'hurdles') in the commercialization of tissue engineering/regenerative medicine products for its members. A semi quantitative online opinion survey instrument was developed that delineated potentially sensitive hurdles to commercialization in each of the TERMIS constituency groups that generally participate in the stream of technology commercialization (Academia, Start Up Companies, Development Stage Companies and Established Companies). The survey was opened to each of the 863 members of TERMIS-NA for a period of five weeks from October to November 2009. By its conclusion, 215 members (25 %) had responded. Their proportionate numbers were closely representative of TERMIS-NA constituencies. The resulting data delineate what each group considers to be its most difficult and also its easiest hurdles in taking a technology to full product development. In addition, each group ranked its perception of the difficult and easy hurdles for all other groups, enabling an assessment of the degree of understanding between groups. The data depict not only critical hurdles in the path to commercialization at each stage in product development but also a variable understanding of perceptions of hurdles between groups. This assessment has provided the Industry Committee with activity foci needed to assist individual groups in the technology-commercialization stream. Moreover, the analysis suggests that enhanced communication between groups engaged in commercialization will be critical to the successful development of products in the tissue engineering/regenerative medicine sector. PMID: 20726816 [PubMed - as supplied by publisher] | | | | | | | | | | | | | | | | | | | | | | | | | Defining a Threshold Surface Density of Vitronectin for the Stable Expansion of Human Embryonic Stem Cells. Tissue Eng Part C Methods. 2010 Aug 20; Authors: Yap L, Li J, Phang IY, Ong LT, Ow JZ, Goh JC, Nurcombe V, Hobley J, Choo A, Oh S, Cool S, Birch W Current methodology for pluripotent human embryonic stem cells (hESCs) expansion relies on murine sarcoma basement membrane substrates (Matrigel), which precludes the use of these cells in regenerative medicine. In order to realize the clinical efficacy of hESCs and their derivatives, expansion of these cells in a defined system that is free of animal components is required. This study reports the successful propagation of hESCs (HES-3 and H1) for more than 20 passages on tissue culture-treated polystyrene (TCPS) plates, coated from 5 mug/ml of human plasma-purified vitronectin (VN) solution. Cells maintain the expression of pluripotent markers Tra1-60 and OCT-4 and are karyotypically normal after 20 passages of continuous culture. In-vitro and in-vivo differentiation of hESC by embryoid body formation and teratoma yielded cells from the ecto- , endo- and mesoderm lineages. VN immobilized on TCPS was characterized using a combination of X-ray photoemission spectroscopy (XPS), atomic force microscopy (AFM), and quantification of the VN surface density with a Bradford protein assay. Ponceau S staining was used to measure VN adsorption and desorption kinetics. Tuning the VN surface density, via the concentration of depositing solution, revealed a threshold surface density of 250 ng/cm2, which is required for hESCs attachment, proliferation and differentiation. Cell attachment and proliferation assays on VN surface densities above this threshold show the substrate properties to be equally viable. PMID: 20726687 [PubMed - as supplied by publisher] | | | | | | | | | | | | | | | | | | | | | | | | | Hepatocyte growth factor incorporated chitosan nanoparticles differentiate murine bone marrow mesenchymal stem cell into hepatocytes in vitro. IET Nanobiotechnol. 2010 Sep;4(3):51 Authors: Pulavendran S, Rajam M, Rose C, Mandal AB Delivery of growth factor for the differentiation of stem cells into lineage specific cells holds great potential in regenerative medicine. Stem cell differentiation is governed by cytokines and growth factors secreted upon the organelle injury and, however, their short half-life necessitates exogenous supply. Development of suitable nanodevices using biodegradable polymers to deliver therapeutic proteins to the targeted site in a sustainable manner attracts scientists and clinicians. Here, for the first time, hepatocyte growth factor (HGF) was incorporated into chitosan nanoparticles (CNP) by ionotrophic gelation method. An average size of nanoparticles prepared was 100 nm, showing sustainable release of HGF. Cytotoxicity study did not reveal any adverse effect on bone marrow mesenchymal stem cells (MSC) up to 4 mg CNP/ml culture medium. To evaluate the effect of HGF incorporated CNP (HGF-CNP) on hepatic differentiation in in vitro, MSC were incubated with HGF-CNP and other supplements. After 21 days, fibroblast-like morphology of MSC became round-shape, a typical characteristic of hepatocyte cell. Immunofluorescence study for albumin expression confirmed the hepatic differentiation. In conclusion, HGF released from the HGF-CNP can differentiate MSC into hepatocytes, and this novel technique could also be extended to deliver therapeutic proteins for a variety of tissue regeneration. PMID: 20726671 [PubMed - in process] | | | | | | | | | | | | | | | | | | | | | | | | | Nanotechnology in Drug Delivery and Tissue Engineering: From Discovery to Applications. Nano Lett. 2010 Aug 20; Authors: Shi J, Votruba AR, Farokhzad OC, Langer R The application of nanotechnology in medicine, referred to as nanomedicine, is offering numerous exciting possibilities in healthcare. Herein, we discuss two important aspects of nanomedicine, drug delivery and tissue engineering, highlighting the advances we have recently experienced, the challenges we are currently facing, and what we are likely to witness in the near future. PMID: 20726522 [PubMed - as supplied by publisher] | | | | | | | | | | | | | | | | | | | | | | | | | In vitro hydrolytic and enzymatic degradation of nestlike-patterned electrospun poly(D,L-lactide-co-glycolide) scaffolds. J Biomed Mater Res A. 2010 Aug 19; Authors: Zhou X, Cai Q, Yan N, Deng X, Yang X A common problem in applying electrospun biodegradable polyester matrixes as tissue-engineering scaffolds is their serious shrinkage with degradation to reduce the porosity drastically. To ameliorate this problem, a nestlike-patterned poly(D,L-lactide-co-glycolide) (PLGA) nanofibrous ( approximately 900 nm) matrix was proposed and fabricated by electropinning. Shrinkage studies demonstrated that the dimension change of nestlike-patterned fibrous membrane was much smaller than those of nonwoven and parallel-aligned fibrous membranes. And the robust framework of the patterned matrix helped to maintain its original nestlike topographical structure during degradation. Compared to hydrolytic-degraded specimens, the PLGA nanofibrous matrixes degraded in the presence of lysozyme showed larger weight loss but slower decrease in molecular weight. Besides, porous fibers with intact surface were detected by scanning electron microscopy after 20-week hydrolysis, and fibers with pores both inside and on surface were observed after enzymatic degradation for 12 weeks. Accordingly, the former presented a bimodal gel permeation chromatography (GPC) peak, while no bi or multimodal GPC peaks were found for the latter as degradation proceeded. These results indicated that an acid autocatalytic effect still existed in the hydrolysis of PLGA nanofibrous matrix. The presence of lysozyme could only accelerate the dissolution of degradation products with low molecular weight, but have no contribution to the chain scission. (c) 2010 Wiley Periodicals, Inc. J Biomed Mater Res Part A, 2010. PMID: 20725988 [PubMed - as supplied by publisher] | | | | | | | | | | | | | | | | | | | | | | | | | In vivo evaluation of MMP sensitive high-molecular weight HA-based hydrogels for bone tissue engineering. J Biomed Mater Res A. 2010 Aug 19; Authors: Kim J, Kim IS, Cho TH, Kim HC, Yoon SJ, Choi J, Park Y, Sun K, Hwang SJ Hyaluronic acid (170 kDa)-based hydrogel was synthesized using acrylated hyaluronic acid (HA) and matrix metalloproteinase (MMP) sensitive HA-based hydrogels were then prepared by conjugation with two different peptides: cell adhesion peptides containing integrin-binding domains (Arg-Gly-Asp: RGD) and a cross-linker with MMP degradable peptides to mimic the remodeling characteristics of natural extracellular matrices by cell-derived MMPs. Mechanical properties of these hydrogels were evaluated with different weight percentages (2.5 and 3.5 wt %) by measuring elastic modulus, viscous modulus, and swelling ratio. Human mesenchymal stem cells (hMSCs) were then cultured in MMP-sensitive or insensitive HA-based hydrogels and/or immobilized cell adhesive RGD peptides in vitro. Actin staining and image analysis proved that cells cultured in the MMP-sensitive hydrogel with RGD peptides showed extensive cell spreading and sprouting. Gene expression analysis showed that bone specific genes such as alkaline phosphatase, osteocalcin, and osteopontin increased in MMP-sensitive hydrogels as biomolecules such as BMPs and cells were added in the gels. For in vivo calvarial defect regeneration, five different samples (MMP insensitive hydrogel, MMP sensitive hydrogel, MMP sensitive hydrogel with BMP-2, MMP sensitive hydrogel with hMSC, and MMP sensitive hydrogel with BMP-2 and hMSC) were prepared. After 4 weeks of implantation, the Masson-Trichrome staining and micro computed tomography scan results demonstrated that the MMP sensitive hydrogels with BMP-2 and hMSCs have the highest mature bone formation. The MMP sensitive HA-based hydrogel could become useful scaffolds in bone tissue engineering with improvements on tissue remodeling rates and regeneration activity. (c) 2010 Wiley Periodicals, Inc. J Biomed Mater Res Part A, 2010. PMID: 20725983 [PubMed - as supplied by publisher] | | | | | | | | | | | | | | | | | | | | | | | | | Mono-dispersed bioactive glass nanospheres: Preparation and effects on biomechanics of mammalian cells. J Biomed Mater Res A. 2010 Aug 19; Authors: Hong Z, Luz GM, Hampel PJ, Jin M, Liu A, Chen X, Mano JF Mono-dispersed SiO(2)-CaO bioactive glass nanospheres (BGNS) were prepared by a two step sol-gel method in the absence of surfactant. The size of BGNS ranged from 200 to 350 nm in diameter and exhibited a rough surface texture. In vitro biomineralization tests showed that BGNS could rapidly induce the deposition of an apatite layer in simulated body fluid (SBF). The effect of bioactive glass on the biomechanical properties of various mammalian cells was first reported in this paper. Atomic force microscopy (AFM) was used for measuring the biomechanical properties of mammalian cells. The result showed that BGNS-medium could significantly decrease the plasma membrane stiffness of bone marrow stem cells (BMSCs) by approximately 50% and stimulate BMSCs spreading. The effect of BGNS on biomechanical properties of bovine aortic endothelial cells (BAECs) was opposite to that on BMSCs. BGNS increased the BAECs' stiffness and stimulated the elongation of endothelial cells and the formation of endothelial networks, which might potentially facilitate the vascularization of implanted BGNS-based biomaterials in tissue engineering as a scaffold or as an injectable system. (c) 2010 Wiley Periodicals, Inc. J Biomed Mater Res Part A, 2010. PMID: 20725980 [PubMed - as supplied by publisher] | | | | | | | | | | | | | | | | | | | | | | | | | Evaluation of dense polylactic acid/beta-tricalcium phosphate scaffolds for bone tissue engineering. J Biomed Mater Res A. 2010 Aug 19; Authors: Yanoso-Scholl L, Jacobson JA, Bradica G, Lerner AL, O'Keefe RJ, Schwarz EM, Zuscik MJ, Awad HA Advances in biomaterial fabrication have introduced numerous innovations in designing scaffolds for bone tissue engineering. Often, the focus has been on fabricating scaffolds with high and interconnected porosity that would allow for cellular seeding and tissue ingrowth. However, such scaffolds typically lack the mechanical strength to sustain in vivo ambulatory stresses in models of load bearing cortical bone reconstruction. In this study, we investigated the microstructural and mechanical properties of dense PLA and PLA/beta-TCP (85:15) scaffolds fabricated using a rapid volume expansion phase separation technique, which embeds uncoated beta-TCP particles within the porous polymer. PLA scaffolds had a volumetric porosity in the range of 30 to 40%. With the embedding of beta-TCP mineral particles, the porosity of the scaffolds was reduced in half, whereas the ultimate compressive and torsional strength were significantly increased. We also investigated the properties of the scaffolds as delivery vehicles for growth factors in vitro and in vivo. The low-surface porosity resulted in sub optimal retention efficiency of the growth factors, and burst release kinetics reflecting surface coating rather than volumetric entrapment, regardless of the scaffold used. When loaded with BMP2 and VEGF and implanted in the quadriceps muscle, PLA/beta-TCP scaffolds did not induce ectopic mineralization but induced a significant 1.8-fold increase in neo vessel formation. In conclusion, dense PLA/beta-TCP scaffolds can be engineered with enhanced mechanical properties and potentially be exploited for localized therapeutic factor delivery. (c) 2010 Wiley Periodicals, Inc. J Biomed Mater Res Part A, 2010. PMID: 20725979 [PubMed - as supplied by publisher] | | | | | | | | | | | | | | | | | | | | | | | | | Novel three-dimensional scaffolds of poly(L-lactic acid) microfibers using electrospinning and mechanical expansion: Fabrication and bone regeneration. J Biomed Mater Res B Appl Biomater. 2010 Aug 19; Authors: Shim IK, Jung MR, Kim KH, Seol YJ, Park YJ, Park WH, Lee SJ Poly(L-lactic acid) (PLLA) microfibrous scaffolds with three-dimensional (3D) structures were fabricated using an electrospinning technique with a subsequent mechanical expansion process. To achieve a 3D fibrous structure, the fusion at the contact points of the as-spun PLLA microfibers was avoided using an appropriate binary solvent system of methylene chloride and acetone. The solvent composition was optimized based on the solvent power, volatility, and viscosity (methylene chloride:acetone = 9:1 volume ratio). The final 3D structure of the electrospun scaffolds was obtained after mechanical expansion of the electrospun microfibrous mats. The pore sizes of the scaffolds were controlled by varying the degree of expansion of the nonbonded microfibrous mats, and they were in the range of several microns up to 400 mum. The 3D scaffolds were examined for their morphological properties and their potential use for the proliferation of osteoblasts. Generally recognized electrospun 2D nanofibrous membranes were also tested in order to compare the cell behaviors using different scaffold geometries. The 3D scaffolds demonstrated a high level of osteoblast proliferation (1.8-fold higher than nanofibrous membranes in a week). The osteoblasts actively penetrated the inside of the 3D scaffold and showed a spatial cell distribution, as confirmed by SEM and H&E staining, while a monolayer formed in the case of the 2D nanofibrous membranes with limited cell infiltration. In vivo results further showed that 3D electrospun microfibrous matrices were a favorable substrate for cell infiltration and bone formation after 2 and 4 weeks, using a rabbit calvarial defect model. In this study, the 3D microfibrous PLLA scaffolds fabricated using electrospinning techniques might be an innovative addition to tissue engineering applications. (c) 2010 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2010. PMID: 20725960 [PubMed - as supplied by publisher] | | | | | | | | | | | | | | | | | | | | | | | | | Silk hydrogel for cartilage tissue engineering. J Biomed Mater Res B Appl Biomater. 2010 Aug 19; Authors: Chao PH, Yodmuang S, Wang X, Sun L, Kaplan DL, Vunjak-Novakovic G Cartilage tissue engineering based on cultivation of immature chondrocytes in agarose hydrogel can yield tissue constructs with biomechanical properties comparable to native cartilage. However, agarose is immunogenic and nondegradable, and our capability to modify the structure, composition, and mechanical properties of this material is rather limited. In contrast, silk hydrogel is biocompatible and biodegradable, and it can be produced using a water-based method without organic solvents that enables precise control of structural and mechanical properties in a range of interest for cartilage tissue engineering. We observed that one particular preparation of silk hydrogel yielded cartilaginous constructs with biochemical content and mechanical properties matching constructs based on agarose. This finding and the possibility to vary the properties of silk hydrogel motivated this study of the factors underlying the suitability of hydrogels for cartilage tissue engineering. We present data resulting from a systematic variation of silk hydrogel properties, silk extraction method, gel concentration, and gel structure. Data suggest that silk hydrogel can be used as a tool for studies of the hydrogel-related factors and mechanisms involved in cartilage formation, as well as a tailorable and fully degradable scaffold for cartilage tissue engineering. (c) 2010 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2010. PMID: 20725950 [PubMed - as supplied by publisher] | | | | | | | | | | | | | | | | | | | | | | | | | Prediction of osteoconductive activity of modified potassium fluorrichterite glass-ceramics by immersion in simulated body fluid. J Mater Sci Mater Med. 2010 Aug 20; Authors: Bhakta S, Pattanayak DK, Takadama H, Kokubo T, Miller CA, Mirsaneh M, Reaney IM, Brook I, van Noort R, Hatton PV Potassium fluorrichterite (KNaCaMg(5)Si(8)O(22)F(2)) glass-ceramics were modified by either increasing the concentration of calcium (GC5) or by the addition of P(2)O(5) (GP2). The stoichiometric composition (GST), GC5 and GP2 were soaked in simulated body fluid (SBF) along with 45S5-type bioglass as a control. After immersion, surface analyses were performed using thin-film X-ray diffraction (TF-XRD), scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS) and Fourier-transform infrared (reflection) spectroscopy (FT-IR). All compositions showed the formation of a calcium phosphate rich surface layer in SBF; GST, GP2 and the bioglass control within 7 days of immersion and GC5 after 14 days. It was concluded that all compositions were likely to be osteoconductive in vivo, with GP2 providing the best performance in terms of the combination of rapid formation of the surface layer and superior mechanical properties. This glass-ceramic system has potential as a load bearing bioceramic for fabrication of medical devices intended for skeletal tissue repair. PMID: 20725768 [PubMed - as supplied by publisher] | | | | | | | | | | | | | | | | | | | | | | | | | Sacral neuromodulations for female lower urinary tract, pelvic floor, and bowel disorders. Curr Opin Obstet Gynecol. 2010 Aug 18; Authors: Wehbe SA, Whitmore K, Ho MH PURPOSE OF REVIEW: In recent years, sacral neuromodulation (SNM) has been investigated for the treatment of various types of lower urinary tract and bowel dysfunctions. This review discusses recently published data related to the therapeutic applications of SNM in female lower urinary tract, pelvic floor, and bowel disorders. RECENT FINDINGS: SNM has been employed initially in the treatment of refractory idiopathic overactive bladder, urge urinary incontinence, and chronic nonobstructive urinary retention. Since then, several studies, including randomized and controlled trials, have confirmed the therapeutic effects of SNM in these disorders. The applications of SNM are now extended to the treatment of other female pelvic problems, such as fecal incontinence, chronic constipation, interstitial cystitis/painful bladder syndrome, sexual dysfunction, and neurogenic disorders, with similar promising results. SUMMARY: SNM is approved by the Food and Drug Administration for the treatment of idiopathic overactive bladder, urge urinary incontinence, and chronic nonobstructive urinary retention. SNM is not yet an approved method for the treatment of other pelvic disorders, but data supporting its benefit are emerging. The major advantage of SNM lies in its potential to treat the bladder, urethral sphincter, anal sphincters, and pelvic floor muscles simultaneously, which might result in better therapeutic effects. PMID: 20724927 [PubMed - as supplied by publisher] | | | | | | | | | | | | | | | | | | | | | | | | | Nanosilver as a new generation of nanoproduct in biomedical applications. Trends Biotechnol. 2010 Aug 17; Authors: Chaloupka K, Malam Y, Seifalian AM Nanosilver (NS), comprising silver nanoparticles, is attracting interest for a range of biomedical applications owing to its potent antibacterial activity. It has recently been demonstrated that NS has useful anti-inflammatory effects and improves wound healing, which could be exploited in developing better dressings for wounds and burns. The key to its broad-acting and potent antibacterial activity is the multifaceted mechanism by which NS acts on microbes. This is utilized in antibacterial coatings on medical devices to reduce nosocomial infection rates. Many new synthesis methods have emerged and are being evaluated for NS production for medical applications. NS toxicity is also critically discussed to reflect on potential concerns before widespread application in the medical field. PMID: 20724010 [PubMed - as supplied by publisher] | | | | | | | | | | | | | | | | | | | | | | | | | Visual Enhancement of Laparoscopic Partial Nephrectomy With 3-Charge Coupled Device Camera: Assessing Intraoperative Tissue Perfusion and Vascular Anatomy by Visible Hemoglobin Spectral Response. J Urol. 2010 Aug 17; Authors: Crane NJ, Gillern SM, Tajkarimi K, Levin IW, Pinto PA, Elster EA PURPOSE: We report the novel use of 3-charge coupled device camera technology to infer tissue oxygenation. The technique can aid surgeons to reliably differentiate vascular structures and noninvasively assess laparoscopic intraoperative changes in renal tissue perfusion during and after warm ischemia. MATERIALS AND METHODS: We analyzed select digital video images from 10 laparoscopic partial nephrectomies for their individual 3-charge coupled device response. We enhanced surgical images by subtracting the red charge coupled device response from the blue response and overlaying the calculated image on the original image. Mean intensity values for regions of interest were compared and used to differentiate arterial and venous vasculature, and ischemic and nonischemic renal parenchyma. RESULTS: The 3-charge coupled device enhanced images clearly delineated the vessels in all cases. Arteries were indicated by an intense red color while veins were shown in blue. Differences in mean regions of interest intensity values for arteries and veins were statistically significant (p >0.0001). Three-charge coupled device analysis of pre-clamp and post-clamp renal images revealed visible, dramatic color enhancement for ischemic vs nonischemic kidneys. Differences in the mean regions of interest intensity values were also significant (p <0.05). CONCLUSIONS: We present a simple use of conventional 3-charge coupled device camera technology in a way that may provide urological surgeons with the ability to reliably distinguish vascular structures during hilar dissection, and detect and monitor changes in renal tissue perfusion during and after warm ischemia. PMID: 20723937 [PubMed - as supplied by publisher] | | | | | | | | | | | | | | | | | | | | | | | | | Vitamin D(3) metabolites induce osteogenic differentiation in human dental pulp and human dental follicle cells. J Steroid Biochem Mol Biol. 2010 Aug 16; Authors: Khanna-Jain R, Vuorinen A, Sándor GK, Suuronen R, Miettinen S Vitamin D(3) metabolites regulate the bone metabolism and 1alpha,25-dihydroxyvitamin D(3) (1alpha,25(OH)(2)D(3)) is known to play an important role in teeth mineralization. However, little is known about the potential of vitamin D as an osteogenic inducer in human dental pulp (hDPCs) and dental follicle cells (hDFCs) in vitro. Therefore, we investigated the effects of vitamin D(3) metabolites 1alpha,25(OH)(2)D(3) and 25-hydroxyvitamin D(3) (25OHD(3)) [10] G.E. Wise, S. Frazier-Bowers and R.N. D'Souza, Cellular, molecular, and genetic determinants of tooth eruption, Crit. Rev. Oral. Biol. Med. 13 (2002), pp. 323-334. View Record in Scopus | Cited By in Scopus (55on proliferation and osteogenic differentiation of hDPCs and hDFCs in vitro. We also examined whether vitamin D(3) metabolic enzymes were regulated in hDFCs and hDPCs. Cell proliferation was decreased by both metabolites in hDPCs and hDFCs. Vitamin D(3) metabolites increased ALP activity and induced mineralization when osteogenic supplements (OS; L-ascorbic acid-2-phosphate+beta- glycerophosphate) were added, though the expression of osteocalcin (OC) and osteopontin (OPN) were regulated without the addition of OS. CYP24 and CYP27B1 expressions were upregulated by vitamin D(3) metabolites and 25OHD(3) was converted into 1alpha,25(OH)(2)D(3) in the culture medium. These results confirm that 1alpha,25(OH)(2)D(3) (10nM, 100nM) and 25OHD(3) (500nM) can be used as osteogenic inducers synergistically with osteogenic supplements for differentiation of hDPCs and hDFCs. Furthermore, our findings strengthen our knowledge about the role of hDPCs and hDFCs as vitamin D(3) target cells. PMID: 20723601 [PubMed - as supplied by publisher] | | | | | | | | | | | | | | | | | | | | | | | | | [Strengthen researches on translational medicine and regenerative medicine in burns.] Zhonghua Shao Shang Za Zhi. 2010 Jun;26(3):167-9 Authors: Huang YS Translational medicine and regenerative medicine are presently the hottest areas in medical research. Translational medicine is regarded as a two-way model of medical research, i.e. bench to bedside and bedside to bench. The purpose of translational research is to test novel therapeutic strategies developed through experimentation in human beings, and to facilitate the transformation of findings resulting from basic research to clinical practice. Regenerative medicine is to search for effective biotherapy methods to promote self repair and regeneration; or to construct new tissues and organs to improve or restore the function of the injured tissues and organs. To strengthen researches on translational medicine and regenerative medicine in burns may promote the application of new clinical therapeutic strategies, and supply effective therapeutic measures for treatment of severe burns. PMID: 20723416 [PubMed - in process] | | | | | | | | | | | | | | | | | | | | | | | | | [Erythropoietin gene-modified conditioned medium of human mesenchymal cells promotes hematopoietic development from human embryonic stem cells.] Zhongguo Shi Yan Xue Ye Xue Za Zhi. 2010 Jul;18(4):976-80 Authors: Yang C, Ji L, Yue W, Wang RY, Li YH, Xi JF, Xie XY, He LJ, Nan X, Pei XT The study was aimed to investigate the effect of deriving hematopoietic cells from human embryonic stem cells (hESCs) by the erythropoietin gene-modified conditioned medium of human mesenchymal cells. The mesenchymal stem cells (MSCs) steadily expressing EPO were established by lentiviral system. The expression of exogenous EPO was detected by RT-PCR and Western blot. After suspension culture, hESCs developed into embryonic bodies (EBs). Then the EB cells were cultured in conditional medium. The hESCs-derived hematopoietic cells were analyzed by immunofluorescence, CFU assay and RT-PCR. The results indicated that the exogenous EPO successfully expressed in the EPO transfected MSCs (EPO/MSCs). The supernatant from EPO/MSCs increased CD34(+) cell population and the expression of globin, and enhanced colony forming unit incidence. These effects were obviously higher than that of control. It is concluded that the EPO gene-modified conditioned medium of human mesenchymal cells can induce the hESCs to differentiate into hematopoietic cells. PMID: 20723312 [PubMed - in process] | | | | | | | | | | | | | | | | | | | | | | | | | Unravelling the development of the visual cortex: implications for plasticity and repair. J Anat. 2010 Aug 16; Authors: Bourne JA Abstract The visual cortex comprises over 50 areas in the human, each with a specified role and distinct physiology, connectivity and cellular morphology. How these individual areas emerge during development still remains something of a mystery and, although much attention has been paid to the initial stages of the development of the visual cortex, especially its lamination, very little is known about the mechanisms responsible for the arealization and functional organization of this region of the brain. In recent years we have started to discover that it is the interplay of intrinsic (molecular) and extrinsic (afferent connections) cues that are responsible for the maturation of individual areas, and that there is a spatiotemporal sequence in the maturation of the primary visual cortex (striate cortex, V1) and the multiple extrastriate/association areas. Studies in both humans and non-human primates have started to highlight the specific neural underpinnings responsible for the maturation of the visual cortex, and how experience-dependent plasticity and perturbations to the visual system can impact upon its normal development. Furthermore, damage to specific nuclei of the visual cortex, such as the primary visual cortex (V1), is a common occurrence as a result of a stroke, neurotrauma, disease or hypoxia in both neonates and adults alike. However, the consequences of a focal injury differ between the immature and adult brain, with the immature brain demonstrating a higher level of functional resilience. With better techniques for examining specific molecular and connectional changes, we are now starting to uncover the mechanisms responsible for the increased neural plasticity that leads to significant recovery following injury during this early phase of life. Further advances in our understanding of postnatal development/maturation and plasticity observed during early life could offer new strategies to improve outcomes by recapitulating aspects of the developmental program in the adult brain. PMID: 20722872 [PubMed - as supplied by publisher] | | | | | | | | | | | | | | | | | | | | | | | | | Cell-mediated neuroprotection in a mouse model of human tauopathy. J Neurosci. 2010 Jul 28;30(30):9973-83 Authors: Hampton DW, Webber DJ, Bilican B, Goedert M, Spillantini MG, Chandran S Tau protein in a hyperphosphorylated state makes up the intracellular inclusions of several neurodegenerative diseases, including Alzheimer's disease and cases of frontotemporal dementia. Mutations in Tau cause familial forms of frontotemporal dementia, establishing that dysfunction of tau protein is sufficient to cause neurodegeneration and dementia. Transgenic mice expressing human mutant tau in neurons exhibit the essential features of tauopathies, including neurodegeneration and abundant filaments composed of hyperphosphorylated tau. Here we show that a previously described mouse line transgenic for human P301S tau exhibits an age-related, layer-specific loss of superficial cortical neurons, similar to what has been observed in human frontotemporal dementias. We also show that focal neural precursor cell implantation, resulting in glial cell differentiation, leads to the sustained rescue of cortical neurons. Together with evidence indicating that astrocyte transplantation may be neuroprotective, our findings suggest a beneficial role for glial cell-based repair in neurodegenerative diseases. PMID: 20668182 [PubMed - indexed for MEDLINE] | | | | | | | | | | | | | | | | | | | | | | | | | The influence of bioreactor geometry and the mechanical environment on engineered tissues. J Biomech Eng. 2010 May;132(5):051006 Authors: Osborne JM, O'Dea RD, Whiteley JP, Byrne HM, Waters SL A three phase model for the growth of a tissue construct within a perfusion bioreactor is examined. The cell population (and attendant extracellular matrix), culture medium, and porous scaffold are treated as distinct phases. The bioreactor system is represented by a two-dimensional channel containing a cell-seeded rigid porous scaffold (tissue construct), which is perfused with a culture medium. Through the prescription of appropriate functional forms for cell proliferation and extracellular matrix deposition rates, the model is used to compare the influence of cell density-, pressure-, and culture medium shear stress-regulated growth on the composition of the engineered tissue. The governing equations are derived in O'Dea et al. "A Three Phase Model for Tissue Construct Growth in a Perfusion Bioreactor," Math. Med. Biol., in which the long-wavelength limit was exploited to aid analysis; here, finite element methods are used to construct two-dimensional solutions to the governing equations and to investigate thoroughly their behavior. Comparison of the total tissue yield and averaged pressures, velocities, and shear stress demonstrates that quantitative agreement between the two-dimensional and long-wavelength approximation solutions is obtained for channel aspect ratios of order 10(-2) and that much of the qualitative behavior of the model is captured in the long-wavelength limit, even for relatively large channel aspect ratios. However, we demonstrate that in order to capture accurately the effect of mechanotransduction mechanisms on tissue construct growth, spatial effects in at least two dimensions must be included due to the inherent spatial variation of mechanical stimuli relevant to perfusion bioreactors, most notably, fluid shear stress, a feature not captured in the long-wavelength limit. PMID: 20459207 [PubMed - indexed for MEDLINE] | | | | | | | | | | | | | | | | | | | | | | | | | Immunohistochemical study of oral epithelial sheets cultured on amniotic membrane for oral mucosal reconstruction. Biomed Mater Eng. 2010 Jan;20(1):37-45 Authors: Amemiya T, Nakamura T, Yamamoto T, Kinoshita S, Kanamura N We immunohistochemically evaluated whether oral epithelial cells grown on amniotic membrane (AM) would be an effective biomaterial for reconstructing oral mucosal defects. Oral mucosal epithelial cells from albino rabbits were grown for 2-3 weeks on an AM carrier in a co-culture with 3T3 fibroblasts. The rabbits' oral mucosal defects were reconstructed by autologous transplantation of the oral epithelial sheets. The oral epithelial sheets and reconstructed tissues were then examined histologically and immunohistochemically. After 2-3 weeks of culture, the rabbit oral mucosal epithelial cells developed 5-7 layers of stratification on the AM. Immunohistochemistry revealed that they expressed keratins 4/13, integrin alpha 6, alpha 5 chain and collagen type III, but not keratins 1/10. The transplanted sheets attached to the mucosal defects, and AM fragments disappeared from the transplant area. Immunohistochemical patterns revealed properties of the mucous membrane and basement membrane components in the reconstructed epithelia. The results of this experiment showed that the AM-cultured oral epithelial sheets resulted in mucosa-like differentiation, and adhered to the mucosal defects. Therefore, AM-cultured oral epithelial sheets might be a useful biomaterial for oral mucosal reconstruction. PMID: 20448302 [PubMed - indexed for MEDLINE] | | | | | | | | | | | | | | | | | | | | | | | | | Preparation and evaluation of microporous organogel scaffolds for cell viability and proliferation. Colloids Surf B Biointerfaces. 2010 Aug 1;79(1):105-12 Authors: Lukyanova L, Franceschi-Messant S, Vicendo P, Perez E, Rico-Lattes I, Weinkamer R Various porous scaffolds utilizing an organogel were prepared by particulate-leaching method. The porous organogels were made of biodegradable, non-toxic ingredients like soybean oil or caprylic/capric triglyceride as the organic liquids and 12-hydroxystearic acid as the gelator. The scaffolds possessed an effective porosity of 56-65%, and good pore interconnectivity with an average pore size from 220 to 290mum. The biodegradability of such materials was evaluated and lipases were able to totally degrade the scaffolds. The porosity of the material associated with high draining led to suitable scaffolds which were evaluated for CHO cell viability and proliferation using the MTT test. This evaluation was performed over a period of 3 weeks and showed a greater ability to promote cell proliferation for the soybean oil based scaffold than for the caprylic/capric triglyceride one. The histological investigations revealed that this scaffold was able to promote cell colonization and attachment and could induce the production of collagen. PMID: 20427161 [PubMed - indexed for MEDLINE] | | | | | | | | | | | | | | | | | | | | | | | | | Cell-laden microengineered gelatin methacrylate hydrogels. Biomaterials. 2010 Jul;31(21):5536-44 Authors: Nichol JW, Koshy ST, Bae H, Hwang CM, Yamanlar S, Khademhosseini A The cellular microenvironment plays an integral role in improving the function of microengineered tissues. Control of the microarchitecture in engineered tissues can be achieved through photopatterning of cell-laden hydrogels. However, despite high pattern fidelity of photopolymerizable hydrogels, many such materials are not cell-responsive and have limited biodegradability. Here, we demonstrate gelatin methacrylate (GelMA) as an inexpensive, cell-responsive hydrogel platform for creating cell-laden microtissues and microfluidic devices. Cells readily bound to, proliferated, elongated, and migrated both when seeded on micropatterned GelMA substrates as well as when encapsulated in microfabricated GelMA hydrogels. The hydration and mechanical properties of GelMA were demonstrated to be tunable for various applications through modification of the methacrylation degree and gel concentration. The pattern fidelity and resolution of GelMA were high and it could be patterned to create perfusable microfluidic channels. Furthermore, GelMA micropatterns could be used to create cellular micropatterns for in vitro cell studies or 3D microtissue fabrication. These data suggest that GelMA hydrogels could be useful for creating complex, cell-responsive microtissues, such as endothelialized microvasculature, or for other applications that require cell-responsive microengineered hydrogels. PMID: 20417964 [PubMed - indexed for MEDLINE] | | | | | | | | | | | | | | | | | | | | | | | | | Molecular assembly and biological activity of a recombinant fragment of fibronectin (FNIII(7-10)) on poly(ethyl acrylate). Colloids Surf B Biointerfaces. 2010 Jul 1;78(2):310-6 Authors: Rico P, González-GarcÃa C, Petrie TA, GarcÃa AJ, Salmerón-Sánchez M Fibronectin (FN) fibrillogenesis is a cell-mediated process involving integrin activation that results in conformational changes of FN molecules and the organization of actin cytoskeleton. A similar process can be induced by some particular chemistries in the absence of cells, e.g., poly(ethyl acrylate) (PEA), which enhance FN-FN interactions leading to the formation of a biologically active network on the material surface. We have investigated the organization of a recombinant fragment of fibronectin (FNIII(7-10)) upon adsorption on this particular chemistry, PEA. Atomic force microscopy (AFM) was used to identify individual molecules of the fragment after adsorption, as well as the evolution of the distribution of adsorbed molecules on the surface of the material as the concentration of the adsorbing solution increased. Globular molecules that turn into small aggregates were found as a function of solution concentration. Above a threshold concentration of the adsorbing solution (50 microg/mL) an interconnected network of the FNIII(7-10) fragment is obtained on the material surface. The bioavailability of specific cell adhesion domains, including RGD, within the molecules was higher on PEA than on the control glass. The biological activity of the fragment was further investigated by evaluating focal adhesion formation and actin cytoskeleton for MC3T3-E1 osteoblast-like cells. Well-developed focal adhesion complexes and insertions of actin stress fibers were found on PEA in a similar way as it happens in the control SAM-OH. Moreover, increasing the hydrophilicity of the surface by incorporating -OH groups led to globular molecules of the fragment homogeneously distributed throughout the surface; and the cell-material interaction is reduced as depicted by the lack of well-developed focal plaques and actin cytoskeleton. PMID: 20409696 [PubMed - indexed for MEDLINE] | | | | | | | | | | | | | | | | | | | | | | | | | The influence hydroxyapatite nanoparticle shape and size on the properties of biphasic calcium phosphate scaffolds coated with hydroxyapatite-PCL composites. Biomaterials. 2010 Jul;31(21):5498-509 Authors: Roohani-Esfahani SI, Nouri-Khorasani S, Lu Z, Appleyard R, Zreiqat H We developed a composite biphasic calcium phosphate (BCP) scaffold by coating a nanocomposite layer, consisting of hydroxyapatite (HA) nanoparticles and polycaprolactone (PCL), over the surface of BCP. The effects of HA particle size and shape in the coating layer on the mechanical and biological properties of the BCP scaffold were examined. Micro-computerized tomography studies showed that the prepared scaffolds were highly porous (approximately 91%) with large pore size (400-700 microm) and an interconnected porous network of approximately 100%. The HA nanoparticle (needle shape)-composite coated scaffolds displayed the highest compressive strength (2.1 +/- 0.17 MPa), compared to pure HA/beta-TCP (0.1 +/- 0.05 MPa) and to the micron HA - composite coated scaffolds (0.29 +/- 0.07 MPa). These needle shaped scaffolds also showed enhanced elasticity and similar stress-strain profile to natural bone. Needle shaped coated HA/PCL particles induced the differentiation of primary human bone derived cells, with significant upregulation of osteogenic gene expression (Runx2, collagen type I, osteocalcin and bone sialoprotein) and alkaline phosphatase activity compared to other groups. These properties are essential for enhancing bone ingrowth in load-bearing applications. The developed composite scaffolds possessed superior physical, mechanical, elastic and biological properties rendering them potentially useful for bone tissue regeneration. PMID: 20398935 [PubMed - indexed for MEDLINE] | | | | | | | | | | | | | | | | | | | | | | | | | In vitro constitution and in vivo implantation of engineered skin constructs with sweat glands. Biomaterials. 2010 Jul;31(21):5520-5 Authors: Huang S, Xu Y, Wu C, Sha D, Fu X Despite the rapid development of engineered skin, such skin still lacks skin appendages. Sweat glands, one of the skin appendages, play key roles in the maintenance of homeostasis and temperature regulation. In this study, we tested whether sweat glands could be integrated into engineered skin constructs to improve the quality of tissue regeneration. Using gelatin microspheres(containing epidermal growth factor [EGF]) as multifunctional vehicles, we cultured sweat gland cells (SGCs) on them and delivered SGCs-microspheres complex (SMC) into the engineered skin construct, which was created in vitro by culturing human keratinocytes on top of a fibroblast-embedded collagen-based matrix in an organotypic co-culture model. This engineered skin construct was then transplanted onto full-thickness cutaneous wounds in an athymic murine model. EGF-loaded microspheres displayed more cellular growth-promoting efficiency, and thus SMC was an available means for SGCs delivery. Constitution of the engineered skin constructs formed a skin-like pattern in vitro. Remarkably, SMC could differentiate toward a sweat gland-like structure in vitro within the hybrid matrix. Furthermore, the degree of wound healing in mice with this skin construct implantation was better than that with controls. This engineered skin construct could be used as a promising tool for regeneration of sweat glands in skin repair and a valuable engineered strategy for constitution of appendage-containing engineered skin models. PMID: 20398932 [PubMed - indexed for MEDLINE] | | | | | | | | | | | | | | | | | | | | | | | | | Can we obtain hyaline cartilage with currently available techniques? Eklem Hastalik Cerrahisi. 2010 Apr;21(1):1 Authors: Atik OS PMID: 20302554 [PubMed - indexed for MEDLINE] | | | | | | | | | | | | | | | | | | | | | | | | | Correlation of cell strain in single osteocytes with intracellular calcium, but not intracellular nitric oxide, in response to fluid flow. J Biomech. 2010 May 28;43(8):1560-4 Authors: Rath AL, Bonewald LF, Ling J, Jiang JX, Van Dyke ME, Nicolella DP Osteocytes compose 90-95% of all bone cells and are the mechanosensors of bone. In this study, the strain experienced by individual osteocytes resulting from an applied fluid flow shear stress was quantified and correlated to two biological responses measured in real-time within the same individual osteocytes: (1) the upregulation of intracellular calcium and (2) changes in intracellular nitric oxide. Osteocyte-like MLO-Y4 cells were loaded with Fluo-4 AM and DAR-4M and exposed to uniform laminar fluid flow shear stresses of 2, 8, or 16 dyn/cm(2). Intracellular calcium and nitric oxide changes were determined by measuring the difference in fluorescence intensity from the cell's basal level prior to fluid flow and the level immediately following exposure. Individual cell strains were calculated using digital image correlation. MLO-Y4 cells showed a linear increase in cell strain, intracellular calcium concentration, and nitric oxide concentration with an increase in applied fluid flow rate. The increase in intracellular calcium was well correlated to the strain that each cell experienced. This study shows that osteocytes exposed to the same fluid flow experienced a range of individual strains and changes in intracellular calcium and nitric oxide concentrations, and the changes in intracellular calcium were correlated with cell strain. These results are among the first to establish a relationship between the strain experienced by osteocytes in response to fluid flow shear and a biological response at the single cell level. Mechanosensing and chemical signaling in osteocytes has been hypothesized to occur at the single cell level, making it imperative to understand the biological response of the individual cell. PMID: 20189178 [PubMed - indexed for MEDLINE] | | | | | | | | | | | | | | | | | | | | | | | | | Injectable gellan gum hydrogels with autologous cells for the treatment of rabbit articular cartilage defects. J Orthop Res. 2010 Sep;28(9):1193-9 Authors: Oliveira JT, Gardel LS, Rada T, Martins L, Gomes ME, Reis RL In this work, the ability of gellan gum hydrogels coupled with autologous cells to regenerate rabbit full-thickness articular cartilage defects was tested. Five study groups were defined: (a) gellan gum with encapsulated chondrogenic predifferentiated rabbit adipose stem cells (ASC + GF); (b) gellan gum with encapsulated nonchondrogenic predifferentiated rabbit adipose stem cells (ASC); (c) gellan gum with encapsulated rabbit articular chondrocytes (AC) (standard control); (d) gellan gum alone (control); (e) empty defect (control). Full-thickness articular cartilage defects were created and the gellan gum constructs were injected and left for 8 weeks. The macroscopic aspect of the explants showed a progressive increase of similarity with the lateral native cartilage, stable integration at the defect site, more pronouncedly in the cell-loaded constructs. Tissue scoring showed that ASC + GF exhibited the best results regarding tissue quality progression. Alcian blue retrieved similar results with a better outcome for the cell-loaded constructs. Regarding real-time PCR analyses, ASC + GF had the best progression with an upregulation of collagen type II and aggrecan, and a downregulation of collagen type I. Gellan gum hydrogels combined with autologous cells constitute a promising approach for the treatment of articular cartilage defects, and adipose derived cells may constitute a valid alternative to currently used articular chondrocytes. PMID: 20187118 [PubMed - indexed for MEDLINE] | | | | | | | | | | | | | | | | | | | | | | | | | Cell therapy for diabetes: stem cells, progenitors or beta-cell replication? Mol Cell Endocrinol. 2010 Jul 8;323(1):55-61 Authors: Gonez LJ, Knight KR The cure for type 1 diabetes (T1D) will require either the replacement or regeneration of insulin-producing cells, together with measures that prevent their immune-mediated destruction. Experiments in rodent models have found that pancreatic stem cells, committed progenitors and replicating beta-cells can all contribute to insulin-producing cell regeneration. The cellular and molecular mechanisms of these cells, both in vitro and in vivo, have been investigated by us and by others. Furthermore, our surgical research laboratory has developed a unique in vivo chamber model of T1D, allowing the assessment of the behaviour of different sources of insulin-producing cells with a view to their potential use in cell-based therapies. PMID: 20026173 [PubMed - indexed for MEDLINE] | | | | | | | | | | | | | | | | | | | | | | | | | A Quality Risk Management Model Approach for Cell Therapy Manufacturing. Risk Anal. 2010 Aug 17; Authors: Lopez F, Bartolo CD, Piazza T, Passannanti A, Gerlach JC, Gridelli B, Triolo F International regulatory authorities view risk management as an essential production need for the development of innovative, somatic cell-based therapies in regenerative medicine. The available risk management guidelines, however, provide little guidance on specific risk analysis approaches and procedures applicable in clinical cell therapy manufacturing. This raises a number of problems. Cell manufacturing is a poorly automated process, prone to operator-introduced variations, and affected by heterogeneity of the processed organs/tissues and lot-dependent variability of reagent (e.g., collagenase) efficiency. In this study, the principal challenges faced in a cell-based product manufacturing context (i.e., high dependence on human intervention and absence of reference standards for acceptable risk levels) are identified and addressed, and a risk management model approach applicable to manufacturing of cells for clinical use is described for the first time. The use of the heuristic and pseudo-quantitative failure mode and effect analysis/failure mode and critical effect analysis risk analysis technique associated with direct estimation of severity, occurrence, and detection is, in this specific context, as effective as, but more efficient than, the analytic hierarchy process. Moreover, a severity/occurrence matrix and Pareto analysis can be successfully adopted to identify priority failure modes on which to act to mitigate risks. The application of this approach to clinical cell therapy manufacturing in regenerative medicine is also discussed. PMID: 20723148 [PubMed - as supplied by publisher] | | | | | | | | | |  | |  | |  |
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