|  |  |  | | | | | TE-RegenMed-StemCell feed | | | | | | | | | | | | | | | | | | Art Torres, co-vice chairman of the California stem cell agency, will be one of the guests on a radio talk show tomorrow at 9 a.m. PDT on station KQED in San Francisco dealing with this week's hESC ruling. You can listen to the program live on the Internet.
The station said,
"National Institutes of Health director Francis Collins said Tuesday that the recent court ruling blocking federally | | | | | | | | | | | | | | | | | | | | | | | | UC Davis stem cell research Paul Knoepfler this afternoon reported on the latest from the NIH on the federal court ruling on hESC research.
Writing on his blog, he quoted the text of the statement and then offered a comment.
"Pursuant to a court order issued August 23, 2010, NIH is not accepting submissions of information about human embryonic stem cell lines for NIH review. All review of human | | | | | | | | | | | | | | | | | | | | | | | | Here are some excerpts and links to interesting coverage of yesterday's federal court ruling on stem cell research.
Text of the judge's ruling from the Washington Post.
Wall Street Journal, reporters Laura Meckler, Gautam Naik and Brent Kendall on election year politics and more.
"It also could inject the divisive issue into election-year politics and spark discussion in Congress whether to | | | | | | | | | | | | | | | | | | | | | | | | | 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] | | | | | | | | | | | | | | | | | | | | | | | | | 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] | | | | | | | | | | | | | | | | | | | | | | | | | 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] | | | | | | | | | | | | | | | | | | | | | | | | | 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 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] | | | | | | | | | | | | | | | | | | | | | | | | | 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] | | | | | | | | | | | | | | | | | | | | | | | | | 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] | | | | | | | | | | | | | | | | | | | | | | | | | 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] | | | | | | | | | | | | | | | | | | | | | | | | | 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] | | | | | | | | | | | | | | | | | | | | | | | | | 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] | | | | | | | | | | | | | | | | | | | | | | | | | 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] | | | | | | | | | | | | | | | | | | | | | | | | | 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] | | | | | | | | | | | | | | | | | | | | | | | | | 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] | | | | | | | | | | | | | | | | | | | | | | | | | 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] | | | | | | | | | |  | |  | |  |
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