|  |  |  | | | | | TE-RegenMed-StemCell feed | | | | | | | | | | | | | | | | | | | Degradable depsipeptide-based multiblock copolymers with polyester or polyetherester segments. Int J Artif Organs. 2011 Mar 1; Authors: Feng Y, Lu J, Behl M, Lendlein A Polydepsipeptides, alternating copolymers of an a-amino acid and a a-hydroxy acid, are an interesting group of degradable polymers. They have gained attention as potential degradable implant materials. Polydepsipeptides are expected to have better biocompatibility in vivo during the degradation process than aliphatic polyesters. Various depsipeptide-based polymers with or without pendant functional groups have been synthesized via ring-opening polymerization of corresponding morpholine-2,5-dione derivatives. The different polymer architectures of the polymers, for example, providing an alternating, random, diblock, triblock, or multiblock structure, can be obtained by appropriate selection of the polymerization reaction, which may be ring-opening or polyaddition. Recently, we synthesized thermoplastic phase-segregated copolymers with a multiblock structure containing polydepsipeptides and poly(e-caprolactone) or poly(p-dioxanone) segments via coupling of the respective diols using an aliphatic diisocyanate. The obtained multiblock copolymers showed good elastic properties at 25°C and 75°C. Furthermore, they exhibited a shape-memory capability. Here, we summarize the synthesis, biodegradation behavior and shape-memory properties of the multiblock copolymers. In addition, we introduce new combinations of depsipeptide/poly(ether)ester segments in multiblock copolymers. The depsipeptide-based multiblock copolymers have potential applications as biomaterials for controlled drug release, tissue engineering scaffolds, or base materials for biofunctional implants. PMID: 21374571 [PubMed - as supplied by publisher] | | | | | | | | | | | | | | | | | | | | | | | | | Mesenchymal stem cells and progenitor cells in connective tissue engineering and regenerative medicine: is there a future for transplantation? Langenbecks Arch Surg. 2011 Mar 4; Authors: Hilfiker A, Kasper C, Hass R, Haverich A PURPOSE: Transplantation surgery suffers from a shortage of donor organs worldwide. Cell injection and tissue engineering (TE), thus emerge as alternative therapy options. The purpose of this article is to review the progress of TE technology, focusing on mesenchymal stem cells (MSC) as a cell source for artificial functional tissue. RESULTS: MSC from many different sources can be minimally invasively harvested: peripheral blood, fat tissue, bone marrow, amniotic fluid, cord blood. In comparison to embryonic stem cells (ESC), there are no ethical concerns; MSC can be extracted from autologous or allogenic tissue and cause an immune modulatory effect by suppressing the graft-versus-host reaction (GvHD). Furthermore, MSC do not develop into teratomas when transplanted, a consequence observed with ESC and iPS cells. CONCLUSION: MSC as multipotent cells are capable of differentiating into mesodermal and non-mesodermal lineages. However, further studies must be performed to elucidate the differentiation capacity of MSC from different sources, and to understand the involved pathways and processes. Already, MSC have been successfully applied in clinical trials, e.g., to heal large bone defects, cartilage lesions, spinal cord injuries, cardiovascular diseases, hematological pathologies, osteogenesis imperfecta, and GvHD. A detailed understanding of the behavior and homing of MSC is desirable to enlarge the clinical application spectrum of MSC towards the in vitro generation of functional tissue for implantation, for example, resilient cartilage, contractile myocardial replacement tissue, and bioartificial heart valves. PMID: 21373941 [PubMed - as supplied by publisher] | | | | | | | | | | | | | | | | | | | | | | | | | Amniotic liquid derived stem cells as reservoir of secreted angiogenic factors capable of stimulating neo-arteriogenesis in an ischemic model. Biomaterials. 2011 Mar 1; Authors: Teodelinda M, Michele C, Sebastiano C, Ranieri C, Chiara G Most urgent health problems are related to a blood vessel formation failure. The use of stem cells from different sources or species for both in vitro and in vivo engineering of endothelium does not necessarily imply their direct commitment towards a vascular phenotype. In the present study, we used human amniotic fluid stem cells (AFSC) to evoke a strong angiogenic response in murine recipients, in terms of host guided-regeneration of new vessels, and we demonstrated that the AFSC secretome is responsible for the vascularising properties of these cells. We indentified in AFSC conditioned media (ACM) pro-angiogenic soluble factors, such as MCP-1, IL-8, SDF-1, VEGF. Our in vitro results suggest that ACM are cytoprotective, pro-differentiative and chemoattractive for endothelial cells. We also tested ACM on a pre-clinical model of hind-limb ischemic mouse, concluding that ACM contain mediators that promote the neo-arteriogenesis, as remodelling of pre-existing collateral arteries to conductance vessels, thus preventing the capillary loss and the tissue necrosis of distal muscles. In line with the current regenerative medicine trend, in the present study we assert the concept that stem cell-secreted mediators can guide the tissue repair by stimulating or recruiting host reparative cells. PMID: 21371750 [PubMed - as supplied by publisher] | | | | | | | | | | | | | | | | | | | | | | | | | A regression analysis of gene expression in ES cells reveals two gene classes that are significantly different in epigenetic patterns. BMC Bioinformatics. 2011;12 Suppl 1:S50 Authors: Park SJ, Nakai K ABSTRACT : BACKGROUND : To understand the gene regulatory system that governs the self-renewal and pluripotency of embryonic stem cells (ESCs) is an important step for promoting regenerative medicine. In it, the role of several core transcription factors (TFs), such as Oct4, Sox2 and Nanog, has been intensively investigated, details of their involvement in the genome-wide gene regulation are still not well clarified. METHODS : We constructed a predictive model of genome-wide gene expression in mouse ESCs from publicly available ChIP-seq data of 12 core TFs. The tag sequences were remapped on the genome by various alignment tools. Then, the binding density of each TF is calculated from the genome-wide bona fide TF binding sites. The TF-binding data was combined with the data of several epigenetic states (DNA methylation, several histone modifications, and CpG island) of promoter regions. These data as well as the ordinary peak intensity data were used as predictors of a simple linear regression model that predicts absolute gene expression. We also developed a pipeline for analyzing the effects of predictors and their interactions. RESULTS : Through our analysis, we identified two classes of genes that are either well explained or inefficiently explained by our model. The latter class seems to be genes that are not directly regulated by the core TFs. The regulatory regions of these gene classes show apparently distinct patterns of DNA methylation, histone modifications, existence of CpG islands, and gene ontology terms, suggesting the relative importance of epigenetic effects. Furthermore, we identified statistically significant TF interactions correlated with the epigenetic modification patterns. CONCLUSIONS : Here, we proposed an improved prediction method in explaining the ESC-specific gene expression. Our study implies that the majority of genes are more or less directly regulated by the core TFs. In addition, our result is consistent with the general idea of relative importance of epigenetic effects in ESCs. PMID: 21342583 [PubMed - in process] | | | | | | | | | | | | | | | | | | | | | | | | | Biofabrication with biopolymers and enzymes: Potential for constructing scaffolds from soft matter. Int J Artif Organs. 2011 Mar 1; Authors: Wu LQ, Bentley WE, Payne GF Purpose: Regenerative medicine will benefit from technologies capable of fabricating soft matter to have appropriate architectures and that provide the necessary physical, chemical and biological cues to recruit cells and guide their development. The goal of this report is to review an emerging set of biofabrication techniques and suggest how these techniques could be applied for the fabrication of scaffolds for tissue engineering. Methods: Electrical potentials are applied to submerged electrodes to perform cathodic and anodic reactions that direct stimuli-responsive film-forming polysaccharides to assemble into hydrogel films. Standard methods are used to microfabricate electrode surfaces to allow the electrical signals to be applied with spatial and temporal control. The enzymes mushroom tyrosinase and microbial transglutaminase are used to catalyze macromolecular grafting and crosslinking of proteins. Results: Electrodeposition of the polysaccharides chitosan and alginate allow hydrogel films to be formed in response to localized electrical signals. Co-deposition of various components (e.g., proteins, vesicles and cells), and subsequent electrochemical processing allow the physical, chemical and biological activities of these films to be tailored. Enzymatic processing allows for the generation of stimuli-responsive protein conjugates that can also be directed to assemble in response to imposed electrical signals. Further, enzyme-catalyzed crosslinking of gelatin allows replica molding of soft matter to create hydrogel films with topological structure. Conclusions: Biofabrication with biological materials and mechanisms provides new approaches for soft matter construction. These methods may enable the formation of tissue engineering scaffolds with appropriate architectures, assembled cells, and spatially organized physical, chemical and biological cues. PMID: 21374563 [PubMed - as supplied by publisher] | | | | | | | | | | | | | | | | | | | | | | | | | α1-adrenoceptor activation induces phosphorylation of β2-adrenoceptors in human prostate tissue. BJU Int. 2011 Mar 4; Authors: Hennenberg M, Strittmatter F, Walther S, Hedlund P, Andersson KE, Stief CG, Gratzke C, Schlenker B OBJECTIVE: • To test whether β1-adrenoceptor activation leads to phosphorylation of the β2-adrenoceptor in human prostate tissue. PATIENTS AND METHODS: • Prostate tissue from patients undergoing radical prostatectomy was stimulated in vitro with the α1-adrenergic agonist phenylephrine (10 µM). • α2-adrenoceptor phosphorylation at serines 345/346 was studied using Western blot analysis with a phospho-specific antibody. • The role of second messenger kinases was assessed by studying the effects of the protein kinase C (PKC) inhibitor Ro 31-8425 and the protein kinase A (PKA) inhibitor H89 on phenylephrine-induced phosphorylation. • The expression of G protein-coupled receptor kinases (GRKs) 2/3 was analysed using quantitative reverse-transcriptase-polymerase chain reaction (RT-PCR), Western blot analysis and immunohistochemistry. RESULTS: • Stimulation of prostate tissue with phenylephrine resulted in phosphorylation of the β2-adrenoceptor (5, 10 and 20 min after stimulation). • This α1-adrenoceptor-induced phosphorylation of β2-adrenoceptors was resistant to inhibition of PKC and PKA. • Changes in phosphorylation levels were not attributable to changes in receptor levels, as these remained constant during stimulation. • RT-PCR and Western blot analysis showed expression of GRK2/3 in human prostate tissues. • Immunohistochemical staining showed that GRK2/3 expression in human prostate tissue is located to stromal and smooth muscle cells. CONCLUSIONS: • Activation of α1-adrenoceptors causes phosphorylation of β2-adrenoceptors in the human prostate. This may enhance α1-adrenergic contraction and is possibly mediated by GRK2, which is expressed in prostate smooth muscle. • Mutual regulation between different adrenergic receptors might be involved in the therapeutic effects of α1-blockers in patients with benign prostate hyperplasia. PMID: 21371241 [PubMed - as supplied by publisher] | | | | | | | | | | | | | | | | | | | | | | | | | Mesenchymal chondroprogenitor cell origin and therapeutic potential. Stem Cell Res Ther. 2011 Feb 18;2(1):8 Authors: O'Sullivan J, D'Arcy S, Barry FP, Murphy JM, Coleman CM ABSTRACT: Mesenchymal progenitor cells, a multipotent adult stem cell population, have the ability to differentiate into cells of connective tissue lineages, including fat, cartilage, bone and muscle, and therefore generate a great deal of interest for their potential use in regenerative medicine. During development, endochondral bone is formed from a template of cartilage that transforms into bone; however, mature articular cartilage remains in the articulating joints, where its principal role is reducing friction and dispersing mechanical load. Articular cartilage is prone to damage from sports injuries or ageing, which regularly progresses to more serious joint disorders, such as osteoarthritis. Osteoarthritis is a degenerative joint disease characterized by the thinning and eventual wearing of articular cartilage, and affects millions of people worldwide. Due to low chondrocyte motility and proliferative rates, and complicated by the absence of blood vessels, cartilage has a limited ability to self-repair. Current pharmaceutical and surgical interventions fail to generate repair tissue with the mechanical and cellular properties of native host cartilage. The long-term success of cartilage repair will therefore depend on regenerative methodologies resulting in the restoration of articular cartilage that closely duplicates the native tissue. For cell-based therapies, the optimal cell source must be readily accessible with easily isolated, abundant cells capable of collagen type II and sulfated proteoglycan production in appropriate proportions. Although a cell source with these therapeutic properties remains elusive, mesenchymal chondroprogenitors retain their expansion capacity with the promise of reproducing the structural or biomechanical properties of healthy articular cartilage. As current knowledge regarding chondroprogenitors is relatively limited, this review will focus on their origin and therapeutic application. PMID: 21371355 [PubMed - as supplied by publisher] | | | | | | | | | | | | | | | | | | | | | | | | | Re-Assessing K15 as an Epidermal Stem Cell Marker. Stem Cell Rev. 2011 Mar 4; Authors: Troy TC, Arabzadeh A, Turksen K The intermediate filament keratin 15 (K15) is present in variable amounts in various stratified epithelia, but has also been reported to be a stem cell marker in the hair follicle. Using peptide specific antibodies, we evaluated the temporal and spatial distribution pattern of K15 expression/localization during normal epidermal development and initiation of hair follicle formation, and in the injured mature epidermis (e.g., during acute injury and repair and in tumorigenesis). During development, K15 expression is first localized to a subset of epidermal basal cells and the overlying periderm at E12.5, but its expression is seen throughout the basal layer by E15.5 and beyond. In hair follicle morphogenesis, initial peg formation occurs in a K15-null area at E14.5 and as peg elongation proceeds through to the mature hair follicle, K15 expression follows the leading edge with positive cells restricted to the outer root sheath. In an epidermal injury model, K15 is first up-regulated and associated with both the basal and suprabasal layers of the interfollicular epidermis then expression becomes sporadic and down-regulated before a basal layer-specific association is re-established in the repaired epidermis. During tumorigenesis, K15 is first mis-expressed, and is ultimately down-regulated. Our data suggest that K15 protein expression may reflect not only expression in a stem or progenitor cell subpopulation, but also reflects the activity and responsiveness of basal-like cells to loss of homeostasis of the epidermal differentiation program. Thus, the data suggest caution in using K15 alone to delineate epidermal stem cells, and underscore the need for further investigation of K15 and other markers in epidermal cell subpopulations. PMID: 21373883 [PubMed - as supplied by publisher] | | | | | | | | | | | | | | | | | | | | | | | | | Degradable polymers in medicine: updating strategies and terminology. Int J Artif Organs. 2011 Mar 1; Authors: Vert M Today, the field of biodegradable materials and devices attracts polymer scientists and healthcare professionals in surgery, dentistry, pharmacology and regenerative medicine. More than one thousand papers are published per year in the literature, while the topic appears in the title of many patents. However, the number of devices or systems that have been successfully developed for clinical and commercial uses is still very small. A critical examination of the literature suggests two main reasons for this. Firstly, biodegradation is generally considered the main goal to reach, so that academic strategies do not take into account the criteria specific to targeted applications. Secondly, the term "biodegradable" is too often used inappropriately and creates confusion. This paper aims specifically to remind readers of the complexity of in vivo polymer degradation and the need for an enriched and universally recognized terminology in order to clearly distinguish between the various possible stages, and to enable clear communication between specialists when discussing related issues. It also emphasizes the need for any novel polymer to be well characterized and to include application-specific requirements in the research strategy from the very beginning, since these determine its potential clinical and commercial uses. Based on more than a decade of efforts, this would appear to be paramount in order to provide a chance for novel polymers to reach the market. PMID: 21374558 [PubMed - as supplied by publisher] | | | | | | | | | | | | | | | | | | | | | | | | | A new role for interferon gamma in neural stem/precursor cell dysregulation. Mol Neurodegener. 2011 Mar 3;6(1):18 Authors: Walter J, Honsek SD, Illes S, Wellen JM, Hartung HP, Rose CR, Dihne M ABSTRACT: BACKGROUND: The identification of factors that compromise neurogenesis is aimed at improving stem cell-based approaches in the field of regenerative medicine. Interferon gamma is a main pro-inflammatory cytokine and up-regulated during several neurological diseases. Interferon gamma is generally thought to beneficially enhance neurogenesis from fetal or adult neural stem/precursor cells (NSPCs). RESULTS: We now provide direct evidence to the contrary that interferon gamma induces a dysfunctional stage in a substantial portion of NSPC-derived progeny in vitro characterized by simultaneous expression of glial fibrillary acid protein (GFAP) and neuronal markers, an abnormal gene expression and a functional phenotype neither typical for neurons nor for mature astrocytes. Dysfunctional development of NSPCs under the influence of interferon gamma was finally demonstrated by applying the microelectrode array technology. Interferon gamma exposure of NSPCs during an initial 7-day proliferation period prevented the subsequent adequate differentiation and formation of functional neuronal networks. CONCLUSIONS: Our results show that immunocytochemical analyses of NSPC-derived progeny are not necessarily indicating the correct cellular phenotype specifically under inflammatory conditions and that simultaneous expression of neuronal and glial markers rather point to cellular dysregulation. We hypothesize that inhibiting the impact of interferon gamma on NSPCs during neurological diseases might contribute to effective neurogenesis and regeneration. PMID: 21371330 [PubMed - as supplied by publisher] | | | | | | | | | | | | | | | | | | | | | | | | | Human hepatic stem cell and maturational liver lineage biology. Hepatology. 2011 Mar;53(3):1035-45 Authors: Turner R, Lozoya O, Wang Y, Cardinale V, Gaudio E, Alpini G, Mendel G, Wauthier E, Barbier C, Alvaro D, Reid LM Livers are comprised of maturational lineages of cells beginning extrahepatically in the hepato-pancreatic common duct near the duodenum and intrahepatically in zone 1 by the portal triads. The extrahepatic stem cell niches are the peribiliary glands deep within the walls of the bile ducts; those intrahepatically are the canals of Hering in postnatal livers and that derive from ductal plates in fetal livers. Intrahepatically, there are at least eight maturational lineage stages from the stem cells in zone 1 (periportal), through the midacinar region (zone 2), to the most mature cells and apoptotic cells found pericentrally in zone 3. Those found in the biliary tree are still being defined. Parenchymal cells are closely associated with lineages of mesenchymal cells, and their maturation is coordinated. Each lineage stage consists of parenchymal and mesenchymal cell partners distinguishable by their morphology, ploidy, antigens, biochemical traits, gene expression, and ability to divide. They are governed by changes in chromatin (e.g., methylation), gradients of paracrine signals (soluble factors and insoluble extracellular matrix components), mechanical forces, and feedback loop signals derived from late lineage cells. Feedback loop signals, secreted by late lineage stage cells into bile, flow back to the periportal area and regulate the stem cells and other early lineage stage cells in mechanisms dictating the size of the liver mass. Recognition of maturational lineage biology and its regulation by these multiple mechanisms offers new understandings of liver biology, pathologies, and strategies for regenerative medicine and treatment of liver cancers. (HEPATOLOGY 2011;). PMID: 21374667 [PubMed - in process] | | | | | | | | | | | | | | | | | | | | | | | | | Elevated Invasive Potential of Glioblastoma Stem Cells. Biochem Biophys Res Commun. 2011 Feb 28; Authors: Cheng L, Wu Q, Guryanova OA, Huang Z, Huang Q, Rich JN, Bao S Glioblastomas (GBMs) are the most lethal and common types of primary brain tumors. The hallmark of GBMs is their highly infiltrative nature. The cellular and molecular mechanisms underlying the aggressive cancer invasion in GBMs are poorly understood. GBM displays remarkable cellular heterogeneity and hierarchy containing self-renewing glioblastoma stem cells (GSCs). Whether GSCs are more invasive than non-stem tumor cells and contribute to the invasive phenotype in GBMs has not been determined. Here we provide experimental evidence supporting that GSCs derived from GBM surgical specimens or xenograts display greater invasive potential in vitro and in vivo than matched non-stem tumor cells. Furthermore, we identified several invasion-associated proteins that were differentially expressed in GSCs relative to non-stem tumor cells. One of such proteins is L1CAM, a cell surface molecule shown to be critical to maintain GSC tumorigenic potential in our previous study. Immunohistochemical staining showed that L1CAM is highly expressed in a population of cancer cells in the invasive fronts of primary GBMs. Collectively, these data demonstrate the invasive nature of GSCs, suggesting that disrupting GSCs through a specific target such as L1CAM may reduce GBM cancer invasion and tumor recurrence. PMID: 21371437 [PubMed - as supplied by publisher] | | | | | | | | | | | | | | | | | | | | | | | | | The Culture of Primary Motor and Sensory Neurons in Defined Media on Electrospun Poly-L-lactide Nanofiber Scaffolds. J Vis Exp. 2011;(48): Authors: Leach MK, Feng ZQ, Gertz CC, Tuck SJ, Regan TM, Naim Y, Vincent AM, Corey JM Electrospinning is a technique for producing micro- to nano-scale fibers. Fibers can be electrospun with varying degrees of alignment, from highly aligned to completely random. In addition, fibers can be spun from a variety of materials, including biodegradable polymers such as poly-L-lactic acid (PLLA). These characteristics make electrospun fibers suitable for a variety of scaffolding applications in tissue engineering. Our focus is on the use of aligned electrospun fibers for nerve regeneration. We have previously shown that aligned electrospun PLLA fibers direct the outgrowth of both primary sensory and motor neurons in vitro. We maintain that the use of a primary cell culture system is essential when evaluating biomaterials to model real neurons found in vivo as closely as possible. Here, we describe techniques used in our laboratory to electrospin fibrous scaffolds and culture dorsal root ganglia explants, as well as dissociated sensory and motor neurons, on electrospun scaffolds. However, the electrospinning and/or culture techniques presented here are easily adapted for use in other applications. PMID: 21372783 [PubMed - in process] | | | | | | | | | | | | | | | | | | | | | | | | | Evaluation of tubular poly(trimethylene carbonate) tissue engineering scaffolds in a circulating pulsatile flow system. Int J Artif Organs. 2011 Mar 1; Authors: Song Y, Wennink JW, Poot AA, Vermes I, Feijen J, Grijpma DW ABSTRACT?Tubular scaffolds (internal diameter approximately 3 mm and wall thickness approximately 0.8 mm) with a porosity of approximately 83% and an average pore size of 116 µm were prepared from flexible poly(trimethylene carbonate) (PTMC) polymer by dip-coating and particulate leaching methods. PTMC is a flexible and biocompatible polymer that crosslinks upon irradiation; porous network structures were obtained by irradiating the specimens in vacuum at 25 kGy before leaching soluble salt particles. To assess the suitability of these scaffolds in dynamic cell culturing for cardiovascular tissue engineering, the scaffolds were coated with a thin (0.1 to 0.2 mm) non-porous PTMC layer and its performance was evaluated in a closed pulsatile flow system (PFS). For this, the PFS was operated at physiological conditions at liquid flows of 1.56 ml/s with pressures varying from 80-120 mmHg at a frequency of 70 pulsations per minute. ?The mechanical properties of these coated porous PTMC scaffolds were not significantly different than non-coated scaffolds. Typical tensile strengths in the radial direction were 0.15 MPa, initial stiffness values were close to 1.4 MPa. Their creep resistance in cyclic deformation experiments was excellent. In the pulsatile flow setup, the distention rates of these flexible and elastic scaffolds were approximately 0.10% per mmHg, which is comparable to that of a porcine carotid artery (0.11% per mmHg). The compliance and stiffness index values were close to those of natural arteries.?In long-term deformation studies, where the scaffolds were subjected to physiological pulsatile pressures for one week, the morphology and mechanical properties of the PTMC scaffolds did not change. This suggests their suitability for application in a dynamic cell culture bioreactor. PMID: 21374572 [PubMed - as supplied by publisher] | | | | | | | | | | | | | | | | | | | | | | | | | Laryngeal regeneration using tissue engineering techniques in a canine model. Ann Otol Rhinol Laryngol. 2011 Jan;120(1):49-56 Authors: Kitani Y, Kanemaru S, Umeda H, Suehiro A, Kishimoto Y, Hirano S, Nakamura T, Ito J We previously reported that polypropylene mesh covered with collagen sponge is a useful material for the regeneration of the trachea and the cricoid cartilage. The aim of this study was to regenerate larynges after partial hemilaryngectomy with this new biomaterial. PMID: 21370680 [PubMed - in process] | | | | | | | | | | | | | | | | | | | | | | | | | Bioreactors for bone tissue engineering. Int J Artif Organs. 2011 Feb 8; Authors: Carpentier B, Layrolle P, Legallais C Bone tissue engineering is a promising solution for patients with bone defects that require reconstruction. This regenerative therapy consists in culturing osteogenic cells on a biodegradable substrate to obtain a bio-hybrid construct that will stimulate bone healing after implantation. This multidisciplinary technology nevertheless requires further development before it can become routine clinical practice. One challenge is to achieve three-dimensional seeding and osteogenic commitment of mesenchymal stem cells on biomaterials under sterile and reproducible conditions. For this purpose, different dynamic culture systems have been developed. This paper reviews recent advances in the field of bioreactors for bone tissue engineering. The purpose of such systems is to improve nutrient delivery to the cells and generate shear stress that may promote cell differentiation into osteoblastic phenotypes. A brief overview of the value of computational fluid dynamics for understanding the cell environment is also provided. Finally, some proposals are made regarding the use of bioreactors as safe and controllable devices that will help commit cells and biomaterials for the regeneration of bone tissue. PMID: 21374561 [PubMed - as supplied by publisher] | | | | | | | | | | | | | | | | | | | | | | | | | Automated and Adaptable Quantification of Cellular Alignment from Microscopic Images for Tissue Engineering Applications. Tissue Eng Part C Methods. 2011 Mar 3; Authors: Xu F, Demirci U Cellular alignment plays a critical role in functional, physical and biological characteristics of many tissue types, such as muscle, tendon, nerve and cornea. Current efforts towards regeneration of these tissues include replicating the cellular microenvironment by developing biomaterials that facilitate cellular alignment. To assess the functional effectiveness of the engineered microenvironments, one essential criterion is quantification of cellular alignment. Therefore, there is a need for rapid, accurate and adaptable methodologies to quantify cellular alignment for tissue engineering applications. To address this need, we developed an automated method: Binarization based Extraction of Alignment Score (BEAS) to determine cell orientation distribution in a wide variety of microscopic images. This method combines a sequenced application of median and band-pass filters, locally adaptive thresholding approaches and image processing techniques. Cellular alignment score is obtained by applying a robust scoring algorithm to the orientation distribution. We validated the BEAS method by comparing the results with the existing approaches reported in literature (i.e., manual, radial FFT-radial sum and gradient based approaches). Validation results indicated that the BEAS method resulted in statistically comparable alignment scores with the manual method (coefficient of determination R2=0.92). Therefore the BEAS method introduced in this study could enable accurate, convenient and adaptable evaluation of engineered tissue constructs and biomaterials in terms of cellular alignment and organization. PMID: 21370940 [PubMed - as supplied by publisher] | | | | | | | | | | | | | | | | | | | | | | | | | Degradable depsipeptide-based multiblock copolymers with polyester or polyetherester segments. Int J Artif Organs. 2011 Mar 1; Authors: Feng Y, Lu J, Behl M, Lendlein A Polydepsipeptides, alternating copolymers of an a-amino acid and a a-hydroxy acid, are an interesting group of degradable polymers. They have gained attention as potential degradable implant materials. Polydepsipeptides are expected to have better biocompatibility in vivo during the degradation process than aliphatic polyesters. Various depsipeptide-based polymers with or without pendant functional groups have been synthesized via ring-opening polymerization of corresponding morpholine-2,5-dione derivatives. The different polymer architectures of the polymers, for example, providing an alternating, random, diblock, triblock, or multiblock structure, can be obtained by appropriate selection of the polymerization reaction, which may be ring-opening or polyaddition. Recently, we synthesized thermoplastic phase-segregated copolymers with a multiblock structure containing polydepsipeptides and poly(e-caprolactone) or poly(p-dioxanone) segments via coupling of the respective diols using an aliphatic diisocyanate. The obtained multiblock copolymers showed good elastic properties at 25°C and 75°C. Furthermore, they exhibited a shape-memory capability. Here, we summarize the synthesis, biodegradation behavior and shape-memory properties of the multiblock copolymers. In addition, we introduce new combinations of depsipeptide/poly(ether)ester segments in multiblock copolymers. The depsipeptide-based multiblock copolymers have potential applications as biomaterials for controlled drug release, tissue engineering scaffolds, or base materials for biofunctional implants. PMID: 21374571 [PubMed - as supplied by publisher] | | | | | | | | | | | | | | | | | | | | | | | | | Microfluidic hydrogels for tissue engineering. Biofabrication. 2011 Mar;3(1):012001 Authors: Huang GY, Zhou LH, Zhang QC, Chen YM, Sun W, Xu F, Lu TJ With advanced properties similar to the native extracellular matrix, hydrogels have found widespread applications in tissue engineering. Hydrogel-based cellular constructs have been successfully developed to engineer different tissues such as skin, cartilage and bladder. Whilst significant advances have been made, it is still challenging to fabricate large and complex functional tissues due mainly to the limited diffusion capability of hydrogels. The integration of microfluidic networks and hydrogels can greatly enhance mass transport in hydrogels and spatiotemporally control the chemical microenvironment of cells, mimicking the function of native microvessels. In this review, we present and discuss recent advances in the fabrication of microfluidic hydrogels from the viewpoint of tissue engineering. Further development of new hydrogels and microengineering technologies will have a great impact on tissue engineering. PMID: 21372342 [PubMed - in process] | | | | | | | | | | | | | | | | | | | | | | | | | Preparation and evaluation of hydrogel-composites from methacrylated hyaluronic acid, alginate, and gelatin for tissue engineering. Int J Artif Organs. 2011 Mar 1; Authors: Möller L, Krause A, Dahlmann J, Gruh I, Kirschning A, Dräger G Hydrogels are three-dimensional water-insoluble hydrophilic natural or synthetic polymer networks made up of crosslinked water-soluble polymers. The purpose of this study was to develop and directly compare photo crosslinked hydrogels on the basis of pure gelatin, alginate and hyaluronic acid as well as their blends. The functionalization of starting materials with methacrylate moieties was evaluated by 1H-NMR spectroscopy. Hydrogels were prepared from methacrylates by photo cross-linking using UV light. The effect of changing the hydrogel composition was quantified through examination of hydrogel swelling behavior and rheological properties. In addition, the viability and adhesion of neonatal rat cardiomyocytes (NRCM) seeded onto the hydrogels was examined by in vivo imaging of NRCM-mediated scaffold contraction as well as by histological evaluation after immunostaining. Biological testing showed good biocompatibility and cell survival in the presence of all materials discussed. Adhesion of cells could only be observed in the presence of gelatin. Blends of gelatin, alginate and hyaluronic acid are promising candidates for the generation of non-toxic, biocompatible hydrogel scaffolds for tissue engineering. Variation of individual compound ratios in the blends can be used for a precise control of mechanical properties and may allow wide-ranging uses in various tissue engineering applications with different mechanical requirements. PMID: 21374568 [PubMed - as supplied by publisher] | | | | | | | | | | | | | | | | | | | | | | | | | Mesenchymal stem cells and progenitor cells in connective tissue engineering and regenerative medicine: is there a future for transplantation? Langenbecks Arch Surg. 2011 Mar 4; Authors: Hilfiker A, Kasper C, Hass R, Haverich A PURPOSE: Transplantation surgery suffers from a shortage of donor organs worldwide. Cell injection and tissue engineering (TE), thus emerge as alternative therapy options. The purpose of this article is to review the progress of TE technology, focusing on mesenchymal stem cells (MSC) as a cell source for artificial functional tissue. RESULTS: MSC from many different sources can be minimally invasively harvested: peripheral blood, fat tissue, bone marrow, amniotic fluid, cord blood. In comparison to embryonic stem cells (ESC), there are no ethical concerns; MSC can be extracted from autologous or allogenic tissue and cause an immune modulatory effect by suppressing the graft-versus-host reaction (GvHD). Furthermore, MSC do not develop into teratomas when transplanted, a consequence observed with ESC and iPS cells. CONCLUSION: MSC as multipotent cells are capable of differentiating into mesodermal and non-mesodermal lineages. However, further studies must be performed to elucidate the differentiation capacity of MSC from different sources, and to understand the involved pathways and processes. Already, MSC have been successfully applied in clinical trials, e.g., to heal large bone defects, cartilage lesions, spinal cord injuries, cardiovascular diseases, hematological pathologies, osteogenesis imperfecta, and GvHD. A detailed understanding of the behavior and homing of MSC is desirable to enlarge the clinical application spectrum of MSC towards the in vitro generation of functional tissue for implantation, for example, resilient cartilage, contractile myocardial replacement tissue, and bioartificial heart valves. PMID: 21373941 [PubMed - as supplied by publisher] | | | | | | | | | | | | | | | | | | | | | | | | | Human embryonic stem cell-derived microvascular grafts for cardiac tissue preservation after myocardial infarction. Biomaterials. 2011 Feb;32(4):1102-9 Authors: Kraehenbuehl TP, Ferreira LS, Hayward AM, Nahrendorf M, van der Vlies AJ, Vasile E, Weissleder R, Langer R, Hubbell JA We present use of a synthetic, injectable matrix metalloproteinase (MMP)-responsive, bioactive hydrogel as an in situ forming scaffold to deliver thymosin β4 (Tβ4), a pro-angiogenic and pro-survival factor, along with vascular cells derived from human embryonic stem cells (hESC) in ischemic injuries to the heart in a rat model. The gel was found to substitute the degrading extracellular matrix in the infarcted myocardium of rats and to promote structural organization of native endothelial cells, while some of the delivered hESC-derived vascular cells formed de novo capillaries in the infarct zone. Magnetic resonance imaging (MRI) revealed that the microvascular grafts effectively preserved contractile performance 3 d and 6 wk after myocardial infarction, attenuated left ventricular dilation, and decreased infarct size as compared to infarcted rats treated with PBS injection as a control (3 d ejection fraction, + ∼7%, P < 0.001; 6 wk ejection faction, + ∼12%, P < 0.001). Elevation in vessel density was observed in response to treatment, which may be due in part to elevations in human (donor)-derived cytokines EGF, VEGF and HGF (1 d). Thus, a clinically relevant matrix for dual delivery of vascular cells and drugs may be useful in engineering sustained tissue preservation and potentially regenerating ischemic cardiac tissue. PMID: 21035182 [PubMed - indexed for MEDLINE] | | | | | | | | | | | | | | | | | | | | | | | | | In vivo tissue responses to thermal-responsive shape memory polymer nanocomposites. Biomaterials. 2011 Feb;32(4):985-91 Authors: Filion TM, Xu J, Prasad ML, Song J To explore the safe use of thermal-responsive shape memory polymers (SMPs) as minimally invasive tissue scaffolds, we recently developed a class of biodegradable POSS-SMP nanocomposites exhibiting stable temporary shape fixing and facile shape recovery within a narrow window of physiological temperatures. The materials were covalently crosslinked from star-branched building blocks consisting a bioinert polyhedral oligomeric silsesquioxane (POSS) core and 8 degradable poly(D,L-lactide) (PLA) arms. Here we examine the degradation profiles and immunogenicity of POSS-SMPs as a function of the PLA arm lengths using a rat subcutaneous implantation model. We show that POSS-SMPs elicited a mild foreign body type immune response upon implantation. The degradation rates of POSS-SMPs, both in vitro and in vivo, inversely correlated with the length of the PLA chains within the crosslinked amorphous network. Upon in vivo degradation of POSS-SMPs, a second acute inflammatory response was elicited locally, and the inflammation was able to resolve over time without medical interventions. One year after the implantation of POSS-SMPs, no pathologic abnormalities were detected from the vital/scavenger organs examined. These minimally immunogenic and biodegradable SMPs are promising candidates for scaffold-assisted tissue repair where both facile surgical delivery and controlled degradation of the scaffold are desired for achieving optimal short-term and long-term clinical outcomes. PMID: 21040968 [PubMed - indexed for MEDLINE] | | | | | | | | | | | | | | | | | | | | | | | | | Biofabrication with biopolymers and enzymes: Potential for constructing scaffolds from soft matter. Int J Artif Organs. 2011 Mar 1; Authors: Wu LQ, Bentley WE, Payne GF Purpose: Regenerative medicine will benefit from technologies capable of fabricating soft matter to have appropriate architectures and that provide the necessary physical, chemical and biological cues to recruit cells and guide their development. The goal of this report is to review an emerging set of biofabrication techniques and suggest how these techniques could be applied for the fabrication of scaffolds for tissue engineering. Methods: Electrical potentials are applied to submerged electrodes to perform cathodic and anodic reactions that direct stimuli-responsive film-forming polysaccharides to assemble into hydrogel films. Standard methods are used to microfabricate electrode surfaces to allow the electrical signals to be applied with spatial and temporal control. The enzymes mushroom tyrosinase and microbial transglutaminase are used to catalyze macromolecular grafting and crosslinking of proteins. Results: Electrodeposition of the polysaccharides chitosan and alginate allow hydrogel films to be formed in response to localized electrical signals. Co-deposition of various components (e.g., proteins, vesicles and cells), and subsequent electrochemical processing allow the physical, chemical and biological activities of these films to be tailored. Enzymatic processing allows for the generation of stimuli-responsive protein conjugates that can also be directed to assemble in response to imposed electrical signals. Further, enzyme-catalyzed crosslinking of gelatin allows replica molding of soft matter to create hydrogel films with topological structure. Conclusions: Biofabrication with biological materials and mechanisms provides new approaches for soft matter construction. These methods may enable the formation of tissue engineering scaffolds with appropriate architectures, assembled cells, and spatially organized physical, chemical and biological cues. PMID: 21374563 [PubMed - as supplied by publisher] | | | | | | | | | | | | | | | | | | | | | | | | | Antioxidant and signal modulation properties of plant polyphenols in controlling vascular inflammation. Eur J Pharmacol. 2011 Feb 28; Authors: Kostyuk VA, Potapovich AI, Suhan TO, de Luca C, Korkina LG Oxidized low-density lipoproteins (oxLDL) play a critical role in the initiation of atherosclerosis through activation of inflammatory signaling. In the present work we investigated the role of antioxidant and signal modulation properties of plant polyphenols in controlling vascular inflammation. Significant decrease in intracellular NO level and superoxide overproduction were found in human umbilical vein endothelial cells (HUVEC) treated with oxLDL, but not with LDL. The redox imbalance was prevented by addition of quercetin or resveratrol. Expression analysis of 14 genes associated with oxidative stress and inflammation revealed oxLDL-mediated up-regulation of genes specifically involved in leukocyte recruitment and adhesion. This up-regulation could be partially avoided by addition of verbascoside or resveratrol, while treatment with quercetin resulted in a further increase in the expression of these genes. Lipopolysaccharide (LPS)-treated HUVEC were also used for the evaluation of anti-inflammatory potency of plant polyphenols. Significant differences between HUVEC treaded with oxLDL and LPS were found in both the expression pattern of inflammation-related genes and the effects of plant polyphenols on cellular responses. The present data indicate that plant polyphenols may affect vascular inflammation not only as antioxidants but also as modulators of inflammatory redox signaling pathways. PMID: 21371465 [PubMed - as supplied by publisher] | | | | | | | | | | | | | | | | | | | | | | | | | Myocardial regeneration: Roles of stem cells and hydrogels. Adv Drug Deliv Rev. 2011 Feb 28; Authors: Ye Z, Zhou Y, Cai H, Tan W Heart failure remains the leading cause of morbidity and mortality. Recent recognition of adult heart having intrinsic regenerative capability prompted a great wave of research efforts in applying cell-based therapies, especially with skeletal myoblasts and bone marrow-derived cells to regenerate broken heart. While the mechanism of action for the observed beneficial effects for bone marrow-derived cells remains obscure, new cell candidates are emerging including embryonic stem (ES) and introduced pluripotent stem (iPS) cells as well as cardiac stem cells (CSCs) from adult heart. Moreover, the very low engraftment efficiency and survival of implanted cells prevent cell therapy from turning into a clinical reality. Injectable hydrogel biomaterials based on hydrophilic, biocompatible polymers as well as peptides hold great advantages in addressing many of these issues by serving as cell/drug delivery vehicle and as a platform for cardiac tissue engineering. In this review, we will discuss the research achievements in the application of stem cells and hydrogels in myocardial regeneration. PMID: 21371512 [PubMed - as supplied by publisher] | | | | | | | | | | | | | | | | | | | | | | | | | Increasing electrospun scaffold pore size with tailored collectors for improved cell penetration. Acta Biomater. 2011 Feb 28; Authors: Vaquette C, Cooper-White J This study investigates the use of patterned collectors to increase the pore size of electrospun scaffolds for enhanced cell infiltration. The morphology of the patterned scaffolds was investigated by SEM and showed that the collector pattern was accurately mimicked by the electrospun fibres. We observed an enlargement in the pore size and in the pore size distribution compared to conventional electrospinning. Mechanical testing revealed that the mechanical properties could be tailored, to some extent, according to the patterning and that the patterned scaffolds were softer than the standard electrospun scaffolds. When 3T3 fibroblasts were seeded onto patterned collectors, improved cell infiltration was observed. Cells were able to penetrate up to 250 μm compared to 30 μm in the standard scaffolds. This increase in the depth of infiltration occurred as early as 24 hours post seeding and remained constant over 7 days. PMID: 21371575 [PubMed - as supplied by publisher] | | | | | | | | | | | | | | | | | | | | | | | | | Fabrication of custom-shaped grafts for cartilage regeneration. Int J Artif Organs. 2010 Oct;33(10):731-7 Authors: Koo S, Hargreaves BA, Gold GE, Dragoo JL to create a custom-shaped graft through 3D tissue shape reconstruction and rapid-prototype molding methods using MRI data, and to test the accuracy of the custom-shaped graft against the original anatomical defect. PMID: 21058268 [PubMed - indexed for MEDLINE] | | | | | | | | | | | | | | | | | | | | | | | | | Influence of Low Intensity Laser Irradiation on Isolated Human Adipose Derived Stem Cells Over 72 Hours and Their Differentiation Potential into Smooth Muscle Cells Using Retinoic Acid. Stem Cell Rev. 2011 Mar 5; Authors: de Villiers JA, Houreld NN, Abrahamse H INTRODUCTION: Human adipose derived stem cells (hADSCs), with their impressive differentiation potential, may be used in autologous cell therapy or grafting to replace damaged tissues. Low intensity laser irradiation (LILI) has been shown to influence the behaviour of various cells, including stem cells. AIMS: This study aimed to investigate the effect of LILI on hADSCs 24, 48 or 72 h post-irradiation and their differentiation potential into smooth muscle cells (SMCs). METHODOLOGY: hADSCs were exposed to a 636 nm diode laser at a fluence of 5 J/cm(2). hADSCs were differentiated into SMCs using retinoic acid (RA). Morphology was assessed by inverted light and differential interference contrast (DIC) microscopy. Proliferation and viability of hADSCs was assessed by optical density (OD), Trypan blue staining and adenosine triphosphate (ATP) luminescence. Expression of stem cell markers, β1-integrin and Thy-1, and SMC markers, smooth muscle alpha actin (SM-αa), desmin, smooth muscle myosin heavy chain (SM-MHC) and smoothelin, was assessed by immunofluorescent staining and real-time reverse transcriptase polymerase chain reaction (RT-PCR). RESULTS: Morphologically, hADSCs did not show any differences and there was an increase in viability and proliferation post-irradiation. Immunofluorescent staining showed expression of β1-integrin and Thy-1 72 h post-irradiation. RT-PCR results showed a down regulation of Thy-1 48 h post-irradiation. Differentiated SMCs were confirmed by morphology and expression of SMC markers. CONCLUSION: LILI at a wavelength of 636 nm and a fluence of 5 J/cm(2) does not induce differentiation of isolated hADSCs over a 72 h period, and increases cellular viability and proliferation. hADSCs can be differentiated into SMCs within 14 days using RA. PMID: 21373882 [PubMed - as supplied by publisher] | | | | | | | | | | | | | | | | | | | | | | | | | Electrically Guiding Migration of Human Induced Pluripotent Stem Cells. Stem Cell Rev. 2011 Mar 5; Authors: Zhang J, Calafiore M, Zeng Q, Zhang X, Huang Y, Li RA, Deng W, Zhao M A major road-block in stem cell therapy is the poor homing and integration of transplanted stem cells with the targeted host tissue. Human induced pluripotent stem (hiPS) cells are considered an excellent alternative to embryonic stem (ES) cells and we tested the feasibility of using small, physiological electric fields (EFs) to guide hiPS cells to their target. Applied EFs stimulated and guided migration of cultured hiPS cells toward the anode, with a stimulation threshold of <30 mV/mm; in three-dimensional (3D) culture hiPS cells remained stationary, whereas in an applied EF they migrated directionally. This is of significance as the therapeutic use of hiPS cells occurs in a 3D environment. EF exposure did not alter expression of the pluripotency markers SSEA-4 and Oct-4 in hiPS cells. We compared EF-directed migration (galvanotaxis) of hiPS cells and hES cells and found that hiPS cells showed greater sensitivity and directedness than those of hES cells in an EF, while hES cells migrated toward cathode. Rho-kinase (ROCK) inhibition, a method to aid expansion and survival of stem cells, significantly increased the motility, but reduced directionality of iPS cells in an EF by 70-80%. Thus, our study has revealed that physiological EF is an effective guidance cue for the migration of hiPS cells in either 2D or 3D environments and that will occur in a ROCK-dependent manner. Our current finding may lead to techniques for applying EFs in vivo to guide migration of transplanted stem cells. PMID: 21373881 [PubMed - as supplied by publisher] | | | | | | | | | | | | | | | | | | | | | | | | | Current controversies in prenatal diagnosis 1: is stem cell therapy ready for human fetuses? Prenat Diagn. 2011 Mar;31(3):228-30 Authors: Mummery C, Westgren M, Sermon K PMID: 21374635 [PubMed - in process] | | | | | | | | | | | | | | | | | | | | | | | | | Autologous stem cell therapy maintains vertebral blood flow and contrast diffusion through the endplate in experimental intervertebral disc degeneration. Spine (Phila Pa 1976). 2011 Mar 15;36(6):E373-9 Authors: Bendtsen M, Bünger CE, Zou X, Foldager C, Jørgensen HS STUDY DESIGN.: Experimental, controlled, randomized, and paired study. OBJECTIVE.: To evaluate regenerative effect of stem cell therapy on the vertebral endplate and introduce dynamic contrast-enhanced magnetic resonance imaging (MRI) as a tool in the investigation of endplate function. SUMMARY OF BACKGROUND DATA.: The vertebral endplate plays a crucial role in nutritional supply to the intervertebral disc. Estimation of endplate function is an important parameter in future biologic therapy of intervertebral disc degeneration (IDD). METHODS.: Four-level IDD was induced in each of 15 Gottingen minipigs. Percutaneous intradiscal injection of two hydrogels (Zimmer Biologics Inc, Austin, TX) and one loaded with stem cells was used as single interventions after 12 weeks. Total observation time was 24 weeks. MRI was performed before the initiation of treatment and killing of animals. RESULTS.: Three animals were excluded because of spondylodiscitis. Stem cell and hydrogel treatment had significantly higher T2 values, relative vertebral blood flow and volume, as well as lower Pfirrmann scores when compared with degenerative controls. No statistical differences were found compared to normal controls. CONCLUSION.: Stem cell and hydrogel therapy is able to partly regenerate IDD and maintain perfusion and permeability of the vertebral endplate and subchondral bone. Dynamic contrast-enhanced MRI may become an important tool in future investigation of the vertebral endplate. PMID: 21372649 [PubMed - in process] | | | | | | | | | |  | |  | |  |
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