|  |  |  | | | | | TE-RegenMed-StemCell feed | | | | | | | | | | | | | | | | | | | In vivo imaging of embryonic stem cell therapy. Eur J Nucl Med Mol Imaging. 2010 Nov 24; Authors: Jiang H, Cheng Z, Tian M, Zhang H Embryonic stem cells (ESCs) have the most pluripotent potential of any stem cell. These cells, isolated from the inner cell mass of the blastocyst, are "pluripotent," meaning that they can give rise to all cell types within the developing embryo. As a result, ESCs have been regarded as a leading candidate source for novel regenerative medicine therapies and have been used to derive diverse cell populations, including myocardial and endothelial cells. However, before they can be safely applied clinically, it is important to understand the in vivo behavior of ESCs and their derivatives. In vivo analysis of ESC-derived cells remains critically important to define how these cells may function in novel regenerative medicine therapies. In this review, we describe several available imaging modalities for assessing cell engraftment and discuss their strengths and limitations. We also analyze the applications of these modalities in assessing the utility of ESCs in regenerative medicine therapies. PMID: 21107558 [PubMed - as supplied by publisher] | | | | | | | | | | | | | | | | | | | | | | | | | A high-throughput microfluidic assay to study neurite response to growth factor gradients. Lab Chip. 2010 Nov 25; Authors: Kothapalli CR, van Veen E, de Valence S, Chung S, Zervantonakis IK, Gertler FB, Kamm RD Studying neurite guidance by diffusible or substrate bound gradients is challenging with current techniques. In this study, we present the design, fabrication and utility of a microfluidic device to study neurite guidance under chemogradients. Experimental and computational studies demonstrated the establishment of a steep gradient of guidance cue within 30 min and stable for up to 48 h. The gradient was found to be insensitive to external perturbations such as media change and movement of device. The effects of netrin-1 (0.1-10 µg mL(-1)) and brain pulp (0.1 µL mL(-1)) were evaluated for their chemoattractive potential on neurite turning, while slit-2 (62.5 or 250 ng mL(-1)) was studied for its chemorepellant properties. Hippocampal or dorsal root ganglion (DRG) neurons were seeded into a micro-channel and packed onto the surface of a 3D collagen gel. Neurites grew into the matrix in three dimensions, and a gradient of guidance cue was created orthogonal to the direction of neurite growth to impact guidance. The average turning angle of each neurite was measured and averaged across multiple devices cultured under similar conditions to quantify the effect of guidance cue gradient. Significant positive turning towards gradient was measured in the presence of brain pulp and netrin-1 (1 µg mL(-1)), relative to control cultures which received no external guidance cue (p < 0.001). Netrin-1 released from transfected fibroblasts had the most positive turning effect of all the chemoattractive cues tested (p < 0.001). Slit-2 exhibited strong chemorepellant characteristics on both hippocampal and DRG neurite guidance at 250 ng mL(-1) concentration. Slit-2 also showed similar behavior on DRG neuron invasion into 3D collagen gel (p < 0.01 relative to control cultures). Taken together, the results suggest the utility of this microfluidic device to generate stable chemogradients for studying neurobiology, cell migration and proliferation, matrix remodeling and co-cultures with other cell lines, with potential applications in cancer biology, tissue engineering and regenerative medicine. PMID: 21107471 [PubMed - as supplied by publisher] | | | | | | | | | | | | | | | | | | | | | | | | | A tissue-specific, activation-inducible, lentiviral vector regulated by human CD40L proximal promoter sequences. Gene Ther. 2010 Nov 25; Authors: Romero Z, Torres S, Cobo M, Muñoz P, Unciti JD, Martín F, Molina IJ The application of new protocols for gene therapy against monogenic diseases requires the development of safer therapeutic vectors, particularly in the case of diseases in which expression of the mutated gene is subject to fine regulation, as it is with CD40L (CD154). CD40L, the gene mutated in the X-linked hyper-immunoglobulin M syndrome (HIGM1), is tightly regulated to allow surface expression of its product only on T cells stimulated by antigen encounter. Previous studies in an HIGM1 animal model showed that transduction of progenitor cells corrected the syndrome but caused a thymic lymphoproliferative disease because of the unregulated expression of the transgene by constitutive vectors. To develop a tissue-specific, activation-inducible, lentiviral vector (LV) for gene therapy to counter HIGM1, we have constructed two self-inactivating LVs, pCD40L-eGFP and pCD40L-CD40L, regulated by a 1.3 kb fragment of the human CD40L proximal promoter. The expression of pCD40L-eGFP LV is restricted to cells in which mRNA transcripts of the endogenous CD40L gene can be detected. Moreover, the expression of the reporter gene in primary T lymphocytes depends on the activation state of the cells. Remarkably, primary HIGM1 lymphocytes transduced with pCD40L-CD40L LV expressed CD40L only after T-cell stimulation. Therefore, the CD40L-promoter-driven vectors are able to achieve a near-physiological expression pattern that follows very closely that of the endogenous CD40L gene.Gene Therapy advance online publication, 25 November 2010; doi:10.1038/gt.2010.144. PMID: 21107438 [PubMed - as supplied by publisher] | | | | | | | | | | | | | | | | | | | | | | | | | Manual vs automated delivery of cells for transplantation: accuracy, reproducibility, and impact on viability. Neurosurgery. 2010 Dec;67(6):1662-8 Authors: Gobbel GT, Kondziolka D, Fellows-Mayle W, Uram M BACKGROUND:: Cellular transplantation holds promise for the management of a variety of neurological disorders. However, there is great variability in cell type, preparation methods, and implantation technique, which are crucial to clinical outcomes. OBJECTIVE:: We compared manual injection with automated injection using a prototype device to determine the possible value of a mechanized delivery system. METHODS:: Neural progenitor cells and bone marrow stromal cells were injected using manual or automated methods. Consistency of injection volumes and cell number and viability were evaluated immediately or 1 day after injection. RESULTS:: When cells were delivered as a series of 3 manual injections from the same syringe, the variation in fluid volume was greater than for single manual injections. Automated delivery of a series of 3 injections resulted in a lower variability in the amount of delivery than manual injection for both cell lines (1.2%-2.6% coefficient of variability for automated delivery vs 4.3%-24.0% for manual delivery). The amount delivered from injection 1 to injection 3 increased significantly with manual injections, whereas the amount injected did not vary over the 3 injections for the automated unit. Cell viability 1 day after injection was typically 30% to 40% of the value immediately after injection for the bone marrow stromal cells and 30% to 70% for the neural progenitor cells. There were no significant differences in viability attributed to the method of injection. CONCLUSION:: The automated delivery device led to enhanced consistency of volumetric cell delivery but did not improve cell viability in the methods tested. Automated techniques could be useful in standardizing reproducible procedures for cell transplantation and improve both preclinical and clinical research. PMID: 21107197 [PubMed - in process] | | | | | | | | | | | | | | | | | | | | | | | | | Clinical Operational Tolerance After Renal Transplantation: Current Status and Future Challenges. Ann Surg. 2010 Dec;252(6):915-928 Authors: Orlando G, Hematti P, Stratta RJ, Burke GW, Cocco PD, Pisani F, Soker S, Wood K In solid organ transplantation, the achievement of an immunosuppression (IS)-free state [also referred to as clinical operational tolerance (COT)] represents the ultimate goal. Although COT is feasible and safe in selected cases after liver transplantation, it is an exceptional finding after other types of solid organ transplantation. In the field of renal transplantation (RT), approximately 100 cases of COT have been reported to date, mainly in patients who were not compliant with their immunosuppressive regimens or in individuals who had previously received a bone marrow transplant for hematological disorders. On the basis of promising results obtained in animal models, several tolerogenic protocols have been attempted in humans, but most have failed to achieve robust and stable COT after RT. Molecule-based regimens have been largely ineffective, whereas cell-based regimens have provided some encouraging results. In these latter regimens, apart from standard IS, patients usually receive perioperative infusion of donor bone marrow-derived stem cells, which are able to interact with the immune cells of the host and mitigate their response to engraftment. Unfortunately, most renal transplant patients who developed acute rejection-occurring either during the weaning protocol or after complete withdrawal of IS-eventually lost their grafts. Currently, the immune monitoring necessary for predicting the presence and persistence of donor-specific unresponsiveness is not available. Overall, the present review will provide a conceptual framework for COT and conclude that stable and robust COT after RT remains an elusive goal and that the different strategies attempted to date are not yet reproducibly safe or effective. PMID: 21107102 [PubMed - as supplied by publisher] | | | | | | | | | | | | | | | | | | | | | | | | | Comparison of a poly-L-lactide-co-{varepsilon}-caprolactone and human amniotic membrane for urothelium tissue engineering applications. J R Soc Interface. 2010 Nov 24; Authors: Sartoneva R, Haimi S, Miettinen S, Mannerström B, Haaparanta AM, Sándor GK, Kellomäki M, Suuronen R, Lahdes-Vasama T The reconstructive surgery of urothelial defects, such as severe hypospadias is susceptible to complications. The major problem is the lack of suitable grafting materials. Therefore, finding alternative treatments such as reconstruction of urethra using tissue engineering is essential. The aim of this study was to compare the effects of naturally derived acellular human amniotic membrane (hAM) to synthetic poly-l-lactide-co-ε-caprolactone (PLCL) on human urothelial cell (hUC) viability, proliferation and urothelial differentiation level. The viability of cells was evaluated using live/dead staining and the proliferation was studied using WST-1 measurement. Cytokeratin (CK)7/8 and CK19 were used to confirm that the hUCs maintained their phenotype on different biomaterials. On the PLCL, the cell number significantly increased during the culturing period, in contrast to the hAM, where hUC proliferation was the weakest at 7 and 14 days. In addition, the majority of cells were viable and maintained their phenotype when cultured on PLCL and cell culture plastic, whereas on the hAM, the viability of hUCs decreased with time and the cells did not maintain their phenotype. The PLCL membranes supported the hUC proliferation significantly more than the hAM. These results revealed the significant potential of PLCL membranes in urothelial tissue engineering applications. PMID: 21106575 [PubMed - as supplied by publisher] | | | | | | | | | | | | | | | | | | | | | | | | | [Stem cell therapy in the inner ear: recent achievements and prospects.] Med Sci (Paris). 2010 Nov;26(11):981-985 Authors: El-Amraoui A, Petit C Because of its high prevalence and social impact, hearing impairment is a major public health problem. Whatever the cause - heredity, acoustic trauma, aminoglycoside antibiotics, noise exposure or aging - the hearing impairment is often caused by an irreversible loss of sensory hair cells. So far, hearing aids and cochlear implants are the only possibility to « treat » profound deafness. With the advent of regenerative medicine, extensive studies aimed to repair, regenerate or replace lost hair cells have been initiated. Recently, Stefan Heller and colleagues described a guidance protocol to induce mouse embryonic stem cells (ESC) and induced pluripotent stem cells (iPSC) to differentiate into mechanosensitive hair cells. The resulting hair cells hold promise as a tool for hair cell molecular physiology and physiopathology, drug discovery, and possibly also hair cell replacement. The next challenges, alternative strategies, their limitations and prospects are also discussed. PMID: 21106181 [PubMed - as supplied by publisher] | | | | | | | | | | | | | | | | | | | | | | | | | Cartilage Tissue Engineering Using Electrospun PCL Nanofiber Meshes and MSCs. Biomacromolecules. 2010 Nov 24; Authors: Alves da Silva ML, Martins A, Costa-Pinto AR, Costa P, Faria S, Gomes M, Reis RL, Neves NM Mesenchymal stem cells (MSCs) have been recognized for their ability to differentiate into cells of different tissues such as bone, cartilage, or adipose tissue, and therefore are of great interest for potential therapeutic strategies. Adherent, colony-forming, fibroblastic cells were isolated from human bone marrow aspirates, from patients undergoing knee arthroplasties, and the MSCs phenotype characterized by flow cytometry. Afterward, cells were seeded onto electrospun polycaprolactone nanofiber meshes and cultured in a multichamber flow perfusion bioreactor to determine their ability to produce cartilagineous extracellular matrix. Results indicate that the flow perfusion bioreactor increased the chondrogenic differentiation of hBM-MSCs, as confirmed either by morphological and RT-PCR analysis. Cartilage-related genes such as aggrecan, collagen type II, and Sox9 were expressed. ECM deposition was also detected by histological procedures. Collagen type II was present in the samples, as well as collagen type I. Despite no statistically significant values being obtained for gene expression, the other results support the choice of the bioreactor for this type of culture. PMID: 21105638 [PubMed - as supplied by publisher] | | | | | | | | | | | | | | | | | | | | | | | | | The Janus face of pluripotent stem cells--connection between pluripotency and tumourigenicity. Bioessays. 2010 Nov;32(11):993-1002 Authors: Wobus AM Pluripotent stem cells have gained special attraction because of their almost unlimited proliferation and differentiation capacity in vitro. These properties substantiate the potential of pluripotent stem cells in basic research and regenerative medicine. Here three types of in vitro cultured pluripotent stem cells (embryonic carcinoma, embryonic stem and induced pluripotent stem cells) are compared in their historical context with respect to their different origin and properties. It became evident that tumourigenicity is an inherent property of pluripotent cells based on p53 down-regulation, expression of tumour-related genes and high telomerase activity that allow unlimited proliferation. In addition, culture-adapted genetic and epigenetic changes may induce tumourigenicity of pluripotent cells. The use of stem cells in regenerative medicine, however, requires non-malignant cell types and strategies that circumvent stages of malignancy.Reprogramming strategies of adult somatic cells that avoid the tumourigenic state of pluripotency may offer alternatives for future biomedical application. PMID: 21105293 [PubMed - in process] | | | | | | | | | | | | | | | | | | | | | | | | | Genipin-crosslinked microcarriers mediating hepatocellular aggregates formation and functionalities. J Biomed Mater Res A. 2011 Jan;96(1):204-11 Authors: Lau TT, Wang C, Png SW, Su K, Wang DA In engineered regenerative medicine, various types of scaffolds have been customized to pursue the optimal environment for different types of therapeutic cells. In liver therapeutic research, hepatocytes require attachment to solid anchors for survival and proliferation before they could grow into cellular aggregates with enhanced functionalities. Among the various biomaterials scaffolds and vehicles, microspherical cell carriers are suited to these requirements. Individual spheres may provide two-dimensional (2D) cell-affinitive surfaces for cell adhesion and spreading; whereas multiple microcarriers may form three-dimensional (3D) matrices with inter-spherical space for cell expansion and multicellular aggregation. In this study, we culture human liver carcinoma cell line (HepG2) cells on genipin-crosslinked gelatin microspheres of two different sizes. Results suggest that both microcarriers support cell adhesion, proliferation, and spontaneous formation of hepatocellular aggregates, among which the spheres with bigger size (200-300 μm) seem more favorable than the smaller ones in terms of aggregate formation and liver specific functionalities. These findings suggest that the genipin-crosslinked microcarrier is a competent vehicle for liver cell delivery. © 2010 Wiley Periodicals, Inc. J Biomed Mater Res Part A, 2010. PMID: 21105169 [PubMed - in process] | | | | | | | | | | | | | | | | | | | | | | | | | Lentiviral vector-mediated knockdown of the neuroglycan 2 proteoglycan or expression of neurotrophin-3 promotes neurite outgrowth in a cell culture model of the glial scar. J Gene Med. 2010 Nov;12(11):863-72 Authors: Donnelly EM, Strappe PM, McGinley LM, Madigan NN, Geurts E, Rooney GE, Windebank AJ, Fraher J, Dockery P, O'Brien T, McMahon SS BACKGROUND: Following spinal cord injury, a highly inhibitory environment for axonal regeneration develops. One of the main sources of this inhibition is the glial scar that is formed after injury by reactive astrocytes. The inhibitory environment is mainly a result of chondroitin sulphate proteoglycans (CSPGs). Neuroglycan 2 (NG2), one of the main inhibitory CSPGs, is up-regulated following spinal cord injury. METHODS: Small interfering RNA (siRNA) was designed to target NG2 and this short hairpin RNA (shRNA) was cloned into a lentiviral vector (LV). The neurotrophic factor neurotrophin-3 (NT-3) promotes the growth and survival of developing neurites and has also been shown to aid regeneration. NT-3 was also cloned into a LV. In vitro assessment of these vectors using a coculture system of dorsal root ganglia (DRG) neurones and Neu7 astrocytes was carried out. The Neu7 cell line is a rat astrocyte cell line that overexpresses NG2, thereby mimicking the inhibitory environment following spinal cord injury. RESULTS AND DISCUSSION: These experiments show that both the knockdown of NG2 via shRNA and over-expression of NT-3 can significantly increase neurite growth, although a combination of both vectors did not confer any additional benefit over the vectors used individually. These LVs show promising potential for growth and survival of neurites in injured central nervous system tissue (CNS). Copyright © 2010 John Wiley & Sons, Ltd. PMID: 21105148 [PubMed - in process] | | | | | | | | | | | | | | | | | | | | | | | | | Osteoblasts Derived from Induced Pluripotent Stem Cells form Calcified Structures in Scaffolds both in vitro and in vitro. Stem Cells. 2010 Nov 23; Authors: Bilousova G, Hyun Jun D, King KB, Delanghe S, Chick WS, Torchia EC, Chow KS, Klemm DJ, Roop DR, Majka SM Reprogramming somatic cells into an embryonic stem (ES) cell-like state, or induced pluripotent stem (iPS) cells, has emerged as a promising new venue for customized cell therapies. In this study, we performed directed differentiation to assess the ability of murine iPS cells to differentiate into bone, cartilage and fat in vitro and to maintain an osteoblast phenotype on a scaffold in vitro and in vivo. Embryoid bodies derived from murine iPS cells were cultured in differentiation medium for eight to twelve weeks. Differentiation was assessed by lineage specific morphology, gene expression, histological stain and immunostaining to detect matrix deposition. After 12 weeks of expansion, iPS derived osteoblasts were seeded in a gelfoam matrix followed by subcutaneous implantation in syngenic ICR mice. Implants were harvested at 12 weeks, and histological analyses of cell, mineral and matrix content were performed. Differentiation of iPS cells into mesenchymal lineages of bone, cartilage and fat was confirmed by morphology, and expression of lineage specific genes. Isolated implants of iPS cell derived osteoblasts expressed matrices characteristic of bone, including osteocalcin and bone sialoprotein. Implants were also stained with alizarin red and von Kossa, demonstrating mineralization and persistence of an osteoblast phenotype. Recruitment of vasculature and microvascularization of the implant was also detected. Taken together, these data demonstrate functional osteoblast differentiation from iPS cells both in vitro and in vivo and reveal a source of cells which merit evaluation for their potential uses in orthopaedic medicine and understanding of molecular mechanisms of orthopaedic disease. PMID: 21104978 [PubMed - as supplied by publisher] | | | | | | | | | | | | | | | | | | | | | | | | | Combined activin A/LiCl/Noggin treatment improves production of mouse embryonic stem cell-derived definitive endoderm cells. J Cell Biochem. 2010 Nov 22; Authors: Li F, He Z, Li Y, Liu P, Chen F, Wang M, Zhu H, Ding X, Wangensteen KJ, Hu Y, Wang X Induction of definitive endoderm (DE) cells is a prerequisite for the whole process of embryonic stem (ES) cells differentiating into hepatic or pancreatic progenitor cells. We have established an efficient method to induce mouse ES cell-derived DE cells in suspension embryonic body (EB) culture. Similar to previous studies, mouse ES cell-derived DE cells, which were defined as Cxcr4(+)c-Kit(+), Cxcr4(+)E-cadherin(+) cells or Cxcr4(+)PDGFRa(-) cells, could be induced in the serum-free EBs at Day 4 of induction. The activations of Wnt, Nodal and FGF signaling pathways in differentiating EBs promoted DE cell differentiation, while activation of BMP4 signaling inhibited the process. In the present study, we found that chemical activation of canonical Wnt signaling pathway by LiCl could synergize with Activin A-mediated Nodal signaling pathway to promote induction of DE cells, and inhibition of Bmp4 signaling by Noggin along with Activin A/LiCl further improved the efficiency of DE cell differentiation. The derived DE cells were proved for their capacities to become hepatic progenitor cells or pancreatic progenitor cells. In conclusion, we significantly improved the efficiency of generating mouse ES cell-derived DE cells by combined Activin A/LiCl/Noggin treatment. Our work will be greatly helpful to generate ES cell-derived hepatic cells and ES cell-derived pancreatic cells for future regenerative medicine. © 2010 Wiley-Liss, Inc. PMID: 21104907 [PubMed - as supplied by publisher] | | | | | | | | | | | | | | | | | | | | | | | | | Placental stem cell differentiation into islets of Langerhans-like glucagon-secreting cells. Rom J Morphol Embryol. 2010;51(4):733-8 Authors: Suşman S, Soriţău O, Rus-Ciucă D, Tomuleasa C, Pop VI, Mihu CM Background and Purpose: For the past few years, in an attempt to find new sources of cells that may be used in cell therapy, numerous researchers have highlighted the particular properties of mesenchymal stem cells. Mesenchymal stem cells can be isolated from adult tissues such as the bone marrow or adipose tissue, but also from other organs such as the human placenta. Our study focuses adult stem cells isolated from the chorionic villi in an attempt to differentiate them into islets of Langerhans in order to study their differentiation potential, as a future background for cell therapy. Experimental Design: Full-term placentas were prelevated from volunteer women that have just delivered a normal pregnancy. After a mechanical fragmentation of the placenta, the chorion fragments are transferred in a dish with dispase before the enzyme is inactivated using fetal calf serum. The cell suspension is filtered in order to obtain a single-cell suspension. After the adherence of the first cells, the proliferation rate increased progressively and cell morphology is kept the same for several passages. In order to correctly differentiate placental stem cells into glucagon-secreting cells, we used a culture method on a scaffold with sequential exposure to different growth factors. The underlying substrate used contained type IV collagen, chytosan, Matrigel and laminin. Molecular biology techniques were carried out to investigate the gene expression of the stem cells. Results: Our results show that exendin-4 is able to induce the differentiation of placental stem cells into glucagon-secreting cells. We also notice the absence of the insulin gene, a conclusion that may be explained by the fact that our phenotype is a partial one, incomplete, closer to islet cell progenitors than to insulin-producing progenitors. Conclusions: The identification of the placenta as a valid source for stem cells has important practical advantages because it is easily accessible, it raises no ethical issues and cells are easily to isolate in a large enough number to use. The future knowledge and manipulation of the signaling pathways that determines the dramatic phenotype shift may provide the basis for efficient cell differentiation, with great impact on regenerative medicine and tissue engineering. PMID: 21103634 [PubMed - in process] | | | | | | | | | | | | | | | | | | | | | | | | | MET signalling: principles and functions in development, organ regeneration and cancer. Nat Rev Mol Cell Biol. 2010 Dec;11(12):834-48 Authors: Trusolino L, Bertotti A, Comoglio PM The MET tyrosine kinase receptor (also known as the HGF receptor) promotes tissue remodelling, which underlies developmental morphogenesis, wound repair, organ homeostasis and cancer metastasis, by integrating growth, survival and migration cues in response to environmental stimuli or cell-autonomous perturbations. The versatility of MET-mediated biological responses is sustained by qualitative and quantitative signal modulation. Qualitative mechanisms include the engagement of dedicated signal transducers and the subcellular compartmentalization of MET signalling pathways, whereas quantitative regulation involves MET partnering with adaptor amplifiers or being degraded through the shedding of its extracellular domain or through intracellular ubiquitylation. Controlled activation of MET signalling can be exploited in regenerative medicine, whereas MET inhibition might slow down tumour progression. PMID: 21102609 [PubMed - in process] | | | | | | | | | | | | | | | | | | | | | | | | | From MYOD1 to iPS cells. Nat Rev Mol Cell Biol. 2010 Dec;11(12):817 Authors: Hochedlinger K PMID: 21102604 [PubMed - in process] | | | | | | | | | | | | | | | | | | | | | | | | | Tissue elongation requires oscillating contractions of a basal actomyosin network. Nat Cell Biol. 2010 Nov 21; Authors: He L, Wang X, Tang HL, Montell DJ Understanding how molecular dynamics leads to cellular behaviours that ultimately sculpt organs and tissues is a major challenge not only in basic developmental biology but also in tissue engineering and regenerative medicine. Here we use live imaging to show that the basal surfaces of Drosophila follicle cells undergo a series of directional, oscillating contractions driven by periodic myosin accumulation on a polarized actin network. Inhibition of the actomyosin contractions or their coupling to extracellular matrix (ECM) blocked elongation of the whole tissue, whereas enhancement of the contractions exaggerated it. Myosin accumulated in a periodic manner before each contraction and was regulated by the small GTPase Rho, its downstream kinase, ROCK, and cytosolic calcium. Disrupting the link between the actin cytoskeleton and the ECM decreased the amplitude and period of the contractions, whereas enhancing cell-ECM adhesion increased them. In contrast, disrupting cell-cell adhesions resulted in loss of the actin network. Our findings reveal a mechanism controlling organ shape and an experimental model for the study of the effects of oscillatory actomyosin activity within a coherent cell sheet. PMID: 21102441 [PubMed - as supplied by publisher] | | | | | | | | | | | | | | | | | | | | | | | | | Effectiveness of scaffolds with pre-seeded mesenchymal stem cells in bone regeneration -Assessment of osteogenic ability of scaffolds implanted under the periosteum of the cranial bone of rats- Dent Mater J. 2010 Nov 19; Authors: Baba S, Inoue T, Hashimoto Y, Kimura D, Ueda M, Sakai K, Matsumoto N, Hiwa C, Adachi T, Hojo M To date, there has been no study on the development of novel regimens based on the following tissue engineering principles: seeding and culturing mesenchymal stem cells (MSCs) on a scaffold before surgery or injecting cultured MSCs into a scaffold during surgery. The purpose of this study was to assess the in vivo osteogenic ability of scaffold/MSCs implanted beneath the periosteum of the cranial bone of rats in three different sample groups: one in which MSCs were pre-seeded and cultured on a scaffold to produce the 3-D woven fabric scaffold/MSC composite using osteo-lineage induction medium, one in which cultured MSCs produced by osteo lineage induction in cell cultivation flasks were injected into a scaffold during surgery and a control group, in which only the 3-D woven fabric scaffold was implanted. The results indicate that pre-seeding MSCs on a scaffold leads to a higher osteogenic ability than injecting cultured MSCs into a scaffold during surgery. PMID: 21099156 [PubMed - as supplied by publisher] | | | | | | | | | | | | | | | | | | | | | | | | | Transient activation of c-MYC expression is critical for efficient platelet generation from human induced pluripotent stem cells. J Exp Med. 2010 Nov 22; Authors: Takayama N, Nishimura S, Nakamura S, Shimizu T, Ohnishi R, Endo H, Yamaguchi T, Otsu M, Nishimura K, Nakanishi M, Sawaguchi A, Nagai R, Takahashi K, Yamanaka S, Nakauchi H, Eto K Human (h) induced pluripotent stem cells (iPSCs) are a potentially abundant source of blood cells, but how best to select iPSC clones suitable for this purpose from among the many clones that can be simultaneously established from an identical source is not clear. Using an in vitro culture system yielding a hematopoietic niche that concentrates hematopoietic progenitors, we show that the pattern of c-MYC reactivation after reprogramming influences platelet generation from hiPSCs. During differentiation, reduction of c-MYC expression after initial reactivation of c-MYC expression in selected hiPSC clones was associated with more efficient in vitro generation of CD41a(+)CD42b(+) platelets. This effect was recapitulated in virus integration-free hiPSCs using a doxycycline-controlled c-MYC expression vector. In vivo imaging revealed that these CD42b(+) platelets were present in thrombi after laser-induced vessel wall injury. In contrast, sustained and excessive c-MYC expression in megakaryocytes was accompanied by increased p14 (ARF) and p16 (INK4A) expression, decreased GATA1 expression, and impaired production of functional platelets. These findings suggest that the pattern of c-MYC expression, particularly its later decline, is key to producing functional platelets from selected iPSC clones. PMID: 21098095 [PubMed - as supplied by publisher] | | | | | | | | | | | | | | | | | | | | | | | | | Textile-templated electrospun anisotropic scaffolds for tissue engineering and regenerative medicine. Conf Proc IEEE Eng Med Biol Soc. 2010;1:255-8 Authors: Senel-Ayaz HG, Perets A, Govindaraj M, Brookstein D, Lelkes PI Cardiovascular diseases, specifically myocardial infarction and end-stage heart failure represent some of the major pathologies that threaten human life. Here we present a novel approach for a bioactive cardiac patch based on a combination of biomedical and textile manufacturing techniques in concert with nano-biotechnology based tissue-engineering stratagems. The technological goal is to create BioNanoTextiles™ (BNT) by using "conventional" fabrics as templates for creating three-dimensional nanofibrous scaffolds. Electrospinning nanofibrous scaffolds templated after "ordinary" textiles is a novel way to create complex-patterned, 3-D scaffolds intrinsically mimicking some of the anisotropic structural features of the ventricular wall's extracellular matrix. In preliminary studies, we established that this approach will yield anisotropic 3-D scaffolds with mechanical properties dependent upon the yarn type of the textile-templates. These scaffolds are biocompatible, as inferred from their support of H9C2 cardiac myoblast adhesion which promotes their proliferation as well as cardiac-like anisotropic organization. The use of textile manufacturing strategies will enhance the complexity of the 3-D scaffold structures and enable their commercialization, while providing an opportunity for the textile industry to advance established "low-tech" manufacturing technologies into the realm of "high-tech" BioNanoTextiles. PMID: 21096749 [PubMed - in process] | | | | | | | | | |  | |  | |  |
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