|  |  |  | | | | | TE-RegenMed-StemCell feed | | | | | | | | | | | | | | | | | | | Stimulus-Responsive Hydrogels Made From Biosynthetic Fibrinogen Conjugates for Tissue Engineering: Structural Characterization. Langmuir. 2011 May 4; Authors: Frisman I, Shachaf Y, Seliktar D, Bianco-Peled H Nanostructured hydrogels based on "smart" polymer conjugates of poloxamers and protein molecules were developed in order to form stimulus-responsive materials with bioactive properties for 3-D cell culture. Functionalized Pluronic F127 was covalently attached to a fibrinopeptide backbone and cross-linked into a structurally versatile and mechanically stable polymer network endowed with bioactivity and temperature-responsive structural features. Small angle X-ray scattering and transmission electron microscopy combined with rheology were used to characterize the structural and mechanical features of this biosynthetic conjugate, both in solution and in hydrogel form. The temperature at which the chemical cross-linking of F127-fibrinopeptide conjugates was initiated had a profound influence on the mechanical properties of the thermo-responsive hydrogel. The analysis of the scattering data revealed modification in the structure of the protein backbone resulting from increases in ambient temperature, whereas the structure of the polymer was not affected by ambient temperature. The hydrogel cross-linking temperature also had a major influence on the modulus of the hydrogel, which was rationally correlated to the molecular structure of the polymer network. The hydrogel structure exhibited a small mesh size when cross-linked at low temperatures and a larger mesh size when cross-linked at higher temperatures. The mesh size was nicely correlated to the mechanical properties of the hydrogels at the respective cross-linking temperatures. The schematic charts that model this material's behavior help to illustrate the relationship that exists between the molecular structure, the cross-linking temperature, and the temperature-responsive features for this class of protein-polymer conjugates. The precise control over structural and mechanical properties that can be achieved with this bioactive hydrogel material is essential in designing a tissue-engineering scaffold for clinical applications. PMID: 21542599 [PubMed - as supplied by publisher] | | | | | | | | | | | | | | | | | | | | | | | | | Growth Factor Priming of Synovium Derived Stem Cells for Cartilage Tissue Engineering. Tissue Eng Part A. 2011 May 4; Authors: Sampat SR, O'Connell G, Fong JV, Alegre-Aguarón E, Ateshian GA, Hung CT This study investigated the potential use of synovium-derived stem cells (SDSCs) as a cell source for cartilage tissue engineering. Harvested SDSCs from juvenile bovine synovium were expanded in culture in the presence ('primed') or absence ('unprimed') of growth factors (1 ng/ml TGF-β1, 10 ng/ml PDGF-ββ, and 5 ng/ml bFGF-2) and subsequently seeded into clinically relevant agarose hydrogel scaffolds. Constructs seeded with growth factor primed SDSCs that received an additional transient application of TGF-β3 for the first 21 days ('release') exhibited significantly better mechanical and biochemical properties compared to constructs that received sustained growth factor stimulation over the entire culture period ('continuous'). In particular, the 'release' group constructs exhibited a Young's modulus (267 ± 96 kPa) approaching native immature bovine cartilage levels, with corresponding glycosaminoglycan content (5.19 ± 1.45 %ww) similar to native values, within seven weeks of culture. These findings suggest that SDSCs may serve as a cell source for cartilage tissue engineering applications. PMID: 21542714 [PubMed - as supplied by publisher] | | | | | | | | | | | | | | | | | | | | | | | | | Development of Myocardial Constructs Using Modulus-Matched Acrylated Polypropylene Glycol Triol (aPPGT) Substrate and Different Non-Myocyte Cell Populations. Tissue Eng Part A. 2011 May 4; Authors: Hudson JE, Brooke G, Blair C, Wolvetang E, Cooper-White JJ Tissue engineering approaches are currently being investigated for the restoration of myocardial function in heart failure patients, most commonly by combining cells with a substrate to form myocardial-like constructs. The final properties of these constructs are dependant on the characteristics of both the substrate and the cells used for fabrication. In order to create a construct with the appropriate mechanical properties required for any future therapeutic, we tailored an acrylated polypropylene glycol triol (aPPGT) substrate to the elastic modulus of heart tissue and then investigated the fabrication of myocardial-like constructs. We firstly assessed the aPPGT substrate alone in vivo, both under normal conditions and in an infarct model in mice, and found that there was a mild foreign body response with good integration of the substrate into the epicardial surface in mice hearts. We next studied the fabrication and properties of myocardial-like constructs by culturing mouse embryonic cardiomyocytes on the aPPGT substrate. In order to achieve myocardial-like concentrically contractile constructs, co-cultures with supportive stromal cells were found to be essential and both mouse heart derived stromal cells or bone-derived mouse mesenchymal stromal progenitor cells (mMSCs) could be used. These different stromal cell types produced myocardial-like constructs with different properties. The average beating rate of the constructs formed from mouse heart derived stromal cells was significantly higher those constructs formed using mMSCs. Conversely, the constructs formed using mMSCs had reduced fibrotic extracellular matrix secretion and increased hepatocyte growth factor expression. Both of these mMSC construct properties may enhance integration and therapeutic efficacy of the construct post implantation on the surface of the infarcted heart. This study thus demonstrates the formation of myocardial-like constructs using mechanically tailored aPPGT substrate and also demonstrates the effects of different stromal cell populations have on the properties of the resultant myocardial-like constructs, both of which are critical for future applications of tissue engineering in heart failure patients. PMID: 21542698 [PubMed - as supplied by publisher] | | | | | | | | | | | | | | | | | | | | | | | | | Stem cell genes are poorly expressed in chondrocytes from microtic cartilage. Int J Pediatr Otorhinolaryngol. 2011 May 2; Authors: Ishak MF, Chua KH, Asma A, Saim L, Aminuddin BS, Ruszymah BH, Goh BS OBJECTIVES: This study was aimed to see the difference between chondrocytes from normal cartilage compared to chondrocytes from microtic cartilage. Specific attentions were to characterize the growth of chondrocytes in terms of cell morphology, growth profile and RT-PCR analysis. STUDY DESIGN: Laboratory experiment using auricular chondrocytes. METHODS: Chondrocytes were isolated from normal and microtic human auricular cartilage after ear reconstructive surgeries carried out at the Universiti Kebangsaan Malaysia Medical Centre. Chondrocytes were cultured in vitro and subcultured until passage 4. Upon confluency, cultured chondrocytes at each passage (P1, P2, P3 and P4) were harvested and subjected to growth profile and gene expression analyses. Comparison was made between the microtic and normal chondrocytes. RESULTS: For growth profile analysis cell viability did not show significant differences between both samples. There are no significance differences between both samples in terms of its growth rate, except in passage 1 where microtic chondrocytes were significant lower in their growth rate. Population doubling time and total number of cell doubling of all samples also did not show any significant differences. Gene expression is measured using Real Time-Reverse Transcriptase Polymerase Chain Reaction (RT-PCR). There is no significant differences in the expression of collagen type I, collagen type II, collagen type X, aggrecan core protein, elastin and sox9 genes in both samples. There are significant lower in the expression of sox2, nestin, BST-1 and OCT-4 gene in microtic chondrocytes compared to the normal chondrocytes. Stem cells markers are included in this study as stemness in cells may imply a greater proliferative potential and plasticity in vitro. CONCLUSION: Chondrocytes from microtic samples have the same properties as chondrocytes from normal samples and hold promises to be used as a starting material in the reconstruction of the external ear in future clinical application. The reduction in sox2, nestin, BST-1 and OCT-4 gene expression in microtic samples could be the possible cause of the arrested development of the external ear. PMID: 21543123 [PubMed - as supplied by publisher] | | | | | | | | | | | | | | | | | | | | | | | | | Directionally Solidified Biopolymer Scaffolds: Mechanical Properties and Endothelial Cell Responses. JOM (1989). 2010 Jul 1;62(7):71-75 Authors: Meghri NW, Donius AE, Riblett BW, Martin EJ, Clyne AM, Wegst UG Vascularization is a primary challenge in tissue engineering. To achieve it in a tissue scaffold, an environment with the appropriate structural, mechanical, and biochemical cues must be provided enabling endothelial cells to direct blood vessel growth. While biochemical stimuli such as growth factors can be added through the scaffold material, the culture medium, or both, a well-designed tissue engineering scaffold is required to provide the necessary local structural and mechanical cues. As chitosan is a well-known carrier for biochemical stimuli, the focus of this study was on structure-property correlations, to evaluate the effects of composition and processing conditions on the three-dimensional architecture and properties of freeze-cast scaffolds; to establish whether freeze-cast scaffolds are promising candidates as constructs promoting vascularization; and to conduct initial tissue culture studies with endothelial cells on flat substrates of identical compositions as those of the scaffolds to test whether these are biocompatible and promote cell attachment and proliferation. PMID: 21544225 [PubMed - as supplied by publisher] | | | | | | | | | | | | | | | | | | | | | | | | | Ruthenium-catalyzed photo cross-linking of fibrin-based engineered tissue. Biomaterials. 2011 Apr;32(10):2479-88 Authors: Bjork JW, Johnson SL, Tranquillo RT Most cross-linking methods utilize chemistry or physical processes that are detrimental to cells and tissue development. Those that are not as harmful often do not provide a level of strength that ultimately meets the required application. The purpose of this work was to investigate the use of a ruthenium-sodium persulfate cross-linking system to form dityrosine in fibrin-based engineered tissue. By utilizing the tyrosine residues inherent to fibrin and cell-deposited proteins, at least 3-fold mechanical strength increases and 10-fold stiffness increases were achieved after cross-linking. This strengthening and stiffening effect was found to increase with culture duration prior to cross-linking such that physiologically relevant properties were obtained. Fibrin was not required for this effect as demonstrated by testing with collagen-based engineered tissue. Cross-linked tissues were implanted subcutaneously and shown to have minimal inflammation after 30 days, similar to non-cross-linked controls. Overall, the method employed is rapid, non-toxic, minimally inflammatory, and is capable of increasing strength and stiffness of engineered tissues to physiological levels. PMID: 21196047 [PubMed - indexed for MEDLINE] | | | | | | | | | | | | | | | | | | | | | | | | | A phosphorus-based dendrimer targets inflammation and osteoclastogenesis in experimental arthritis. Sci Transl Med. 2011 May 4;3(81):81ra35 Authors: Hayder M, Poupot M, Baron M, Nigon D, Turrin CO, Caminade AM, Majoral JP, Eisenberg RA, Fournié JJ, Cantagrel A, Poupot R, Davignon JL Dendrimers are highly branched "tree-like" polymers that have demonstrated therapeutic potential in drug delivery, medical imaging, and tissue engineering in recent years. In addition, we have shown that an azabisphosphonate (ABP)-capped dendrimer selectively targets monocytes and directs them toward anti-inflammatory activation. We explored this property to assess the therapeutic potential of dendrimer ABP in the treatment of an inflammatory disease, rheumatoid arthritis. Intravenous injections of dendrimer ABP inhibited the development of inflammatory arthritis in two animal models: IL-1ra(-/-) mice and mice undergoing K/BxN serum transfer. Suppression of disease was characterized by normal synovial membranes, reduced levels of inflammatory cytokines, and the absence of cartilage destruction and bone erosion. Dendrimer ABP also exhibited anti-osteoclastic activity on mouse and human cells, mediated by c-FMS (cellular-feline McDonough strain sarcoma virus oncogene homolog) inhibition. These preclinical demonstrations suggest the potential use of dendrimer ABP as a nanotherapeutic for rheumatoid arthritis. PMID: 21543721 [PubMed - in process] | | | | | | | | | | | | | | | | | | | | | | | | | Bioinspired Strong and Highly Porous Glass Scaffolds. Adv Funct Mater. 2011 Mar 22;21(6):1058-1063 Authors: Fu Q, Saiz E, Tomsia AP The quest for more efficient energy-related technologies is driving the development of porous and high-performance structural materials with exceptional mechanical strength. Natural materials achieve their strength through complex hierarchical designs and anisotropic structures that are extremely difficult to replicate synthetically. We emulate nature's design by direct-ink-write assembling of glass scaffolds with a periodic pattern, and controlled sintering of the filaments into anisotropic constructs similar to biological materials. The final product is a porous glass scaffold with a compressive strength (136 MPa) comparable to that of cortical bone and a porosity (60%) comparable to that of trabecular bone. The strength of this porous glass scaffold is ~100 times that of polymer scaffolds and 4-5 times that of ceramic and glass scaffolds with comparable porosities reported elsewhere. The ability to create both porous and strong structures opens a new avenue for fabricating scaffolds for a broad array of applications, including tissue engineering, filtration, lightweight composites, and catalyst support. PMID: 21544222 [PubMed - as supplied by publisher] | | | | | | | | | | | | | | | | | | | | | | | | | Hydrogel network design using multifunctional macromers to coordinate tissue maturation in ovarian follicle culture. Biomaterials. 2011 Apr;32(10):2524-31 Authors: Shikanov A, Smith RM, Xu M, Woodruff TK, Shea LD Synthetic hydrogels with tunable properties are appealing for regenerative medicine. A critical limitation in hydrogel design at low solids concentration is the formation of defects, which increase gelation times and swelling, and reduce elasticity. Here, we report that trifunctional cross-linking peptides applied to 4-arm poly-(ethylene glycol) (PEG) hydrogels decreased swelling and gelation time relative to bi-functional crosslinkers. In contrast to bi-functional peptides, the third cross-linking site on the peptide created a branch point if an intramolecular cross-link formed, which prevented non-functional "dangling-ends" in the hydrogel network and enhanced the number of elastically active cross-links. The improved network formation enabled mouse ovarian follicle encapsulation and maturation in vitro. Hydrogels with bi-functional crosslinkers resulted in cellular dehydration, likely due to osmosis during the prolonged gelation. For trifunctional crosslinkers, the hydrogels supported a 17-fold volumetric expansion of the tissue during culture, with expansion dependent on the ability of the follicle to rearrange its microenvironment, which is controlled through the sensitivity of the cross-linking peptide to the proteolytic activity of plasmin. The improved network design enabled ovarian follicle culture in a completely synthetic system, and can advance fertility preservation technology for women facing premature infertility from anticancer therapies. PMID: 21247629 [PubMed - indexed for MEDLINE] | | | | | | | | | | | | | | | | | | | | | | | | | Effects of metoprolol therapy on cardiac gap junction remodelling and conduction in human chronic atrial fibrillation. Br J Pharmacol. 2011 May 4; Authors: Dhein S, Rothe S, Busch A, Rojas Gomez DM, Boldt A, Reutemann A, Seidel T, Salameh A, Pfannmüller B, Rastan A, Kostelka M, Mohr FW Background: We investigated the influence of metoprolol on gap junction proteins connexin43 (Cx43) and connexin40 (Cx40) in atrial tissue from patients with/without atrial fibrillation(AF). Methods: Left atrial tissue samples from 160 patients with AF or sinus rhythm (SR) with or without metoprolol (mean daily dose: 65.2 ± 9.1 mg/d) were analysed for Cx43 and Cx40 by Western blot and immunohistology. Transverse and longitudinal conduction velocities were determined by 64-multi-electrode mapping. Results: Both Cx43 and Cx40 expression were significantly increased in patients with AF vs. SR. Cx43-expression in AF was significantly higher if patients received metoprolol, while Cx40 expression was unaffected by metoprolol-treatment. In AF the ratio of lateral/polar expression of Cx43 and Cx40 was enhanced due to increased expression at the lateral sides of the cells and a loss at the cell poles. This AF-induced increase in lateral/polar expression regarding Cx43, but not Cx40, was significantly antagonized by metoprolol-treatment. Functionally, in AF-patients transverse conduction velocity was significantly enhanced, which was also significantly antagonized by metoprolol. Conclusion: AF leads to enhanced lateral expression of Cx43 and Cx40 together with enhanced transverse conduction velocity. Alterations in Cx43-localisation and conduction-changes are both antagonized by metoprolol, thus showing that a pharmacological influence on gap junction remodelling in principle seems possible, which may open new perspectives for the development of antiarryhthmics. PMID: 21542828 [PubMed - as supplied by publisher] | | | | | | | | | | | | | | | | | | | | | | | | | Adipocyte Origins: Weighing the Possibilities. Stem Cells. 2011 May 4; Authors: Majka SM, Barak Y, Klemm DJ Adipose tissue is the primary energy reservoir in the body and an important endocrine organ that plays roles in energy homeostasis, feeding, insulin sensitivity and inflammation. While it was tacitly assumed that fat in different anatomical locations had a common origin and homogenous function, it is now clear that regional differences exist in adipose tissue characteristics and function. This is exemplified by the link between increased deep abdominal or visceral fat, but not peripheral adipose tissue, and the metabolic disturbances associated with obesity. Regional differences in fat function are due in large part to distinct adipocyte populations that comprise the different fat depots. Evidence accrued primarily in the last decade indicate that the distinct adipocyte populations are generated by a number of processes during and after development. These include the production of adipocytes from different germ cell layers, the formation of distinct preadipocyte populations from mesenchymal progenitors of mesodermal origin, and the production of adipocytes from hematopoietic stem cells from the bone marrow. This review will examine each of these process and their relevance to normal adipose tissue formation and contribution to obesity-related diseases. PMID: 21544899 [PubMed - as supplied by publisher] | | | | | | | | | | | | | | | | | | | | | | | | | Non-Cell Autonomous Reprogramming: A Nucleic Acid Free Approach to Induction of Pluripotency. Stem Cells. 2011 May 4; Authors: Parameswaran S, Balasubramanian S, Rao MS, Ahmad I The reprogramming of somatic cells to a pluripotent state by the expression of a defined set of exogenous transcription factors represents a significant breakthrough for the use of stem cells in regenerative medicine. It has the potential to make autologous stem cell therapy practical and promote better understanding of the disease processes by generating patient specific stem cells. Several strategies have been used to generate induced pluripotent (iPS) cells that include nucleic acid and non-nucleic acid based approaches, with and without epigenetic modifications. The purpose of these different approaches for generating iPS cells, besides understanding the underlying mechanism, is to develop a facile method for reprogramming without genetic alteration, suitable for clinical use. Here, we discuss different strategies for generating iPS cells, with an emphasis on a recent non-cell autonomous approach to reprogram somatic progenitors that regenerate cornea to a pluripotent state through the recruitment of endogenous transcription factors. PMID: 21544901 [PubMed - as supplied by publisher] | | | | | | | | | | | | | | | | | | | | | | | | | Interspecies chimera between primate embryonic stem cells and mouse embryos: Monkey ESCs engraft into mouse embryos, but not post-implantation fetuses. Stem Cell Res. 2011 Mar 25; Authors: Simerly C, McFarland D, Castro C, Lin CC, Redinger C, Jacoby E, Mich-Basso J, Orwig K, Mills P, Ahrens E, Navara C, Schatten G Unequivocal evidence for pluripotency in which embryonic stem cells contribute to chimeric offspring has yet to be demonstrated in human or nonhuman primates (NHPs). Here, rhesus and baboons ESCs were investigated in interspecific mouse chimera generated by aggregation or blastocyst injection. Aggregation chimera produced mouse blastocysts with GFP-nhpESCs at the inner cell mass (ICM), and embryo transfers (ETs) generated dimly-fluorescencing abnormal fetuses. Direct injection of GFP-nhpESCs into blastocysts produced normal non-GFP-fluorescencing fetuses. Injected chimera showed >70% loss of GFP-nhpESCs after 21h culture. Outgrowths of all chimeric blastocysts established distinct but separate mouse- and NHP-ESC colonies. Extensive endogenous autofluorescence compromised anti-GFP detection and PCR analysis did not detect nhpESCs in fetuses. NhpESCs localize to the ICM in chimera and generate pregnancies. Because primate ESCs do not engraft post-implantation, and also because endogenous autofluorescence results in misleading positive signals, interspecific chimera assays for pluripotency with primate stem cells is unreliable with the currently available ESCs. Testing primate ESCs reprogrammed into even more naïve states in these inter-specific chimera assays will be an important future endeavor. PMID: 21543277 [PubMed - as supplied by publisher] | | | | | | | | | | | | | | | | | | | | | | | | | Purification and long-term expansion of multipotent endothelial-like cells with potential cardiovascular regeneration. Stem Cells Dev. 2011 May 4; Authors: Marchal JA, Picón M, Perán M, Bueno C, Jiménez-Navarro M, Carrillo E, Boulaiz H, Rodríguez N, Alvarez P, Menendez P, de Teresa E, Aránega A Aims─Endothelial progenitor cells (EPC) represent a relatively rare cell population, and expansion of sufficient cell numbers remains a challenge. Nevertheless, human adipose-derived stem cells (hASC) can be easily isolated and possess the ability to differentiate into endothelial cells. Here, we propose the isolation and characterization of multipotent endothelial-like cells (ME-LC) with the capacity to maintain their vascular progenitor properties for long periods of time. Methods and Results─hASC were isolated from lipoaspirates and cultured through distinct consecutive culture stages for two months to enrich ME-LC: first in DMEM-FBS (stage I), followed by a stage of culture in absent of FBS (stage II), a culture in SFO3 medium (stage III) and finally, the culture of ME-LC into collagen IV-coated flasks in EGM-2 medium (stage IV). ME-LC display increased expression levels of endothelial and hematopoietic lineage markers (CD45, KDR and CXCR4) and EPC markers (CD34 and CD133) whereas the expression of CD31 was barely detectable. RT-PCR assays showed expression of genes involved in early stages of EPC differentiation and decreased expression of genes associated to differentiated EPC (TIE-2, DLL4 and FLT-1). ME-LC formed capillary-like structures when grown on Matrigel, secreted increased levels of SDF-1 and showed the ability to migrate attracted by SDF-1, VEGF and HGF cytokines. Importantly, ME-LC retained the capacity to differentiate into cardiomyocyte-like cells. Conclusions─We present a simplified and efficient method to generate large numbers of autologous ME-LC from lipoaspirates-derived hASC, opening up potential cell-based therapies for cardiovascular regenerative medicine. PMID: 21542697 [PubMed - as supplied by publisher] | | | | | | | | | | | | | | | | | | | | | | | | | [Application of small molecule compounds inducing differentiation of stem cells]. Yao Xue Xue Bao. 2011 Feb;46(2):121-6 Authors: Li X, Shan L, Li WL, Zhang SD, Zhang WD With the development of stem cells and regenerative medicine (treatment of various diseases using stem cells) research, the induction of differentiation of human stem cell technology has also made significant progress. The development of chemical biology offers a variety of small biological molecules for stem cell biology. This review focuses on how small molecule compounds (natural and synthetic) induce differentiation of stem cells. PMID: 21542280 [PubMed - in process] | | | | | | | | | | | | | | | | | | | | | | | | | Cell therapy with human T regulatory type 1 cells in allogeneic transplantations. Immunotherapy. 2011 Apr;3(4 Suppl):27 Authors: Bacchetta R, Gregori S, Barbarella L, Roncarolo MG Regulatory T cells (Tregs) are a specialized subset of T cells able to control immune responses and promote and maintain immune tolerance. Deficiency or defective function of Tregs has been correlated with autoimmunity, whereas their presence has been associated with tolerance. CD4(+) Tregs have been classified into two major subsets according to their origin: the natural occurring Tregs, which develop in the thymus and are present in mice and healthy human individuals since birth, and the inducible Tregs that are generated in the periphery under different tolerogenic conditions. Among the inducible Tregs, the T regulatory type 1 (Tr1) cells represent one of the most extensively characterized subset. Tr1 cells develop in the periphery upon chronic antigen stimulation in the presence of IL-10 produced by tolerogenic antigen-presenting cells. Tr1 cells are characterized by the capacity to produce high levels of IL-10 in the absence of IL-4 and can suppress undesired immune responses mainly through cytokine-mediated mechanisms. However, we recently demonstrated that immunomodulatory activities of Tr1 cells reside not only in their ability to secrete suppressive cytokines but also in their property of cell-to-cell contact-dependent killing of target myeloid cells mediated by granzyme B and perforin. Tr1 cells are distinct from natural occurring Tregs since they are independent from FOXP3 expression for both their function and generation, as demonstrated by Tr1 cell identification in IPEX patients. The presence of Tr1 cells in vivo is associated with tolerance, whereas defects in Tr1 cells lead to autoimmune diseases or to chronic inflammation. In humans, we showed that both exogenous IL-10 or IL-10-derived from tolerogenic dendritic cells (DC-10) can be used to generate alloantigen-specific Tr1 cells in vitro suitable for cell therapy. Moreover, a homogeneous population of IL-10-producing T cells with Tr1-like phenotype and functions can be generated by transducing human CD4(+) T cells with a lentiviral vector encoding for human IL-10. A cellular therapy protocol for the ex vivo use of IL-10 to induce alloantigen-specific unresponsiveness in donor-derived T cells for adoptive transfer in patients transplanted with haploidentical hematopoietic stem cells is being applied for patients with high-risk hematopoietic malignancies. In our clinical trial, donor T cells anergized in vitro in the presence of IL-10 are infused post-transplantation into the host with the ultimate goal of providing immune reconstitution with donor T cells that are anergic towards host antigens and contain precursors of host-specific Tr1 cells. This cellular therapy has proven to be safe and to provide immunoreconstitution associated, in most of the patients, with only moderate graft-versus-host disease (GVHD) at a cell dose that, if transferred untreated, would have caused severe acute GVHD. A similar approach could be also foreseen in the clinical setting of HLA-matched unrelated donor to prevent acute and chronic GVHD. Ad hoc experimental settings have been established using dendritic cells as antigen-presenting cells to induce anergy in the context of HLA-matched donors. These recently developed methods allowing the ex vivo induction of Tregs for in vivo infusion represent the first step toward an enlarged use of these cells as cellular therapy not only to inhibit GVHD after allogeneic hematopoietic stem cell transplantation, but also to other transplantation settings, or to re-establish tolerance in autoimmune or allergic diseases. PMID: 21524165 [PubMed - in process] | | | | | | | | | | | | | | | | | | | | | | | | | Paving new paths for neuregulin-1-assisted cardiac regenerative medicine. Am J Physiol Cell Physiol. 2011 May 4; Authors: Lemmens K, De Keulenaer GW N/A. PMID: 21543744 [PubMed - as supplied by publisher] | | | | | | | | | | | | | | | | | | | | | | | | | Functions of the nigrostriatal dopaminergic synapse and the use of neurotransplantation in Parkinson's disease. J Neurol. 2011 May 5; Authors: Tsui A, Isacson O While pharmaceutical options remain the overwhelmingly accepted treatment of choice for neurological and psychiatric diseases, significant accomplishments in regenerative neuroscience research have demonstrated the potential of cellular and synaptic functional repair in future therapies. Parkinson's disease stands out as an example in which repair by dopaminergic neurons appears a viable potential therapy. This article describes the basic neurobiological underpinnings of the rationale for cell therapy for Parkinson's disease and the challenges ahead for the use of regenerative medicine in the treatment for this disease. PMID: 21544566 [PubMed - as supplied by publisher] | | | | | | | | | | | | | | | | | | | | | | | | | Derivation and characterization of Chinese human embryonic stem cell line with high potential to differentiate into pancreatic and hepatic cells. Chin Med J (Engl). 2011 Apr;124(7):1037-43 Authors: Shi C, Shen H, Jiang W, Song ZH, Wang CY, Wei LH Human embryonic stem cells have prospective uses in regenerative medicine and drug screening. Every human embryonic stem cell line has its own genetic background, which determines its specific ability for differentiation as well as susceptibility to drugs. It is necessary to compile many human embryonic stem cell lines with various backgrounds for future clinical use, especially in China due to its large population. This study contributes to isolating new Chinese human embryonic stem cell lines with clarified directly differentiation ability. PMID: 21542965 [PubMed - in process] | | | | | | | | | | | | | | | | | | | | | | | | | Epigenetic regulation of satellite cell activation during muscle regeneration. Stem Cell Res Ther. 2011 Apr 19;2(2):18 Authors: Dilworth FJ, Blais A ABSTRACT: Satellite cells are a population of adult muscle stem cells that play a key role in mediating muscle regeneration. Activation of these quiescent stem cells in response to muscle injury involves modulating expression of multiple developmentally regulated genes, including mediators of the muscle-specific transcription program: Pax7, Myf5, MyoD and myogenin. Here we present evidence suggesting an essential role for the antagonistic Polycomb group and Trithorax group proteins in the epigenetic marking of muscle-specific genes to ensure proper temporal and spatial expression during muscle regeneration. The importance of Polycomb group and Trithorax group proteins in establishing chromatin structure at muscle-specific genes suggests that therapeutic modulation of their activity in satellite cells could represent a viable approach for repairing damaged muscle in muscular dystrophy. PMID: 21542881 [PubMed - as supplied by publisher] | | | | | | | | | | | | | | | | | | | | | | | | | The X-inactivation trans-activator Rnf12 is negatively regulated by pluripotency factors in embryonic stem cells. Hum Genet. 2011 May 5; Authors: Navarro P, Moffat M, Mullin NP, Chambers I X-inactivation, the molecular mechanism enabling dosage compensation in mammals, is tightly controlled during mouse early embryogenesis. In the morula, X-inactivation is imprinted with exclusive silencing of the paternally inherited X-chromosome. In contrast, in the post-implantation epiblast, X-inactivation affects randomly either the paternal or the maternal X-chromosome. The transition from imprinted to random X-inactivation takes place in the inner cell mass (ICM) of the blastocyst from which embryonic stem (ES) cells are derived. The trigger of X-inactivation, Xist, is specifically downregulated in the pluripotent cells of the ICM, thereby ensuring the reactivation of the inactive paternal X-chromosome and the transient presence of two active X-chromosomes. Moreover, Tsix, a critical cis-repressor of Xist, is upregulated in the ICM and in ES cells where it imposes a particular chromatin state at the Xist promoter that ensures the establishment of random X-inactivation upon differentiation. Recently, we have shown that key transcription factors supporting pluripotency directly repress Xist and activate Tsix and thus couple Xist/Tsix control to pluripotency. In this manuscript, we report that Rnf12, a third X-linked gene critical for the regulation of X-inactivation, is under the control of Nanog, Oct4 and Sox2, the three factors lying at the heart of the pluripotency network. We conclude that in mouse ES cells the pluripotency-associated machinery exerts an exhaustive control of X-inactivation by taking over the regulation of all three major regulators of X-inactivation: Xist, Tsix, and Rnf12. PMID: 21544581 [PubMed - as supplied by publisher] | | | | | | | | | | | | | | | | | | | | | | | | | Mitochondria Determine the Differentiation Potential of Cardiac Mesoangioblasts. Stem Cells. 2011 May 4; Authors: San Martin N, Cervera AM, Cordova C, Covarello D, McCreath KJ, Galvez BG An understanding of cardiac progenitor cell biology would facilitate their therapeutic potential for cardiomyocyte restoration and functional heart repair. Our previous studies identified cardiac mesoangioblasts as pre-committed progenitor cells from the postnatal heart, which can be expanded in vitro and efficiently differentiated in vitro and in vivo to contribute new myocardium after injury. Based on their proliferation potential in culture, we show here that two populations of mesoangioblasts can be isolated from explant cultures of mouse and human heart. Although both populations express similar surface markers, together with a panel of instructive cardiac transcription factors, they differ significantly in their cellular content of mitochondria. Slow dividing cells, containing many mitochondria, can be efficiently differentiated with 5-azacytidine to generate cardiomyocytes expressing mature structural markers. In contrast fast dividing mesoangioblasts, which contain decreased quantities of mitochondria, do not respond to 5-azacytidine treatment. Notably, increasing mitochondrial numbers using pharmacological nitric oxide donors reverses the differentiation block in fast-dividing mesoangioblasts and leads to a progressive maturation to cardiomyocytes; conversely decreasing mitochondrial content, using respiratory chain inhibitors and chloramphenicol, perturbs cardiomyocyte differentiation in slow dividing populations. Furthermore, isolated cardiac mesoangioblasts from mouse and human aged hearts are found to be almost exclusively mitochondria-low, fast dividing populations, which are permissive for cardiomyocyte differentiation only after nitric oxide treatment. Taken together, this study illustrates a key role for mitochondria in cardiac mesoangioblast differentiation and raises the interesting possibility that treatments, which increase cellular mitochondrial content, may have utility for cardiac stem cell therapy. PMID: 21544900 [PubMed - as supplied by publisher] | | | | | | | | | | | | | | | | | | | | | | | | | Non-Cell Autonomous Reprogramming: A Nucleic Acid Free Approach to Induction of Pluripotency. Stem Cells. 2011 May 4; Authors: Parameswaran S, Balasubramanian S, Rao MS, Ahmad I The reprogramming of somatic cells to a pluripotent state by the expression of a defined set of exogenous transcription factors represents a significant breakthrough for the use of stem cells in regenerative medicine. It has the potential to make autologous stem cell therapy practical and promote better understanding of the disease processes by generating patient specific stem cells. Several strategies have been used to generate induced pluripotent (iPS) cells that include nucleic acid and non-nucleic acid based approaches, with and without epigenetic modifications. The purpose of these different approaches for generating iPS cells, besides understanding the underlying mechanism, is to develop a facile method for reprogramming without genetic alteration, suitable for clinical use. Here, we discuss different strategies for generating iPS cells, with an emphasis on a recent non-cell autonomous approach to reprogram somatic progenitors that regenerate cornea to a pluripotent state through the recruitment of endogenous transcription factors. PMID: 21544901 [PubMed - as supplied by publisher] | | | | | | | | | | | | | | | | | | | | | | | | | Optimized labeling of bone marrow mesenchymal cells with superparamagnetic iron oxide nanoparticles and in vivo visualization by magnetic resonance imaging. J Nanobiotechnology. 2011 Feb 9;9(1):4 Authors: Jasmin , Torres AL, Nunes HM, Passipieri JA, Jelicks LA, Gasparetto EL, Spray DC, Campos de Carvalho AC, Mendez-Otero R ABSTRACT: BACKGROUND: Stem cell therapy has emerged as a promising addition to traditional treatments for a number of diseases. However, harnessing the therapeutic potential of stem cells requires an understanding of their fate in vivo. Non-invasive cell tracking can provide knowledge about mechanisms responsible for functional improvement of host tissue. Superparamagnetic iron oxide nanoparticles (SPIONs) have been used to label and visualize various cell types with magnetic resonance imaging (MRI). In this study we performed experiments designed to investigate the biological properties, including proliferation, viability and differentiation capacity of mesenchymal cells (MSCs) labeled with clinically approved SPIONs. RESULTS: Rat and mouse MSCs were isolated, cultured, and incubated with dextran-covered SPIONs (ferumoxide) alone or with poly-L-lysine (PLL) or protamine chlorhydrate for 4 or 24 hrs. Labeling efficiency was evaluated by dextran immunocytochemistry and MRI. Cell proliferation and viability were evaluated in vitro with Ki67 immunohistochemistry and live/dead assays. Ferumoxide-labeled MSCs could be induced to differentiate to adipocytes, osteocytes and chondrocytes. We analyzed ferumoxide retention in MSCs with or without mitomycin C pretreatment. Approximately 95% MSCs were labeled when incubated with ferumoxide for 4 or 24 hrs in the presence of PLL or protamine, whereas labeling of MSCs incubated with ferumoxide alone was poor. Proliferative capacity was maintained in MSCs incubated with ferumoxide and PLL for 4 hr, however, after 24 hrs it was reduced. MSCs incubated with ferumoxide and protamine were efficiently visualized by MRI; they maintained proliferation and viability for up to 7 days and remained, competent to differentiate. After 21 days MSCs pretreated with mitomycin C still showed a large number of ferumoxide-labeled cells. CONCLUSIONS: The efficient and long lasting uptake and retention of SPIONs by MSCs using a protocol employing ferumoxide and protamine may be applicable to patients, since both ferumoxides and protamine are approved for human use. PMID: 21542946 [PubMed - as supplied by publisher] | | | | | | | | | | | | | | | | | | | | | | | | | Adipocyte Origins: Weighing the Possibilities. Stem Cells. 2011 May 4; Authors: Majka SM, Barak Y, Klemm DJ Adipose tissue is the primary energy reservoir in the body and an important endocrine organ that plays roles in energy homeostasis, feeding, insulin sensitivity and inflammation. While it was tacitly assumed that fat in different anatomical locations had a common origin and homogenous function, it is now clear that regional differences exist in adipose tissue characteristics and function. This is exemplified by the link between increased deep abdominal or visceral fat, but not peripheral adipose tissue, and the metabolic disturbances associated with obesity. Regional differences in fat function are due in large part to distinct adipocyte populations that comprise the different fat depots. Evidence accrued primarily in the last decade indicate that the distinct adipocyte populations are generated by a number of processes during and after development. These include the production of adipocytes from different germ cell layers, the formation of distinct preadipocyte populations from mesenchymal progenitors of mesodermal origin, and the production of adipocytes from hematopoietic stem cells from the bone marrow. This review will examine each of these process and their relevance to normal adipose tissue formation and contribution to obesity-related diseases. PMID: 21544899 [PubMed - as supplied by publisher] | | | | | | | | | | | | | | | | | | | | | | | | | Tools for the identification of bioactives impacting the metabolic syndrome: screening of a botanical extract library using subcutaneous and visceral human adipose-derived stem cell-based assays. J Nutr Biochem. 2011 May 2; Authors: Buehrer BM, Duffin DJ, Lea-Currie YR, Ribnicky D, Raskin I, Stephens JM, Cefalu WT, Gimble JM Plant extracts continue to represent an untapped source of renewable therapeutic compounds for the treatment and prevention of illnesses including chronic metabolic disorders. With the increase in worldwide obesity and its related morbidities, the need for identifying safe and effective treatments is also rising. As such, use of primary human adipose-derived stem cells represents a physiologically relevant cell system to screen for bioactive agents in the prevention and treatment of obesity and its related complications. By using these cells in a primary screen, the risk and cost of identifying artifacts due to interspecies variation and immortalized cell lines is eliminated. We demonstrate that these cells can be formatted into 384-well high throughput screens to rapidly identify botanical extracts that affect lipogenesis and lipolysis. Additionally, counterscreening with human primary stem cells from distinct adipose depots can be routinely performed to identify tissue specific responses. In our study, over 500 botanical extracts were screened and 16 (2.7%) were found to affect lipogenesis and 4 (0.7%) affected lipolysis. PMID: 21543201 [PubMed - as supplied by publisher] | | | | | | | | | |  | |  | |  |
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