http://stemcellres.com The latest research articles published by Stem Cell Research & Therapy 2010-08-26T00:00:00Z This is an RSS newsfeed from BioMed Central It is intended to be used with an RSS reader. For more information about RSS newsfeeds from BioMed Central, visit http://www.biomedcentral.com/info/about/rss/ Cellular commitment during vertebrate embryogenesis is controlled by an interplay of intrinsic regulators and morphogenetic signals. These mechanisms recruit a subset of cells in the developing organism to become the ancestors of skeletal muscle. Signals that control progression through the myogenic lineage converge on a battery of hierarchically organized transcription factors which modulate the cells to either remain in a primitive state or allow their commitment and differentiation into skeletal muscle fibers. A small population of cells will retain a largely unspecified state throughout development. Such stem cells, in conjunction with more committed myogenic progenitors, form a heterogeneous population that colonizes adult skeletal muscle as satellite cells. The satellite cell pool is responsible for the remarkable regenerative capacity of skeletal muscle. Similar to their counterparts during embryonic development, satellite cells are capable of self-renewal and can give rise to myogenic progeny. Impaired satellite cell homeostasis has been associated with numerous muscular disorders. Due to intense research efforts in the past two decades, the complex biology of muscle stem cells has now revealed some of its secrets and new avenues for the development of therapeutic molecules have emerged. In the present review we focus on the extrinsic mechanisms that control self-renewal, specification and differentiation of satellite cells and their significance for the development of biologic drugs. http://stemcellres.com/content/1/3/27 C. Bentzinger Julia von Maltzen Michael Rudnicki Stem Cell Research & Therapy 2010, 1:27 2010-08-26T00:00:00Z doi:10.1186/scrt27 Stem Cell Research & Therapy 1757-6512 1 27 2010-08-26T00:00:00Z XML Derivation of autologous induced pluripotent stem cells (iPSCs) through direct reprogramming of easily accessible somatic cells holds the potential to transform the field of regenerative medicine. Since Takahashi and Yamanaka's groundbreaking study describing the generation of iPSCs by retroviral-mediated delivery of defined transcription factors, substantial progress has been made to improve both the efficiency and safety of the method. These advances have provided new insights into the molecular mechanisms of reprogramming and promise to accelerate the clinical translation of iPSC technology. Here, we summarize current reprogramming methodologies with a focus on the production of transgene-free or genetically unmanipulated iPSCs and highlight important technical details that ultimately may influence the biological properties of pluripotent stem cells. http://stemcellres.com/content/1/3/26 Cesar Sommer Gustavo Mostoslavsky Stem Cell Research & Therapy 2010, 1:26 2010-08-10T00:00:00Z doi:10.1186/scrt26 Stem Cell Research & Therapy 1757-6512 1 26 2010-08-10T00:00:00Z XML Mesenchymal stem cells have a natural tropism for tumours and their metastases, and are also considered immunoprivileged. This remarkable combination of properties has formed the basis for many studies investigating their potential as tumour-specific delivery vehicles for suicide genes, oncolytic viruses and secreted therapeutic proteins. The aim of the present review is to discuss the range of approaches that have been used to exploit the tumour-homing capacity of mesenchymal stem cells for gene delivery, and to highlight advances required to realize the full potential of this promising approach. http://stemcellres.com/content/1/3/25 Roisin Dwyer Sonja Khan Frank Barry Timothy O'Brien Michael Kerin Stem Cell Research & Therapy 2010, 1:25 2010-08-09T00:00:00Z doi:10.1186/scrt25 Stem Cell Research & Therapy 1757-6512 1 25 2010-08-09T00:00:00Z XML The study of pluripotent stem cells has generated much interest in both biology and medicine. Understanding the fundamentals of biological decisions, including what permits a cell to maintain pluripotency, that is, its ability to self-renew and thereby remain immortal, or to differentiate into multiple types of cells, is of profound importance. For clinical applications, pluripotent cells, including both embryonic stem cells and adult stem cells, have been proposed for cell replacement therapy for a number of human diseases and disorders, including Alzheimer's, Parkinson's, spinal cord injury and diabetes. One challenge in their usage for such therapies is understanding the mechanisms that allow the maintenance of pluripotency and controlling the specific differentiation into required functional target cells. Because of regulatory restrictions and biological feasibilities, there are many crucial investigations that are just impossible to perform using pluripotent stem cells (PSCs) from humans (for example, direct comparisons among panels of inbred embryonic stem cells from prime embryos obtained from pedigreed and fertile donors; genomic analysis of parent versus progeny PSCs and their identical differentiated tissues; intraspecific chimera analyses for pluripotency testing; and so on). However, PSCs from nonhuman primates are being investigated to bridge these knowledge gaps between discoveries in mice and vital information necessary for appropriate clinical evaluations. In this review, we consider the mRNAs and novel genes with unique expression and imprinting patterns that were discovered using systems biology approaches with primate pluripotent stem and germ cells. http://stemcellres.com/content/1/3/24 Ahmi Ben-Yehudah Charles Easley Brian Hermann Carlos Castro Calvin Simerly Kyle Orwig Shoukhrat Mitalipov Gerald Schatten Stem Cell Research & Therapy 2010, 1:24 2010-08-05T00:00:00Z doi:10.1186/scrt24 Stem Cell Research & Therapy 1757-6512 1 24 2010-08-05T00:00:00Z XML IntroductionGenetic manipulation of human embryonic stem cells (hESC) has been limited by their general resistance to common methods used to introduce exogenous DNA or RNA. Efficient and high throughput transfection of nucleic acids into hESC would be a valuable experimental tool to manipulate these cells for research and clinical applications. Methods: We investigated the ability of two commercially available electroporation systems, the Nucleofection® 96-well Shuttle® System from Lonza and the Neon™ Transfection System from Invitrogen to efficiently transfect hESC. Transfection efficiency was measured by flow cytometry for the expression of the green fluorescent protein and the viability of the transfected cells was determined by an ATP catalyzed luciferase reaction. The transfected cells were also analyzed by flow cytometry for common markers of pluripotency. Results: Both systems are capable of transfecting hESC at high efficiencies with little loss of cell viability. However, the reproducibility and the ease of scaling for high throughput applications led us to perform more comprehensive tests on the Nucleofection® 96-well Shuttle® System. We demonstrate that this method yields a large fraction of transiently transfected cells with minimal loss of cell viability and pluripotency, producing protein expression from plasmid vectors in several different hESC lines. The method scales to a 96-well plate with similar transfection efficiencies at the start and end of the plate. We also investigated the efficiency with which stable transfectants can be generated and recovered under antibiotic selection. Finally, we found that this method is effective in the delivery of short synthetic RNA oligonucleotides (siRNA) into hESC for knockdown of translation activity via RNA interference. Conclusions: Our results indicate that these electroporation methods provide a reliable, efficient, and high-throughput approach to the genetic manipulation of hESC. http://stemcellres.com/content/1/3/23 Jennifer Moore Kristin Atze Percy Yeung Alana Toro-Ramos Cynthia Camarillo Kevin Thompson Christopher Ricupero Mark Brenneman Rick Cohen Ronald Hart Stem Cell Research & Therapy 2010, 1:23 2010-07-26T00:00:00Z doi:10.1186/scrt23 Stem Cell Research & Therapy 1757-6512 1 23 2010-07-26T00:00:00Z XML Quyn and colleagues report that gut stem cells have a biased spindle orientation and asymmetric retention of label-retaining DNA. These features are lost in mouse and human tissues when the microtubule binding protein Apc is mutated. In the developing kidney, Apc acts downstream from primary cilium signaling to influence spindle orientation when noncanonical Wnt signaling predominates. Do gut stem cells also have primary cilia? http://stemcellres.com/content/1/3/21 Peter Satir Stem Cell Research & Therapy 2010, 1:21 2010-07-23T00:00:00Z doi:10.1186/scrt21 Stem Cell Research & Therapy 1757-6512 1 21 2010-07-23T00:00:00Z XML IntroductionOn the basis of the recently recognized potential of hematopoietic stem cells (HSCs) to give rise to hepatocytes, we have assessed the potential of granulocyte colony-stimulating factor (G-CSF)-mobilized bone marrow-derived CD34+ HSCs to contribute to faster recovery and promote regeneration process after acute liver injury by radiation. Methods: G-CSF-mobilized CD34+ HSCs (1 × 105 cells per mouse) were injected via tail vein in the irradiated femal nonobese diabetic/severe combined immunodeficient mice. Irradiated control animals received only saline infusion. Results: The mobilized CD34+ HSCs significantly ameliorated radiation-induced liver damage. In the liver of recipient mice killed 21 days after irradiation, human albumin+ Y-chromosome+ hepatocyte-like cells, or human cytokeratin+ Y-chromosome+ hepatocyte-like cells formed cords of hepatocytes, occupied ~30% of the 4-μm section surrounding portal tracts. Furthermore, human-specific albumin mRNA expressed in the liver and human albumin was detected in the serum only in the CD34+ HSC-treated mice. Conclusions: Treatment with G-CSF-mobilized CD34+ HSCs from bone marrow into peripheral blood could significantly promote tissue reparation after acute liver injury by radiation in mice, possibly by the ability of CD34+ HSCs to generate hepatocytes. So mobilization of CD34+ HSCs might offer a novel therapeutic approach for the treatment of radiation-induced complications after radiotherapy or other acute liver diseases in humans. http://stemcellres.com/content/1/3/22 Ning Li Li Zhang Huixiang Li Baijun Fang Stem Cell Research & Therapy 2010, 1:22 2010-07-15T00:00:00Z doi:10.1186/scrt22 Stem Cell Research & Therapy 1757-6512 1 22 2010-07-15T00:00:00Z XML IntroductionAmniotic fluid harbors cells indicative of all three germ layers, and pluripotent fetal amniotic fluid stem cells (AFSs) are considered potentially valuable for applications in cellular therapy and tissue engineering. We investigated whether it is possible to direct the cell fate of AFSs in vivo by transplantation experiments into a particular microenvironment, the mammary fat pad. This microenvironment provides the prerequisites to study stem cell function and the communication between mesenchymal and epithelial cells. On clearance of the endogenous epithelium, the ductal tree can be reconstituted by the transfer of exogenously provided mammary stem cells. Analogously, exogenously provided stem cells from other tissues can be investigated for their potential to contribute to mammary gland regeneration. Methods: We derived pluripotent murine AFSs, measured the expression of stem cell markers, and confirmed their in vitro differentiation potential. AFSs were transplanted into cleared and non cleared fat pads of immunocompromised mice to evaluate their ability to assume particular cell fates under the instructive conditions of the fat-pad microenvironment and the hormonal stimulation during pregnancy. Results: Transplantation of AFSs into cleared fat pads alone or in the presence of exogenous mammary epithelial cells caused their differentiation into stroma and adipocytes and replaced endogenous mesenchymal components surrounding the ducts in co-transplantation experiments. Similarly, transplantation of AFSs into fat pads that had not been previously cleared led to AFS-derived stromal cells surrounding the elongating endogenous ducts. AFSs expressed the marker protein α-SMA, but did not integrate into the myoepithelial cell layer of the ducts in virgin mice. With pregnancy, a small number of AFS-derived cells were present in acinar structures. Conclusions: Our data demonstrate that the microenvironmental cues of the mammary fat pad cause AFSs to participate in mammary gland regeneration by providing mesenchymal components to emerging glandular structures, but do not incorporate or differentiate into ductal epithelial cells. http://stemcellres.com/content/1/3/20 Petra Klemmt Vida Vafaizadeh Bernd Groner Stem Cell Research & Therapy 2010, 1:20 2010-07-07T00:00:00Z doi:10.1186/scrt20 Stem Cell Research & Therapy 1757-6512 1 20 2010-07-07T00:00:00Z XML Adipose tissue is now recognized as an accessible, abundant, and reliable site for the isolation of adult stem cells suitable for tissue engineering and regenerative medicine applications. The past decade has witnessed an explosion of preclinical data relating to the isolation, characterization, cryopreservation, differentiation, and transplantation of freshly isolated stromal vascular fraction cells and adherent, culture-expanded, adipose-derived stromal/stem cells in vitro and in animal models. This body of work has provided evidence supporting clinical translational applications of adipose-derived cells in safety and efficacy trials. The present article reviews the case reports and phase I-III clinical evidence using autologous adipose-derived cells that have been published, to date, in the fields of gastroenterology, neurology, orthopedics, reconstructive surgery, and related clinical disciplines. Future directions and challenges facing the field are discussed and evaluated. http://stemcellres.com/content/1/2/19 Jeffrey Gimble Farshid Guilak Bruce Bunnell Stem Cell Research & Therapy 2010, 1:19 2010-06-29T00:00:00Z doi:10.1186/scrt19 Stem Cell Research & Therapy 1757-6512 1 19 2010-06-29T00:00:00Z XML IntroductionMesenchymal stem cells (MSCs) offer promise for intervertebral disc (IVD) repair and regeneration because they are easily isolated and expanded, and can differentiate into several mesenchymal tissues. Notochordal (NC) cells contribute to IVD development, incorporate into the nucleus pulposus (NP), and stimulate mature disc cells. However, there have been no studies investigating the effects of NC cells on adult stem cell differentiation. The premise of this study is that IVD regeneration is more similar to IVD development than to IVD maintenance, and we hypothesize that soluble factors from NC cells differentiate MSCs to a phenotype characteristic of nucleus pulposus (NP) cells during development. The eventual clinical goal would be to isolate or chemically/recombinantly produce the active agent to induce the therapeutic effects, and to use it as either an injectable therapy for early intervention on disc disease, or in developing appropriately pre-differentiated MSC cells in a tissue engineered NP construct. Methods: Human MSCs from bone marrow were expanded and pelleted to form high-density cultures. MSC pellets were exposed to either control medium (CM), chondrogenic medium (CM with dexamethasone and transforming growth factor, (TGF)-β3) or notochordal cell conditioned medium (NCCM). NCCM was prepared from NC cells maintained in serum free medium for four days. After seven days culture, MSC pellets were analyzed for appearance, biochemical composition (glycosaminoglycans and DNA), and gene expression profile (sox-9, collagen types-II and III, laminin-β1 and TIMP1(tissue inhibitor of metalloproteinases-1)). Results: Significantly higher glycosaminoglycan accumulation was seen in NCCM treated pellets than in CM or TGFβ groups. With NCCM treatment, increased gene expression of collagen III, and a trend of increasing expression of laminin-β1 and decreased expression of sox-9 and collagen II relative to the TGFβ group was observed. Conclusions: Together, results suggest NCCM stimulates mesenchymal stem cell differentiation toward a potentially NP-like phenotype with some characteristics of the developing IVD. http://stemcellres.com/content/1/2/18 Casey Korecki Juan Taboas Rocky Tuan James Iatridis Stem Cell Research & Therapy 2010, 1:18 2010-06-16T00:00:00Z doi:10.1186/scrt18 Stem Cell Research & Therapy 1757-6512 1 18 2010-06-16T00:00:00Z XML