StemCellGateway

Stem Cell Reviews and Reports: Stem Cell Competition for Niche Occupancy: Emerging Themes and Mechanisms

Rui Zhao; Rongwen Xi — 2010-09-01

Type: Review Paper

Tissue-specific adult stem cells are responsible for generating a range of various differentiated cells during their life time; these cells are intimately associated with niche for maintenance and function. Recent studies of germline stem cell niches in Drosophila gonad suggest that stem cells within a niche constantly compete with each other for niche occupancy. Competition within a niche occurs between same type of stem cells as well as different types. In both cases, cell adhesion molecules are critical in mediating the competition.

Stem Cell Reviews and Reports: Risks and Mechanisms of Oncological Disease Following Stem Cell Transplantation

Sergey Anisimov; Asuka Morizane; Ana Correia — 2010-09-01

Type: Review Paper

Unique biological properties of stem cells make them a precious source of cell material for treatment of a number of pathological conditions. Among issues inhibiting transition of stem cell technologies to the clinics, the risk of oncological complications of stem cell-based therapies is the most critical. A massive amount of clinical and experimental data demonstrates that both hematological (including acute and chronic myeloid leukemia) and non-hematological (including teratoma and non-teratoma tumors) malignancies could arise from donor stem cells of different types. A wide spectrum of mechanisms could underlie the development of oncological disease in recipients, including: i) blast transformation of proliferating donor stem cells under persistent action of certain factors in the recipient, thus causing de novo malignancies; ii) contamination of donor cell material with malignant cells; iii) transmission of particular viral subtypes with donor stem cells, combined with immunosuppression therapy effects; iv) uncontrollable proliferation of residual undifferentiated stem cells of various plasticity; and v) karyotypic instability in stem cells following prolonged culturing/expansion in vitro. Potential preventive strategies are diverse and include i) high-throughput cell sorting-based strategies; ii) introduction of suicide genes into the donor stem cell genome; iii) application of apoptosis-inducing epigenetic factors; and some other options.

Stem Cell Reviews and Reports: Stem/Precursor Cell-Based CNS Therapy: The Importance of Circumventing Immune Suppression by Transplanting Autologous Cells

Iris Kulbatski — 2010-09-01

Type: Original Paper

Stem/precursor cell (SPC) therapy for neurodegeneration and neurotrauma has enormous therapeutic potential, but despite ongoing research efforts the success of clinical trials remains limited. Therapies that utilize immune suppression in combination with SPC transplantation have thus far failed to consider the beneficial role of the immune system in central nervous system (CNS) recovery. Systemic immune suppression may prevent neural repair, and in some cases exacerbate the underlying disorder. Until about a decade ago, immunosuppression for CNS disorders was viewed as a therapeutic target, based on the perception that all immune activity in the CNS was destructive. However, recent studies show that the infiltration of blood-borne immune cells into the CNS following neurotrauma and during chronic neurodegeneration promote CNS protection and regeneration. In the context of SPC therapies, although immune suppression prevents rejection of non-autologous cell grafts, it also prevents the restorative immune response by eliminating the immune mediated guidance cues that are required for SPCs to migrate to the location they are needed, and preventing SPC-mediated immunomodulation. This article argues in favor of transplanting autologous SPCs, particularly bone marrow derived cells. The therapeutic use of autologous SPCs for neural repair circumvents the need for concomitant immune suppression, exploits the immunomodulatory capacity of these cells, and maintains the immune niche that supports neural repair and is required to guide these cells to their appropriate locations. Overall, such an approach accommodates the requirements for translational therapeutics, and provides a standardized platform for reconciling the inherent controversies in the science.

Stem Cell Reviews and Reports: Advances in Reprogramming Somatic Cells to Induced Pluripotent Stem Cells

Minal Patel; Shuying Yang — 2010-09-01

Type: Review Paper

Traditionally, nuclear reprogramming of cells has been performed by transferring somatic cell nuclei into oocytes, by combining somatic and pluripotent cells together through cell fusion and through genetic integration of factors through somatic cell chromatin. All of these techniques changes gene expression which further leads to a change in cell fate. Here we discuss recent advances in generating induced pluripotent stem cells, different reprogramming methods and clinical applications of iPS cells. Viral vectors have been used to transfer transcription factors (Oct4, Sox2, c-myc, Klf4, and nanog) to induce reprogramming of mouse fibroblasts, neural stem cells, neural progenitor cells, keratinocytes, B lymphocytes and meningeal membrane cells towards pluripotency. Human fibroblasts, neural cells, blood and keratinocytes have also been reprogrammed towards pluripotency. In this review we have discussed the use of viral vectors for reprogramming both animal and human stem cells. Currently, many studies are also involved in finding alternatives to using viral vectors carrying transcription factors for reprogramming cells. These include using plasmid transfection, piggyback transposon system and piggyback transposon system combined with a non viral vector system. Applications of these techniques have been discussed in detail including its advantages and disadvantages. Finally, current clinical applications of induced pluripotent stem cells and its limitations have also been reviewed. Thus, this review is a summary of current research advances in reprogramming cells into induced pluripotent stem cells.

Stem Cell Reviews and Reports: Endoplasmic Reticulum Stress Signals in Defined Human Embryonic Stem Cell Lines and Culture Conditions

2010-09-01

Type: Original Paper

Human embryonic stem cells (hESCs) are especially resistant to several cellular stresses, but the existence and induction of Endoplasmic Reticulum (ER) stress by culture conditions are unknown. Using qPCR, here, we investigated the behavior of the principal sensors of ER stress and their relation with the feeder layer, the type of conditioned media used in feeder free systems and the upregulation of several differentiation markers. We observed the preservation of pluripotency, and detected differential expression of differentiation markers in HS181 and SHEF1 hESCs growing on Adipose-derived mesenchymal stem cells (ASCs) and feeder-free system with different conditioned media (HEF-CM and ASC-CM). Taken together, these results demonstrate evidence of ER stress events that cells must resolve to survive and maintenance of markers of pluripotency. The early differentiation status defined could progress into a more differentiated state, and may be influenced by culture conditions.

Stem Cell Reviews and Reports: The iPS Technique Provides Hope for Parkinson’s Disease Treatment

Liang Xu; Yu-Yan Tan; Jian-Qing Ding; Sheng-Di Chen — 2010-09-01

Type: Review Paper

More recently, reprogramming of somatic cells to an embryonic stem cell-like state presents a milestone in the realm of stem cells, making it possible to derive all cell types from any patients bearing specific genetic mutations. With the development of induced pluripotent stem (iPS) cells, we are now able to use the derivatives of iPS cells to study the mechanisms of disease and to perform drug screening and toxicology testing. In addition, differentiated iPS cells are now close to be used in clinical practice. Here we review the progress of iPS technique and the possible application in the area of Parkinson’s disease treatment.

Stem Cell Reviews and Reports: Variation in Hematopoietic Potential of Induced Pluripotent Stem Cell Lines

Kasem Kulkeaw; Yuka Horio; Chiyo Mizuochi; Minetaro Ogawa; Daisuke Sugiyama — 2010-09-01

Type: Report

Induced pluripotent stem (iPS) cells were originally generated from somatic cells by ectopic expression of four transcription factor genes: Oct3/4, Sox2, Klf4 and c-Myc. Currently, iPS cell lines differ in tissue origin, the combination of factors used to construct them, the method of gene delivery and expression of pluripotency markers. Thus to evaluate iPS cells for haematotherapy, the hematopoietic potential among iPS lines should be compared. Here, we compare differentiation capacity of six iPS lines into mesodermal cells and hematopoietic cells (HCs) through embryoid body (EB) formation. We show that the mouse embryonic fibroblast (MEF)-derived iPS lines 20D17 and 178B5 resemble CCE ES cells in terms of morphology in culture, number and size of EBs and differentiation capacity into mesodermal cells compared to iPS cells derived from adults, although all iPS lines could form EBs. The number of mesodermal cells differentiated from MEF-derived iPS cell lines showed a 3.9–407-fold increase compared to that from iPS lines derived from adults. Furthermore, 178B5 iPS cells generated Ter119⁺ erythroid cells (3.35%) efficiently in culture. We conclude that hematopoietic potential differs among the six lines and that MEF-derived 20D17 and 178B5 iPS cells generate HCs more efficiently than adult–derived iPS cells.

Stem Cell Reviews and Reports: Culture Conditions and Signalling Networks Promoting the Establishment of Cell Lines from Parthenogenetic and Biparental Pig Embryos

2010-09-01

Type: Report

The generation of porcine embryonic stem cells (pESC) would potentially have great impact in the biomedical field given the long-standing history of the pig as a prime animal model for pre-clinical biomedical applications. These cells would also be beneficial for the agricultural area, allowing efficient genetic engineering of this animal, to improve health and production traits. Despite numerous reports, no conclusive results have been obtained on the isolation and propagation of pESC lines and the establishment of pluripotent cells from the pig has remained an elusive goal. In the present study we performed a systematic analysis of different culture media for their ability to support the establishment of homogenous outgrowths from in vitro-produced embryos. Furthermore, we investigated which molecular networks are responsive to the factors contained in the most efficient media, since the identification of dominant signaling pathways that regulate porcine stem-cell pluripotency is likely to facilitate the generation of genuine pESC. Finally we compared IVF blastocysts versus parthenotes as a possible source for putative pESC in terms of blastocyst rate, resilience to immunosurgery procedures, ability to attach to the feeder, to generate outgrowths and to establish stable cell lines.

Stem Cell Reviews and Reports: Selective Removal of Undifferentiated Embryonic Stem Cells from Differentiation Cultures Through HSV1 Thymidine Kinase and Ganciclovir Treatment

Ortwin Naujok; Joanna Kaldrack; Terbish Taivankhuu; Anne Jörns; Sigurd Lenzen — 2010-09-01

Type: Report

Pluripotent cell lines such as embryonic stem cells are an attractive source for a potential cell replacement therapy. However, transplantation of differentiated cells harbors the risk of teratoma formation, presenting a serious health risk. To overcome this obstacle, a negative selection system was established that permits selective removal of undifferentiated cells during in vitro differentiation. Use of the HSV1 thymidine kinase and eGFP under the control of the Oct4 promoter allowed the destruction of undifferentiated ES cells by ganciclovir treatment; differentiated cells were unharmed. Clonal ES cells remained pluripotent and showed positive staining for a wide range of embryonic markers. Thus, treatment with ganciclovir during in vitro differentiation effectively removed the population of undifferentiated cells and provided a pure population of completely differentiated cells. This approach may pave the way for a safe application of ES cells in regenerative medicine in the future.

Stem Cell Reviews and Reports: Regulation of Human Stem Cell Research in South Korea

Kyu Jung — 2010-09-01

Type: Brief Communication

Human stem cell research has been performed for many years in South Korea. It has been supported by the South Korean government, like other biomedical research. Like many other countries, human embryonic stem cell research, human adult stem cell research and iPS cell research have been performed in South Korea. The Bioethics and Safety Act is the main law which regulates human stem cell research. It took effect on 1 January 2005. However, this Act does not include all the fields of biomedical research and some provisions were not clear. After Hwang’s scandal, there have been heated debates about the revision of the Bioethics and Safety Act. It was revised several times and a new revised version is under consideration now.

Stem Cell Reviews and Reports: Generation of Human Embryonic Stem Cell Reporter Lines Expressing GFP Specifically in Neural Progenitors

Parinya Noisa; Alai Urrutikoetxea-Uriguen; Meng Li; Wei Cui — 2010-09-01

Type: Report

Generation of lineage-specific human embryonic stem cell (hESC) reporter lines will facilitate the real time monitoring of differentiation in live cells and the identification of factors governing these processes. It will also enable researchers to purify specific cell populations from heterogeneous differentiated hESC progeny. Here we report the generation of clonally derived nestin-EGFP reporter hESC lines that express GFP under the control of the neuroepithelial specific nestin 2nd intron enhancer. We show that the nestin-EGFP hESC reporter lines retain the features of undifferentiated hESCs, are able to self-renew in hESC culture conditions and to differentiate into cells of all three germ layers. The nestin-EGFP reporter exhibited high expression in neural progenitor cells upon differentiation, although it is detectable at a low level in the undifferentiated state. Furthermore, the expression of the transgene is exclusively confined to the neural progenitors after differentiation. The specific expression of the transgene is determined by collaborative binding motifs of POU and SOX transcription factors in the nestin enhancer. Deletion of either of the binding elements resulted in a significant reduction of enhancer/promoter activity. Taken together, the nestin-EGFP reporter hESC lines are invaluable not only for the study of the neural differentiation process from hESCs but also for the enrichment of neural progenitor cells from other cell lineages.

Stem Cell Reviews and Reports: Human Embryonic Stem Cells (hESCs) Cultured Under Distinctive Feeder-Free Culture Conditions Display Global Gene Expression Patterns Similar to hESCs from Feeder-Dependent Culture Conditions

2010-09-01

Type: Report

Human embryonic stem cell (hESC)–based assay systems and genetically modified hESCs are very useful tools for screening drugs that regulate stemness and differentiation and for studying the molecular mechanisms involved in hESC fate determination. For these types of studies, feeder cell–dependent cultures of hESCs are often problematic because the physiology of the feeder cells is perturbed by the drug treatments or genetic modifications, which potentially obscures research outcomes. In this study, we evaluated three commonly used feeder-free culture conditions to determine whether they supported the undifferentiated growth of hESCs and to determine whether the hESCs grown in these conditions displayed gene expression patterns that were similar to the expression patterns of feeder cell-dependent hESCs. Our results demonstrate that hESCs grown in the three feeder-free conditions expressed undifferentiation marker genes as strongly as hESCs that were grown in the feeder-dependent cultures. Furthermore, genome-wide gene expression profiles indicated that the gene expression patterns of hESCs that were grown under feeder-free or feeder-dependent culture conditions were highly similar. These results indicate that the feeder-free culture conditions support the undifferentiated growth of hESCs as effectively as the feeder-dependent culture conditions. Therefore, feeder-free culture conditions are potentially suitable for drug screening and for the genetic manipulation of hESCs in basic research.

Stem Cell Reviews and Reports: Transplantation of Mammalian Embryonic Stem Cells and Their Derivatives to Avian Embryos

Ronald Goldstein — 2010-09-01

Type: Review Paper

Xenografting of normal and transformed mammalian tissues and cells to chick embryos has been performed for almost 100 years. Embryonic stem cells, derived more than 25 years ago from murine, and more than 10 years ago from human blastocysts, have transformed many fields of biological research. There is a growing body of studies combining these two widely-used experimental systems. This review surveys those reports in which murine or human embryonic stem cells, or differentiated derivatives of these pluripotent stem cells, were transplanted to embryonated chick eggs. Many of these studies have utilized the unique characteristics of both experimental models to obtain answers to developmental questions that are difficult or impossible to approach with xenografting to adult rodents or tissue culture-only techniques.

Stem Cell Reviews and Reports: Viable Fertile Mice Generated from Fully Pluripotent iPS Cells Derived from Adult Somatic Cells

2010-09-01

Type: Report

Previous studies demonstrated that induced pluripotent stem (iPS) cells could produce viable mice through tetraploid complementation, which was thought to be the most stringent test for pluripotency. However, these highly pluripotent iPS cells were previously reported to be generated from fibroblasts of embryonic origin. Achieving fully pluripotent iPS cells from multiple cell types, especially easily accessible adult tissues, will lead to a much greater clinical impact. We successfully generated high-pluripotency iPS cells from adult tail tip fibroblasts (TTF) that resulted in viable, full-term, fertile TTF-iPS animals with no obvious teratoma formation or other developmental abnormalities. Comparison of iPS cells from embryonic origin (MEF), progenitor cells (neural stem cells) or differentiated somatic cells (TTF) reveals that fully pluripotent developmental potential can be reached by each cell type, although with different induction efficiencies. This work provides the means for studying the mechanisms and regulation of direct reprogramming, and has encouraging implications for future clinical applications and therapeutic interventions.

Stem Cell Reviews and Reports: G-protein Coupled Receptors in Stem Cell Self-Renewal and Differentiation

Nao Kobayashi; Susan Hawes; Jeremy Crook; Alice Pébay — 2010-09-01

Type: Review Paper

Stem cells have great potential for understanding early development, treating human disease, tissue trauma and early phase drug discovery. The factors that control the regulation of stem cell survival, proliferation, migration and differentiation are still emerging. Some evidence now exists demonstrating the potent effects of various G-protein coupled receptor (GPCR) ligands on the biology of stem cells. This review aims to give an overview of the current knowledge of the regulation of embryonic and somatic stem cell maintenance and differentiation by GPCR ligands.

Stem Cell Reviews and Reports: Popular Culture Representations of Science: Views from the Canadian Stem Cell Research Community

Timothy Caulfield; Amy Zarzeczny — 2010-09-01

Type: Original Paper
No abstract available.

Stem Cell Reviews and Reports: The Regenerative Potential of the Kidney: What Can We Learn from Developmental Biology?

2010-08-17

Type: Original Paper

Cell turnover in the healthy adult kidney is very slow but the kidney has a strong capacity for regeneration after acute injury. Although many molecular aspects of this process have been clarified, the source of the newly-formed renal epithelial cells is still being debated. Several studies have shown, moreover, that the repair of injured renal epithelium starts from mature tubular cells, which enter into an activated proliferative state characterized by the reappearance of mesenchymal markers detectable during nephrogenesis, thus pointing to a marked plasticity of renal epithelial cells. The regenerative potential of mature epithelial cells might stem from their almost unique morphogenetic process. Unlike other tubular organs, all epithelial and mesenchymal cells in the kidney derive from the same germ layer, the mesoderm. In a fascinating view of vertebrate embryogenesis, the mesoderm might be seen as a cell layer capable of oscillating between epithelial and mesenchymal states, thus acquiring a remarkable plasticity that lends it an extended potential for innovation and a better control of three-dimensional body organization. The renal papilla contains a population of cells with the characteristic of adult stem cells. Mesenchymal stromal stem cells (MSC) have been found to reside in the connective tissue of most organs, including the kidney. Recent studies indicate that the MSC compartment extends throughout the body postnatally as a result of its perivascular location. Developmental biology suggests that this might be particularly true of the kidney and that the papilla might represent the perivascular renal stem cell niche. The perivascular niche hypothesis fits well with the evolving concept of the stem cell niche as an entity of action. It is its dynamic capability that makes the niche concept so important and essential to the feasibility of regenerative medicine.

Stem Cell Reviews and Reports: ROCK Inhibitor Y-27632 Increases Thaw-Survival Rates and Preserves Stemness and Differentiation Potential of Human Wharton’s Jelly Stem Cells After Cryopreservation

2010-08-14

Type: Original Paper

The ROCK inhibitor Y-27632 inhibits apoptosis and increases proliferation of frozen-thawed cells. We examined the role of Y-27632 on human umbilical cord Wharton’s jelly stem cells (hWJSCs) for (1) thaw-survival (2) proliferation and (3) preservation of stemness and differentiation potential after cryopreservation. hWJSCs were allotted to 4 groups [Gp I: Untreated hWJSC controls; Gp II: Pretreatment with Y-27632 (10 μM) for 24 h before freezing; Gp III: Y-27632 (10 μM) in freezing medium and Gp IV: Pretreatment with Y-27632 (10 μM) for 24 h and inclusion in freezing medium]. All groups were frozen using a rapid freezing method and stored at -196°C in liquid nitrogen for 90 days before evaluation for apoptosis, cell proliferation, stemness and differentiation. After thawing, Groups II, III and IV showed improved cell attachment, increased thaw-survival (live/dead cell counts) and increased cell proliferation (Trypan blue and MTT assay) compared to controls. CD marker stemness profiles, morphology and normal karyotypes were maintained in the treatment groups after thawing and there was no obvious evidence of apoptosis (Annexin V-FITC and TUNEL assays). After thawing, qRT-PCR demonstrated up-regulation of the anti-apoptotic BCL2 gene and down-regulation of the pro-apoptotic BAX gene and cell cycle regulators (P53 and P21) in the treatment groups. Treated frozen-thawed hWJSCs from all groups differentiated into a neuronal phenotype (neuronal morphology and expression of GFAP, β-3 tubulin and SOX2). Increased thaw-survival and retention of stemness and differentiation potential in hWJSCs following cryopreservation is useful for their storage in cord blood banks for future regenerative medicine purposes.

Stem Cell Reviews and Reports: Human Embryonic Stem Cell-extracts Inhibit the Differentiation and Function of Monocyte-derived Dendritic Cells

Kanishka Mohib; David Allan; Lisheng Wang — 2010-08-14

Type: Report

Embryonic stem cells (ESC) possess inherent properties of immune privilege with the capacity to evade allogeneic immune responses. Moreover, ESCs have been shown to prevent immune activation in response to third party antigen presenting cells in vitro and have the capacity to promote allograft survival in vivo. However, clinical use of human ESCs to treat immunological disorders may risk teratoma or ectopic tissue formation. Here, we show that cellular extracts from both human and mouse ESCs retain the immune modulatory properties of intact cells. ESC-extracts that contained 12–24 μg of total protein effectively prevented T cell proliferation in allogeneic mixed lymphocyte reactions (MLR), whereas control fibroblast extracts did not affect proliferation. Cellular mechanisms underlying hESC extract-mediated immune modulation involve the maturation of monocyte derived dendritic cells (mDC). hESC extract-treated mDCs had reduced surface expression of co-stimulatory and maturation markers CD80, HLA-DR and CD83 and secreted lower levels of IL12p40. Accordingly, hESC extract-treated DCs were found to be poor stimulators of purified allogeneic T cells compared to those DCs treated with vehicle or fibroblast extracts. Our results demonstrate that ESC extracts retain the immune modulatory properties of ESCs and for the first time demonstrates that ESC derived factors can inhibit human mDC maturation and function.

Stem Cell Reviews and Reports: Glioma Stem/Progenitor Cells Contribute to Neovascularization via Transdifferentiation

2010-08-10

Type: Report
Objective

Previous studies suggest that tumor cells might be the progenitor for tumor vasculature. Whether vascular tube formation from transdifferentiation of human glioma stem/progenitor cells (hGSPCs) contribute to angiogenesis of gliomas remain largely uncertain.

Methods

hGSPCs were isolated from thirteen surgical specimens of gliomas and cultured in medium favored for stem cell growth. In vitro transdifferentiation of hGSPCs was performed under hypoxia. Expression of vascular endothelial cells (VECs) markers CD31, CD34, kinase insert domain receptor (KDR), and von Willebrand factor (vWF) were analyzed with real-time quantitative RT-PCR and immunofluorescence techniques. Vasculogenic mimicry of hGSPCs was evaluated in a tumor stem cell xenograft model in vivo. Relationships between content of hGSPCs and expression levels of both VECs markers and proangiogenic factors in large number of clinical specimens were further investigated in glioma tissue microarray.

Results

In vitro, hGSPCs can transdifferentiate into VECs under hypoxia, they manifested typical “flagstone” pattern when cultivated in medium containing VEGF for a few days; when cultivated on Matrigel they were capable of forming capillary-like structures. Expression of VECs markers including CD31, CD34, KDR, and vWF were significantly up-regulated after transdifferentiation. Human leukocyte antigen (HLA) positively stained vessels were observed inside the xenograft tumors after intracerebral transplantation of hGSPCs in athymic nude mice, implied part of tumor cells with human origin were involved in formation of tumor vessels. In surgical specimens of human glioma, tumor vascular cells coexpressing the markers of early VECs (CD34) and markers of hGSPCs (ABCG2 and nestin) suggest that these vascular cells may stemmed from hGSPCs.

Conclusions

Our observations suggest the functional role of hGSPCs as endothelial progenitors, which have properties that give rise to VECs, and have the ability to form vascular endothelial tubes. However, unspecific markers (ABCG2, nestin) that stain for both endothelial as well as glioma stem cells, were found to be expressed in tumor vasculature of human specimen, and limit further interpretation of this finding.

Stem Cell Reviews and Reports: In Silico Analyses of Proteomic Data Suggest a Role for Heat Shock Proteins in Umbilical Cord Blood Hematopoietic Stem Cells

Angelo D’Alessandro; Giuliano Grazzini; Bruno Giardina; Lello Zolla — 2010-08-10

Type: Review Paper

Umbilical-cord blood (UCB) has growingly become an accepted alternative source of hematopoietic stem cells for transplantation purposes. However, the low cell dose limit within a single unit is still an obstacle hindering the way of a broader diffusion. The real deal is the lack of knowledge about the molecular processes governing the events of expansion and differentiation of these cells. In order to fill this void, several studies were focused on the identification of the peculiar whole protein profile of UCB-derived hematopoietic stem cells. In this review article we provide a referenced list of overall proteins from UCB-derived hematopoietic stem and progenitor cells. This list has been elaborated for pathway and network analyses, along with GO term enrichment for biological and molecular functions, in order to individuate main classes of proteins governing functioning of these cells. From these analyses it seems to emerge a central role for heat shock proteins in immature hematopoietic stem cells. Their role might be relevant in protecting crucial transcription factors which drive proliferation and differentiation towards a specific lineage (e.g. erythroid, myeloid). Hereby we also stress the helpfulness of interactomics elaboration in providing a unified overview of independent proteomics data. It appears that maturation, other than representing a bottleneck to protein expression, could sculpt interaction maps via reducing complexity of immature interactomics profiles.

Stem Cell Reviews and Reports: Effects of Microgravity Modeled by Large Gradient High Magnetic Field on the Osteogenic Initiation of Human Mesenchymal Stem Cells

2010-08-10

Type: Report

Microgravity (MG) leads to a decrease in osteogenic potential of human bone marrow-derived mesenchymal stem cells (hMSCs). In the present study, we used large gradient high magnetic field (LGHMF) produced by a superconducting magnet to model MG (LGHMF-MG) and analyzed the effects of LGHMF-MG on survival, cytoskeleton and osteogenic potential of hMSCs. Results showed that the LGHMF-MG treatment for 6 h disrupted the cytoskeleton of hMSCs, and the LGHMF-MG treatment for 24 h led to cell death. LGHMF-MG treatments for 6 h in early stages of osteogenic induction (the pre-treatment before osteogenic induction, the beginning-treatment in the beginning-stage of osteogenic induction and the middle-treatment in the middle-stage of osteogenic induction) resulted in suppression on osteogenesis of hMSCs. The suppression intensity was reduced gradually as the treatment stage of LGHMF-MG was postponed. The LGHMF-MG treatment for 6 h in the ending-stage of osteogenic induction (the ending-treatment) had no obvious effect on osteogenesis of hMSCs. These results indicated that LGHMF-MG should affect the initiation of osteogenesis. Finally, the possible mechanism for the inhibition effect of LGHMF-MG on osteogenesis of hMSCs is discussed.

Stem Cell Reviews and Reports: Enhanced Functions of Human Embryonic Stem Cell-derived Hepatocyte-like Cells on Three-dimensional Nanofibrillar Surfaces

2010-08-07

Type: Report

Human embryonic stem cell (hESC)-derived hepatocytes provide a promising unlimited resource for the treatment of liver disease. However, current protocols for the generation of mature and functional hepatocytes are inefficient. Therefore, in order to better differentiate and maintain the function of differentiating hESCs, we have hypothesized that hESCs undergo better differentiation into hepatocyte-like cells (HLCs) when induced on three-dimensional nanofibrillar surfaces. We have demonstrated that, during stepwise differentiation of induction, the markers of hepatic lineage expressed and finally lead to the generation of functional mature cells. In the presence of an ultraweb nanofiber, HLCs produced lower AFP, greater urea, glycogen storage, metabolic PROD activity, uptake of LDL and organic anion ICG, all of which are indicative of the differentiation of HLCs. These results show that topographically treated hESCs at the nano level have a distinct hepatic functionality profile which has implications for cell therapies.

Stem Cell Reviews and Reports: The Proliferation and Differentiation of Stem Cell Journals

Paul Sanberg; Cesar Borlongan — 2010-08-07

Type: Brief Communication

As scientists position themselves in translating the therapeutic potential of stem cells from laboratory to clinical applications, publishing companies have taken this rapidly evolving field as a unique opportunity to launch new journals for dissemination of stem cell research. Over the last decade, the significant increase in the number of stem cell-based journals has created a conundrum. At stake is the pressure for these new journals to build their reputation by maintaining publication standards, while at the same time attracting a cadre of stem cell researchers to consider their journals as the publication of choice. We discuss here a prophetic path of survival for these journals which likely will closely mimic the core scientific and translational value of stem cells, namely their capacity to proliferate and differentiate into something meaningful!

Stem Cell Reviews and Reports: Inflammatory Cytokine Induced Regulation of Superoxide Dismutase 3 Expression by Human Mesenchymal Stem Cells

Kevin Kemp; Elizabeth Gray; Elizabeth Mallam; Neil Scolding; Alastair Wilkins — 2010-08-04

Type: Report

Increasing evidence suggests that bone marrow derived-mesenchymal stem cells (MSCs) have neuroprotective properties and a major mechanism of action is through their capacity to secrete a diverse range of potentially neurotrophic or anti-oxidant factors. The recent discovery that MSCs secrete superoxide dismutase 3 (SOD3) may help explain studies in which MSCs have a direct anti-oxidant activity that is conducive to neuroprotection in both in vivo and in vitro. SOD3 attenuates tissue damage and reduces inflammation and may confer neuroprotective effects against nitric oxide-mediated stress to cerebellar neurons; but, its role in relation to central nervous system inflammation and neurodegeneration has not been extensively investigated. Here we have performed a series of experiments showing that SOD3 secretion by human bone marrow-derived MSCs is regulated synergistically by the inflammatory cytokines TNF-alpha and IFN-gamma, rather than through direct exposure to reactive oxygen species. Furthermore, we have shown SOD3 secretion by MSCs is increased by activated microglial cells. We have also shown that MSCs and recombinant SOD are able to increase both neuronal and axonal survival in vitro against nitric oxide or microglial induced damage, with an increased MSC-induced neuroprotective effect evident in the presence of inflammatory cytokines TNF-alpha and IFN-gamma. We have shown MSCs are able to convey these neuroprotective effects through secretion of soluble factors alone and furthermore demonstrated that SOD3 secretion by MSCs is, at least, partially responsible for this phenomenon. SOD3 secretion by MSCs maybe of relevance to treatment strategies for inflammatory disease of the central nervous system.

Stem Cell Reviews and Reports: The Effect of Human Umbilical Cord Blood Cells on Survival and Cytokine Production by Post-Ischemic Astrocytes in Vitro

2010-08-03

Type: Report

Cerebral ischemia induces death of all neural cell types within the region affected by the loss of blood flow. We have shown that administering human umbilical cord blood cells after a middle cerebral artery occlusion in rats significantly reduces infarct size, presumably by rescuing cells within the penumbra. In this study we examined whether the cord blood cells enhanced astrocyte survival in an in vitro model of hypoxia with reduced glucose availability. Primary astrocyte cultures were incubated for 2 h in no oxygen (95% N, 5% CO₂) and low glucose (1% compared to 4.5%) media. Cord blood mononuclear cells were added to half the cultures at the beginning of hypoxia. Astrocyte viability was determined using fluorescein diacetate/propidium iodide (FDA/PI) labeling and cytokine production by the astrocytes measured using ELISA. In some studies, T cells, B cells or monocytes/macrophages isolated from the cord blood mononuclear fraction with magnetic antibody cell sorting (MACS) were used instead to determine which cellular component of the cord blood mononuclear fraction was responsible for the observed effects. Co-culturing mononuclear cord blood cells with astrocytes during hypoxia stimulated production of IL-6 and IL-10 during hypoxia. The cord blood T cells decreased survival of the astrocytes after hypoxia but had no effect on the examined cytokines. Our data demonstrate that the tested cord blood fractions do not enhance astrocyte survival when delivered individually, suggesting there is either another cellular component that is neuroprotective or an interaction of all the cells is essential for protection.

Alert: 1st Stem Cell Symposium with International Participation

2010-08-03

Type: Alert

Alert: Hematopoietic Stem Cell Biology by Kondo, Motonari

2010-05-14

Type: Alert
Hematopoietic Stem Cell Biology concisely describes our current understanding of normal hemato/lymphopoiesis as well as abnormal hematopoiesis, which may lead to leukemia.

Alert: NEW! Announcing increased 2009 Impact Factor of 5.083!

2009-07-20

Type: Alert