Long-term culture and differentiation of rat embryonic stem cell-like cells into neuronal, glial, endothelial, and hepatic lineages

Understanding and Regulating Cell-Matrix Interactions Using Hydrogels of Designable Mechanical Properties

Similar to natural tissues, hydrogels contain abundant water, so they are considered as promising biomaterials for studying the influence of the mechanical properties of extracellular matrices (ECM) on various cell functions. In recent years, the growing research on cellular mechanical response has revealed that many cell functions, including cell spreading, migration, tumorigenesis and differentiation, are related to the mechanical properties of ECM. Therefore, how cells sense and respond to the extracellular mechanical environment has gained considerable attention. In these studies, hydrogels are widely used as the in vitro model system. Hydrogels of tunable stiffness, viscoelasticity, degradability, plasticity, and dynamical properties have been engineered to reveal how cells respond to specific mechanical features. In this review, we summarize recent process in this research direction and specifically focus on the influence of the mechanical properties of the ECM on cell functions, how cells sense and respond to the extracellular mechanical environment, and approaches to adjusting the stiffness of hydrogels.

Toward Customized Extracellular Niche Engineering: Progress in Cell-Entrapment Technologies

The primary aim in tissue engineering is to repair, replace, and regenerate dysfunctional tissues to restore homeostasis. Cell delivery for repair and regeneration is gaining impetus with our understanding of constructing tissue-like environments. However, the perpetual challenge is to identify innovative materials or re-engineer natural materials to model cell-specific tissue-like 3D modules, which can seamlessly integrate and restore functions of the target organ. To devise an optimal functional microenvironment, it is essential to define how simple is complex enough to trigger tissue regeneration or restore cellular function. Here, the purposeful transition of cell immobilization from a cytoprotection point of view to that of a cell-instructive approach is examined, with advances in the understanding of cell-material interactions in a 3D context, and with a view to further application of the knowledge for the development of newer and complex hierarchical tissue assemblies for better examination of cell behavior and offering customized cell-based therapies for tissue engineering.

Differentiation of Spermatogonia Stem Cells into Functional Mature Neurons Characterized with Differential Gene Expression

Transplantation of embryonic stem cells (ESCs) is a promising therapeutic approach for the treatment of neurodegenerative diseases. However, ESCs are not usable clinically due to immunological and ethical limitations. The identification of an alternative safe cell source opens novel options via autologous transplantation in neuro-regeneration circumventing these problems. Here, we examined the neurogenic capacity of embryonic stem-like cells (ES-like cells) derived from the testis using neural growth factor inducers and utilized them to generate functional mature neurons. The neuronal differentiation of ES-like cells is induced in three stages. Stage 1 is related to embryoid body (EB) formation. To induce neuroprogenitor cells, EBs were cultured in the presence of retinoic acid, N₂ supplement and fibroblast growth factor followed by culturing in a neurobasal medium containing B₂₇, N₂ supplements for additional 10 days, to allow the maturation and development of neuronal progenitor cells. The neurogenic differentiation was confirmed by immunostaining for markers of mature neurons. The differentiated neurons were positive for Tuj1 and Tau1. Real-time PCR dates indicated the expression of Nestin and Neuro D (neuroprogenitor markers) in induced cells at the second stage of the differentiation protocol. The differentiated mature neurons exhibited the specific neuron markers Map2 and β-tubulin. The functional maturity of neurons was confirmed by an electrophysiological analysis of passive and active neural membrane properties. These findings indicated a differentiation capacity of ES-like cells derived from the testis to functionally mature neurons, which proposes them as a novel cell source for neuroregenerative medicine.

Using carbohydrate-based biomaterials as scaffolds to control human stem cell fate

This review describes the current state and applications of several important and extensively studied natural polysaccharide and glycoprotein scaffolds that can control the stem cell fate.

Exacerbating Pressure Overload-Induced Cardiac Hypertrophy: Novel Role of Adaptor Molecule Src Homology 2-B3

The adaptor protein Src homology 2-B3 (SH2B3), which belongs to a subfamily of Src homology 2 proteins, is a broad inhibitor of growth factors and cytokine signaling in hematopoietic cells. However, the role of SH2B3 in nonhematopoietic systems, particularly cardiomyocytes, has not been defined. In this study, we observed noticeable increase in SH2B3 protein expression during pathological cardiac remodeling in both humans and rodents. Follow-up in vitro gain- and loss-of-function studies suggested that SH2B3 promotes the cardiomyocyte hypertrophy response. Consistent with the cell phenotype, SH2B3 knockout (SH2B3(-/-)) mice exhibited attenuated cardiac remodeling with preserved cardiac function after chronic pressure overload. Conversely, cardiac-specific SH2B3 overexpression aggravated pressure overload-triggered cardiac hypertrophy, fibrosis, and dysfunction. Mechanistically, SH2B3 accelerates and exacerbates cardiac remodeling through the activation of focal adhesion kinase, which, in turn, activates the prohypertrophic downstream phosphoinositide 3-kinase-AKT-mammalian target of rapamycin/glycogen synthase kinase 3β signaling pathway. Finally, we generated a novel SH2B3 knockout rat line and further confirmed the protective effects of SH2B3 deficiency on cardiac remodeling across species. Collectively, our data indicate that SH2B3 functions as a novel and effective modulator of cardiac remodeling and failure.

Dual-micropillar-based microfluidic platform for single embryonic stem cell-derived neuronal differentiation

We developed the dual-micropillar-based microfluidic platform to direct embryonic stem (ES) cell fate. 4 × 4 dual-micropillar-based microfluidic platform consisted of 16 circular-shaped outer micropillars and 8 saddle-shaped inner micropillars in which single ES cells were cultured. We hypothesized that dual-micropillar arrays would play an important role in controlling the shear stress and cell docking. Circular-shaped outer micropillars minimized the shear stress, whereas saddle-shaped innermicropillars allowed for docking of individual ES cells. We observed the effect of saddle-shaped inner micropillars on cell docking in response to hydrodynamic resistance. We also demonstrated that ES cells cultured for 6 days within the dual-micropillar-based microfluidic platform differentiated into neural-like cells. Therefore, this dual-micropillar-based microfluidic platform could be a potentially powerful method for screening of lineage commitments of single ES cells.

Several important in vitro improvements in the amplification, differentiation and tracing of fetal liver stem/progenitor cells

Objective

We previously isolated fetal liver stem/progenitor cells (FLSPCs), but there is an urgent need to properly amplify FLSPCs, effectively induce FLSPCs differentiation, and steadily trace FLSPCs for in vivo therapeutic investigation.

Methods

FLSPCs were maintained in vitro as adherent culture or soft agar culture for large-scale amplification. To direct the differentiation of FLSPCs into hepatocytes, FLSPCs were randomly divided into four groups: control, 1% DMSO-treated, 20 ng/ml HGF-treated and 1% DMSO+20 ng/ml HGF-treated. To trace FLSPCs, the GFP gene was introduced into FLSPCs by liposome-mediated transfection.

Results

For amplifying FLSPCs, the soft agar culture were more suitable than the adherent culture, because the soft agar culture obtained more homogeneous cells. These cells were with high nuclear:cytoplasmic ratio, few cell organelles, high expression of CD90.1 and CD49f, and strong alkaline phosphatase staining. For inducing FLSPCs differentiation, treatment with HGF+DMSO was most effective (P<0.05), which was strongly supported by the typical morphological change and the significant decrease of OV-6 positive cells (P<0.01). In addition, the time of indocyanine green elimination, the percentage of glycogen synthetic cells, and the expressions of ALB, G-6-P, CK-8, CK-18 and CYP450-3A1 in HGF+DMSO-treated group were higher than in any other group. For tracing FLSPCs, after the selection of stable FLSPC transfectants, GFP expression continued over successive generations.

Conclusions

FLSPCs can properly self-renew in soft agar culture and effectively differentiate into hepatocyte-like cells by HGF+DMSO induction, and they can be reliably traced by GFP expression.

Hepatocyte differentiation of mesenchymal stem cells

BACKGROUND

Liver cell transplantation and bioartificial liver may provide metabolic support of liver function temporary and are prospective treatments for patients with liver failure. Mesenchymal stem cells (MSCs) are expected to be an ideal cell source for transplantation or liver tissue engineering, however the hepatic differentiation of MSCs is still insufficient for clinical application.

DATA SOURCES

A PubMed search on "mesenchymal stem cells", "liver cell" and "hepatocyte differentiation" was performed on the topic, and the relevant articles published in the past ten years were reviewed.

RESULTS

Hepatocyte-like cells differentiated from MSCs are a promising cell source for liver regeneration or tissue engineering. Although it is still a matter of debate as to whether MSC-derived hepatocytes may efficiently repopulate a host liver to provide adequate functional substitution, the majority of animal studies support that MSCs can become key players in liver-directed regenerative medicine. However the clinical application of human stem cells in the treatment of liver diseases is still in its infancy.

CONCLUSIONS

Future studies are required to improve the efficacy and consistency of hepatic differentiation from MSCs. It is necessary to better understand the mechanism to achieve transdifferentiation with high efficiency. More clinical trials are warranted to prove their efficacy in the management of patients with liver failure.

Isolation of rat embryonic stem-like cells: a tool for stem cell research and drug discovery

The establishment of rat embryonic stem cells constitutes a precious tool since rat has been extensively used in biomedical research, in particular for the generation of human neurodisease animal models. Up to now only a few studies have described the isolation of rat embryonic stem-like cells. One out of 9 isolated rat embryonic stem-like cell lines (B1-RESC) obtained from a 4.5-day post-coitum blastocyst were extensively characterized and kept in culture for up to 80 passages on feeders with LIF. The stable growth of these cells and the expression of pluripotent markers were confirmed up to a high number of passages in culture, also in the absence of feeders and LIF. B1-RESC expresses the three germ layers markers both in vitro, within differentiating embryoid bodies, and in vivo through teratoma formation. Collectively, the B1-RESC line with a stable near-diploid karyotype can be used as a highly sensitive tool for testing anti-proliferative molecules.

Insulin-like growth factor 1 (IGF-I) improves hepatic differentiation of human bone marrow-derived mesenchymal stem cells

The ability of MSCs (mesenchymal stem cells) to differentiate between other cell types makes these cells an attractive therapeutic tool for cell transplantation. This project was designed to improve transdifferentiation of human MSCs into liver cells using IGF-I (insulin-like growth factor 1) which, despite its important role in liver development, has not been used for in vitro hepatic differentiation. In the present study, the MSCs derived from healthy human bone marrow samples were cultured and characterized by immunophenotyping and differentiation potential into osteoblast and adipocytes. Transdifferentiation into hepatocyte-like cells was performed in the presence/absence of IGF-I in combination with predefined hepatic differentiation cocktail. To evaluate transdifferentiation, morphological features, immuno-cytochemical staining of specific biological markers and hepatic functions were assessed. Morphological assessment and evaluation of glycogen content, albumin and AFP (α-feto protein) expression as well as albumin and urea secretion revealed statistically significant difference between experimental groups compared with the control. Morphology and function (albumin secretion) of IGF-I-treated cells were significantly better than IGF-I-free experimental group. To the best of our knowledge, our study is the first to demonstrate that the combination of IGF-I with the predefined hepatic differentiation cocktail will significantly improve the morphological features of the differentiated cells and albumin secretion.

Derivation and characterization of embryonic stem cells lines derived from transgenic Fischer 344 and Dark Agouti rats

Rat embryonic stem cell (ESC) lines are not widely available, and there are only 2 lines available for distribution. Here, ESC lines were derived and characterized from Fischer 344 (F344) rats that express marker transgenes either β-galactosidase or human placental alkaline phosphatase (AP), nontransgenic F344 rats, and from Dark Agouti (DA) rats. The ESC lines were maintained in an undifferentiated state as characterized by colony morphology, expression of Oct4, Nanog, Sox-2, Cdx2, and Stella, staining for AP, and stage-specific embryonic antigen-1. Pluripotency was demonstrated in vitro by differentiation to embryoid bodies, followed by embryonic monsters. The Cdx2 expression by ESCs was unexpected and was confirmed via reverse transcriptase-polymerase chain reaction, immunocytochemistry. Pluripotency of ESCs was demonstrated in vivo by production of teratoma after an injection into F344 nontransgenic rats, and by an injection of male DA ESCs into F344 or Sprague-Dawley rat blastocysts and the generation of chimeric rats and germline contribution. ESCs from both F344 and DA contributed to chimeric rats, and one DA ESC line was proved to be germline competent. ESC sublines were created by transfection with a plasmid expressing enhanced green fluorescent protein (eGFP) under the control of a beta actin promoter and cytomegalovirus enhancer (pCX-eGFP) or by transfection with a plasmid expressing GFP under the control of a 3.1 kb portion of the rat Oct4 promoter (pN1-Oct4-GFP). In pN1-Oct4-GFP sublines, GFP gene expression and fluorescence were shown to be correlated with endogenous Oct4 gene expression. Therefore, these new ESC lines may be useful for tissue engineering and transplantation studies or for optimizing culture conditions required for self-renewal and differentiation of rat ESCs. While they made chimeric rats, further work is needed to confirm whether the transgenic F344 rat ESCs described here are germline-competent ESCs.

Embryonic stem cells, derived either after in vitro fertilization or nuclear transfer, prolong survival of semiallogeneic heart transplants

Tolerance induction toward allogeneic organ grafts represents one of the major aims of transplantation medicine. Stem cells are promising candidates for promoting donor-specific tolerance. In this study, we investigated the immunomodulatory properties of murine embryonic stem cells (ESCs), obtained either by in vitro fertilization (IVF-ESCs) or by nuclear transfer (NT-ESCs), in heart transplant mouse models. IVF-ESCs did not prolong the survival of fully allogeneic cardiac transplants but significantly prolonged the survival of semiallogeneic hearts from the same ESC donor strain for >100 d in 44% of the animals. However, 28% of transplanted animals infused with IVF-ESCs experienced development of a teratoma. NT-ESCs similarly prolonged semiallogeneic heart graft survival (>100 d in 40% of the animals) but were less teratogenic. By in vitro studies, IVF-ESC and NT-ESC immunoregulation was mediated both by cell contact-dependent mechanisms and by the release of soluble factors. By adding specific inhibitors, we identified PGE(2) as a soluble mediator of ESC immunoregulation. Expansion of regulatory T cells was found in lymphoid organs and in the grafts of IVF-ESC- and NT-ESC-tolerized mice. Our study demonstrates that both IVF-ESCs and NT-ESCs modulate recipient immune response toward tolerance to solid organ transplantation, and that NT-ESCs exhibit a lower tendency for teratoma formation. Because NT-ESCs are obtained by NT of a somatic cell from living individuals into an enucleated oocyte, they could represent a source of donor-derived stem cells to induce tolerance to solid organ allograft.

Reconstructing the differentiation niche of embryonic stem cells using biomaterials

The biochemical cues and topographical architecture of the extracellular environment extensively influence ES cell fate. The microenvironment surrounding the developing embryo presents these instructive cues in a complex and interactive manner in order to guide cell fate decisions. Current stem cell research aims to reconstruct this multifaceted embryonic niche to recapitulate development in vitro. This review focuses on 2D and 3D differentiation niches created from natural and synthetic biomaterials to guide the differentiation of ES cells toward specific lineages. Biomaterials engineered to present specific physical constraints are also reviewed for their role in differentiation.

Cell reprogramming: expectations and challenges for chemistry in stem cell biology and regenerative medicine

The possibility of reprogramming adult somatic cells into pluripotent stem cells (iPSCs) has generated a renewed interest into stem cell research and promises to overcome several key issues, including the ethical concerns of using human embryonic stem cells and the difficulty of obtaining large numbers of adult stem cells (Belmonte et al., Nat Rev Genet, 2009). This approach is also not free from challenges like the mechanism of the reprogramming process, which has yet to be elucidated, and the warranties for safety of generated pluripotent cells, especially in view of their possible therapeutic use. Very recently, several new reprogramming methods have surfaced, which seem to be more appropriate than genetic reprogramming. Particularly, chemically induced pluripotent cells (CiPSs), obtained with recombinant proteins or small synthetic molecules, may represent a valid approach, simpler and possibly safer than the other ones.

Generation of novel rat and human pluripotent stem cells by reprogramming and chemical approaches

Although embryonic stem cells (ESCs) have been established from mice since 1981, attempts to derive its counterparts from various other mammals, including rats, have not succeeded. Recently, induced pluripotent stem cells (iPSCs) have been generated from both mouse and human somatic cells by genetic transduction. We had successfully established novel rat iPSCs (riPSCs), which can be homogenously maintained by LIF and a cocktail of ALK5 inhibitor, GSK3 inhibitor and MEK inhibitor. riPSCs share conventional mouse ESC characteristics and most importantly can contribute extensively to chimeras. We also generated novel human iPSCs (hiPSCs) with "mouse ESC-like" characteristics, which can be surprisingly maintained in culture in the presence of MEK inhibitor and ALK5 inhibitor.

Engineered microenvironments for controlled stem cell differentiation

In a developing organism, tissues emerge from coordinated sequences of cell renewal, differentiation, and assembly that are orchestrated by spatial and temporal gradients of multiple regulatory factors. The composition, architecture, signaling, and biomechanics of the cellular microenvironment act in concert to provide the necessary cues regulating cell function in the developing and adult organism. With recent major advances in stem cell biology, tissue engineering is becoming increasingly oriented toward biologically inspired in vitro cellular microenvironments designed to guide stem cell growth, differentiation, and functional assembly. The premise is that to unlock the full potential of stem cells, at least some aspects of the dynamic three-dimensional (3D) environments that are associated with their renewal, differentiation, and assembly in native tissues need to be reconstructed. In the general context of tissue engineering, we discuss the environments for guiding stem cell function by an interactive use of biomaterial scaffolds and bioreactors, and focus on the interplay between molecular and physical regulatory factors. We highlight some illustrative examples of controllable cell environments developed through the interaction of stem cell biology and tissue engineering at multiple levels.

Effects of deferasirox and deferiprone on cellular iron load in the human hepatoma cell line HepaRG

Two oral chelators, CP20 (deferiprone) and ICL670 (deferasirox), have been synthesized for the purpose of treating iron overload diseases, especially thalassemias. Given their antiproliferative effects resulting from the essential role played by iron in cell processes, such compounds might also be useful as anticancer agents. In the present study, we tested the impact of these two iron chelators on iron metabolism, in the HepaRG cell line which allowed us to study proliferating and differentiated hepatocytes. ICL670 uptake was greater than the CP20 uptake. The iron depletion induced by ICL670 in differentiated cells increased soluble transferrin receptor expression, decreased intracellular ferritin expression, inhibited (55)Fe (III) uptake, and reduced the hepatocyte concentration of the labile iron pool. In contrast, CP20 induced an unexpected slight increase in intracellular ferritin, which was amplified by iron-treated chelator exposure. CP20 also promoted Fe(III) uptake in differentiated HepaRG cells, thus leading to an increase of both the labile pool and storage forms of iron evaluated by calcein fluorescence and Perls staining, respectively. In acellular conditions, compared to CP20, iron removing ability from the calcein-Fe(III) complex was 40 times higher for ICL670. On the whole, biological responses of HepaRG cells to ICL670 treatment were characteristic of expected iron depletion. In contrast, the effects of CP20 suggest the potential involvement of this compound in the iron uptake from the external medium into the hepatocytes from the HepaRG cell line, therefore acting like a siderophore in this cell model.

Small molecules that modulate embryonic stem cell fate and somatic cell reprogramming

Recent breakthroughs in stem cell biology, especially the development of induced pluripotent stem cell technique, have generated tremendous enthusiasm and efforts to explore the therapeutic potential of stem cells in regenerative medicine. Improved understanding of stem cell biology, in addition to better control of stem cell fate, is critical to realize this potential. Small molecules, targeting specific signaling pathways and/or mechanisms, have been shown to be useful chemical tools in manipulating cell fate, state and function. These small molecules are starting to play increasingly important roles in both elucidating the fundamental biology of stem cells and facilitating the development of therapeutic approaches toward regenerative medicine. Such approaches could involve cell replacement therapies using homogenous functional cells produced under chemically defined conditions in vitro and the development of small-molecule drugs that can stimulate patients' endogenous cells to repair and regenerate. Here, we review recent progress in using small molecules to sustain pluripotency, or induce differentiation of embryonic stem cells. We also highlight small molecules that can replace transcription factors and/or enhance efficiency during somatic cell reprogramming.

In vitro differentiation of embryonic and adult stem cells into hepatocytes: state of the art

Stem cells are a unique source of self-renewing cells within the human body. Before the end of the last millennium, adult stem cells, in contrast to their embryonic counterparts, were considered to be lineage-restricted cells or incapable of crossing lineage boundaries. However, the unique breakthrough of muscle and liver regeneration by adult bone marrow stem cells at the end of the 1990s ended this long-standing paradigm. Since then, the number of articles reporting the existence of multipotent stem cells in skin, neuronal tissue, adipose tissue, and bone marrow has escalated, giving rise, both in vivo and in vitro, to cell types other than their tissue of origin. The phenomenon of fate reprogrammation and phenotypic diversification remains, though, an enigmatic and rare process. Understanding how to control both proliferation and differentiation of stem cells and their progeny is a challenge in many fields, going from preclinical drug discovery and development to clinical therapy. In this review, we focus on current strategies to differentiate embryonic, mesenchymal(-like), and liver stem/progenitor cells into hepatocytes in vitro. Special attention is paid to intracellular and extracellular signaling, genetic modification, and cell-cell and cell-matrix interactions. In addition, some recommendations are proposed to standardize, optimize, and enrich the in vitro production of hepatocyte-like cells out of stem/progenitor cells.

The possible use of stem cells in regenerative medicine: dream or reality?

Stem cells are one of the most fascinating areas in regenerative medicine today. They play a crucial role in the development and regeneration of human life and are defined as cells that continuously reproduce themselves while maintaining the ability to differentiate into various cell types. Stem cells are found at all developmental stages, from embryonic stem cells that differentiate into all cell types found in the human body to adult stem cells that are responsible for tissue regeneration. The general opinion postulates that clinical therapies based on the properties of stem cells may have the potential to change the treatment of degenerative diseases or important traumatic injuries in the "near" future. We here briefly review the literature in particularly for the liver, heart, kidney, cartilage, and bone regeneration.

Low immunogenicity of endothelial derivatives from rat embryonic stem cell-like cells

Embryonic stem cells (ESC) are suggested to be immune-privileged, but they carry the risk of uncontrolled expansion and malignancy. Upon differentiation they lose their tumor-forming capacity, but they become immunogenic by the expression of a normal set of MHC molecules. This immunogenicity might trigger rejection after application in regenerative therapies. In this study MHC expression of and immune responses to endothelial derivatives of rat embryonic stem cell-like cells (RESC) under inflammatory conditions were determined in comparison to primary rat aortic endothelial cells (ECs). Cellular as well as humoral allo-recognition was analyzed in vitro. In addition, immune reactions in vivo were assessed by allo-antibody production and determination of interferon-gamma (IFNgamma)-secreting allo-reactive T cells. RESC derivatives expressed low but significant levels of MHC class I, and no MHC class II. In response to IFNgamma MHC class I expression was enhanced, while class II transactivator induction failed completely in these cells; MHC class II expression remained consistently absent. Functionally, the RESC derivatives showed a reduced allo-stimulatory capacity, protection against humoral allo-recognition in vitro and a slightly diminished susceptibility to cytotoxic T cell lysis. Furthermore, in vivo experiments demonstrated that these cells do not trigger host immune reactions, characterized by no allo-antibody production and no induction of allo-reactive memory T cells. Our results show that endothelial derivatives of RESC have a distinctive reduced immunogenic potency even under inflammatory conditions.

Cloning and Characterization of 3.1kb Promoter Region of the Oct4 Gene from the Fischer 344 Rat

Here, the role of methylation in regulation of rat Oct4 gene was evaluated during embryonic development, in adult tissues and in embryo-derived cells. First, the region 3.1 kb upstream to the rat Oct4 ATG site was cloned and sequenced. The rat Oct4 upstream sequence was similar to that in bovine, mouse and human with two upstream elements: proximal (PE) and distal enhancers (DE) and four homology conserved regions (CR1-4). The conserved regions in the rat have 69% - 96% homology with bovine, human, mouse sequences. Next, the methylation pattern in the promoter was determined during embryonic development, in adult tissues, in rat embryonic stem cell (ESC)-like cells and umbilical cord-derived cells (the feeder for ESC-like cells) using the bisulfite method and DNA sequencing. The promoter was methylated in adult and fetal tissues, and in days post coitus (DPC) 10.5 and 12.5 embryos and hypomethylated in DPC4.5 embryos and in rat ESC-like cells. The expression of Oct4 was evaluated by qRT-PCR. DPC4.5 embryos and rat ESC-like cells had higher expression of the Oct4 gene compared to DPC10.5 and 12.5 embryos, adult tissues and embryoid bodies derived from rat ESC-like cells. Thus, the methylation status correlated with the qRT-PCR results. These results indicate that the rat Oct4 3.1kb promoter region is organized and contains transcription binding and regulatory sites similar to those described for bovine, mouse and human. The rat Oct4 promoter is methylated during embryonic development after 4.5 DPC and during differentiation of rat ESC-like cells to embryoid bodies.

Establishment of rat embryonic stem-like cells from the morula using a combination of feeder layers

Embryonic stem (ES) cells are characterized by pluripotency, in particular the ability to form a germline on injection into blastocysts. Despite numerous attempts, ES cell lines derived from rat embryos have not yet been established. The reason for this is unclear, although certain intrinsic biological differences among species and/or strains have been reported. Herein, using Wistar-Imamichi rats, specific characteristics of preimplantation embryos are described. At the blastocyst stage, Oct4 (also called Pou5f1) was expressed in both the inner cell mass (ICM) and the trophectoderm (TE), whereas expression of Cdx2 was localized to the TE. In contrast, at an earlier stage, expression of Oct4 was detected in all the nuclei in the morula. These stages were examined using a combination of feeder layers (rat embryonic fibroblast [REF] for primary outgrowth and SIM mouse embryo-derived thioguanine- and ouabain-resistant [STO] cells for passaging) to establish rat ES-like cell lines. The rat ES-like cell lines obtained from the morula maintained expression of Oct4 over long-term culture, whereas cell lines derived from blastocysts lost pluripotency during early passage. The morula-derived ES-like cell lines showed Oct4 expression in a long-term culture, even after cryogenic preservation, thawing and EGFP transfection. These results indicate that rat ES-like cell lines with long-term Oct4 expression can be established from the morula of Wistar-Imamichi rats using a combination of feeder layers.

Comparative transcriptional analysis of embryoid body versus two-dimensional differentiation of murine embryonic stem cells

Understanding the process of ex vivo embryonic stem (ES) cell differentiation is important for generating higher yields of desirable cell types or lineages and for understanding fundamental aspects of ES differentiation. We used DNA microarray analysis to investigate the differentiation of mouse ES cells cultured under three differentiation conditions. Embryoid body (EB) formation was compared to differentiation on surfaces coated with either gelatin (GEL) or matrigel (MAT). Based on the transcriptional patterns of a list of literature-based "stemness" genes, ES cell differentiation on the two coated surfaces appeared similar but not identical to EB differentiation. A notable difference was the GEL and MAT upregulation but EB downregulation of nine such stemness genes, which are related to cell adhesion and epithelial differentiation. Further, GEL and MAT differentiation showed higher expression of bone formation-related genes (Spp1, Csf1, Gsn, Bmp8b, Crlf1). Gene ontology analysis shows an increase in the expression of genes related to migration and cell structure in all three conditions. Overall, GEL and MAT conditions resulted in a more similar to each other transcriptional profile than to the EB condition, and such differences are apparently related to higher nutrient and metabolite gradients and limitations in the EB versus the GEL or MAT cultures.

Rat embryonic stem-like (ES-like) cells can contribute to extraembryonic tissues in vivo

Despite significant advances achieved through gene targeting in mouse embryonic stem (ES) cells, this technology is presently only available in mice. Because the rat is a species of undeniable importance to biomedical research, attempts at derivation of rat ES cell lines have been ongoing for many years; however, the putative rat ES cell lines that have been reported to date have not yet displayed the ability to contribute in vivo to developing tissues following embryo injection. In contrast to previous studies, we describe herein the successful derivation and characterization of rat ES-like cell lines that not only express markers of undifferentiated cells, alkaline phosphatase (AP) activity and stage-specific embryonic antigen-1 (SSEA-1) cell surface antigen, but also retain expression of Oct4 (also known as Pou5f1) a homeodomain transcription factor and molecular marker of pluripotent cells. Notably, these rat ES-like cells, when injected into blastocysts transferred to pseudopregnant females, can contribute to developing extraembryonic tissues. This report demonstrates for the first time that rat ES-like cells can be derived efficiently, can express a panel of pluripotent cell markers, can be genetically modified in vitro and cryopreserved, and importantly, are capable of contributing to extraembryonic tissues in vivo.

Effect of different induction conditions on hepatocyte-like cells induced in vitro by rat bone marrow mesenchymal stem cells

AIM: To study the optimal conditions for in vitro induction and culture of rat bone marrow mesenchymal stem cells (MSCs) in order to provide the theoretical basis for the treatment of severe liver disease patients with MSCs.

METHODS: MSCs were isolated by gradient density centrifugation and plastic adherence and purified. MSCs were induced by different concentrations of FBS and cytokines. Levels of AFP and albumin in the supernatant were measured by radioimmunoassay on days 15, 21 and 27. On day 27, cells were collected. Glycogen store of heoatocytes was determined by periodic acid-Schiff staining and the expression of CK-18 and CK-19 in MSCs were detected by immunocytochemical analysis.

RESULTS: The level of AFP was higher in induced MSCs than in non-induced MSCs on days 15, 21, 27, and reached its highest on day 21. There was no significant difference in albumin levels on day 15, between induced and non-induced MSCs. However, on days 21 and 27, the albumin level was higher in induced MSCs than in non-induced MSCs. Glycogen storage in induced MSCs was observed on day 27 but not in non-induced MSCs. The induced MSCs expressed CK-18 and CK-19 while the non-induced MSCs did not. Multiple factor analysis by ANOVA showed that MSCs should be cultured in Dulbecco's modified Eagle's medium supplemented with 200 mL/L FBS, 20 μg/L hepatocyte growth factor (HGF) and 20 μg/L fibroblast growth factor 4 (FGF-4), which might be the best induction conditions for MSCs.

CONCLUSION: Rat MSCs can differentiate into hepatocyte-like cells with hepatic phenotypes and functions in the presence HGF and/or FGF-4 in vitro. The concentrations of fetal bovine serum, HGF and FGF-4 affect the differentiation of rat MSCs into hepatocyte-like cells. MSCs can be used in the treatment of severe hepatic diseases.

Controlled differentiation of stem cells

The extracellular microenvironment plays a significant role in controlling cellular behavior. Identification of appropriate biomaterials that support cellular attachment, proliferation and, most importantly in the case of human embryonic stem cells, lineage-specific differentiation is critical for tissue engineering and cellular therapy. In addition to growth factors and morphogenetic factors known to induce lineage commitment of stem cells, a number of scaffolding materials, including synthetic and naturally-derived biomaterials, have been utilized in tissue engineering approaches to direct differentiation. This review focuses on recent emerging findings and well-characterized differentiation models of human embryonic stem cells. Additionally, we also discuss about various strategies that have been used in stem cell expansion.

Designing synthetic materials to control stem cell phenotype

The micro-environment in which stem cells reside regulates their fate, and synthetic materials have recently been designed to emulate these regulatory processes for various medical applications. Ligands inspired by the natural extracellular matrix, cell-cell contacts, and growth factors have been incorporated into synthetic materials with precisely engineered density and presentation. Furthermore, material architecture and mechanical properties are material design parameters that provide a context for receptor-ligand interactions and thereby contribute to fate determination of uncommitted stem cells. Although significant progress has been made in biomaterials development for cellular control, the design of more sophisticated and robust synthetic materials can address future challenges in achieving spatiotemporal control of cellular phenotype and in implementing histocompatible clinical therapies.

Pedigreed primate embryonic stem cells express homogeneous familial gene profiles

Human embryonic stem cells (hESCs) hold great biomedical promise, but experiments comparing them produce heterogeneous results, raising concerns regarding their reliability and utility, although these variations may result from their disparate and anonymous origins. To determine whether primate ESCs have intrinsic biological limitations compared with mouse ESCs, we examined expression profiles and pluripotency of newly established nonhuman primate ESC (nhpESCs). Ten pedigreed nhpESC lines, seven full siblings (fraternal quadruplets and fraternal triplets), and nine half siblings were derived from 41 rhesus embryos; derivation success correlated with embryo quality. Each line has been growing continuously for approximately 1 year with stable diploid karyotype (except for one stable trisomy) and expresses in vitro pluripotency markers, and eight have already formed teratomas. Unlike the heterogeneous gene expression profiles found among hESCs, these nhpESCs display remarkably homogeneous profiles (>97%), with full-sibling lines nearly identical (>98.2%). Female nhpESCs express genes distinct from their brother lines; these sensitive analyses are enabled because of the very low background differences. Experimental comparisons among these primate ESCs may prove more reliable than currently available hESCs, since they are akin to inbred mouse strains in which genetic variables are also nearly eliminated. Finally, contrasting the biological similarities among these lines with the heterogeneous hESCs might suggest that additional, more uniform hESC lines are justified. Taken together, pedigreed primate ESCs display homogeneous and reliable expression profiles. These similarities to mouse ESCs suggest that heterogeneities found among hESCs likely result from their disparate origins rather than intrinsic biological limitations with primate embryonic stem cells.

Generation of rat mutants using a coat color-tagged Sleeping Beauty transposon system

A significant barrier to exploiting the full potential of the rat as a biomedical model is the lack of tools to easily modify its germline. Here we show that a tyrosinase-tagged Sleeping Beauty transposon can be used as a simple, efficient method to generate rat mutants in vivo. By making two lines of transgenic rats, one carrying the transposon and another expressing the transposase in germ cells, we are able to obtain bigenic males in which transposition occurs in the germ cells. We show that transposition leads to the appearance of new coat colors in the offspring. Using such bigenic males, we obtained an average of 1.2 transpositions per gamete and identified 19 intragenic integration events among 96 transposition sites that were sequenced. In addition, gene trapping was confirmed and rats with evidence for transposon-induced dominant ocular anomalies were identified. These data suggest that the modified Sleeping Beauty transposon represents a powerful new tool for producing molecularly defined mutagenesis in the rat.

Neural differentiation of embryonic stem cells is induced by signalling from non-neural niche cells

BACKGROUND/AIMS

Embryonic stem cell (ESC) transplantation offers new therapeutic strategies for neurodegenerative diseases and injury. However, the mechanisms underlying integration and differentiation of engrafted ESCs are poorly understood. This study elucidates the influence of exogenous signals on ESC differentiation using in vitro modelling of non-stem/stem cell interactions.

METHODS

Murine ESCs were co-cultured with endothelial cells and astrocytes or conditioned medium obtained from endothelial or astrocyte cultures. After 7 days of co-culture isolated RNA was analysed using RT-PCR for the expression of pluripotency marker oct-4, neural progenitor marker nestin, and neurofilament (NFL), an early marker of neuronal lineage commitment. The presence of the glial cell surface marker A2B5 was determined in ESCs by flow cytometry.

RESULTS

Neuronal differentiation was inhibited in ESCs when grown in close vicinity to cerebral endothelial or glial cells. Under these conditions, ESC differentiation was predominantly directed towards a glial fate. However, treatment of ESCs with endothelial cell- or astrocyte-conditioned medium promoted neuronal as well as glial differentiation.

CONCLUSION

Our results indicate that ESC fate is determined by endothelial and glial cells that comprise the environmental niche of these stem cells in vivo. The direction of differentiation processes appears to be dependent on humoral factors secreted by adjacent cell lines.

Derivation of oocyte-like cells from a clonal pancreatic stem cell line

Adult pancreatic stem cells (PSCs) are able to differentiate spontaneously in vitro into various somatic cell types. Stem cells isolated from rat pancreas show extensive self-renewal ability and grow in highly viable long-term cultures. Additionally, these cells express typical stem cell markers such as Oct-4, nestin and SSEA-1. Although differentiation potential is slightly decreasing in long-term cultures, it is possible to keep cell lines up to passage 140. Clonal cell lines could be established from different passages and showed similar characteristics. Remarkably, one clonal cell line, generated from passage 75, showed deviant properties during further culture. Clonal cells formed aggregates, which built tissue-like structures in suspension culture. These generated 3D aggregates produced permanently new cells at the outside margin. Released cells had remarkable size, and closer examination by light microscopy analysis revealed oocyte-like morphology. A comparison of the gene expression patterns between primary cultures of passages 8 and 75, the clonal cell line and the produced oocyte-like cells (OLCs) from tissue-like structures demonstrated some differences. Expression of various germ cell markers, such as Vasa, growth differentiation marker 9 and SSEA-1, increased in the clonal cell line, and OLCs showed additionally expression of meiosis-specific markers SCP3 and DMC1. We here present a first pilot study investigating the putative germ line potential of adult PSCs.

The potential for derivation of embryonic stem cells in vertebrates

An analysis of embryonic stem cell (ESC) derivation in vertebrates has revealed that the potential to form ESC is dependent on the setting aside of a pluripotent lineage from extraembryonic lineages early in development. Derivation of ESCs from all amniotes and also many lower vertebrates with that pattern of lineage allocation is thus predictable. Culture conditions during derivation in all groups share some similar characteristics, most of which are related to retaining potency coupled with extensive proliferative capacity. This in turn probably reflects the environment that maintains and causes the primordial germ cells (PGC) to proliferate in vivo. Hence culture usually involves feeder layers and serum or factors derived from them and the use of small clumps of pluriblast or epiblast cells instead of total dissociation, to facilitate cell-cell signalling. Currently addition of FGF has proven to be important but that of LIF has not been fully explored.

Undifferentiated Murine Embryonic Stem Cells Cannot Induce Portal Tolerance but May Possess Immune Privilege Secondary to Reduced Major Histocompatibility Complex Antigen Expression

Induction of donor-specific tolerance using embryonic stem (ES) cells followed by transplantation of ES cell-derived tissues from the same allogeneic strain could theoretically engender successful transplantation without immunosuppression. We sought to induce tolerance using bona fide murine ES cells in immunocompetent mice. ES cells were evaluated for the expression of markers restricted to undifferentiated cells [stage-specific embryonic antigen-1 (SSEA-1) and OCT-4] and the ability to form teratomas in immunodeficient mice. BALB/cByJ mice underwent intraportal inoculation with YC5-EYFP ES cells (129 strain; R1-derived) or saline followed by transplantation with 129X1/SvJ, CBA/J, or BALB/cByJ nonvascularized, neonatal cardiac grafts. Mice were sacrificed at graft failure and underwent histologic evaluation of transplanted grafts and lymphoid organs. ES cells and early differentiated progeny underwent real time (RT)-PCR and fluorescence-activated cell sorting (FACS) analysis to detect major histocompatibility complex (MHC) gene transcription and antigen expression. ES cells expressed markers restricted to undifferentiated cells while maintaining the ability to form teratomas in immunodeficient mice. No prolongation of allograft survival or evidence of lymphoid chimerism was observed in immunocompetent recipient mice despite hepatic teratoma formation. MHC class I, class II, and nonclassical antigens were undetectable on ES cells and early differentiated progeny despite the presence of mRNA transcripts. Class I expression was strongly upregulated upon exposure to gamma-interferon. Intraportal inoculation with murine ES cells does not produce lymphoid chimerism or induce donor-specific unresponsiveness to neonatal cardiac grafts in unmanipulated immunocompetent hosts. However, specific differentiated cell types such as ES cellderived dendritic cells, or alternate routes of ES cell administration, may be effective. ES cells appear to have immune privilege, allowing them to form teratomas in immunocompetent mice.

Multipotent Adult Progenitor Cell Lines Originating from the Peripheral Blood of Green Fluorescent Protein Transgenic Swine

Multipotent self-renewing stem cell lines have been established using peripheral blood mononuclear cells from adult green fluorescent protein transgenic swine. These cells proliferate as nonadherent spheroids in primordial-specific culture media and readily differentiate into angiogenic, osteogenic, adipogenic, and neurogenic phenotypes when cultured under the appropriate conditions. These cells are designated peripheral blood-derived multipotent adult progenitor cells (PBD-MAPCs). When differentiated in endothelial-specific media, these cells exhibit a cobblestone morphology and express von Willebrand factor (vWF), take up 1,1'-dioctadecyl-3,3,3',3'-tetramethyl-indocarboxyanine-labeled acetylated low-density lipoprotein DiI-Ac-LDL, and form tubes with lumens when grown on pads of Matrigel. Under different culture conditions, the cells appear whorl-like in appearance and express alpha-actin, indicative of smooth muscle phenotype. In the presence of dexamethasone and ascorbic acid, PBD-MAPCs differentiate into cells that produce Alizarin Red-staining extracellular mineral, consistent with an osteogenic potential. Under different conditions the cells produce Oil Red O-staining lipid vacuoles, suggestive of an adipocyte phenotype. We have also developed conditions that induce PBDMAPCs to differentiate into neural cells, confirmed by the expression of specific neuron- and glial-specific markers. Upon transplantation into rat brain, the neurogenic cells survive and migrate throughout the striatum and corpus callosum. The cells remain brightly fluorescent throughout their time in culture, during in vitro differentiation, and after in vivo transplantation. PBD-MAPCs have been maintained in primordial cell media for more than 100 doublings, yet can be induced to differentiate rapidly and efficiently into distinct cell types. PBD-MAPCs are ideal tools to study the mechanisms of differentiation and may be superior to embryonic stem cells as cellular therapeutics.

Androgenic and antiandrogenic effects and expression of androgen receptor in mouse embryonic stem cells

OBJECTIVE

To investigate the effects of androgen and antiandrogen and the expression of androgen receptor on mouse embryonic stem cells (ESCs) and the inner cell mass.

DESIGN

Controlled laboratory study.

SETTING

Academic university hospital.

ANIMAL(S)

Blastocysts from mice developed at the Institute for Cancer Research and 129/Sv mice embryonic stem cell line.

INTERVENTION(S)

Cultured mouse ESCs were exposed to testosterone (T), dihydrotestosterone (DHT), or the antiandrogen nilutamide.

MAIN OUTCOME MEASURE(S)

Immunohistochemistry for androgen receptor (AR), quantitative real-time polymerase chain reaction analysis, cell colorimetric assays, and Western blot analysis.

RESULT(S)

Androgen receptor messenger RNA (mRNA) was first detected both in the inner cell mass from blastocysts and in undifferentiated ESCs. It increased stage-dependently during ESC differentiation. Although both T and DHT had marginal effects on AR mRNA expression level and cell growth in vitro, the nonsteroidal antiandrogen nilutamide significantly stimulated ESC growth and induced Akt expression. The enhancing effects of nilutamide on mouse ESCs indicated that the Akt pathway may be involved in nilutamide-promoted ESC growth.

CONCLUSION(S)

These findings provide the first evidence of the existence of AR in ESCs. During differentiation, the expression level of AR was increased in a stage-dependent but not a ligand-dependent manner. Nilutamide promoted cell growth and increased Akt expression in ESCs.

Fibroblast growth factor-4 and hepatocyte growth factor induce differentiation of human umbilical cord blood-derived mesenchymal stem cells into hepatocytes

AIM

To investigate the differentiation of human umbilical cord blood (HUCB)-derived mesenchymal stem cells (MSCs) into hepatocytes by induction of fibroblast growth factor-4 (FGF-4) and hepatocyte growth factor (HGF), and to find a new source of cell types for therapies of hepatic diseases.

METHODS

MSCs were isolated by combining gradient density centrifugation with plastic adherence. When HUCB-derived MSCs reached 70% confluence, they were cultured in Iscove modified Dulbecco medium (IMDM) supplemented with 10 mL/L FBS, 20 ng/mL HGF and 10 ng/mL FGF-4. The medium was changed every 4 d and stored for albumin, alpha-fetoprotein (AFP) and urea assay. Expression of CK-18 was detected by immunocytochemistry. Glycogen storage in hepatocytes was determined by PAS staining.

RESULTS

By combining gradient density centrifugation with plastic adherence, we could isolate MSCs from 25.6% of human umbilical cord blood. When MSCs were cultured with FGF-4 and HGF, approximately 63.6% of cells became small, round and epithelioid on d 28 by morphology. Compared with the control, the level of AFP increased significantly from d 12 to 18.20+/-1.16 microg/L (t = 2.884, P<0.05) in MSCs cultured with FGF-4 and HGF, and was higher (54.28+/-3.11 microg/L) on d 28 (t = 13.493, P<0.01). Albumin increased significantly on d 16 (t = 6.68, P<0.01) to 1.02+/-0.15 microg/mL, and to 3.63+/-0.30 microg/mL on d 28 (t = 11.748, P<0.01). Urea (4.72+/-1.03 micromol/L) was detected on d 20 (t = 4.272, P<0.01), and continued to increase to 10.28+/-1.06 micromol/L on d 28 (t = 9.276, P<0.01). Cells expressed CK-18 on d 16. Glycogen storage was observed on d 24.

CONCLUSION

HUCB-derived MSCs can differentiate into hepatocytes by induction of FGF-4 and HGF. HUCB-derived MSCs are a new source of cell types for cell transplantation therapy of hepatic diseases.

Transgenic modifications of the rat genome

The laboratory rat (R. norvegicus) is a very important experimental animal in several fields of biomedical research. This review describes the various techniques that have been used to generate transgenic rats: classical DNA microinjection and more recently described techniques such as lentiviral vector-mediated DNA transfer into early embryos, sperm-mediated transgenesis, embryo cloning by nuclear transfer and germline mutagenesis. It will also cover techniques associated to transgenesis such as sperm cryopreservation, embryo freezing and determination of zygosity. The availability of several technologies allowing genetic manipulation in the rat coupled to genomic data will allow biomedical research to fully benefit from the rat as an experimental animal.

Stem cells for the treatment of liver disease

Stem cells tantalise. They alone have the capacity to divide exponentially, recreate the stem cell compartment as well as create differentiated cells to build tissues. They should be the natural candidates to provide a renewable source of cells for transplantation. Does the reality support the promise of this exciting alternative to conventional therapies for metabolic and degenerative liver disease? Can techniques be developed to provide the large number of cells that could be required? Must there be "space" in the liver to accept the cells? To what extent is the liver immunoprivileged, and is immunosuppression necessary for stem cell therapy? Is it better to use haematopoietic stem cells, fetal stem cells, mesenchymal cells, embryonic stem cells, hepatocytes or all of the above, but for different disease indications? This paper discusses why the exploration of stem cells for the treatment of liver disease is of great potential, and delineates some of the hurdles that need to be overcome before patients see benefits from laboratory-based research into stem cell transplantation and function.

Rat bone marrow mesenchymal stem cells differentiate into hepatocytes in vitro

AIM: To investigate the mechanism and regulation of differentiation from bone marrow mesenchymal stem cells (MSCs) into hepatocytes and to find a new source of cell types for therapies of hepatic diseases.

METHODS: MSCs were isolated by combining gradient density centrifugation with plastic adherence. The cells were cultured in osteogenic or adipogenic differentiation medium and determined by histochemical staining. MSCs were plated in plastic culture flasks that were not coated with components of extracellular matrix (ECM). When MSCs reached 70% confluence, they were cultured in low glucose Dulbecco’s modified Eagle’s medium supplemented with 10 mL/L fetal bovine serum, 20 ng/mL hepatocyte growth factor (HGF) and 10 ng/mL fibroblast growth factor-4 (FGF-4). The medium was changed every 3 d and stored for albumin, alpha-fetoprotein (AFP) and urea assay. Glycogen store of hepatocytes was determined by periodic acid-Schiff staining.

RESULTS: By combining gradient density centrifugation with plastic adherence, we isolated a homogeneous population of cells from rat bone marrow and differentiated them into osteocytes and adipocytes. When MSCs were cultured with FGF-4 and HGF, approximately 56.6% of cells became small round and epithelioid on d 24 by morphology. Compared with the control, levels of AFP increased significantly from d 12 to 15.5±1.4 µg/L (t = 2.31, P<0.05) in MSCs cultured with FGF-4 and HGF, and were higher (46.2±1.5 µg/L) on d 21 (t = 41.926, P<0.01), then decreased to 24.8±2.2 µg/L on d 24 (t = 10.345, P<0.01). Albumin increased significantly on d 21 (t = 3.325, P<0.01) to 1.4±0.2 µg/mL, and to 2.1±0.7 µg/mL on d 24 (t = 3.646, P<0.01). Urea (2.3±0.4 mmol/L) was first detected on d 21 (t = 6.739, P<0.01), and continued to increase to 2.6±0.9 mmol/L on d 24 (t = 4.753, P<0.01). Glycogen storage was first seen on d 21.

CONCLUSION: The method combining gradient density centrifugation with plastic adherence can isolate MSCs. Rat MSCs may be differentiated into hepatocytes by FGF-4 and HGF. Cytokines may play a more important role in differentiation from rat MSCs into hepatocytes.

Comparison of Matrigel™ and gelatin substrata for feeder-free culture of undifferentiated mouse embryonic stem cells for toxicity testing

Murine embryonic stem (mES) cells have been used to evaluate cytotoxicity and developmental injury following exposure to embryotoxic agents. However, maintaining a homogeneous population of undifferentiated mES cells for this purpose has been complicated by the need for continuous co-culture with murine embryonic fibroblast (mEF) cells or limited passaging on plastic surfaces coated with gelatin. Here, we compare the synthetic basement membrane Matrigel with 0.1% gelatin substratum for feeder-free propagation of undifferentiated mES cells. Biomarkers of pluripotentiality, chromosome number, caspase-3 expression, and cardiomyocyte differentiation were monitored for mES cells cultured on Matrigel or 0.1% gelatin up to passage 7 (P7). Our results suggest that choice of substratum had no significant effect on population doubling time, cell viability, stage-specific embryonic antigen-1 (SSEA-1) expression, or early passage formation of beating cardiomyocytes (all P>or=0.09). In other comparisons, however, Matrigel supported significantly higher synthesis of alkaline phosphatase (7.7x10(-3)+/-0.8 vs 6.6x10(-3)+/-0.8 units/liter/cell, respectively, P=0.012), overall expression of activated caspase-3 following exposure to 5, 10, 50, 100 and 500 parts per billion (ppb) sodium arsenite (P<0.0001), and percent development to beating cardiomyocytes at P7 (P=0.01). Together, our findings suggest that Matrigel shows promise as a substrate for feeder-free propagation of undifferentiated mES cells for embryotoxicity endpoints.

Donor age affects differentiation of rat ventral mesencephalic stem cells

This study examined the effect of gestational age of rat ventral mesencephalon (VM) on the characteristics of neurospheres generated from this region and on the yield of each cell type after differentiation of these neurospheres. Neurospheres generated from embryonic day (E) 12 and E13 VM had significantly larger diameters and volumes than those from E14 VM. Subsequent differentiation of these neurospheres resulted in decreasing yield of neurones (E12>E13>E14) and increasing yields of both astroglia and oligodendroglia (E12<E13<E14) with increasing donor age. Dopaminergic neurones were generated in low numbers from E12 and E13 cultures, and were virtually absent in E14 cultures. This study suggests that gestational age is a critical factor in the selection of tissue to generate particular cell types from neural stem cells. This has important implications for the use of neural stem cells in transplantation approaches to neurodegenerative diseases.