Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “stem cell differentiation”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 109 records · Page 6Linked to original sources
PubMed2005

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 microg/L (t = 2.31, P<0.05) in MSCs cultured with FGF-4 and HGF, and were higher (46.2+/-1.5 microg/L) on d 21 (t = 41.926, P<0.01), then decreased to 24.8+/-2.2 microg/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 microg/mL, and to 2.1+/-0.7 microg/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.

Animals↗
PubMed2001

Embryonic stem cell differentiation: the role of extracellular factors.

Embryonic stem (ES) cells have the capacity to self renew and to differentiate into cellular derivatives of the endodermal, ectodermal, and mesodermal lineages. Therefore, ES cells have been used to analyse the effects of exogenous factors on the developmental pattern during in vitro differentiation. By using an in vitro loss-of-function approach based on beta1 integrin-deficient ES cells, it was found that integrin-dependent mechanisms are involved in the regulation of Wnt-1 and BMP-4 expression. Antagonistic effects of the signalling molecules Wnt-1 and BMP-4, morphogens involved in early differentiation events, have been observed in vivo and in vitro: BMP-4 acts as a potent mesoderm inducer, whereas Wnt-1 plays a critical role in the determination of neuroectoderm. Here, we summarise data of ES cell-derived cardiac, myogenic, and neuronal differentiation of wild type and beta1 integrin-deficient ES cells. We present evidence that the interaction of cells with the extracellular matrix via integrins determines the expression of the signalling molecules BMP-4 and Wnt-1, resulting in the activation of the mesodermal and neuroectodermal lineage, respectively. The results support the idea that the influence of the extracellular 'niche' on the developmental fate of pluripotent stem cells is determined not only by soluble factors, but also by the extracellular matrix.

Animals↗
PubMed2003

Germ line stem cell differentiation in Drosophila requires gap junctions and proceeds via an intermediate state.

Gap junctions coordinate processes ranging from muscle contraction to ovarian follicle development. Here we show that the gap junction protein Zero population growth (Zpg) is required for germ cell differentiation in the Drosophila ovary. In the absence of Zpg the stem cell daughter destined to differentiate dies. The zpg phenotype is novel, and we used this phenotype to genetically dissect the process of stem cell maintenance and differentiation. Our findings suggest that germ line stem cells differentiate upon losing contact with their niche, that gap junction mediated cell-cell interactions are required for germ cell differentiation, and that in Drosophila germ line stem cell differentiation to a cystoblast is gradual.

Animals↗
PubMed2004

Quantitative screening of embryonic stem cell differentiation: endoderm formation as a model.

Embryonic stem (ES) cells have attracted much attention as a possible source of functional cells for regenerative medicine. Therapeutic use of ES cells requires control over the types and frequencies of cells generated during their in vitro differentiation. Due to the complexity of factors that impact upon ES cell differentiation, novel approaches for the optimization of tissue-specific development are required. This motivates our use of factorial and composite design methods to make empirical investigations more efficient, and to reveal unexpected interactions missed by conventional dose-response analysis. Factorial experiments would benefit from the high content evaluation of a large number of test conditions, necessitating the development of a quantitative screening technology (QST) capable of reporting the absolute number and frequency of target cells. We have developed and validated such a technology for ES cell differentiation analysis using automated fluorescence microscopy, employing endoderm differentiation as a model system. To test this platform, a two-level factorial experiment was carried out to identify major and interactive effects of glucose, insulin, retinoic acid (RA), basic fibroblast growth factor (bFGF), and epidermal growth factor (EGF) on endoderm formation. RA was found to have inhibitory effects on endoderm formation, while low glucose proved beneficial. QST was demonstrated to be a powerful tool to study factors impacting endoderm-specific ES cell differentiation, and should be applicable to the analysis of a range of ES cell-derived tissues.

Algorithms↗
PubMed1995

Cytoskeletal control of myogenesis: a desmin null mutation blocks the myogenic pathway during embryonic stem cell differentiation.

A differentiating system based on embryonic stem (ES) cell-derived embryoid bodies (EBs) which recapitulates the in vivo cardiac, skeletal, and smooth muscle myogenesis of mouse embryos was developed and used to investigate the effects of the disruption of the desmin gene on muscle cell differentiation. Wild-type, heterozygous, and homozygous cell lines with the mutated desmin allele were evaluated. Skeletal myogenesis was totally inhibited in desmin null mutant EBs, as manifested by the absence of myotube formation, contractility, and myoD, myogenin, myf5, and myosin heavy chain expression. Smooth muscle formation was also completely blocked in the absence of desmin. On the other hand, there were no obvious effects on cardiomyocyte differentiation in these desmin null mutant EBs. However, reduced desmin expression in EBs heterozygous for the desmin mutation leads to partial inhibition of cardiac muscle formation. These data suggest that in contrast to early cardiocyte differentiation, desmin is indispensable for skeletal and smooth muscle formation.

Animals↗
PubMed1994

Maturation arrest of stem cell differentiation is a common pathway for the cellular origin of teratocarcinomas and epithelial cancers.

Analysis of the cellular origin of carcinomas of different organs indicates that there is in each instance, a determined stem cell required for tissue renewal that is the cell of origin for carcinomas. The normal tissue-determined stem cells are the result of differentiation in the embryo and are little changed, if at all, from the embryonic cells. Malignant stem cells are derived from these normal stem cells of adult tissues. The resultant tumors are caricatures of the normal process of tissue renewal with many stem cells and imperfect differentiation (14). This imparts an undifferentiated appearance to the tumors, not a dedifferentiated one. Study of the regulation of normal stem cells in the embryo should lead to rational therapies for malignant ones, and conversely, study of secretions and regulation of malignant stem cells will provide insights into normal regulation. The cancer-derived differentiated cells are benign (12, 74) if not normal (39, 53) leading to the conclusion that attempts to direct normal differentiation of malignant stem cells might serve as an alternative to cytotoxic therapy. Attempts to develop such therapies are currently underway (208). The degree of differentiation of a carcinoma depends on the proportion of undifferentiated tumor stem cells, the stage of maturation arrest of the majority of cells in the tumor, and on the ability of some cells to escape arrest and to differentiate (Fig. 1). These concepts of the stem cell contribution to tumors originated largely from studies of teratocarcinoma (209) and were not widely accepted because many considered the lessons learned were unique to teratocarcinomas and would not apply to other tissues. On the basis of the concepts covered in this review, it is clear that teratocarcinomas are unique only in the potential of their stem cells. Other stem cells have more limited potential. The balance of expression of the differentiated histiotype of the tumor cell lineage and the undifferentiated phenotype of the tumor stem cells determine the morphology of the tumor. Normal tissue renewal of epithelial organs is also from stem cells or their differentiating progeny. The cellular events during liver development and regeneration and the changes that precede the development of liver cancer during hepatocarcinogenesis are similar to the cellular response in pancreas, prostate, breast, lung, and gut. In liver, as in the leukopoietic system, the primitive tissue-specific stem cell is not primarily involved in renewal because that would be too slow a process; individuals would die before generation of sufficient replacement cells.(ABSTRACT TRUNCATED AT 400 WORDS)

Adenocarcinoma↗
PubMed2006

Functional arterial and venous fate is determined by graded VEGF signaling and notch status during embryonic stem cell differentiation.

OBJECTIVE: The aim of this work was to develop a mouse embryonic stem (ES) cell system addressing the early specification of the developing vasculature into functional arteries and veins. METHODS AND RESULTS: ES cells were differentiated 4 days on collagen-type IV coated dishes to obtain Flk1+ endothelial precursors. Sub-culture of these precursors for additional 4 days robustly generated, in a VEGF dose-dependent manner, mature endothelial cells. Arterial marker genes were specifically expressed in cultures differentiated with high VEGF concentration whereas the venous marker gene COUP-TFII was upregulated in endothelial cells induced through low and intermediate VEGF concentrations. This VEGF-dependent arterialization could be blocked by inhibition of Notch resulting in an arterial to venous fate switch. Functional and morphological studies, ie, measurement of sprout length, pericyte recruitment, and interleukin-I-induced leukocyte adhesion, further confirmed their arterial and venous identity. CONCLUSIONS: We conclude that endothelial cells with distinct molecular, morphological, and functional characteristics of arteries and veins can be derived through in vitro differentiation of ES cells in a VEGF dose-dependent and Notch-regulated manner.

Animals↗
PubMed1998

Regulation of neural stem cell differentiation in the forebrain.

In the developing forebrain, mounting evidence suggests that neural stem cell proliferation and differentiation is regulated by growth factors. In vitro in the presence of serum, stem cell proliferation is predominantly mediated by fibroblast growth factor-2 (FGF-2) whereas neuronal differentiation can be triggered by FGF-1 in association with a specific heparan sulphate proteoglycan. On the other hand, astrocyte differentiation in vivo and in vitro appears to be dependent on signalling through the leukaemia inhibitory factor receptor (LIFR). The evidence suggests that in the absence of LIFR signalling, the stem cell population is present at approximately the same frequency and can generate neurons but is blocked from producing astrocytes that express glial fibrillary acidic protein (GFAP) or have trophic functions. The block can be overcome by other growth factors such as BMP-2/4 or interferon-gamma, providing further evidence that the inhibition to astrocyte development does not result from loss of a precursor population. Signalling through the LIFR, in addition to stimulating astrocyte differentiation, may also inhibit neuronal differentiation, which may explain why this receptor is expressed at the earliest stages of neurogenesis. Another signalling system which also exerts its influence on neurogenesis through active inhibition is Delta-Notch. We show in vitro that at high cell densities which impede neuronal production by FGF-1, lowering the levels of expression of the receptor Notch by antisense oligonucleotide results in a significant increase in neuronal production. Thus, stem cell differentiation appears to be dependent on the outcome of interactions between a number of signalling pathways, some which promote specific lineages and some which inhibit.

Animals↗
PubMed2002

Hematopoietic stem cells differentiate into vascular cells that participate in the pathogenesis of atherosclerosis.

Excessive accumulation of smooth-muscle cells (SMCs) has a key role in the pathogenesis of vascular diseases. It has been assumed that SMCs derived from the outer medial layer migrate, proliferate and synthesize extracellular matrix components on the luminal side of the vessel. Although much effort has been devoted to targeting migration and proliferation of medial SMCs, there is no effective therapy that prevents occlusive vascular remodeling. We show here that in models of post-angioplasty restenosis, graft vasculopathy and hyperlipidemia-induced atherosclerosis, bone-marrow cells give rise to most of the SMCs that contribute to arterial remodeling. Notably, purified hematopoietic stem cells differentiate into SMCs in vitro and in vivo. Our findings indicate that somatic stem cells contribute to pathological remodeling of remote organs, and may provide the basis for the development of new therapeutic strategies for vascular diseases through targeting mobilization, homing, differentiation and proliferation of bone marrow-derived vascular progenitor cells.

Animals↗
PubMedDate not supplied

Embryonic stem cells differentiated in vitro as a novel source of cells for transplantation.

The controlled differentiation of mouse embryonic stem (ES) cells into near homogeneous populations of both neurons and skeletal muscle cells that can survive and function in vivo after transplantation is reported. We show that treatment of pluripotent ES cells with retinoic acid (RA) and dimethylsulfoxide (DMSO) induce differentiation of these cells into highly enriched populations of gamma-aminobutyric acid (GABA) expressing neurons and skeletal myoblasts, respectively. For neuronal differentiation, RA alone is sufficient to induce ES cells to differentiate into neuronal cells that show properties of postmitotic neurons both in vitro and in vivo. In vivo function of RA-induced neuronal cells was demonstrated by transplantation into the quinolinic acid lesioned striatum of rats (a rat model for Huntington's disease), where cells integrated and survived for up to 6 wk. The response of embryonic stem cells to DMSO to form muscle was less dramatic than that observed for RA. DMSO-induced ES cells formed mixed populations of muscle cells composed of cardiac, smooth, and skeletal muscle instead of homogeneous populations of a single muscle cell type. To determine whether the response of ES cells to DMSO induction could be further controlled, ES cells were stably transfected with a gene coding for the muscle-specific regulatory factor, MyoD. When induced with DMSO, ES cells constitutively expressing high levels of MyoD differentiated exclusively into skeletal myoblasts (no cardiac or smooth muscle cells) that fused to form myotubes capable of spontaneous contraction. Thus, the specific muscle cell type formed was controlled by the expression of MyoD. These results provided evidence that the specific cell type formed (whether it be muscle, neuronal, or other cell types) can be controlled in vitro. Further, these results demonstrated that ES cells can provide a source of multiple differentiated cell types that can be used for transplantation.

Animals↗
PubMed2004

Embryonic stem cells differentiate into insulin-producing cells without selection of nestin-expressing cells.

We present a new strategy for the differentiation of embryonic stem (ES) cells into insulin-producing cells via a multi-step process without selection and induction of nestin-positive cells. During ES cell differentiation, transcript levels of genes characteristic of early and mature beta cells including Pdx1, Pax4, insulin and islet amyloid pancreatic peptide are up regulated. Islet-like clusters are characterized by expression of C-peptide, insulin and partially cytokeratin 19 as well as by ion channel activity similar to that found in embryonic beta cells. Cells of islet-like clusters show glucose-dependent insulin release at terminal stage. At an intermediate stage, nestin is partially co-expressed with C-peptide and cytokeratin 19, whereas islet-like clusters at the terminal stage are nestin-negative. We conclude that expression of nestin and cytokeratin 19 is a normal property of ES cells preceding differentiation into C-peptide/insulin-producing cells without any selection for nestin-positive phenotypes.

Animals↗
PubMed2005

Developmental activation of the Rb-E2F pathway and establishment of cell cycle-regulated cyclin-dependent kinase activity during embryonic stem cell differentiation.

To understand cell cycle control mechanisms in early development and how they change during differentiation, we used embryonic stem cells to model embryonic events. Our results demonstrate that as pluripotent cells differentiate, the length of G(1) phase increases substantially. At the molecular level, this is associated with a significant change in the size of active cyclin-dependent kinase (Cdk) complexes, the establishment of cell cycle-regulated Cdk2 activity and the activation of a functional Rb-E2F pathway. The switch from constitutive to cell cycle-dependent Cdk2 activity coincides with temporal changes in cyclin A2 and E1 protein levels during the cell cycle. Transcriptional mechanisms underpin the down-regulation of cyclin levels and the establishment of their periodicity during differentiation. As pluripotent cells differentiate and pRb/p107 kinase activities become cell cycle dependent, the E2F-pRb pathway is activated and imposes cell cycle-regulated transcriptional control on E2F target genes, such as cyclin E1. These results suggest the existence of a feedback loop where Cdk2 controls its own activity through regulation of cyclin E1 transcription. Changes in rates of cell division, cell cycle structure and the establishment of cell cycle-regulated Cdk2 activity can therefore be explained by activation of the E2F-pRb pathway.

Animals↗
PubMed2004

Wnt11 facilitates embryonic stem cell differentiation to Nkx2.5-positive cardiomyocytes.

Wnt signaling plays a crucial role in the control of morphogenesis in several tissues. Herein, we describe the role of Wnt11 during cardiac differentiation of embryonic stem cells. First, we examined the expression profile of Wnt11 during the course of differentiation in embryoid bodies, and then compared its expression in retinoic acid-treated embryoid bodies with that in untreated. In differentiating embryoid bodies, Wnt11 expression rose along with that of Nkx2.5 expression and continued to increase. When the embryoid bodies were treated with retinoic acid, Wnt11 expression decreased in parallel with the decreased expression of cardiac genes. Further, treatment of embryoid bodies with medium containing Wnt11 increased the expression of cardiac marker genes. Based on these results, we propose that Wnt11 plays an important role for cardiac development by embryoid bodies, and may be a key regulator of cardiac muscle cell proliferation and differentiation during heart development.

Animals↗
PubMed2006

Expression of the Wnt inhibitor Dickkopf-1 is required for the induction of neural markers in mouse embryonic stem cells differentiating in response to retinoic acid.

Cultured mouse D3 embryonic stem (ES) cells differentiating into embryoid bodies (EBs) expressed several Wnt isoforms, nearly all isotypes of the Wnt receptor Frizzled and the Wnt/Dickkopf (Dkk) co-receptor low-density lipoprotein receptor-related protein (LRP) type 5. A 4-day treatment with retinoic acid (RA), which promoted neural differentiation of EBs, substantially increased the expression of the Wnt antagonist Dkk-1, and induced the synthesis of the Wnt/Dkk-1 co-receptor LRP6. Recombinant Dkk-1 applied to EBs behaved like RA in inducing the expression of the neural markers nestin and distal-less homeobox gene (Dlx-2). Recombinant Dkk-1 was able to inhibit the Wnt pathway, as shown by a reduction in nuclear beta-catenin levels. Remarkably, the antisense- or small interfering RNA-induced knockdown of Dkk-1 largely reduced the expression of Dlx-2, and the neuronal marker beta-III tubulin in EBs exposed to RA. These data suggest that induction of Dkk-1 and the ensuing inhibition of the canonical Wnt pathway is required for neural differentiation of ES cells.

Animals↗
PubMed2006

MMP-2, MT1-MMP, and TIMP-2 are essential for the invasive capacity of human mesenchymal stem cells: differential regulation by inflammatory cytokines.

Human mesenchymal stem cells (hMSCs) represent promising tools in various clinical applications, including the regeneration of injured tissues by endogenous or transplanted hMSCs. The molecular mechanisms, however, that control hMSC mobilization and homing which require invasion through extracellular matrix (ECM) barriers are almost unknown. We have analyzed bone marrow-derivedhMSCs and detected strong expression and synthesis of matrix metalloproteinase 2 (MMP-2), membrane type 1 MMP (MT1-MMP), tissue inhibitor of metalloproteinase 1 (TIMP-1), and TIMP-2. The ability of hMSCs to traverse reconstituted human basement membranes was effectively blocked in the presence of synthetic MMP inhibitors. Detailed studies by RNA interference revealed that gene knock-down of MMP-2, MT1-MMP, or TIMP-2 substantially impaired hMSC invasion, whereas silencing of TIMP-1 enhanced cell migration, indicating opposing roles of both TIMPs in this process. Moreover, the inflammatory cytokines TGF-beta1, IL-1beta, and TNF-alpha up-regulated MMP-2, MT1-MMP, and/or MMP-9 production in these cells, resulting in a strong stimulation of chemotactic migration through ECM, whereas the chemokine SDF-1alpha exhibited minor effects on MMP/TIMP expression and cell invasion. Thus, induction of specific MMP activity in hMSCs by inflammatory cytokines promotes directed cell migration across reconstituted basement membranes in vitro providing a potential mechanism in hMSC recruitment and extravasation into injured tissues in vivo.

Bone Marrow Cells↗
PubMed1997

Increased expression of c-jun, but not retinoic acid receptor beta, is associated with F9 teratocarcinoma stem cell differentiation induced by polyamine depletion.

alpha-Difluoromethylornithine (DFMO), an enzyme-activated irreversible inhibitor of ornithine decarboxylase, and all-trans-retinoic acid (RA) are known to induce F9 teratocarcinoma stem cell differentiation. Both compounds induce the formation of the same cell type, i.e., parietal endoderm-like cells expressing tissue plasminogen activator and collagen type IV alpha-1. The present study shows that DFMO and RA induce terminal differentiation of F9 cells through different pathways. Thus, retinoic acid receptor (RAR) alpha mRNA is weakly expressed during DFMO treatment, but strongly induced during an early phase of RA treatment. RAR beta mRNA is not detectable in DFMO-treated cells, but very strongly induced by RA and maintained at a high level throughout the differentiative process. RAR gamma mRNA is relatively strongly expressed in untreated control cells and remains at approximately the same level during DFMO-induced differentiation. In RA-treated cells, however, RAR gamma mRNA is rapidly down-regulated and becomes nondetectable during the final course of differentiation. These experiments show that the differentiation of F9 cells into parietal endoderm-like cells does not necessarily involve changes in any of the RAR mRNA subtypes. Even though the steady-state levels of the RAR alpha and RAR gamma transcripts may be sufficient to support the differentiative process, our data clearly show that induction of RAR beta mRNA transcription is neither a prerequisite for F9 cell differentiation, nor an absolute consequence of the elevated c-jun mRNA expression that is consistently observed during the course of parietal endoderm differentiation.

Animals↗
PubMed2006

Astrocytogenesis of embryonic stem-cell-derived neural stem cells: Default differentiation.

Neural stem cells differentiate from embryonic stem cells via formation of neural stem spheres under free-floating conditions in astrocyte-conditioned medium. Subsequent culture of neural stem spheres on an adhesive substrate with fibroblast growth factor-2 promotes the migration of neural stem cells onto the substrate, resulting in an increase in the number of cells. These embryonic stem cell-derived neural stem cells can be differentiated almost exclusively into astrocytes by withdrawing fibroblast growth factor-2 from the medium without any additional instructions.

Animals↗
PubMed2004

Hes genes regulate size, shape and histogenesis of the nervous system by control of the timing of neural stem cell differentiation.

Radial glial cells derive from neuroepithelial cells, and both cell types are identified as neural stem cells. Neural stem cells are known to change their competency over time during development: they initially undergo self-renewal only and then give rise to neurons first and glial cells later. Maintenance of neural stem cells until late stages is thus believed to be essential for generation of cells in correct numbers and diverse types, but little is known about how the timing of cell differentiation is regulated and how its deregulation influences brain organogenesis. Here, we report that inactivation of Hes1 and Hes5, known Notch effectors, and additional inactivation of Hes3 extensively accelerate cell differentiation and cause a wide range of defects in brain formation. In Hes-deficient embryos, initially formed neuroepithelial cells are not properly maintained, and radial glial cells are prematurely differentiated into neurons and depleted without generation of late-born cells. Furthermore, loss of radial glia disrupts the inner and outer barriers of the neural tube, disorganizing the histogenesis. In addition, the forebrain lacks the optic vesicles and the ganglionic eminences. Thus, Hes genes are essential for generation of brain structures of appropriate size, shape and cell arrangement by controlling the timing of cell differentiation. Our data also indicate that embryonic neural stem cells change their characters over time in the following order: Hes-independent neuroepithelial cells, transitory Hes-dependent neuroepithelial cells and Hes-dependent radial glial cells.

Animals↗