SEARCH · PubMed Health

Results for “transdifferentiation”

Explore indexed PubMed citations for clinical trials, systematic reviews and public health research. Read source abstracts and follow each citation to its original PubMed record.

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

At least 37 records · Page 2Linked to original sources

PubMed1993

Basic fibroblast growth factor as one of the essential factors regulating lens transdifferentiation of pigmented epithelial cells.

In vitro transdifferentiation of retinal pigmented epithelial cells of the chick embryo into lens cells can be markedly enhanced by culture in the presence of testicular hyaluronidase and phenylthiourea. Since the commercial preparations of hyaluronidase that had previously been used were very crude, a search for the actual effective molecule(s) enhancing lens transdifferentiation was conducted. First, we purified the enzyme and tested the effect of the purified hyaluronidase. Highly purified hyaluronidase itself did not enhance lens transdifferentiation. The crude hyaluronidase was then separated according to affinity with heparin, considering the possibility that the fibroblast growth factor (FGF) is contained in the crude hyaluronidase. Transdifferentiation-enhancing activity was detected in the fraction which was bound to heparin and eluted with 2 M NaCl, where no hyaluronate-degrading activity existed. Analysis of the fraction by SDS-PAGE revealed the existence of an 18 kDa protein whose NH2-terminal sequence was identical to that of basic FGF. The basic FGF derived from bovine brain also enhanced lens transdifferentiation of pigmented epithelial cells. These findings suggest that basic FGF must play a major role in enhancing transdifferentiation of pigmented epithelial cells to lens cells.

Amino Acid Sequence↗

PubMed1998

Direct transdifferentiation in the vertebrate retina.

Transdifferentiation is the process by which differentiated cells alter their identity to become other, distinct cell types. The conversion of neural retina into lens epithelium is one of the most spectacular examples of transdifferentiation. We show that the redirection of cell fate from neural retina to lens and subsequent transdifferentiation is independent of cell replication as it occurs in growth-arrested cell populations. Using DNA ratiometry of individual cells in these cultures we show that, indeed, individual amitotic cells do transdifferentiate. Hence, choice of fate in transdifferentiating cells does not rely on a "community effect" but instead can be categorized as a < > For lack of overt lens progenitors, and most importantly, for its mitotic independence, we conclude that lens colony formation in vitro does occur by direct transdifferentiation and not by clonal proliferation of progenitor cells.

Animals↗

PubMed2026

Loss of function of ALDH3B2 transdifferentiates human pancreatic duct cells into β-like cells.

Replenishment of pancreatic β cells is key to a cure for diabetes. β cell regeneration is achieved predominantly by self-replication, especially in rodents, but it was also shown that pancreatic duct cells can transdifferentiate into β cells. How pancreatic duct cells are transdifferentiated and whether we can manipulate transdifferentiation to replenish β cell mass are not well understood. Using a genome-wide clustered regularly interspaced short palindromic repeats (CRISPR) screen, we found that the loss of function of aldehyde dehydrogenase family 3 member B2 (ALDH3B2) was sufficient to transdifferentiate cell line-based and human pancreatic duct cells into functional β-like cells. The transdifferentiated cells had substantially increased the expression of β cell marker genes, secreted insulin in response to glucose, and lowered blood glucose to near normal for 6 weeks after transplantation into streptozotocin-induced diabetic mice under the kidney capsule. Our study identifies a gene that could potentially be targeted in human pancreatic duct cells to replenish β cell mass for diabetes therapy.

Humans↗

PubMed1997

Basic fibroblast growth factor (FGF-2) induced transdifferentiation of retinal pigment epithelium: generation of retinal neurons and glia.

In the present study we report that basic fibroblast growth factor (bFGF, FGF-2) promotes the transdifferentiation of Xenopus laevis larval retinal pigment epithelium (RPE) into neural retina. Using specific antibodies we have examined the cellular composition of the regenerated retinal tissue. Our results show that, in addition to retinal neurons and photoreceptors, glial cells were also regenerated from the transdifferentiated RPE. These results were specific to FGF-2, since other factors that were tested, including acidic FGF (aFGF, FGF-1), epidermal growth factor (EGF), laminin, ECL, and Matrigel, exhibited no activity in inducing retinal regeneration. These results are the first in amphibians demonstrating the functional role of FGF-2 in inducing RPE transdifferentiation. Transplantation studies were carried out to investigate retinal regeneration from the RPE in an in vivo environment. Sheets of RPE implanted into the lens-less eyes of larval hosts transformed into neurons and glial cells only when under the influence of host retinal factors. In contrast, no retinal transdifferentiation occurred if the RPE was implanted into the enucleated orbit. Taken together, these results show that the amphibian RPE is capable of transdifferentiation into neuronal and glial cell-phenotypes and implicate FGF-2 as an important factor in inducing retinal regeneration in vitro.

Animals↗

PubMed2003

Transdifferentiation--fact or artifact.

Normal development appears to involve a progressive restriction in developmental potential. However, recent evidence suggests that this progressive restriction is not irreversible and can be altered to reveal novel phenotypic potentials of stem, progenitor, and even differentiated cells. While some of these results can be explained by the presence of contaminating cell populations, persistence of pluripotent stem cells, cell fusion, etc., several examples exist that are difficult to explain as anything other than "true transdifferentiation" and/or dedifferentiation. These examples of transdifferentiation are best explained by understanding how the normal process of progressive cell fate restriction occurs during development. We suggest that subversion of epigenetic controls regulating cell type specific gene expression likely underlies the process of transdifferentiation and it may be possible to identify specific factors to control the transdifferentiation process. We predict, however, that transdifferentiation will not be reliable or reproducible and will probably require complex manipulations.

Animals↗

PubMed2006

Transdifferentiated mesenchymal stem cells as alternative therapy in supporting nerve regeneration and myelination.

AIMS: Demyelination plays a crucial role in neurodegenerative processes and traumatic disorders. One possibility to achieve remyelination and subsequent restoration of neuronal function is to provide an exogenous source of myelinating cells via transplantation. In this context, mesenchymal stem cells (MSCs) have attracted interest. They are multipotent stem cells that differentiate into cells of the mesodermal lineage like bone, cartilage, fat, and muscle. Although adult, their differentiation potential is remarkable, and they are able to transdifferentiate. METHODS: We transformed cultivated rat MSCs into myelinating cells by using a cytokine cocktail. Transdifferentiated MSCs were characterized by an enhanced expression of LNGF-receptor, Krox20, and CD104, and a decreased expression of BMP receptor-1A as compared to untreated MSCs. The myelinating capacity was evaluated in vitro and in vivo. Therefore, PC12 cells, normally unmyelinated, were cocultivated with MSCs, transdifferentiated MSCs, and Schwann cells, or the respective cells were grafted into an autologous muscle conduit bridging a 2-cm gap in the rat sciatic nerve. Myelination of PC12 cells was demonstrated by electron microscopy. In vivo, after 3 and 6 weeks regeneration including myelination was monitored histologically and morphometrically. Autologous nerves and cell-free muscle grafts were used as control. RESULTS: Schwann cells and transdifferentiated MSCs were able to myelinate PC12 cells after 14 days in vitro. In vivo, autologous nerve grafts demonstrated the best results in all regenerative parameters. An appropriate myelination was noted in the Schwann cell groups and, albeit with restrictions, in the transdifferentiated MSC groups, while regeneration in the MSC groups and in the cell-free groups was impaired. CONCLUSION: Our findings demonstrate that it may be possible to differentiate MSCs into therapeutically useful cells for clinical applications in myelin defects.

Animals↗

PubMed1983

Recent progress in studies of the transdifferentiation of eye tissue in vitro.

A major switch in the overt differentiation phenotypes, which we call transdifferentiation, occurs very often in cultures of embryonic eye tissues. The systems provide irrevocable evidence for instability in the results of cell differentiation, and hence, studies on this topic are expected to contribute much to the understanding of the basic mechanisms of cell differentiation. In this article, recent work on transdifferentiation, mostly with chick embryos, was reviewed. Several new systems of lens transdifferentiation starting from brains, adenohypophyses, and other tissues have recently been discovered. Regarding the widely known cases of transdifferentiation starting from neural and pigmented retina cells, there has been considerable progress in elucidating the factors controlling such major switches in differentiation. In particular, efforts are under way to attempt to understand the mechanisms of transdifferentiation in relation to the transcriptional control of genes coding lens-specific proteins.

Animals↗

PubMed2006

Involvement of phosphatidylinositol 3-kinase and extracellular-regulated kinase in hepatic stellate cell antioxidant response and myofibroblastic transdifferentiation.

Liver fibrogenesis is dependent upon transdifferentiation of hepatic stellate cells to a profibrogenic phenotype. Prooxidant stress purportedly stimulates both an antioxidant response and myofibroblastic transdifferentiation with fibrogenic gene expression; however, mechanisms by which oxidative stress mediates stellate cell activation remain unclear. To this end, stellate cells were treated with tert-butylhydroquinone (tBHQ), a known inducer of antioxidant response genes. As anticipated, tBHQ induced expression of antioxidant response element (ARE)-regulated genes via the transcription factor Nrf2. Further, tBHQ promoted transdifferentiation of quiescent stellate cells cultured on Engelbreth-Holm-Swarm extracellular matrix. Pretreatment of cultured stellate cells with a phosphatidylinositol 3-kinase (PI3K) inhibitor blocked tBHQ-mediated ARE-dependent gene induction as well as stellate cell transdifferentiation. In contrast, extracellular signal-regulated kinase, which was demonstrated to be prominently phosphorylated following tBHQ treatment, was not found to affect either induction of the antioxidant response nor stellate cell transdifferentiation. These data implicate involvement of PI3K pathways in tBHQ-mediated stellate cell activation and demonstrate a requirement for PI3K in the antioxidant response of hepatic stellate cells.

Animals↗

PubMed2005

Profiling molecular targets of TGF-beta1 in prostate fibroblast-to-myofibroblast transdifferentiation.

The development of age-related proliferative disorders of the prostate gland is supported by transdifferentiation and cellular senescence processes in the stroma. Both processes are involved in remodeling of stromal tissue, as observed in benign prostatic hyperplasia (BPH), and in "reactive stroma" adjacent to prostate cancer (PCa). It has been assumed that TGF-beta1 plays a key role in the aging prostate by inducing premature senescence and favoring myofibroblast differentiation. Therefore, we evaluated the stromal cell phenotypes of human primary adult prostatic fibroblasts (n=3) and the molecular and cellular mechanisms of growth arrest after treatment with TGF-beta1 and of in vitro cellular senescence. Microarray analysis, quantitative PCR, immunofluorescence and western blot revealed that cellular senescence and transdifferentiation of fibroblasts have distinct underlying mechanisms, pathways and gene and protein expression profiles in human PrSCs. In clear contrast to senescent cells, TGF-beta1-treated cells morphologically transdifferentiated into myofibroblasts with dense cytoskeletal fibers and increased expression of smooth muscle cell alpha-actin, calponin and tenascin. TGF-beta1 induced neither expression of senescence-associated markers nor genes involved in terminal growth arrest, such as senescence-associated beta-galactosidase and cyclin-dependent kinase (cdk) inhibitors p16(Ink4A) and p21(Cip1) but increased p15(Ink4B) protein expression. Differentiation inhibitor (Id-1) protein level down-regulation was observed under both conditions. Genes specifically up-regulated by transdifferentiation but not by cellular senescence of PrSCs were metalloproteinase 1 tissue inhibitor (Timp1), transgelin (Tagln), gamma 2 actin (Actg2), plasminogen activator inhibitor 1 (Serpinel), insulin-like growth factor binding protein 3 (Igfbp3), parathyroid hormone-like hormone (Pthlp), Tgfb-1, four and a half LIM domains 2 (Fhl-2), hydrogen peroxide-inducible clone 5 (Hic5) and cartilage oligomeric matrix protein (Comp). Other genes, such as Cdc28 protein kinase 1 (Cks1b), v-myb myeloblastosis viral oncogene homolog (MybL2), pyruvate kinase, muscle 2 (Pkm2) and Forkhead box M1 (FoxM1), were down-regulated only upon TGF-beta1 treatment but not by cellular senescence. Pyruvate dehydrogenase kinase 3 (Pdk3) and connective tissue growth factor (Ctgf) were up-regulated and hyaluronan synthase 3 (Has3) down-regulated under both conditions. Moreover, GageC1, a prostate/testis-specific protein overexpressed in symptomatic BPH and PCa was induced in transdifferentiated stromal cells. Genes such as GageC1 could be promising targets for therapeutic inhibitors of stromal tissue remodeling and progression of BPH and PCa.

Cell Differentiation↗

PubMed2005

Transdifferentiation-dependent expression of alpha-SMA in hepatic stellate cells does not involve TGF-beta pathways leading to coinduction of collagen type I and thrombospondin-2.

Hepatic stellate cells (HSC) cultured on plastic spontaneously transdifferentiate to a myofibroblast-like cell type (MFB). This model system of hepatic fibrogenesis is characterized by phenotypic changes of the cells and increased matrix synthesis. Here, we analyzed if transdifferentiation-dependent induction of ECM components, e.g., collagen type I and thrombospondin-2 (TSP-2), and phenotypic changes are coregulated events and if both processes are mediated via TGF-beta pathway(s). Blocking the TGF-beta-dependent p38 MAPK pathway in HSC with the specific inhibitor SB203580 strongly reduces collagen I and TSP-2 mRNA expression without inhibiting upregulation of the typical MFB-marker, alpha-smooth-muscle actin (alpha-SMA). Similarly, interference with the Smad2/3/4 pathway using dexamethasone also heavily decreased expression of collagen type I and TSP-2 whereas transdifferentiation of HSC to the typical morphology of MFB with loss of fat droplets and increasing alpha-SMA was unchanged. Further, p38 MAPK mediated induction of collagen I and TSP-2 expression by TGF-beta1 was still achieved in the presence of dexamethasone, showing that dexamethasone does not block p38 while it delays Smad2 phosphorylation and antagonizes stimulation of a Smad3/Smad4 dependent TGF-beta reporter construct. Interestingly, in contrast to SB203580 and dexamethasone, overexpression of the TGF-beta antagonist Smad7 reduced ECM expression and simultaneously inhibited morphologic transdifferentiation, indicating that Smad7 fulfills additional features in HSC. In conclusion, our data show that phenotypic changes of transdifferentiating HSC and induction of matrix synthesis are independent processes, the latter being stimulated by both, Smad dependent and MAPK dependent TGF-beta signaling.

Actins↗

PubMed2004

Induction and regulation of acute phase proteins in transdifferentiated hepatocytes.

Acute phase proteins (APPs) are predominantly synthesized in the liver and play an important role in restoring homeostasis. In the present study, we set out to answer two questions using transdifferentiated hepatocytes induced from pancreatic cells as a model for studying the acute phase response. Firstly, do transdifferentiated hepatocytes express acute phase proteins following culture with glucocorticoid and cytokines? Secondly, what is the molecular basis of the induction of acute phase proteins in transdifferentiated hepatocytes? Hepatic transdifferentiation was induced in 11.5-day mouse embryonic pancreas or the pancreatic cell line AR42J-B13 (B13) by culture with dexamethasone. We found that acute phase proteins [alpha2-macroglobulin (MG), haptoglobin (Hp)] were induced in both systems following culture with dexamethasone. The combined treatment of dexamethasone and oncostatin M (OSM) enhanced the expression of the acute phase proteins in B13 cells and the mechanism of the up-regulation by the cytokine is probably mediated by phosphorylation of STAT3 and STAT1. In addition, ectopic expression of either C/EBPbeta or C/EBPalpha in B13 cells induced haptoglobin expression and culture with oncostatin M was sufficient to enhance the expression of haptoglobin in C/EBPbeta transfected cells from 18% to 43%. The results of the present study indicate transdifferentiated hepatocytes have the potential to be a useful model to study liver function in vitro.

Acute-Phase Proteins↗

PubMed2001

Aortic valve endothelial cells undergo transforming growth factor-beta-mediated and non-transforming growth factor-beta-mediated transdifferentiation in vitro.

Cardiac valves arise from endocardial cushions, specialized regions of the developing heart that are formed by an endothelial-to-mesenchymal cell transdifferentiation. Whether and to what extent this transdifferentiation is retained in mature heart valves is unknown. Herein we show that endothelial cells from mature valves can transdifferentiate to a mesenchymal phenotype. Using induction of alpha-smooth muscle actin (alpha-SMA), an established marker for this process, two distinct pathways of transdifferentiation were identified in clonally derived endothelial cell populations isolated from ovine aortic valve leaflets. alpha-SMA expression was induced by culturing clonal endothelial cells in medium containing either transforming growth factor-beta or low levels of serum and no basic fibroblast growth factor. Cells induced to express alpha-SMA exhibited markedly increased migration in response to platelet-derived growth factor-BB, consistent with a mesenchymal phenotype. A population of the differentiated cells co-expressed CD31, an endothelial marker, along with alpha-SMA, as seen by double-label immunofluorescence. Similarly, this co-expression of endothelial markers and alpha-SMA was detected in a subpopulation of cells in frozen sections of aortic valves, suggesting the transdifferentiation may occur in vivo. Hence, the clonal populations of valvular endothelial cells described here provide a powerful in vitro model for dissecting molecular events that regulate valvular endothelium.

Animals↗

PubMed1997

Possible monocytic origin of chondrosarcoma: in vitro transdifferentiation of HLA-DR blood monocyte-like cells from a patient with chondrosarcoma, into neo-fibroblasts and chondrocyte-like cells.

Nodules and multilayered areas composed of fibroblasts and chondrocyte-like cells embedded in an abundant extracellular matrix appeared spontaneously in in vitro culture of mononucleated blood cells taken from a patient with chondrosarcoma. Using specific antibodies it was demonstrated that the neo-fibroblasts which developed in the culture resulted from a direct transdifferentiation of monocytes expressing HLA-DR specificity. The experiment was carried out twice, once before surgery and then two years later. In both cases the spontaneous transdifferentiation of HLA-DR monocytes into neo-fibroblasts was observed. Previously it was shown that normal monocytes were also able to give rise in vitro to neo-fibroblasts. However, the latter are normally rapidly destroyed by cell-cell contact with T-cells. Normal T-cells adhere to normal neo-fibroblasts by which they are finally engulfed. As a result, the neo-fibroblasts lose their fibroblastic shape, no longer adhere to their support and die. Therefore the abnormal proliferation and persistence of neo-fibroblasts in pathological situations such as the present case may result either from an intrinsic defect in monocytes, T-cells or both. The question is whether or not this transdifferentiation process observed in vitro accounts for the development of chondrosarcoma in vivo. The present results suggest that in vivo chondrosarcoma may start in a necrotic zone (resulting for instance from trauma) and attract HLA-DR monocytes, where they accumulate and transdifferentiate into neo-fibroblasts and chondrocyte-like cells. The uncontrolled transdifferentiation of these HLA-DR monocytes resulting from a dysregulation of the immune system is probably linked to the malignant process which may have a retroviral origin. The question is raised regarding the embryologic origin of this special sub-population of blood monocytes in which pluripotential capabilities are retained; its origin may differ from that of the other circulating monocytes.

Cartilage↗

PubMed1999

Transforming growth factor-beta regulates tubular epithelial-myofibroblast transdifferentiation in vitro.

BACKGROUND: We recently found evidence of tubular epithelial-myofibroblast transdifferentiation (TEMT) during the development of tubulointerstitial fibrosis in the rat remnant kidney. This study investigated the mechanisms that induce TEMT in vitro. METHODS: The normal rat kidney tubular epithelial cell line (NRK52E) was cultured for six days on plastic or collagen type I-coated plates in the presence or absence of recombinant transforming growth factor-beta1 (TGF-beta1). Transdifferentiation of tubular cells into myofibroblasts was assessed by electron microscopy and by expression of alpha-smooth muscle actin (alpha-SMA) and E-cadherin. RESULTS: NRK52E cells cultured on plastic or collagen-coated plates showed a classic cobblestone morphology. Culture in 1 ng/ml TGF-beta caused only very minor changes in morphology, but culture in 10 or 50 ng/ml TGF-beta1 caused profound changes. This involved hypertrophy, a loss of apical-basal polarity and microvilli, with cells becoming elongated and invasive, the formation of a new front-end back-end polarity, and the appearance of actin microfilaments and dense bodies. These morphological changes were accompanied by phenotypic changes. Double immunohistochemistry staining showed that the addition of TGF-beta1 to confluent cell cultures caused a loss of the epithelial marker E-cadherin and de novo expression of alpha-SMA. An intermediate stage in transdifferentiation could be seen with hypertrophic cells expressing both E-cadherin and alpha-SMA. De novo alpha-SMA expression was confirmed by Northern blotting, Western blotting, and flow cytometry. In particular, cells with a transformed morphology showed strong alpha-SMA immunostaining of characteristic microfilament structures along the cell axis. There was a dose-dependent increase in the percentage of cells expressing alpha-SMA with increasing concentrations of TGF-beta1, which was completely inhibited by the addition of a neutralizing anti-TGF-beta1 antibody. Compared with growth on plastic, cell culture on collagen-coated plates showed a threefold increase in the percentage of cells expressing alpha-SMA in response to TGF-beta1. CONCLUSION: TGF-beta1 is a key mediator that regulates, in a dose-dependent fashion, transdifferentiation of tubular epithelial cells into alpha-SMA+ myofibroblasts. This transdifferentiation is markedly enhanced by growth on collagen type I. These findings have identified a novel pathway that may contribute to renal fibrosis associated with overexpression of TGF-beta1 within the diseased kidney.

Actins↗

PubMed2002

Visualization by comprehensive microarray analysis of gene expression programs during transdifferentiation of mesophyll cells into xylem cells.

Plants have a unique transdifferentiation mechanism by which differentiated cells can initiate a new program of differentiation. We used a comprehensive analysis of gene expression in an in vitro zinnia (Zinnia elegans L.) culture model system to gather fundamental information about the gene regulation underlying the transdifferentiation of plant cells. In this model, photosynthetic mesophyll cells isolated from zinnia leaves transdifferentiate into xylem cells in a morphogenic process characterized by features such as secondary-wall formation and programmed cell death. More than 8,000 zinnia cDNA clones were isolated from an equalized cDNA library prepared from cultured cells transdifferentiating into xylem cells. Microarray analysis using these cDNAs revealed several types of unique gene regulation patterns, including: the transient expression of a set of genes during cell isolation, presumably induced by wounding; a rapid reduction in the expression of photosynthetic genes and the rapid induction of protein synthesis-associated genes during the first stage; the preferential induction of auxin-related genes during the subsequent stage; and the transient induction of genes closely associated with particular morphogenetic events, including cell-wall formation and degradation and programmed cell death during the final stage. This analysis also revealed a number of previously uncharacterized genes encoding proteins that function in signal transduction, such as protein kinases and transcription factors that are expressed in a stage-specific manner. These findings provide new clues to the molecular mechanisms of both plant transdifferentiation and wood formation.

Asteraceae↗

PubMed2024

Loss-of-function of ALDH3B2 transdifferentiates human pancreatic duct cells into beta-like cells.

Replenishment of pancreatic beta cells is a key to the cure for diabetes. Beta cells regeneration is achieved predominantly by self-replication especially in rodents, but it was also shown that pancreatic duct cells can transdifferentiate into beta cells. How pancreatic duct cells undergo transdifferentiated and whether we could manipulate the transdifferentiation to replenish beta cell mass is not well understood. Using a genome-wide CRISPR screen, we discovered that loss-of-function of ALDH3B2 is sufficient to transdifferentiate human pancreatic duct cells into functional beta-like cells. The transdifferentiated cells have significant increase in beta cell marker genes expression, secrete insulin in response to glucose, and reduce blood glucose when transplanted into diabetic mice. Our study identifies a novel gene that could potentially be targeted in human pancreatic duct cells to replenish beta cell mass for diabetes therapy.

Journal Article↗

PubMed2006

Down-regulation of Sox10 with specific small interfering RNA promotes transdifferentiation of Schwannoma cells into myofibroblasts.

Neural crest-derived cells are noted for the long lasting plasticity during lineage commitment process and the potential for transdifferentiation into other neural crest derivatives. Schwann cells in particular have been reported to transdifferentiate into melanocytes and myofibroblasts. Detailed studies of transdifferentiation at the molecular level have been hampered by difficulty in isolating sufficient quantity of primary cells or cellular materials. Here, we describe a robust in vitro system in which Schwannoma cells undergo an apparent transdifferentiation into myofibroblasts. Importantly, we induce the transdifferentiation by down-regulating a single transcription factor, Sox10, thereby identifying a key molecular event in this process. Myofibroblasts thus generated showed carbachol-stimulated contraction and calcium transients and express several established myofibroblast-specific genes. These results suggest that generating desired cell types based on "knock-down" of critical genes may be a viable strategy.

Actins↗

PubMed2002

Mature vascular endothelium can give rise to smooth muscle cells via endothelial-mesenchymal transdifferentiation: in vitro analysis.

Though in the past believed to be a rare phenomenon, endothelial-mesenchymal transdifferentiation has been described with increasing frequency in recent years. It is believed to be important in embryonic vascular development, yet less is known regarding its role in the adult vasculature. Using FACS and immunomagnetic (Dynabeads) purification techniques (based on uptake of DiI-acetylated low-density lipoproteins and/or PECAM-1 expression) and double-label indirect immunostaining (for endothelial and smooth muscle [SM] markers), we demonstrate that mature bovine vascular endothelium contains cells of an endothelial phenotype (defined by VE-cadherin, von Willebrand factor, PECAM-1, and elevated uptake of acetylated low-density lipoproteins) that can undergo endothelial-mesenchymal transdifferentiation and further differentiate into SM cells (as defined by expression of alpha-SM-actin, SM22alpha, calponin, and SM-myosin). "Transitional" cells, coexpressing both endothelial markers and alpha-SM-actin, were consistently observed. The percentage of cells capable of endothelial-mesenchymal transdifferentiation within primary endothelial cultures was estimated as 0.01% to 0.03%. Acquisition of a SM phenotype occurred even in the absence of proliferation, in gamma-irradiated (30 Gy) and/or mitomycin C-treated primary cell cultures. Initiation of transdifferentiation correlated with disruption of cell-cell contacts (marked by loss of VE-cadherin expression) within endothelial monolayers, as well as with the action of transforming growth factor-beta(1). In conclusion, our in vitro data show that mature bovine systemic and pulmonary endothelium contains cells that can acquire a SM phenotype via a transdifferentiation process that is transforming growth factor-beta(1)- and cell-cell contact-dependent, but proliferation-independent.

Actins↗