Reprogramming mediated by stem cell fusion

Advances in mammalian cloning prove that somatic nuclei can be reprogrammed to a state of totipotency by transfer into oocytes. An alternative approach to reprogram the somatic genome involves the creation of hybrids between somatic cells and other cells that contain reprogramming activities. Potential fusion partners with reprogramming activities include embryonic stem cells, embryonic germ cells, embryonal carcinoma cells, and even differentiated cells. Recent advances in fusion-mediated reprogramming are discussed from the standpoints of the developmental potency of hybrid cells, genetic and epigenetic correlates of reprogramming, and other aspects involved in the reprogramming process. In addition, the utility of fusion-mediated reprogramming for future cell-based therapies is discussed.     

Cyclic strain induces expression of specific smooth muscle cell markers in human endothelial cells

The objective of this study was to determine whether cyclic strain could promote human umbilical vein endothelial cells (HUVECs) to express markers in common with the mature smooth muscle cell (SMC) phenotype, suggesting endothelial cell to SMC transdifferentiation. HUVECs were cultured on stretched membranes at 10% stretch and 60 cycles/min for 24-96 hr, and demonstrated elongation with enhanced and organized F-actin distribution. By using real-time polymerase chain reaction analysis, the mRNA levels of five specific SMC markers, SM22-alpha, alpha-smooth muscle actin (alpha-SMA), caldesmon-1, smooth muscle myosin heavy chain (SMMHC), and calponin-1 were significantly increased in cyclic strain-treated HUVECs as compared with those in static control cells. Protein levels of SM22-alpha and alpha-SMA were also substantially increased by Western blot and immunofluorescence staining. In addition, two specific endothelial markers, von Willebrand factor (vWF) and vascular endothelial growth factor receptor-2 (VEGFR-2), showed a reduction in mRNA expression. In addition, cyclic strain-induced increase of SM22-alpha and alpha-SMA expression were reversible when cells were cultured back to the static condition. These results demonstrate a possible endothelial cell to SMC transdifferentiation in response to cyclic strain. Hemodynamic forces in modulating endothelial phenotype may play an important role in the vascular system.     

In vitro osteogenesis from human skin-derived precursor cells

Embryonic tissue and organ development are initiated from three embryonic germ layers: ectoderm (skin and neuron), mesoderm (blood, bone, muscle, cartilage and fat) and endoderm (respiratory and digestive tract). In former times, it was believed that cell types in each germ layer are specific and do not cross from one to another throughout life. A new finding is that one tissue lineage can differentiate across to another tissue lineage, and this is termed transdifferentiation. We were interested in studying the transdifferentiation of skin-derived precursor cells (ectoderm layer) to osteoblastic cells (mesoderm layer). Human skin-derived precursor cells (hSKP) were isolated and induced into an osteoblastic lineage using osteogenic induction medium (alpha-MEM plus 10% fetal bovine serum supplemented with ascorbic acid, beta-glycerophosphate and dexamethasone). The specific characteristics of osteoblastic cells, including the expression of enzyme alkaline phosphatase, the deposition of mineral and the expression of osterix, bone sialoprotein and osteocalcin, were detected only from the inductive group. The results in our study show that SKP from human skin are a practically available source for osteogenesis. The samples are easily obtainable for autologous use with a high expansion capacity.     

诱导型细胞的研究进展

胚胎干细胞(ES细胞)和诱导型多能干细胞(iPS细胞)的研究进展为生物学基础研究注入了新的活力,然而免疫排斥、致瘤性以及诱导效率低等缺陷制约其进一步快速发展和临床应用．最近,科学家借鉴iPS细胞诱导技术和传统的诱导体系,将终末分化细胞直接诱导为功能性细胞,如心肌细胞、神经细胞和肝脏细胞,称为诱导型细胞．这些研究进展极大地促进了细胞分化、重编程和表观遗传学的研究,也为人类再生医学的研究提供了新的途径．     

Aldosterone induces myofibroblastic transdifferentiation and collagen gene expression through the Rho-kinase dependent signaling pathway in rat mesangial cells

There is accumulating evidence indicating the role of aldosterone in the pathogenesis of hypertension and renal injury. In this study, we investigated the role of the Rho-kinase dependent signaling pathway in aldosterone-induced myofibroblastic transdifferentiation and collagen gene expression in rat mesangial cells (RMCs). Stimulation with aldosterone (1 nmol/L) significantly increased phosphorylation of myosin phosphatase target subunit-1 (MYPT-1), a marker of Rho-kinase activity, with a peak at 20 min in RMCs. Pre-incubation with a selective mineralocorticoid receptor antagonist, eplerenone (10 µmol/L), or a specific Rho-kinase inhibitor, Y27632 (10 µmol/L), attenuated the aldosterone-induced increase in MYPT-1 phosphorylation. Aldosterone also induced hypertrophy in RMCs, accompanied by an increase in actin polymerization and expression of α-smooth muscle actin (α-SMA), a myofibroblastic transdifferentiation marker. Collagen type I, III and IV mRNA levels were also increased with aldosterone stimulation. Pre-treatment with eplerenone or Y27632 prevented the aldosterone-induced cell hypertrophy, actin polymerization, the increase in α-SMA expression and the increases of collagen type I, III, IV mRNA levels in RMCs. These results suggest that aldosterone-induced mesangial cell hypertrophy is associated with cell transformation, leading to an increase in collagen gene expression via the Rho-kinase dependent signaling pathway.     

Artemether Does Not Turn α Cells into β Cells

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Developmental History Provides a Roadmap for the Emergence of Tumor Plasticity

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Upregulation of matrix metalloproteinase triggers transdifferentiation of retinal pigmented epithelial cells in Xenopus laevis: A Link between inflammatory response and regeneration

In adult Xenopus eyes, when the whole retina is removed, retinal pigmented epithelial (RPE) cells become activated to be retinal stem cells and regenerate the whole retina. In the present study, using a tissue culture model, it was examined whether upregulation of matrix metalloproteinases (Mmps) triggers retinal regeneration. Soon after retinal removal, Xmmp9 and Xmmp18 were strongly upregulated in the tissues of the RPE and the choroid. In the culture, Mmp expression in the RPE cells corresponded with their migration from the choroid. A potent MMP inhibitor, 1,10‐PNTL, suppressed RPE cell migration, proliferation, and formation of an epithelial structure in vitro. The mechanism involved in upregulation of Mmps was further investigated. After retinal removal, inflammatory cytokine genes, IL‐1β and TNF‐α , were upregulated both in vivo and in vitro. When the inflammation inhibitors dexamethasone or Withaferin A were applied in vitro, RPE cell migration was severely affected, suppressing transdifferentiation. These results demonstrate that Mmps play a pivotal role in retinal regeneration, and suggest that inflammatory cytokines trigger Mmp upregulation, indicating a direct link between the inflammatory reaction and retinal regeneration. © 2017 Wiley Periodicals, Inc. Develop Neurobiol 77: 1086–1100, 2017     

Microarray analyses of transdifferentiated mesenchymal stem cells

The molecular events associated with the age-related gain of fatty tissue in human bone marrow are still largely unknown. Besides enhanced adipogenic differentiation of mesenchymal stem cells (MSCs), transdifferentiation of osteoblast progenitors may contribute to bone-related diseases like osteopenia. Transdifferentiation of MSC-derived osteoblast progenitors into adipocytes and vice versa has previously been proven feasible in our cell culture system. Here, we focus on mRNA species that are regulated during transdifferentiation and represent possible control factors for the initiation of transdifferentiation. Microarray analyses comparing transdifferentiated cells with normally differentiated cells exhibited large numbers of reproducibly regulated genes for both, adipogenic and osteogenic transdifferentiation. To evaluate the relevance of individual genes, we designed a scoring scheme to rank genes according to reproducibility, regulation level, and reciprocity between the different transdifferentiation directions. Thereby, members of several signaling pathways like FGF, IGF, and Wnt signaling showed explicitly differential expression patterns. Additional bioinformatic analysis of microarray analyses allowed us to identify potential key factors associated with transdifferentiation of adipocytes and osteoblasts, respectively. Fibroblast growth factor 1 (FGF1) was scored as one of several lead candidate gene products to modulate the transdifferentiation process and is shown here to exert inhibitory effects on adipogenic commitment and differentiation.     

Therapeutic Effects of Suppressors of Cytokine Signaling in Diabetic Nephropathy

Inflammation is an important pathophysiological mechanism in diabetic nephropathy (DN). Tubular epithelial cell-myofibroblast transdifferentiation (TEMT), which can be induced by many cytokines, is an important event in DN. Oncostatin M (OSM), an inflammatory cytokine, can induce TEMT in vitro. The suppressors of cytokine signaling (SOCS) proteins are negative-feedback regulators of cytokine signaling. The purpose of this study was to investigate the role of SOCS in DN. The results demonstrated that overexpression of SOCS ameliorated proteinuria, the expression of α-SMA and OSM in tubular epithelial cells, and interstitial extracellular matrix accumulation in the renal tissue of CD-1 mice. In addition, our previous studies indicated that OSM induced TEMT by activating the JAK/STAT pathway, which could be inhibited by SOCS. These results indicate that overexpression of SOCS has a therapeutic effect in DN.