Cancer-like epigenetic derangements of human pluripotent stem cells and their impact on applications in regeneration and repair

Base-Resolution Methylome of Retinal Pigment Epithelial Cells Used in the First Trial of Human Induced Pluripotent Stem Cell-Based Autologous Transplantation

The first-in-human trial of induced pluripotent stem cell (iPSC)-based autologous transplantation was successfully performed on a female patient with age-related macular degeneration. Here we delineated the base-resolution methylome of the iPSC-derived retinal pigment epithelium (iRPE) used in this trial. The methylome of iRPE closely resembled that of native RPE (nRPE), although partially methylated domains (PMDs) emerged in iRPE but not nRPE. Most differentially methylated regions between iRPE and nRPE appeared to originate from (de)methylation errors during differentiation, whereas errors at reprogramming resulted in aberrant genomic imprinting and X chromosome reactivation. Moreover, non-CpG methylation was prominent in nRPE but not iRPE. Intriguingly, xenotransplantation to mouse remodeled the iRPE methylome to demethylate a subset of suppressed genes and accumulate non-CpG methylation, but failed to resolve PMDs and hypermethylated CpG islands. Although the impacts of these alterations remain elusive, our findings should provide a useful guide for methylome analyses of other iPSC-derived cells.

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The methylome of iPSC-derived RPE closely resembled that of native RPE

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Most methylomic differences originated from errors during differentiation

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Errors at reprogramming induced loss of imprinting and X chromosome reactivation

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Some of the differences were mitigated by xenotransplantation to mouse

Effect of resveratrol on drug resistance in colon cancer chemotherapy

To investigate the effects of resveratrol on the drug resistance of 5-FU in the colon cancer chemotherapy, an MTT assay was used to detect the effects of 5-FU and resveratrol combined with 5-FU on the proliferation of the LoVo and SW480 cell lines. Flow cytometry was used to detect the effect of 5-FU combined with resveratrol on the survival rate of the LoVo and SW480 cells. A western blot was used to detect the expression levels of the proteins associated with colon cancer. After flow sorting, the percentage of the SW480 and the LoVo cell line CD133+ was 97.5% and 95.8%, respectively. The cells cultured in vitro showed more rapid cell proliferation and differentiation. The MTT assay showed that as compared with the survival rate of the blank group LoVo and CD133+ LoVo cells, the survival rate of the cells containing the 5-FU group was lower (P < 0.05). When 5-FU was used in combination with different concentrations of resveratrol, the abovementioned phenomenon was more prominent. The sorted colon cancer cells have dry stem cells, and the sorted CD133+ cells are more resistant to drugs; the combination of resveratrol and 5-FU has the best effect on the colon cancer cells. Preliminary studies on the mechanism of action of the drug show that a combination of 5-FU and resveratrol regulates apoptosis in CD133+ colon cancer stem cells by regulating the BAX gene; however, more complex mechanisms may also be involved.

Epigallocatechin Gallate Inhibits Mouse Mesenchymal Stem Cell Differentiation to Adipogenic Lineage

Epigallocatechin gallate (EGCG) is a major component of green tea polyphenols having a potent anti-oxidant potential. Besides inhibiting the growth of many cancer cell types and inducing proliferation and differentiation in keratinocytes, it has been shown to promote reduction of body fat. The fact that mesenchymal stem cells (MSCs) have ability to self-renew and differentiate into the cells of mesodermal lineages, such as fat and bone, it is, thus, possible that EGCG may directly be involved in affecting fat metabolism through its effect on mesenchymal stem cells. Hence, with this aim, the present study was designed to determine the effect of EGCG on mouse mesenchymal stem cells, C3H10T1/2 cells differentiation into adipocytes. To understand this process, the cells were incubated with varying concentrations of EGCG (1 μM, 5 μM, 10 μM, 50 μM) in the presence and /or absence of adipogenic medium for 9 days. The results demonstrated that, EGCG inhibited the cells proliferation, migration and also prevented their differentiation to adipogenic lineage. These effects were analyzed through the inhibition of wound healing activity, reduction in Oil red O stained cells, together with decrease in the expression of Adipisin gene following EGCG treatment. These observations thus demonstrated anti-adipogenic effect of EGCG with a possibility of its role in the therapeutic intervention of obesity.

Nuclear Reprogramming by Defined Factors: Quantity Versus Quality

The generation of induced pluripotent stem cells (iPSCs) and directly converted cells holds great promise in regenerative medicine. However, after in-depth studies of the murine system, we know that the current methodologies to produce these cells are not ideal and mostly yield cells of poor quality that might hold a risk in therapeutic applications. In this review we address the duality found in the literature regarding the use of 'quality' as a criterion for the clinic. We discuss the elements that influence reprogramming quality, and provide evidence that safety and functionality are directly linked to cell quality. Finally, because most of the available data come from murine systems, we speculate about what aspects can be applied to human cells.