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Epiblast stem cells (EpiSCs) derived from epiblast tissue of post-implantation embryos are pluripotent and can give rise to all three germ layers in teratoma assays. Introduction of the four transcription factors Oct4, Sox2, Klf4 and c-Myc into somatic cells has been shown to generate induced pluripotent stem cells (iPSCs) that are very similar to embryonic stem cells (ESCs) in a number of characteristics. However, generation of EpiSCs by the direct reprogramming of somatic cells using these transcription factors has not been shown to date. Here, we show that these transcription factors can be used to directly generate induced EpiSCs (iEpiSCs) under EpiSC culture conditions. iEpiSCs resemble EpiSCs in morphology, gene expression pattern, epigenetic status and chimaera-forming capability. This study demonstrates that the culture environment in transcription factor-mediated reprogramming determines the cell fate of the reprogrammed cell. We therefore hypothesize that it will eventually be possible to shape the identity of a directly reprogrammed cell simply by modulating culture conditions. [ABSTRACT FROM AUTHOR]

Reprogramming of somatic cells is a valuable tool to understand the mechanisms of regaining pluripotency and further opens up the possibility of generating patient-specific pluripotent stem cells. Reprogramming of mouse and human somatic cells into pluripotent stem cells, designated as induced pluripotent stem (iPS) cells, has been possible with the expression of the transcription factor quartet Oct4 (also known as Pou5f1), Sox2, c-Myc and Klf4 (refs 1–11). Considering that ectopic expression of c-Myc causes tumorigenicity in offspring and that retroviruses themselves can cause insertional mutagenesis, the generation of iPS cells with a minimal number of factors may hasten the clinical application of this approach. Here we show that adult mouse neural stem cells express higher endogenous levels of Sox2 and c-Myc than embryonic stem cells, and that exogenous Oct4 together with either Klf4 or c-Myc is sufficient to generate iPS cells from neural stem cells. These two-factor iPS cells are similar to embryonic stem cells at the molecular level, contribute to development of the germ line, and form chimaeras. We propose that, in inducing pluripotency, the number of reprogramming factors can be reduced when using somatic cells that endogenously express appropriate levels of complementing factors. [ABSTRACT FROM AUTHOR]

It has been established that certain heavy metals including silver have antibacterial properties, and that they may be useful components of antibacterial materials. This knowledge of the antibacterial activity of silver has already been put to use to decrease the occurrence of urinary catheter infections and to develop topical antibacterial agents for burn victims. In this study, the ability of silver-coated ceramic beads (Ag-CBs), sintered at 375, 400, 425, or 450 °C, to sterilize Sphingomonas sp. in commercial mineral water was evaluated. Over 3% (w/v) Ag-CBs in mineral water completely sterilized Sphingomonas sp. after 6 h, regardless of the sintering temperature. The Ag-CBs sintered at 400 °C were the most useful since they did not produce clouding in the water and the bacteria were effectively killed. The antimicrobial activity of the 400 °C-sintered Ag-CBs was comparable to that of free silver ions at 15 μg/l, showing that the silver ions released from the Ag-CBs resulted in the complete sterilization of the microbial cells in mineral water. These results suggest that Ag-CBs present an easy-to-use option for mineral water sterilization. [ABSTRACT FROM AUTHOR]

Green tea polyphenol (GTP) together with dimethylsulphoxide (DMSO) were added to a freezing solution of osteoblastic cells (rat calvarial osteoblasts and human osteosarcoma cells) exposed to repeated freeze/thaw cycles (FTC) to induce oxidative stress. When cells were subjected to 3 FTCs, freezing medium containing 10% (v/v) DMSO and 500 μg GTP ml−1 significantly ( p < 0.05) suppressed cell detachment and growth inhibition by over 63% and protected cell morphology. Furthermore, the alkaline phosphatase activity of osteoblastic cells was appreciably maintained after 2 and 3 FTCs in this mixture. Polyphenols may thus be of use as a cell cryopreservant and be advantageous in such fields as cell transplantation and tissue engineering. [ABSTRACT FROM AUTHOR]

Neural cortical cells, isolated from prenatal rat cerebra, were grown on surface-modified poly(lactic-co-glycolic acid, 65:35) (PLGA) films coated with poly-D-lysine (PDL) with either laminin (LN), fibronectin (FN) or collagen (CN). Immunocytochemistry showed that the isolated cells were highly immunopositive for both neurofilament and MAP-2 with well-organized neurites and somatodendritic localization. The presence of PDL with LN or FN on the PLGA films was essential for increased neural cell growth. Also, PLGA films coated with either PDL/LN or PDL/FN mixtures had higher neurite outgrowth and regular differentiation. [ABSTRACT FROM AUTHOR]

Studies examining somatic cell nuclear transfer (SCNT) have demonstrated that the cytoplasm of an oocyte can reprogram the genome of a somatic cell to an embryonic state. Reprogramming of a somatic cell to a pluripotent state can also be achieved either by fusion with embryonic stem cells or by the ectopic expression of defined transcription factors. Pluripotent stem cells derived by this means can be differentiated in defined tissues, and serve as model systems for the study and treatment of human diseases. Using the first application of stable RNA interference in human embryonic stem cells, we showed that knockdown of Oct4 and Nanog gene expression promotes their differentiation into cells expressing trophectodermal and endodermal markers, thereby demonstrating a conserved role for these factors in the self - renewal of human embryonic stem cells (Zaehres et al., 2005). We have developed retro / lentivirus vectors for efficient transgene expression in mouse and human embryonic stem cells as well as progenies derived thereof (Zaehres and Daley, 2006). We are further developing transgenic reporter systems expressing green fluorescent protein (GFP) and other selection markers under the control of mouse and human Oct4 and Nanog promoter elements. Currently we are applying these vector systems to explore reprogramming induced by fusion of somatic cells with mouse and human embryonic stem cells and to explore reprogramming of mouse and human somatic cells with defined transcription factors. These technologies are instrumental in providing a detailed, molecular understanding of the genomic reprogramming process with the ultimate goal to induce pluripotent cells in vitro and in vivo by the use of defined transcription factors and small molecules. [ABSTRACT FROM AUTHOR]