| Embryonic stem cells (ESCs) can maintain differentiation potential and self-renewal in many passages in vitro, and differentiate into three embryonic layers. Therefore, ESCs have enormous utilization potential and incomparable predomination in regenerative medicine and clinical treatment. Ethical issues restrict human iPSC (hiPSC) and hESC research prior to the blastocyst stage, so the development potential and safety of hIPSCs and hESC remain ambiguous. Thus, moral and ethical concerns are significant challenges for hIPSCs and hESC research and application. An alternative model is necessary for hiPSC and hESC research. We understand the mechanism of iPSC induction and ESC in mouse. Mouse is a classic animal model, but significantly differs from human in physiology and morphology. Monkeys are similar to humans in evolution, but the research cost is high. Pig and rabbit are also similar to human in physiology and morphology, and have a relatively short reproduction term and suitable size. Therefore, these two animals have gained increasing attention from researchers, and become important animal models for development processes and diseases, as well as a suitable animal model for hiPSC research. Induced pluripotent stem cell (iPSC) is the solution for problems of immune rejection and ethical concerns with more sources which makes it a better solution for tissue or organ transplantation than ESCs. A few iPSC reports on pig and rabbit have been published. IPSC research has not been progressive because of the lack of suitable reports and culture systems. Therefore a suitable and effective induction and culture condition is needed.Zscan4is important in telomere maintenance and long-term genomic stability in ESC cells. Also Zscan4could shorten the mouse iPS induction process and dramatically improve the quality of iPS cells. In our research of pig iPSC (piPSC) induction, Zscan4genes was forcibly co-expressed with human OSKM factors in pig fetal fibroblasts. PiPSC clones were obtained successfully, but the efficiency, clone shape, and quality were not high, unlike those in miPSC induction.In rabbit iPS research, we also constructed a rabbit OCT4-EGFP report system to trace the pluripotency of ESC and iPSC. GFP expression was observed in rabbit inner cell mass and genital ridges. Two transgene embryos were obtained, and rabbit fetal fibroblasts and rabbit neural stem cells (RNSCs) were derived. Two types of rabbit iPSCs (riPSCs) were obtained in two different culture systems through forced expression of OKSM in RNSC. RT-PCR, immunofluorescence, and differentiation potential were conducted on riPSCs.On one hand, we induced piPSCs by OSKM with zscan4, and results show that zscan4could not improve the iPSC quality and provide a critical reference in obtaining naive piPSC. On the other hand, a practical rabbit pluripotency report system was obtained in riPSC induction. Thus, a new report system and iPSC induction protocol have been provided for riPSC research. |
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