Mouse embryonic stem cells(mESCs)derived from inner cell mass(ICM)of pre-implantation embryos,can maintain undifferentiated state when cultured in N2B27 medium supplemented with GSK3inhibitor CHIR99021 and MEK inhibitor PD0325901(‘‘2i’’)and leukemia inhibitor factor(LIF).Compare to conventional culture medium,all components of this medium are defined.With the N2B27 medium,‘‘2i’’and LIF,mESCs can contribute to the germline of the chimeric embryos,however,whether the‘‘all-ES cells’’mice can been generated by tetraploid complementation is unclear yet,while the tetraploid complementation serve as a golden standard to assess the pluripotency of ES cells.Here,our study showed that mESCs derived and cultured with the N2B27 complete medium could generate fertile mice by tetraploid complementation.In addition,the survival rate of tetraploid complementation mice produced by inbred mES cell lines is higher than the conventional culture condition,and increased the percentage of Oct4 positive cells contrast to conventional medium either.Therefore,the N2B27 medium supplemented with‘‘2i’’and LIF is an alternative choice forthe derivation and long-term culture of mouse embryonic stem cells.
Induced pluripotent stem （iPS） cells can be generated by forced expression of four pluripotency factors in somatic cells. This has received much attention in recent years since it may offer us a promising donor cell source for cell transplantation therapy. There has been great progress in iPS cell research in the past few years. However, several issues need to be further addressed in the near future before the clinical application of iPS cells, like the immunogenieity of iPS cells, the variability of differentiation potential and most importantly tumor formation of the iPS derivative cells. Here, we review recent progress in research into the pluripotency of iPS cells.
