Fibroblast growth factors (FGFs) are essential for maintaining self-renewal in human embryonic stem cells and induced pluripotent stem cells. Recombinant basic FGF (bFGF or FGF2) is conventionally used to culture pluripotent stem cells; however, because of bFGF instability, repeated addition of fresh bFGF into the culture medium is required in order to maintain its concentration. In this study, we demonstrate that a heat-stable chimeric variant of FGF, FGFC, can be successfully used for maintaining human pluripotent stem cells. FGFC is a chimeric protein composed of human FGF1 and FGF2 domains that exhibits higher thermal stability and protease resistance than do both FGF1 and FGF2. Both human embryonic stem cells and induced pluripotent stem cells were maintained in ordinary culture medium containing FGFC instead of FGF2. Comparison of cells grown in FGFC with those grown in conventional FGF2 media, showed no significant differences in terms of the expression of pluripotency markers, global gene expression, karyotype, or differentiation potential into the three germ lineages. We therefore propose FGFC, as an effective alternative to FGF2, for maintenance of human pluripotent stem cells.
Gene expressions in human ES and iPS cells were measured at 4-50 days cultured with FGFC, in place of bFGF.