In order to avoid the use of MEFs, human feeders has been used as an alternative method to maintain hES cells, including embryonic fibroblasts, adult fallopian tube epithelium, bone marrow stromal cells, foreskin fibroblasts, human cell lines, adult skin cells, and placenta cells. But recently, Rajala et al. test nine previously reported xenofree culture media formats, and conclud that none could maintain the undifferentiated growth of hES cells. So more effective human feeder cells should be selected by comparing each type of feeder cell for their capability to support the growth and maintenance of hES cells. hES cells established on the most effective human feeder cells will apparently promote the development of cell-based therapies. The other systems to avoid using MEFs as feeders is to use a feeder-free environment that cultures hES cells in special media supplemented with Matrigel matrix or fibronectin. However, some require culture on Matrigel but this contains a variety of extracellular matrix components, most likely associated with an ill-defined mixture of growth factors. Recently, successful attempts have been made to develop chemically defined culture medium. In the most present study, the authors introduce a defined serum free medium, hESF9, in which bFGF was the only protein components. Nevertheless, there is no consensus as to the optimal formulation of the chemically defined medium. Moreover, it is likely that feeder-free culture are not optimal for developing transplantable hES cell derivative, for feeder-free cultures usually display a higher degree of spontaneous Axitinib VEGFR/PDGFR inhibitor differentiation than conventional culture. And feeder-free systems, using bFGF and other additional growth factors, will significantly increase the cost of the hES cell culture. So, it is not suitable to use in large scale expansion of hES cells for clinical applications. For the time being, the use of feeder cells is still the safest and most cost-effective option to derive and propagate stable hES cells. Despite the evolution of these culture conditions and the addition of several factors, all require supplementation with bFGF to sustain hES cell potential. bFGF appears to be of similar WZ8040 EGFR/HER2 inhibitor importance for hES cells self-renewal as leukemia inhibitory factor is for mouse ES cells. But the basis to using bFGF to maintain hES cells still remains unknown. In a previous study, very high concentrations of bFGF was used to maintain hES cells, this suggests that either bFGF is operating through an receptor that it is relatively unstable or inefficiently presented to the cells in the culture conditions used.