Enhancement of adipogenic and osteogenic differentiation of human bone-marrow-derived mesenchymal stem cells by supplementation with umbilical cord blood serum.

Umbilical cord blood serum (UCBS) is a promising replacement for animal sera for the culture of human mesenchymal stem cells (hMSC), the unique serum composition of UCBS appearing to have variable effects on their proliferation and differentiation. Conditioning UCBS with methods such as charcoal stripping assists specific processes such as adipogenesis and osteogenesis in hMSCs. The charcoal stripping of serum removes lipophilic materials such as oestrogens, which are known inhibitors of adipogenesis. hMSC cultures supplemented with charcoal-stripped UCBS (CS-UCBS) show enhanced adipogenesis in adipogenic induction medium (AIM) containing indomethacin, 3-isobutyl-1-methylxanthine and dexamethasone. To obtain efficient adipogenesis without CS-UCBS, we have developed a modified protocol in which cells cultured separately with UCBS and CS-UCBS are constantly treated with minimal doses of insulin (1.1 μg/ml) for 10 days prior to the addition of AIM. hMSC cultures differentiated by using the modified protocol show improved adipogenesis under fetal bovine serum (FBS), UCBS and CS-UCBS conditions, with levels of adipogenesis being highest in UCBS, thereby eliminating the need for charcoal stripping. Furthermore, in each of the three sera, the insulin-pre-treated hMSCs accumulate lipid droplets faster and exhibit improved adipogenesis overall when compared with normal AIM-induced adipogenesis. We have also compared the levels of osteogenesis in hMSCs by using an induction medium devoid of dexamethasone. Maximum calcium deposition has been observed in hMSCs cultured with UCBS, as compared with those cultured with FBS or CS-UCBS. Our newly developed methods with a humanized serum supplement thus enhance the differentiation of cultured hMSCs.