Differentiation of mesenchymal stem cells to germ-like cells under induction of Sertoli cell-conditioned medium and retinoic acid.

The aim of this research was to find a way to differentiate germ cells from umbilical cord Wharton's jelly mesenchymal stem cells (MSCs) to support in vitro spermatogenesis. A small piece of Wharton's jelly was cultured in high-glucose Dulbecco's modified Eagle's medium in present of 10% foetal calf serum. After the fourth passage, the cells were isolated and cultured in Sertoli cell-conditioned medium under induction of two different doses of retinoic acid (10-5 , 10-6  m). The differentiation of MSC to germ-like cells was evaluated by expression of Oct4, Nanog, Plzf, Stra8 and Prm1 genes during different days of culture through qPCR. The results showed that there were downregulation of Oct4 and Nanog and upregulation of pre-meiotic germ cell marker (stra8) and haploid cell marker (Prm1) when MSCs are differentiated over time. The expression of Bax gene (an apoptotic marker) was significantly observed in high dosage of retinoic acid (RA). As a result, RA has positive effects on proliferation and differentiation of MSCs, but its effects are related to dosage. The success of this method can introduce umbilical cord MSC as a source of germ cells for treatment of infertility in future.