Human spermatagonial stem cells: a novel therapeutic hope for cardiac regeneration and repair?

Effects of different Sertoli cell types on the maintenance of adult spermatogonial stem cells in vitro

Spermatongonial stem cells (SSCs) are unique testis cells that are able to proliferate, differentiate, and transmit genetic information to the next generation. However, the effect of different Sertoli cell types on the expression of specific SSC genes is not yet well understood. In this study, we compare the in vitro effect of adult Sertoli cells, embryonic Sertoli cells, and TM4 (a Sertoli cell line) as feeder layers on the expression of SSC genes. SSCs were isolated from the testis of adult male mice and purified by differential plating. Following enrichment, SSCs were cultivated for 1 and 2 wk in the presence of various feeders. The expression of SSC-specific genes (Mvh, ZBTB, and c-kit) was evaluated by real-time polymerase chain reaction. Our results revealed that expression of the specific SSC genes was significantly higher in the embryonic Sertoli cells after 1 and 2 wk compared to the adult Sertoli cells and the TM4 group. Our finding suggest that co-culturing of SSCs with embryonic Sertoli cells is helpful for in vitro cultivation of SSCs and might improve the self-renewal of these stem cells.

MicroRNA-based system in stem cell reprogramming; differentiation/dedifferentiation

Stem cells (SCs) have self-renew ability and give rise to committed progenitors of a single or multiple lineages. Elucidating the genetic circuits that govern SCs to self-renew and to differentiate is essential to understand the roles of SCs and promise of these cells in regenerative medicine. MicroRNAs are widespread agents playing critical roles in regulatory networks of transcriptional expression and have been strongly linked with SCs for simultaneous maintenance of pluripotency properties such as self-renewal. This review aims to provide state-of-the-art presentations on microRNA-dependent molecular mechanisms contribute to the maintenance of pluripotency. Understanding the microRNA signature interactions, in conjunction with cell signaling, is critical for development of improved strategies to reprogram differentiated cells or direct differentiation of pluripotent cells.