Embryonic stem cell-like cells derived from adult human testis.

BACKGROUND: Given the significant drawbacks of using human embryonic stem (hES) cells for regenerative medicine, the search for alternative sources of multipotent cells is ongoing. Studies in mice have shown that multipotent ES-like cells can be derived from neonatal and adult testis. Here we report the derivation of ES-like cells from adult human testis.

METHODS: Testis material was donated for research by four men undergoing bilateral castration as part of prostate cancer treatment. Testicular cells were cultured using StemPro medium. Colonies that appeared sharp edged and compact were collected and subcultured under hES-specific conditions. Molecular characterization of these colonies was performed using RT-PCR and immunohistochemistry. (Epi)genetic stability was tested using bisulphite sequencing and karyotype analysis. Directed differentiation protocols in vitro were performed to investigate the potency of these cells and the cells were injected into immunocompromised mice to investigate their tumorigenicity.

RESULTS: In testicular cell cultures from all four men, sharp-edged and compact colonies appeared between 3 and 8 weeks. Subcultured cells from these colonies showed alkaline phosphatase activity and expressed hES cell-specific genes (Pou5f1, Sox2, Cripto1, Dnmt3b), proteins and carbohydrate antigens (POU5F1, NANOG, SOX2 and TRA-1-60, TRA-1-81, SSEA4). These ES-like cells were able to differentiate in vitro into derivatives of all three germ layers including neural, epithelial, osteogenic, myogenic, adipocyte and pancreatic lineages. The pancreatic beta cells were able to produce insulin in response to glucose and osteogenic-differentiated cells showed deposition of phosphate and calcium, demonstrating their functional capacity. Although we observed small areas with differentiated cell types of human origin, we never observed extensive teratomas upon injection of testis-derived ES-like cells into immunocompromised mice.

CONCLUSIONS: Multipotent cells can be established from adult human testis. Their easy accessibility and ethical acceptability as well as their non-tumorigenic and autogenic nature make these cells an attractive alternative to human ES cells for future stem cell therapies.