[Investigation of tumorigenicity ability of immature male mouse spermatogonial stem cells after in vitro cultivation and inoculation in athymic animals]

ABSTRACT

It is hypothesized that stem cells have the capability to form tumors after transplantation. Spermatogonial stem cells have proliferation potency and colonization ability related to express pluripotency genes such as c-Myc. The primary aim of this study is to investigate tumorigenicity ability of these cells after in vitro cultivation and inoculation in athymic animals. Spermatogonial stem cells from 3-5 day-old neonatal mice testes [NMRI] were cultured following two-step enzymatic digestion. After one month of culturing the spermatogonial stem cells, the obtained colonies were identified by Oct4 and PLZF markers. Expressions of Nanog, Oct4 and c-Myc pluripotency genes were subsequently studied. We subcutaneously inoculated 5 x 106 cells into athymic mice and assessed tumor formation after 8 weeks. Mouse embryonic stem cells [CCE line] were used as the positive control. Generated tumors were measured by a caliper. The colonies expressed Oct4 and PLZF proteins. Ratio of pluripotency gene expressions in these cells compared to embryonic stem cells significantly decreased [P Mouse embryonic stem cells formed tumors however the spermatogonial colonies did not form any tumors. Mouse spermatogonial stem cells in comparison with embryonic stem cells are not capable of forming tumors in vivo. We have observed that the tumorigenic ability of these cells decreased significantly with down regulation of pluripotency gene expressions, particularly c-Myc. However, this study should be reassessed by using human tissue samples