Reversible inhibition of the blood-testis barrier protein improves stem cell homing in mouse testes

Stem cell homing is a complex phenomenon that involves multiple steps; thus far, attempts to increase homing efficiency have met with limited success. Spermatogonial stem cells (SSCs) migrate to the niche after microinjection into seminiferous tubules, but the homing efficiency is very low. Here we report that reversible disruption of the blood-testis barrier (BTB) between Sertoli cells enhances the homing efficiency of SSCs. We found that SSCs on a C57BL/6 background are triggered to proliferate in vitro when MHY1485, which stimulates MTORC, were added to culture medium. However, the cultured cells did not produce offspring by direct injection into the seminiferous tubules. When acyline, a gonadotropin-releasing hormone (GnRH) analogue, was administered into infertile recipients, SSC colonization increased by ~5-fold and the recipients sired offspring. In contrast, both untreated individuals and recipients that received leuprolide, another GnRH analogue, remained infertile. Acyline not only decreased CLDN5 expression but also impaired the BTB, suggesting that increased colonization was caused by efficient SSC migration through the BTB. Enhancement of stem cell homing by tight junction protein manipulation constitutes a new approach to improve homing efficiency, and similar strategy may be applicable to other self-renewing tissues.