Transplantation of CD51+ Stem Leydig Cells: A New Strategy for the Treatment of Testosterone Deficiency.

Stem Leydig cell (SLC) transplantation could provide a new strategy for treating the testosterone deficiency. Our previous study demonstrated that CD51 (also called integrin αv) might be a putative cell surface marker for SLCs, but the physiological function and efficacy of CD51+ SLCs treatment remain unclear. Here, we explore the potential therapeutic benefits of CD51+ SLCs transplantation and whether these transplanted cells can be regulated by the hypothalamic-pituitary-gonadal (HPG) axis. CD51+ cells were isolated from the testes of 12-weeks-old C57BL/6 mice, and we showed that such cells expressed SLC markers and that they were capable of self-renewal, extensive proliferation, and differentiation into multiple mesenchymal cell lineages and LCs in vitro. As a specific cytotoxin that eliminates Leydig cells (LCs) in adult rats, ethane dimethanesulfonate (EDS) was used to ablate LCs before the SLC transplantation. After being transplanted into the testes of EDS-treated rats, the CD51+ cells differentiated into mature LCs, and the recipient rats showed a partial recovery of testosterone production and spermatogenesis. Notably, a testosterone analysis revealed a circadian rhythm of testosterone secretion in cell-transplanted rats, and these testosterone secretions could be suppressed by decapeptyl (a luteinizing hormone-releasing hormone agonist), suggesting that the transplanted cells might be regulated by the HPG axis. This study is the first to demonstrate that CD51+ SLCs can restore the neuroendocrine regulation of testicular function by physiologically recovering the expected episodic changes in diurnal testosterone serum levels and that SLC transplantation may provide a new tool for the studies of testosterone deficiency treatment. Stem Cells 2017;35:1222-1232.