LAUSR

The present study was designed to investigate the therapeutic effect of bone marrow MSC‐derived factors on gonadotropic toxicity induced by busulfan in vivo. The conditioned media (CM) was obtained from MSCs in serum‐free incubation for 48 hr and concentrated ~25‐fold by ultrafiltration. The CM of HEK 293 cells was treated as control (293‐CM). MSC‐CM was injected into busulfan mice via caudal veins after 1 day of busulfan treatment for 2 weeks (200 μl per dose/twice weekly）. Compared to the 293‐CM group, testicular injury was delayed in MSC‐CM group, including reduced vacuolations of cells in the basal compartment of the seminiferous epithelium and detachment of cells from basement membrane. Apoptotic spermatogenic cells were significantly decreased in MSC‐CM group (p ＜ 0.05). Interesting N‐cadherin，ICAM‐1 and P‐cadherin expressions significantly increased in MSC‐CM group, while occludin, ZO‐1 and connexin 43 expressions showed no difference among MSC‐CM, 293‐CM and busulfan groups. Present results suggest MSC‐secreted factors protect spermatogenesis impairment after busulfan treatment by reducing the apoptosis of spermatogenic cells and enhancing intercellular adhesion molecule expressions.