[Bone marrow mesenchymal stem cell-derived exosomes protect TM3 Leydig cells from cyclophosphamide-induced injury].

Objective: To investigate the effect of exosomes derived from mouse bone marrow mesenchymal stem cells (BMSC) on the injury of TM3 Leydig cells induced by cyclophosphamide (CP).

Methods: The exosomes from BMSCs were extracted by ultrahigh speed centrifugation, and their particle size and morphology observed under the electron microscope, and their typical marker proteins examined by Western blot. The uptake of exosomes by TM3 Leydig cells was observed by co-culturing the exosomes with the TM3 cells. The viability and apoptosis rate of the TM3 cells in the normal control, CP-induction and CP+exosomes groups were detected using the CCK-8 method and flow cytometry respectively. ELISA was used to measure the testosterone (T) level in the cell supernatant, and Western blot adopted to determine the expression level of the steroidogenic acute regulatory (StAR) protein, a key enzyme related to T synthesis.

Results: The viability of the TM3 Leydig cells was markedly decreased and the apoptosis rate of the cells remarkably increased in the CP-induction group compared with that in the normal control, but both significantly restored after co-culture with exosomes (P < 0.01 and P < 0.05). The T level in the supernatant and the expression of the StAR protein in the cells were lower in the CP-induction than in the normal control group, but both dramatically increased in the CP+exosomes group (P < 0.01).

Conclusion: Exosomes from BMSCs and protect TM3 Leydig cells from cyclophosphamide-induced injury and restore the level of testosterone secreted by the TM3 cells to a certain extent.