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Cyclophosphamide-induced testosterone deficiency (CPTD) during the treatment of cancers and autoimmune disorders severely influences the quality of life of patients. Currently, several guidelines recommend patients suffering from CPTD receive testosterone replacement therapy (TRT). However, TRT has many disadvantages underscoring the requirement for alternative, nontoxic treatment strategies. We previously reported bone marrow mesenchymal stem cells-derived exosomes (BMSCs-exos) could alleviate cyclophosphamide (CP)-induced spermatogenesis dysfunction, highlighting their role in the treatment of male reproductive disorders. Therefore, we further investigated whether BMSCs-exos affect autophagy and testosterone synthesis in Leydig cells (LCs). Here, we examined the effects and probed the molecular mechanisms of BMSCs-exos on CPTD in vivo and in vitro by detecting the expression levels of genes and proteins related to autophagy and testosterone synthesis. Furthermore, the testosterone concentration in serum and cell-conditioned medium, and the photophosphorylation protein levels of adenosine monophosphate-activated protein kinase (AMPK) and mammalian target of rapamycin (mTOR) were measured. Our results suggest that BMSCs-exos could be absorbed by LCs through the blood–testis barrier in mice, promoting autophagy in LCs and improving the CP-induced low serum testosterone levels. BMSCs-exos inhibited cell death in CP-exposed LCs, regulated the AMPK-mTOR signaling pathway to promote autophagy in LCs, and then improved the low testosterone synthesis ability of CP-induced LCs. Moreover, the autophagy inhibitor, 3-methyladenine (3-MA), significantly reversed the therapeutic effects of BMSCs-exos. These findings suggest that BMSCs-exos promote LC autophagy by regulating the AMPK-mTOR signaling pathway, thereby ameliorating CPTD. This study provides novel evidence for the clinical improvement of CPTD using BMSCs-exos.

Spermatogenic dysfunction caused by cyclophosphamide (CP) chemotherapy has seriously influenced the life quality of patients. Unfortunately, treatments for CP-induced testicular spermatogenic dysfunction are limited, and the molecular mechanisms are not fully understood. For the first time, here, we explored the effects of bone marrow mesenchymal stem cell-derived exosomes (BMSC-exos) on CP-induced testicular spermatogenic dysfunction in vitro and in vivo. BMSC-exos could be taken up by spermatogonia (GC1-spg cells). CP-injured GC1-spg cells and BMSC-exos were cocultured at various doses, and then, cell proliferation was measured using 3-[4,5-dimethylthiazol-2-yl]-2,5 diphenyl tetrazolium bromide (MTT) assay. In addition, photophosphorylation of extracellular-regulated kinase (ERK), p38 mitogen-activated protein kinase (p38MAPK), and protein kinase B (AKT) proteins was evaluated by western blotting as well as apoptosis in GC1-spg cells measured using flow cytometry. Treatment with BMSC-exos enhanced cell proliferation and reduced apoptosis of CP-injured GCI-spg cells. Phosphorylated levels of ERK, AKT, and p38MAPK proteins were reduced in CP-injured spermatogonia when co-treated with BMSC-exos, indicating that BMSC-exos acted against the reproductive toxicity of CP via the p38MAPK/ERK and AKT signaling pathways. In experiments in vivo, CP-treated rats received BMSC-exos by injection into the tail vein, and testis morphology was compared between treated and control groups. Histology showed that transfusion of BMSC-exos inhibited the pathological changes in CP-injured testes. Thus, BMSC-exos could counteract the reproductive toxicity of CP via the p38MAPK/ERK and AKT signaling pathways. The findings provide a potential treatment for CP-induced male spermatogenic dysfunction using BMSC-exos.