Background: Azoospermia is a common cause of male infertility. The latest hope for more affordable and safer therapies comes from stem cell research. In this study, the effect of mesenchymal stem cells derived from Wharton's jelly on spermatogenesis in azoospermic mice with scrotal hyperthermia was investigated.
Methods: For the experimental study, 24 adult male mice were divided into four groups:1. control (Cont), 2. scrotal hyperthermia (Hyp), 3. scrotal hyperthermia + DMEM (10μl) (Hyp/DMEM), 4. scrotal hyperthermia + conditioned medium (10μl) (Hyp/CM). A temperature of 43 °C was applied for 20 minutes every other day for two weeks to induce hyperthermia. The mice in the experimental group received 10µl of hJWSC-CM intraperitoneally every other day for 35 days after hyperthermia. Animals were sacrificed after the experiments to perform additional molecular, biochemical and stereological analyses.

Results: The results showed that CM significantly increased both the total amount of sperm and the number of testicular cells, including spermatids, primary spermatocytes, spermatogonia, Leydig cells, and Sertoli cells, compared with Hyp and Hyp/DMEM; in addition, the biochemical characteristics of testicular tissue were significantly higher in the Hyp/CM group compared with the hyperthermia-induced groups. Further analysis revealed that when the Hyp/CM group was compared with the Hyp and Hyp/DMEM groups, Sox9 protein expression and proliferative gene expression increased significantly and the percentage of apoptotic testicular cells and pro-inflammatory gene expression decreased significantly. 

Conclusion: These results suggest that realistic therapeutic approaches for reproductive and regenerative medicine could benefit from hWJSC-CM.