Therapeutic effect of single intra-testicular injection of lyophilized xenogenous and allogeneic mesenchymal stem cell-derived extracellular vesicles on oligozoospermia in male dogs.

Abstract

Oligozoospermia is the most common cause of infertility in male canine reproduction. Practitioners look for specific therapies to solve this problem. So, the aim of the present investigation is to study for the first time the impact of a single intra-testicular injection of lyophilized canine and human MSCs-derived EVs on the oligospermia of male dogs. Dogs were randomly allocated into three groups. Group I is the control group (n = 5), without any treatment; Group II is the lyophilized canine MSCs-derived EVs (n = 5); and Group III is the lyophilized human MSCs-derived EVs (n = 5). Dogs were subjected to semen collection, blood collection, and Doppler examination. The assessment was performed on day 0 before injection, and the examination was extended to 8 weeks. The results showed that there was a notable (P ˂ 0.01) increase in testicular volume in either the canine or human MSCs-derived EVs group from the 6^th to the 8^th weeks of the study as compared to Day 0. The maximum volume of right or left testis in dogs treated with either canine or human MSCs-derived EVs was observed at 8 weeks post injections compared to Day 0 before treatments. The Doppler indices (PSV and EDV) were significantly improved in dogs treated with canine or human MSCs-derived EVs. The maximum values of PSV and EDV were attained in the 8^th week following injection. However, the PI and RI of the testicular arteries were significantly decreased as compared to the Day 0 and control group. The human MSCs-derived EVs group had lower values of RI and PI than the canine MSCs-derived EVs group. The single intra-testicular injection of lyophilized canine MSCs-derived EVs resulted in a highly significant (P<0.001) increase in the sperm cell concentration, motility, live/dead ratio, and normal spermatozoa compared to those obtained in lyophilized human MSCs-derived EVs. In addition, the canine MSCs-derived EVs group showed higher values (P<0.001) of testosterone levels from 2^nd to 8^th weeks than those in the human MSCs-derived EVs group. The reverse trend was observed for NO levels. In conclusion, a single intra-testicular injection of MSCs-derived EVs could improve testicular vascularization by increasing Doppler velocities. In addition, it could improve semen quality, steroids (testosterone), and nitric oxide.