The effects of testicular stromal stem cells on surgically injured testicular tissue in rats

This study investigated the effects of transplanted testicular stromal stem cells (tSSCs) on surgically damaged testis tissue. Ten-week-old male Wistar albino rats were divided into three groups: control (n = 6), damage (DG) (n = 6) and testicular stromal stem cell (TSSC) (n = 6) groups. Surgically induced damage was inflicted on the left testes of both the DG and TSSC groups, with no intervention on the right testes. In the TSSC group, damaged testes were treated with transplanted tSSCs, followed by orchiectomy after 15 days. Testes tissues were stained with haematoxylin-eosin (H&E), and recovery rates of functional structures were assessed by modified Johnsen scoring. The effects of tSSCs on testicular tissue were demonstrated by immunohistochemistry using BAX, BCL-2 and caspase 3. Serum testosterone levels were analysed using the enzyme-linked immunosorbent assay (ELISA) method. Surgical damage caused germ cell degeneration in some seminiferous tubules and a decrease in interstitial areas. With tSSC treatment, improvements in testicular architecture were identified through spermatogenesis in the seminiferous tubules and normal histological structures in the interstitial areas. Correspondingly, in the modified Johnsen score, the DG group showed a significant difference compared to the other groups (p = 0.001). High expressions of BAX, BCL-2 and caspase-3 in the DG group revealed prominent features of apoptosis. With the injection of tSSCs, these expressions significantly normalized according to H score analysis (all p = 0.004). Although serum testosterone levels in the tSSC group were higher compared to the control and DG groups, this difference was not statistically significant (p = 0.119). This study suggests transplanting tSSCs could accelerate tissue healing after testicular sperm extraction (TESE) surgery for azoospermia patients, potentially paving the way for a new and important clinical treatment.