Short‐Term Bovine Ovarian Tissue Heterotopic Autotransplantation: VEGF Beneficial and Detrimental Effects

Ovarian tissue transplantation (OTT) has been suggested as an alternative to preserving female fertility in livestock species, as currently performed in women. The OTT technique has been tested as xenografting or autografting in different body sites and animal species. Currently, there are no reports available regarding the autotransplantation of ovarian tissue using the bovine model and also testing the effect of vascular endothelial growth factor (VEGF) on graft survival. This study evaluated the effects of ovarian tissue short-term exposure to VEGF before heterotopic autotransplantation into a subcutaneous site (flank region) for 7 days in cattle. The initial finding was that after OTT and without pre-exposure to VEGF, the ovarian grafts had 42% of normal preantral follicles, which indicates a substantial step forward for this technique in cattle. Furthermore, VEGF exposure actively facilitated the process of neoangiogenesis, the proliferation capability of the stromal cells for activation of the cell cycle, maintained the balance between types I and III collagen fibers, and reduced the total collagen of the grafted tissue. Moreover, ovarian fragments previously exposed to VEGF tended to have greater follicular density; however, a detrimental effect of VEGF on follicular morphology was noticed. In conclusion, this study marks a significant step forward in bovine OTT and provides a foundation for further investigations into the specific pathways, stages, and durations of VEGF exposure to unveil strategies for refining ovarian transplantation techniques in cattle and other species.