An in vitro study on oocyte and follicles of transplanted ovaries treated with vascular endothelial growth factor

OBJECTIVE: Retrieval of high quality follicles and oocytes from transplanted ovaries is essential for higher fertility preservation efficiency. The effect of vascular endothelial growth factor (VEGF) was evaluated on the survival rate of preantral follicles following ovarian transplantation. MATERIAL AND METHODS: Prepubertal female mice were divided to 6 groups including: control (C), transplanted with no VEGF treatment (T) and transplanted with different dosages of VEGF [0.5 µg/mL (TV1), 1 µg/mL (TV2), 2 µg/mL (TV3), and 4 µg/mL (TV4)]. Twenty-one days later, the left ovaries were removed and transplanted on gluteal muscle. Each dose was injected directly into transplanted ovary. Twenty-one days after transplantation, the ovaries were taken, and follicles and cumulus-oocyte-complexes (COCs) were released using 26-gauge needles with a stereo microscope. The number of healthy COCs, matured oocytes, and in vitro developed embryos after fertilization in vitro were evaluated to determine the best dose of VEGF. Follicle number and follicular growth was evaluated relative to the dose of VEGF provided. Transplantation and VEGF treatment with the best dose was performed as mentioned above and in vitro follicle growth in transplanted ovaries was compared with opposite ovaries (OPP). RESULTS: COC retrieval was significantly lower in the transplanted groups compared with the control group (p<0.05). The percentage of metaphase II oocytes was significantly lower in the group treated with 4 µg/mL VEGF compared with the controls (p<0.01). In the TV2 (1 µg/mL) and TV3 (2 µg/mL) groups, the percentages of morula and blastocysts were significantly improved compared with the T group (p<0.01). In the OPP group, the number of follicles was significantly higher compared with the transplanted groups (p<0.01). CONCLUSION: The improving effect of VEGF on in vitro maturation and in vitro development outcome indicates that VEGF administration may increase transplantation efficiency for fertility preservation.