Differences in maturation and quality of oocytes/follicles with polycystic ovarian syndrome following freezing-thawing

Differences in maturation and quality of oocytes/follicles with polycystic ovarian syndrome following freezing-thawing
Sajedeh Afzalnia,^1,* Fatemeh Ghasemian ,² Tooba Mirzapoor,³
1. Department of Biology, Faculty of Science, University of Guilan, Rasht, Iran
2. Department of Biology, Faculty of Science, University of Guilan, Rasht, Iran
3. Department of Biology, Faculty of Science, University of Guilan, Rasht, Iran
Introduction: Background and purpose: One of the current methods during assisted reproductive techniques is cryopreservation, specially freezing of oocytes/follicles. During this process, the genes involved in apoptosis may change and can effect on the quality of the frozen oocytes/follicles. There is still no information on the difference in in-vitro maturation potential and quality of PCOs follicles/oocytes (such as apoptosis rate) following freezing-thawing process compared to normal oocytes/follicles, which has been studied in this study. The expression of BAX and BCL2 genes was investigated as apoptosis genes in normal and PCOs oocytes/follicles following freezing-thawing.
Methods: Materials and methods: 10 NMRI mice were divided into two groups: control and PCOs groups. The PCOs mice were induced by intramuscular injection of 4 mg/kg estradiol valerate dissolved in 0.2 mg Sesame oil once a day. After 60 days, mice of each group were sacrificed and their ovarian tissue was collected. After separating the oocytes/follicles, the freeze process was done. Then, thawed oocytes and follicles were cultured in IVM medium (MEM-alpha culture medium with 10% FBS serum), and incubated for 24 to 48 hours. The oocytes/follicles were examined to express the BAX and BCL2 genes using Real Time-qPCR method.
Results: Results: The results showed that 58% of oocytes and 50% of follicles were matured in the PCOs group following freeze-thaw method. In addition, 65% of oocytes and 88% of follicles were matured in the normal freezed-thawed group. The rate of in-vitro oocyte maturation in the normal freezed-thawed group was higher than the PCOs freezed-thawed group (P< 0.05). Also, the apoptosis rate was also increased in PCOs freezed-thawed group compared to control group (P< 0.05).
Conclusion: Conclusion: PCOs oocyte/follicle quality was decreased after freeze-thaw process. The maturation and survival rate of PCOs oocytes was also changed during cryopreservation that it states that the freezing process is not recommended for these oocytes/follicles.
Keywords: Keywords: IVM, Vitrification, Polycystic ovarian syndrome, Cryopreservation, Oocyte, BAX, BCL2.