Assessment of DNA Repair Gene Expressions in Vitrified Mouse Preantral Follicles

OBJECTIVE: Vitrification of the ovarian tissue is one of the techniques recommended for preserving the fertility of women who are dealing with infertility. Despite its benefits, our information about the molecular aspects of ovarian follicles vitrification is somehow ambiguous. Therefore, the aim of this study was to evaluate the expression pattern of DNA repair genes in vitrified preantral follicles. MATERIALS AND METHODS: In this experimental study, the isolated preantral follicles (n=906) from 14-16 days old mice (n=12) were divided into three groups: fresh, toxic and vitrified which were cultured in vitro for 12 days. Preantral follicles were vitrified using cryotop followed by exposure to equilibration solution for five minutes and vitrification solution (VS) for 30 seconds. In the toxic group, preantral follicles were only placed in equilibration and vitrification media and they were then placed in the warming solutions without exposure to liquid nitrogen. On the second and sixth days of the culture period, real-time quantitative reverse transcription-polymerase chain reaction (qRT-PCR) was carried out to evaluate expression of the selected genes involved in DNA repair, including Msh6 (MutS homolog 6), Mre11 (Meiotic recombination 11), Brca1 (Breast cancer type 1), Rad51 (RAD51 recombinase), Pcna (Proliferating cell nuclear antigen) and Atm (ATM serine/threonine kinase). In addition, developmental parameters including growth, survival rate, antrum cavity formation and ovulation were analyzed. RESULTS: The relative mRNA expression of Msh6, Mre11, Brca1, Rad51, Pcna and Atm on the second and sixth days of the culture period in vitrified group was significantly higher than those of the control and toxic groups, but there was no significant difference between the toxic and control groups. In addition, developmental parameters of follicles were similar in both toxic and control groups, while both were significantly higher than that of vitrified group. CONCLUSION: Vitrification changes the expression pattern of DNA repair genes of the mouse preantral follicles.