Mouse ovarian tissue cryopreservation has only a minor effect on in vitro follicular maturation and gene expression

To establish a protocol for ovarian tissue cryopreservation which can retain fertility potential after thawing and to evaluate the impact of cryopreservation on development and gene expression during folliculogenesis.

A controlled randomized study in a clinical and academic research setting in a university medical center was conducted to study cryopreservation and in vitro maturation (IVM) of mouse ovarian follicles. Preantral follicles isolated from either fresh (Group A) or cryopreserved (Group B) murine ovarian tissues were used to test their fertility potential by in vitro culture-in vitro maturation (IVC-IVM). Expression of Graafian follicles derived from both groups were detected by DNA microarray techniques for comparison.

Although there were no significant differences in IVM outcomes and follicular gene expression between the two experimental groups, cryopreservation appears to induce the expression of heat shock proteins, DNA-damage-inducible protein 45 and death-related apoptosis genes (i.e., Fas and Fas-ligand).

Cryopreservation may trigger biological events not amenable to normal cell function and follicular development. However, neither follicular development nor gene expression was dramatically changed after cryopreservation. These data suggest that although our current cryopreservation techniques yield competent follicles and mature oocytes, subtle changes observed in gene expression imply that the present cryopreservation techniques need to be further refined.