Evaluation of the effect of cryopreservation on human gametes on the basis of morphological and functional parameters

There is increasing evidence that treatment of sperms with pentoxyphyllin, an inhibitor of the enzyme phosphodiesterase, results in improved sperm motility and better pregnancy rate after homologue insemination. However, the data concerning the heterologue (donor) insemination or the experiences with pentoxyphyllin treated cryopreserved sperms are still lacking. The aim of this study is to improve the quality of cryopreserved sperms by optimalization of freezing-thawing methods. We address the question of whether treatment of thawed donor sperms with different concentrations of pentoxyphyllin in vitro results in better motility and pregnancy rate after insemination. This dose-finding in vitro study is followed by an in vivo evaluation of the efficacy of pentoxyphyllin where the donor volunteers will be treated with pentoxyphyllin for at least 5 months prior to sperm donation. The main outcome of these experiments could be the overall improvement of sperm quality of cryopreserved sperms obtained from donor males and better pregnancy rates. The increase in pregnancy rates results in less treated cycles and lower treatment costs.

On the other hand, cryopreservation of the ovarian tissue prior to radical medical treatment (e.g. chemotherapy) followed by autotransplantation is one of the most promising tool to restore fertility in patients after finishing the anticancer treatment. The other goal of this study is the morphological and functional examination of ovarian tissue following long term storage in liquid nitrogen. Tissue parts will be thawed and placed in an organ explant cultures. The in vitro maturation-related morphological and functional changes as well as the gonadotropin-dependent androgen, estrogen and inhibin production will be examined. For the critical evaluation of the effects of cryopreservation on the vitality, parallel experiments with oocyte-granulosa-cumulus complex obtained from the ovarian cortex will be planned to improve the culture conditions. The optimalization of cryopreservation and maturation techniques of human ovarian tissue, as a basic criteria for the success of possible autotransplantation, would open new promising perspectives for ovarectomyzed women who wants to became pregnant or is suffering from the symptoms of menopause as a consequence of low estrogen levels.