Transplantation of intact rat gonads using vascular anastomosis: effects of cryopreservation, ischaemia and genotype.

BACKGROUND: A limited store of ovarian follicles is present at birth and its progressive decline during ageing is hastened by alkylating agents and ionizing radiation during treatment for cancer or autoimmune disease. Oligo- or azoospermia can arise for similar reasons in men. There is some experimental evidence showing that targeted gene deletion or drugs to produce hypogonadotrophism can protect germ cells from wastage. Another strategy for conserving fertility is to cryopreserve ovarian or testicular tissue for subsequent transplantation. To maximize gonadal function, it is desirable to preserve whole gonads for transplantation using vascular anastomosis.

METHODS AND RESULTS: We investigated this strategy in the rat model. All freshly isotransplanted ovaries (n = 8) survived and resumed follicle growth and secretion and, although ischaemia for 24 h at 4 degrees C did not disrupt ovarian function, the organs had fewer follicles. Four out of seven (57%) cryopreserved transplants survived for > or =60 days, were ovulatory and one pregnancy was established, but the ovarian reserve was compromised by fewer follicles. Ovarian allotransplants were vigorously rejected, even with moderate immunosuppression using cyclosporin A. On the other hand, only three out of seven (42%) fresh testicular isotransplants had active spermatogenesis, and none of the cryopreserved testes was functional.

CONCLUSIONS: The effects of gonadectomy in rats can be reversed by isotransplants, but the results are more successful with ovaries than testes, and allotransplants were never successful. Intact cryopreserved ovaries can be restored to function after transplantation with vascular anastomoses.