Time to re-think: ovarian tissue transplantation versus whole ovary transplantation

Transplantation of cryobanked ovarian tissue is a promising strategy to restore fertility in cancer patients. However, ischaemia following ovarian tissue grafting can lead to significant follicular loss. Transplantation of the whole ovary by vascular anastomosis has been considered as a method of preventing ischaemic damage that occurs with avascular transplantation of ovarian tissue. Even so, the unavailability of the cryotechnology for whole organs can be a major barrier to whole ovary transplantation. Severe cryoinjury will cause not only follicular death but also irreversible damage to the vascular system of the ovary. Damaged ovarian vasculatures can induce thromboembolism after transplantation which leads to severe tissue ischaemia and follicular loss. As a consequence, follicular loss after the frozen–thawed whole ovary was transplanted with microsurgical vascular anastomosis has been shown to be as severe as that which occurred after ovarian tissue was grafted. In addition, the risk of cancer cell reintroduction can be potentially higher with whole ovary transplantation with vascular anastomosis. The safety and efficacy of the new procedure should be proven before any further clinical applications take place. Nevertheless, research on whole ovary cryopreservation should not be discouraged.