Ovarian tissue cryopreservation and transplantation: a review on reactive oxygen species generation and antioxidant therapy

Cancer is the leading cause of death worldwide. Fortunately, the survival rate of cancer continues to rise, owing to advances in cancer treatments. However, these treatments are gonadotoxic and cause infertility. Ovarian tissue cryopreservation and transplantation (OTCT) is the most flexible option to preserve fertility in women and children with cancer. However, OTCT is associated with significant follicle loss and an accompanying short lifespan of the grafts. There has been a decade of research in cryopreservation-induced oxidative stress in single cells with significant successes in mitigating this major source of loss of viability. However, despite its success elsewhere and beyond a few promising experiments, little attention has been paid to this key aspect of OTCT-induced damage. As more and more clinical practices adopt OTCT for fertility preservation, it is a critical time to review oxidative stress as a cause of damage and to outline potential ameliorative interventions. Here we give an overview of the application of OTCT for female fertility preservation and existing challenges; clarify the potential contribution of oxidative stress in ovarian follicle loss; and highlight potential ability of antioxidant treatments to mitigate the OTCT-induced injuries that might be of interest to cryobiologists and reproductive clinicians.

Ovarian Auto-Transplantation of Cryopreserved Tissue on Muscle Surface Compared With Subrenal Capsular in Rats

BACKGROUND

Fertility protection and ovarian function preservation are important to those undergoing radiation therapy to fight female reproductive cancers. The aim of this study was to explore a new ovarian transplantation position, the surface of thigh muscle, which was biceps femoris muscle in rats.

METHODS

We hypothesized that this procedure was comparable to traditional subrenal capsular transplantation and realized a normal ovarian function. The ovarian tissue, after cryopreservation, were transplanted to surface of biceps femoris muscle by suturing.

RESULTS

Histologic examination indicated that the transplanted tissues would survive and support a lower level of follicle growth compared with subrenal capsular (17 ± 2.6 vs 8.9 ± 4; P = .0018). According to weight gaining record, muscle surface transplantation supported appropriate weight gain although the β-estradiol levels did not completely recover. This new procedure could support a basic normal estrous cycle.

CONCLUSION

Ovarian transplantation through this procedure partly rebuilt ovarian function, which was more likely to be an alternative way for those not suitable for subrenal capsular transplantation.

Ovarian tissue damage after grafting: systematic review of strategies to improve follicle outcomes

Frozen-thawed human ovarian tissue endures large-scale follicle loss in the early post-grafting period, characterized by hypoxia lasting around 7 days. Tissue revascularization occurs progressively through new vessel invasion from the host and neoangiogenesis from the graft. Such reoxygenation kinetics lead to further potential damage caused by oxidative stress. The aim of the present manuscript is to provide a systematic review of proangiogenic growth factors, hormones and various antioxidants administered in the event of ovarian tissue transplantation to protect the follicle pool from depletion by boosting revascularization or decreasing oxidative stress. Although almost all investigated studies revealed an advantage in terms of revascularization and reduction in oxidative stress, far fewer demonstrated a positive impact on follicle survival. As the cascade of events driven by ischaemia after transplantation is a complex process involving numerous players, it appears that acting on specific molecular mechanisms, such as concentrations of proangiogenic growth factors, is not enough to significantly mitigate tissue damage. Strategies exploiting the activated tissue response to ischaemia for tissue healing and remodelling purposes, such as the use of antiapoptotic drugs and adult stem cells, are also discussed in the present review, since they yielded promising results in terms of follicle pool protection.