O-272 Oral administration of antioxidants can support follicle survival in xenografted human ovarian tissue
Authors: Olesen H Ø , Subiran Adrados C , Pedersen A T , Kristensen S G 
Published: June 2023

Abstract

Study question
Can oral administration of antioxidants improve follicle survival in human ovarian tissue through reduction of oxidative stress in a xenotransplantation model?

Summary answer
Daily oral administration of antioxidants for 7 days post-transplantation had a positive effect on follicle survival in grafted human ovarian tissue.

What is known already
Today cryopreservation and autotransplantation of ovarian tissue is an established fertility preservation method in many centres. Hundreds of live births have been achieved but the efficacy of this procedure is hampered by a critical loss of follicles following transplantation. The ovarian tissue is subjected to hypoxia and ischemia postoperative which leads to oxidative damage in the tissue. Postoperative supplementation with antioxidants has been shown to decrease oxidative stress in transplanted ovarian tissue and increase follicle survival, however, these results were mainly obtained through intraperitoneal injections to host animals. Oral administration of antioxidants could be a better alternative for clinical application.

Study design, size, duration
Pieces of frozen-thawed ovarian cortex tissue (total of 56) from 12 women were transplanted to immunodeficient mice in a short- and long-term xenograft study, for 7 and 28 days respectively. In each study the mice were administered daily doses of hazelnut cream (control group) for 7 days post-transplantation or hazelnut cream containing either 150 mg/kg N-acetylcysteine (NAC) or FERTILIX (containing Vitamin E, D and C, Mixed Tocopherols and Tocotrienols, Lycopene, and Coenzyme Q10).

Participants/materials, setting, methods
Cryopreserved ovarian tissue was donated by 12 women undergoing ovarian tissue cryopreservation at Copenhagen University Hospital. Grafts were retrieved after 7 and 28 days of xenografting and histologically processed for follicle counts, immunohistochemistry, and qPCR analysis. The number of surviving follicles and ovarian graft volume were evaluated histologically after 7 and 28 days xenografting. Gene expression analysis of antioxidant defence markers (Sod1, Hmox and Catalase) and angiogenic factor Vegfa were performed after 7 days xenografting.

Main results and the role of chance
After 7 days xenografting, the follicle density was similar for all groups (control group: 33.03±14.85 (mean±SEM) follicles/mm3; NAC-group: 26.34±10.54 follicles/mm3, FERTILIX-group: 35.12±10.88 follicles/mm3). However, the NAC- and FERTILIX-group had a 3- and 3.7-fold increase in follicle density respectively compared to the control group. However, after 28 days of xenografting there was a higher density of surviving follicles in both antioxidant groups, compared to control (control group: 9.51±2.9 follicles/mm3; NAC-group: 14.9±6.02 follicles/mm3, FERTILIX-group: 14.43±5.83 follicles/mm3), which resulted in a 3.2-fold increase in follicle density in the NAC-group and 2.4-fold increase in the FERTILIX-group compared to the control group. The findings were not statistically significantly different in either the 7 days or 28 days study (p = 0.7072; p = 0.5691). The relative gene expression of the antioxidant defence genes Hmox and Catalase was overall like the control for all treatment groups after 7 days xenografting, but for Sod1 the expression was significantly lower for the NAC- and FERTILIX-group compared to the control group (p = 0.0407; p = 0.0255). For Vegfa the expression was similar overall and not significantly different from the control group (p &gt; 0.05).

Limitations, reasons for caution
The distribution of follicles in human ovarian cortex is highly heterogeneous and can vary tremendously between cortex pieces from the same woman and between patients. Statistically significant results were not obtained for the follicle data in the current study; thus, the conclusions should be interpreted with caution.

Wider implications of the findings
Oral administration of antioxidants had a positive effect on follicle survival in xenotransplanted human ovarian tissue. These findings provide a step toward potential clinical administration of antioxidants like NAC or FERTILIX postoperative of ovarian tissue transplantation, which could improve follicle outcomes in a feasible way for the patient.

Trial registration number
Not applicable