P-368 In vitro culture with rutin and VEGF-A before xenotransplantation protects ovarian tissue from ischemia and oxidative damage but not from growing follicle depletion
Authors: Grubliauskaite M , Breimelyte D , Prokofjeva V , Rascon J , Gudleviciene Z 
Published: July 2024

Abstract

Study question
Can pre-treatment with antioxidant and vascular endothelial factor (VEGF-A) help to maintain healthy tissue structure and follicle pool in xenotransplanted human ovarian tissue?

Summary answer
Rutin and VEGF-A help to prevent fibrosis and oxidative stress damage in grafted ovarian tissue but cannot preserve growing follicles.

What is known already
Nowadays, ovarian tissue (OT) cryopreservation and autotransplantation become established fertility preservation methods in numerous countries. However, even if hundreds of children has been born thanks to this procedure, most crucial process during which 70-80% of the follicles are lost in the graft is the transplantation itself. As the graft restores vascularisation and regains its function the tissue undergoes ischemia and oxidative stress. There have been attempts made to improve this critical postoperative period by administration of different growth factors, hormones, antoxidants or mechanical tissue damage.

Study design, size, duration
Pieces of frozen-tharwed OT (2,5 × 2,5 mm) from 10 women were transplanted into immunodeficient mice for 4 weeks. Before xenotransplantation OT fragments were in vitro cultured for 36h in culture media supplemented with 1 μg/ml rutin and 50 ng/ml VEGF-A (n = 10 OT, pretreated grafted) or without (n = 10 OT, non-pretreated grafted). Frozen-thawed OTs were used as non-grafted controls for ischemia-reperfusion injury, apoptosis and follicle loss evaluation.

Participants/materials, setting, methods
OTs were received from cancer patients (n = 10) undergoing cryopreservation at National Cancer Institute. Xenotransplantation was performed at Life Sciences Centre, Vilnius University. Retrieved grafts were devided into one small piece for immunochistochemical evaluation of α-SMA and apoptosis by TUNEL, and one bigger piece for qPCR analysis of genes related to tissue integrity (PRDX1, SOD1, FN1, COL6A1, CASP3, ANGPT2, mouse CD31) and follicle development (FOXO3, FSHR, GDF9), house keeping gene being GAPDH/Gapdh.

Main results and the role of chance
After 4 weeks of grafting, multiple genes and protein expressions were evaluated. Vascularisation evaluation: compared to non-grafted group, in grafted OTs we observed significantly more vessels (α-SMA staining, p &lt; 0.0001 and ANGPT2 expression, p &lt; 0.05), as well 1,5-fold higher relative expression of mouse CD31 in pretreated grafted group vs non-pretreated grafted group. Qxidative stress and apoptosis evaluation: expression of SOD2, PRDX1 and CASP3 genes was lower in both grafted groups compared to non-grafted control, significant alterations between xenotransplanted groups were found. Structural gene evaluation: in non-grafted control we could find higher expression of COL6A1 and FN1 genes compared to grafted groups and statistical difference of COL6A1 expression in between grafted groups (p &lt; 0.05). Follicle pool evaluation: primordial follicle activation was measured by FOXO3 gene expression change, though we did not find significant differences between any of three groups, p = 0.06 was observed between grafted OT groups. Maturing follicles were evaluated by expression changes in GDF9 and FSHR genes. We observed significant decrese in expression of these genes in grafted groups (p &lt; 0.05). Results from TUNEL are awaited, thus are the quantification of apoptotic cells, which will provide valuable insights for correlation with vascularisation and oxidative stress.

Limitations, reasons for caution
This study was performed only in a long-term xenotransplantation setting, we cannot know if rutin and VEGF-A had a significant influence during the first days of OT transplantation. Due to the small size of OT grafted, counting and distribution of follicles was not performed,

Wider implications of the findings
This study shows that pretreatment of OTs with rutin and VEGF-A could be potentially used in human setting due to protection of ischemia and oxidative stress, especially if the survival of growing follicles is not required, as it is in cases of prepubertal girls.

Trial registration number
not applicable