P-665 High FSH level impairs VEGF secretion by thawed human ovarian tissue

Abstract

Abstract Study question How does a high FSH level as related to POI (premature ovarian insufficiency) affect VEGF secretion by thawed human ovarian tissue? Summary answer After thawing, the high FSH concentration of 175mIU/mL (10ng/mL) significantly decreased VEGF secretion by human ovarian tissue by 25.6%. 17.5mIU/mL did not change VEGF secretion. What is known already Cryopreservation of ovarian cortical tissue has become an important method in fertility preservation. However, 70% of the follicles do not survive the reimplantation process due to an insufficient blood supply and oxidative stress. Human ovarian tissue secretes angiogenic factors, including VEGF, spontaneously. Its regulation by FSH is not known although 50% of the reimplantation patients show increased FSH levels (>25mIU/mL) due to POI. Study design, size, duration Provided a signed consent, biopsy punches of ovarian cortical tissue from 8 patients undergoing fertility preservation were studied. Slow freezing and thawing was applied as in the intern routine instructions. Participants/materials, setting, methods Human ovarian cortical tissue was cultured in full medium at 37 °C for 48h after thawing in presence or absence of 17.5mIU/mL (1ng/mL) or 175mIU/mL (10ng/mL) recombinant human FSH. VEGF-A secretion was measured by ELISA. The expression of VEGF-A, HIF-1α and FSHR was assessed by immunohistofluorescence per follicle. The effect of FSH was assessed by one-way-ANOVA with Tukey’s post test. The effect of culture or follicular maturation stage was analyzed by t test. Main results and the role of chance After thawing, VEGF secretion recovers and rises over time. The addition of 175mIU/mL FSH significantly impaired VEGF-A expression compared to untreated ovarian tissue (p = 0.016). The analysis of 481 follicles showed similar results of FSH affecting VEGF-A expression by immunostaining. In particular, primordial follicles expressed significantly less VEGF-A compared to growing follicles (primary+secondary; p < 0.0001). 48h tissue culture significantly increased VEGF-A expression in primordial follicles (p = 0.0041). The addition of the high FSH level significantly decreased VEGF-A expression in growing follicles (p = 0.0005). Limitations, reasons for caution Although VEGF-A is a key factor in angiogenesis, more factors are known to affect angiogenesis. The direct effect on angiogenesis should be evaluated. Moreover, the conditions in tissue culture may not represent those after reimplantation. Wider implications of the findings High FSH levels, as seen in patients with POI, might impair ovarian VEGF expression and angiogenesis. Hormone replacement therapy (HRT) might be endorsed before and during ovarian tissue reimplantation. More clinical and biological data are required to understand the regulators of angiogenesis after ovarian tissue reimplantation adequately. Trial registration number not applicable