Exploratory In-vitro Study Evaluating the Addition of Super-GDF9 During Capacitation-in-vitro Maturation (CAPA-IVM) of Donated Human Cumulus-oocyte Complexes (COCs) Derived From Small Antral Follicles

CAPA-IVM (In Vitro Maturation) technology is an assisted reproductive method offering significant benefits in terms of safety and treatment costs, particularly for high-risk patients. These include individuals with ovarian hyperstimulation syndrome (OHSS), venous thrombosis, ovarian torsion, or polycystic ovary syndrome (PCOS) - who typically present with a high number of antral follicles (constituting nearly 15% of all patients). Although the live birth rate following the first transfer in the CAPA-IVM group is 35.2%, which is not statistically different from the conventional IVF group at 43.2% (risk difference: -8.1%; 95% confidence interval: -16.6% to 0.5%), the number of good-quality embryos per cycle and the cumulative clinical pregnancy rate remain lower than in conventional IVF. Therefore, improving the CAPA-IVM culture process to achieve the optimal number and quality of oocytes is essential.

Concurrently, adding growth factors commonly found in follicular fluid to the culture medium represents a remarkable advancement in improving oocyte quality in CAPA-IVM. Some somatic compartments, such as expansion, metabolism, and apoptosis, are regulated by soluble growth factors, known as oocyte secretion factors (OSFs). Two OSFs, Growth differentiation factor 9 (GDF9) and Bone morphogenetic protein 15 (BMP15), have been identified as critical for follicular development and fertility in various species such as mice, sheep, and humans. During IVM culture, both the immature and mature forms of these factors as well as their homo- and heterodimer structures have been tested. Notably, the heterodimer structure has shown the most positive effects on cumulus-oocyte complexes (COCs) during IVM culture.

Although both growth factors exist in homodimeric forms, recent studies have found that the GDF9 and BMP15 heterodimer can also form a more potent growth factor called cumulin. BMP15 activates latent GDF9 in cumulin, leading to strong signaling in granulosa cells via type I receptors (ALK4/5) and SMAD2/3 transcription factors. Biomedically engineered cumulin has been proposed to noticeably improve embryo outcomes in mouse and porcine models. Recently, a modified version of wild-type GDF9, called super GDF9, has been demonstrated to be >1000 times more potent than GDF9 and 4 times more activity than cumulin in SMAD2/3-responsive transcriptional assays in granulosa cells. Previous research has illustrated that adding super GDF9 to CAPA-IVM media in mice induces gene expression in the ovulatory cascade during CAPA-IVM maturation that closely resembles in vivo maturation. Super GDF9 effectively promotes cumulus cell expansion and enhances oocyte developmental competence in vitro. Hence, super GDF9 can potentially replace cumulin, which faces challenges in production and purification.

This study investigates the impact of supplementing super GDF9 during CAPA-IVM culture, aiming to improve outcomes of cumulus-oocyte complexes (COCs) from small follicles and ultimately enhance treatment success.

This study will recruit 300 COCs (an estimated 10 needed patients). 100 COCs will be allocated to the research arm (sGDF-9), while 200 COCs will be allocated to the control arm.