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.
Cumulus-oocyte complexes (COCs) from small follicles after OPU will be divided into 2
groups:
Group 1 (sGDF-9): donated COCs will be cultured in the CAPA and IVM steps, adding
50ng/ml Super-GDF9 during both steps in CAPA-IVM
Group 2 (Control): The subject's remaining COCs will be cultured in the CAPA and IVM
steps without adding Super-GDF9 during CAPA-IVM.
Groups 1 and 2: Collecting after the capacitation step: spent media and blank wells.
Collecting after the maturation step: spent media, cumulus cell, and blank wells.
- CAPA and Maturation culture: CAPA and Maturation culture will be performed routinely
following current laboratory protocols. ICSI will be used to fertilize mature
oocytes.