Low vs. Air Oxygen Concentration CAPA-IVM Culture of Cumulus-oocyte Complexes

Effect of Low Versus Air Oxygen Concentration in In-vitro Maturation With Biphasic Capacitation-IVM (CAPA-IVM) Culture of Human Cumulus-oocyte Complexes in PCOS Patients: a Sibling Oocyte Pilot Study

IVM with a pre-maturation step, known as capacitation IVM (CAPA-IVM), has demonstrated enhanced maturation of human oocytes in vitro and successful live births. However, CAPA-IVM has shown lower rates of embryo formation when compared to conventional in vitro fertilization/ intra cytoplasmic sperm injection (IVF/ICSI) cycles. To optimize the CAPA-IVM culture system, this pilot study aims to evaluate the impact of low oxygen versus air oxygen concentrations on embryological outcomes in PCOS patients.

Oocyte in vitro maturation (IVM) is an alternative approach to assisted reproductive technology (ART) that has the advantage of minimal stimulation, resulting in reduced hormone-related side effects and risks, especially in women with polycystic ovary syndrome (PCOS). Oocytes retrieved for IVM procedures are derived from a diverse pool of follicles with an average diameter of between 2 and 10mm and are characterized by variable cellular and molecular attributes that indicate their immature status. Therefore, the development of an IVM culture system that could enable and enhance the acquisition and synchronization of meiotic and developmental competence prior to the meiotic resumption is essential for optimizing human IVM protocols.

IVM with a pre-maturation step, known as capacitation IVM (CAPA-IVM), has been shown to improve the competence of human oocytes matured in vitro and result in live births. The pre-maturation culture of CAPA-IVM utilizes C-type natriuretic peptide (CNP), and maturation takes place in the presence of amphiregulin (AREG), both of which are physiological compounds that have been shown to prevent spontaneous meiotic resumption of oocytes (CNP) and enhance oocyte competence (AREG) during IVM.

To date, the results of pilot studies have shown that CAPA-IVM increases the rates of oocyte maturation, good-quality embryos on day 3 and good-quality blastocysts, resulting in a result, a higher embryo yield was obtained compared with standard IVM. Additionally, the reported cumulative live birth rate after use of CAPA-IVM, and its non-inferiority to the cumulative live birth rate with standard in vitro fertilization highlight the clinical utility and potential of this approach. Improvements in the culture system could make CAPA-IVM more effective, but these need to be investigated.

The oxygen concentration during the IVM process plays a crucial role in oocyte maturation. The use of oxygen concentrations higher than physiological levels can lead to cell damage and affect embryo development. Recent studies in mice have suggested using lower oxygen concentrations to improve IVM outcomes. However, the effectiveness of using lower oxygen concentrations in human IVM remains unproven. Therefore, this pilot study aims to compare the effectiveness of lower oxygen concentration conditions versus air oxygen in CAPA-IVM on embryology outcomes in PCOS women.

Inclusion Criteria:

• ≤38 years
• Having polycystic ovarian morphology: at least 25 follicles (2-9 mm) throughout the whole ovary and/or increased ovarian volume (>10ml)
• Having at least 20 follicles on the Oocyte Pick-up day
• Patients consent to culture embryos to the blastocyst

Exclusion Criteria:

• Cases with severe male factor (concentration <5 million/ml, cryptozoospermia, azoospermia)
• Oocyte donation
• Pre-implantation genetic testing