Single vs. Group CAPA-IVM Culture of Cumulus-oocyte Complexes

Oocyte in vitro maturation (IVM) is a minimal-stimulation ART with reduced hormone-related side effects and risks for the patients. However, the approach is not widely used because of an efficiency gap compared to conventional ART.

Oocytes retrieved for IVM procedures derive from a heterogeneous pool with variable cellular and molecular characteristics that indicate its immature status. Thus, in vitro systems that permit and enhance acquisition and synchronization of meiotic competence (ability to resume meiosis in response to an ovulatory stimulus) and developmental competence (ability to be fertilized and support early embryo development) before the meiotic trigger are crucial for the optimization of human IVM systems.

A novel two-step IVM culture system (named CAPA-IVM) involving a pre-maturation culture with C-type natriuretic peptide (CNP) and a maturation step in presence of Amphiregulin (AREG), both more physiological compounds improving oocyte competence, have been introduced in previous clinical studies. So far these pilot studies proved to increase the rates of oocyte maturation, good quality embryos on day 3, good quality blastocyst, and as a result a higher embryo yield. CAPA-IVM blastocysts have shown similar rates of methylation and gene expression at gDMRs compared to COS embryos; and the expression of ma-jor epigenetic regulators was similar between both groups. Furthermore, an improvement in pregnancy rates strengthens the clinical relevance of the use of CAPA-IVM strategy.

In order to further optimize and adapt the CAPA-IVM system in the IVM clinic, this pilot study aims to check the feasibility of applying a single COC CAPA-IVM strategy versus the group COC culture CAPA-IVM. A single COC culture would permit to perform a non-invasive molecular analysis per matured oocyte, in order to identify quality genes ex-pressed in cumulus cells post-IVM (cumulus biomarkers), which could be subsequently used to identify the embryo(s) with highest potential of implantation.

Inclusion criteria

• Having polycystic ovarian morphology: at least 25 follicles (2-9 mm) throughout the whole ovary and/or increased ovarian volume (>10ml) (it is sufficient that 1 ovary fits these criteria)
• No major uterine or ovarian abnormalities
• Having at least 15 follicles on the OPU day
• Patients consent to participate in the study

Exclusion criteria

• High (>grade 2) grade endometriosis
• Cases with extremely poor sperm (serve OAT: density <1 million, mobility <10% and sperm from testicular surgery)