Embryo Developmental Potential in a Novel 2-step IVM System

In vitro maturation is a valid option for PCO(S) patients in the daily ART clinic, however maturation and embryologic development are not yet matching the efficiency levels obtained by standard COS treatment. To further enhance embryo quality after IVM, it was hypothesized to keep the connection and communication between oocyte and cumulus cells intact for a prolonged pre-maturation culture before IVM was initiated. This has been investigated and established using a meiotic blocker C-type Natriuretic peptide (CNP). The CNP peptide is present in high concentrations in the growing follicle, is produced by the mural granulosa cell compartment and binds to the Natriuretic peptide receptor 2 (NRP2) present in the cumulus cells. Binding of CNP on NRP2 leads to intracellular cGMP increase in cumulus cells, which travels through the transzonal projections to the oocyte. In the oocyte, cGMP will block the resumption of meiosis. Using CNP as natural inhibitor of meiosis, a new medium was designed to allow oocyte and surrounding cumulus cells to communicate and hence gain in competence for an additional culture period: the pre-maturation phase or Capacitation phase (CAPA). This system was devel-oped in mouse, tested in human in UZ Brussel on research material (toelating federaal EC: CFE-FCE ADV\_073\_ZUBrussel, toelating lokaal EC: 2016/411 BUN 143201630723) and used in a clinical setting in Vietnam.