New Application of Sequential in Vitro Muturation System for Infertility Patients With Polycystic Ovary Syndrome

Oocyte in vitro maturation (IVM) is an artificial reproductive technologies (ART) in which cumulus-oocyte complex (COC) are collected at the immature germinal vesicle (GV) stage from unstimulated or FSH-primed ovaries and matured in vitro before fertilization. IVM has been proposed as a more patient-friendly ART alternative to conventional IVF. Contrary to IVF, IVM is the only ART method with no cases of OHSS reported. Hence, patients with PCOS represent the major target population for IVM treatment. In clinical practice of standard IVM, COCs are aspirated from unstimulated or mildly stimulated ovaries and rapidly removed from the meiotic-inhibiting influence of the follicle and the follicular fluid. Regardless of in vitro gonadotrophin treatment, oocytes mature spontaneously in vitro, hence undergoing meiotic resumption in the absence of the usual elaborate cascade of endocrine and paracrine molecular signals that induce maturation in vivo. As such, the maturation of oocytes by standard IVM techniques is an artefact that compromises subsequent oocyte developmental competence. Numbers of studies have been proposed to improve the efficiency of IVM system. Synchronization of meiotic and cytoplasmic maturation in antral oocytes arrested at the immature GV-stage remains a major challenge and is of fundamental importance for successful fertilization. High intra-oocyte levels of cyclic adenosine monophosphate (cAMP), is crucial to maintain the nearly fully-grown oocytes under meiotic arrest and to induce oocyte maturation. Research in animal models has indicated that a non-physiological drop of cAMP levels in the oocyte results in asynchronous nuclear and cytoplasmic maturation. Investigators have reported the development of a novel in vitro simulated sequential oocyte maturation system. Critical to success of the approach is a pre-IVM phase that generates a rapid increase in COC cAMP levels. Secondly, the system utilizes an extended IVM phase containing sufficient FSH