Improved maturation competence of ovarian tissue oocytes using a biphasic in vitro maturation system for patients with gynecological malignancy: a study on sibling oocytes.

PURPOSE: To investigate the developmental competence of ovarian tissue oocytes from patients with gynecological tumors using a biphasic in vitro maturation system with capacitation (CAPA-IVM) in comparison with standard IVM. METHODS: This sibling pilot study included 210 oocytes in 10 patients with gynecological malignancies. After ovariectomies, ovaries were cut into even halves and immature cumulus-oocyte complexes (COCs) were retrieved from the ovarian tissue. COCs were separately cultured in either a biphasic CAPA-IVM system for 53 h or in standard IVM for 48 h. After IVM, all COCs were denuded and mature oocytes were either vitrified (N=5) or used for ICSI (N=5). Embryos were cultured for 5-6 days and obtained blastocysts were vitrified. RESULTS: Use of the CAPA-IVM system led to a higher meiotic maturation rate in ovarian tissue oocytes (OTO) compared to standard IVM (56 vs 35%, p=0.0045) and had a tendency to result in lower degeneration after IVM. Only the CAPA-IVM method supported blastocyst formation. CONCLUSIONS: The biphasic in vitro maturation system improved the competence of OTO in comparison to the standard IVM method. The study suggests that fertility preservation programs could become more efficient using IVM after capacitation culture.

Biphasic in vitro maturation (CAPA-IVM) specifically improves the developmental capacity of oocytes from small antral follicles.

PURPOSE: To investigate the effectiveness of a biphasic IVM culture strategy at improving IVM outcomes in oocytes from small follicles (< 6 mm) compared with routine Standard IVM in patients with polycystic ovaries. METHODS: This prospective pilot study was performed in 40 women with polycystic ovaries whose oocytes were randomized to two IVM culture methods. Patients received a total stimulation dose of 450 IU rFSH. Cumulus-oocyte complexes (COCs) from follicles < 6 mm and ≥ 6 mm were retrieved and cultured separately in either a prematuration medium with c-type natriuretic peptide followed by IVM (CAPA-IVM), or STD-IVM. Primary outcomes were maturation rate, embryo quality, and the number of vitrified day 3 embryos per patient. RESULTS: Use of the CAPA-IVM system led to a significant improvement in oocyte maturation (p < 0.05), to a doubling in percentage of good and top-quality day 3 embryos per COC, and to an increased number of vitrified day 3 embryos (p < 0.001), compared to STD IVM. Oocytes from follicles < 6 mm benefited most from CAPA-IVM, showing a significant increase in the amount of good and top-quality embryos compared to STD IVM. CAPA-IVM yielded significantly (p < 0.0001) less GV-arrested oocytes and larger oocyte diameters (p < 0.05) than STD IVM. CONCLUSIONS: CAPA-IVM brings significant improvements in maturation and embryological outcomes, most notably to oocytes from small antral follicles (< 6 mm), which can be easily retrieved from patients with a minimal ovarian stimulation. The study demonstrates the robustness and transferability of the CAPA-IVM method across laboratories and populations.

Immature Oocytes from Unprimed Juvenile Mice Become a Valuable Source for Embryo Production When Using C-Type Natriuretic Peptide as Essential Component of Culture Medium.

C-type natriuretic peptide (CNP) and its receptor natriuretic peptide receptor 2 (NPR2) play a paramount role in the maintenance of oocyte meiotic arrest in antral follicles via the regulation of the intra-oocyte levels of cyclic guanosine monophosphate and cyclic adenosine monophosphate. We investigated the potential of CNP 1) to maintain oocyte meiotic arrest during a prolonged prematuration culture and 2) to sustain acquisition of developmental competence of immature cumulus-oocyte complexes (COCs). Compact COCs were collected from small antral follicles of prepubertal unprimed mice and placed in prematuration culture under different CNP-supplemented media conditions. A preliminary analysis showed a dose-dependent effect of CNP on the maintenance of meiotic arrest. A dose of 25 nM maintained oocytes under meiotic arrest for 24 h, and this period was extended to 48 h in the presence of estradiol. Analysis of transzonal projections of COCs cultured with CNP indicated that oocyte-cumulus connections were well preserved after the prolonged prematuration culture. Furthermore, CNP medium supplemented with FSH and GDF9 promoted oocyte growth and induced a shift in oocyte chromatin configuration from a predominantly dispersed to a condensed configuration. Following in vitro maturation, oocytes cultured under CNP were capable of extruding the first polar body at a high rate (around 80%). Blastocyst formation was significantly improved when oocytes were cultured under CNP-supplemented medium containing FSH and GDF9. This study reports for the first time a prolonged prematuration culture system, with CNP as the pivotal factor, that can efficiently maintain oocytes retrieved from unprimed prepubertal mice under meiotic arrest while promoting their acquisition of developmental competence.