Pre-maturation culture system: the association of dbcAMP and sildenafil as meiotic arrest modulators to improve oocyte maturation and embryo production

• Grant number: 25/09646-8
• Support Opportunities: Scholarships abroad - Research Internship - Post-doctor
• Start date: July 01, 2025
• End date: June 30, 2026
• Field of knowledge: Agronomical Sciences - Veterinary Medicine - Animal Reproduction
• Principal Investigator: Cláudia Lima Verde Leal
• Grantee: Priscila Helena dos Santos
• Supervisor: Alberto Maria Luciano
• Host Institution: Faculdade de Zootecnia e Engenharia de Alimentos (FZEA). Universidade de São Paulo (USP). Pirassununga , SP, Brazil
• Institution abroad: Università Degli Studi Di Milano, Sedi Lodi, Italy
• Associated to the scholarship: 23/16602-1 - Can the interaction of extracellular vesicles with the cumulus-oocyte complex during pre-maturation and in vitro maturation influence oocyte competence and epigenetic regulation?, BP.PD

Abstract

Although it has already reached a commercially relevant number, in vitro embryo production still faces an important challenge: overcoming the asynchrony between nuclear, cytoplasmic, and molecular maturations that occurs in the cumulus-oocyte complexes (COC) aspirated from small-mid antral follicles, which are still at different stages of germinal vesicle (GV), in a way that provides a better rate of embryo production and quality. A better understanding of folliculogenesis, oogenesis, cumulus-oocyte communication via gap junctions (GJ), has led to the development of protocols capable of maintaining the oocyte in meiotic arrest during in vitro culture, providing the oocyte with additional time for better synchronization of oocyte maturation. This study aims to compare three different protocols for temporary and reversible meiotic arrest (pre-maturation, PMIV) in oocytes at any GV stage or in a population enriched with GV1-stage oocytes. The communication between cumulus cells and oocytes via GJ will also be assessed. For this, viable oocytes from slaughterhouses will be randomly subjected or classified based on morphology (population enriched with GV1 stage) to three different PMIV protocols: i) NPPC, FSH, and steroids; ii) cAMP analogue (dbcAMP) in association with PDE5 inhibitor (Sildenafil); iii) PDE3 inhibitor (Cilostamide). In all protocols, PMIV will be applied for 9 hours, and the medium will be supplemented with 4% polyvinylpyrrolidone to increase viscosity. After PMIV, the oocytes will be evaluated for: 1) nuclear maturation, 2) intracellular communication, 3) global oocyte transcriptional activity, 4) cumulus cell transcripts, 5) embryo production and quality rates. This project aims to gain new knowledge regarding the response of GV1-stage oocytes to different PMIV protocols and whether it is possible to maintain the open oocyte-cumulus communication pathways via GJ, providing improvements in in vitro embryo production conditions. (AU)