Follicular environment and its role in the acquisition of oocyte competence: Experimental models to uncover mechanisms associated with miRNA delivery to the oocyte cytoplasm

• Grant number: 25/13194-5
• Support Opportunities: Scholarships in Brazil - Doctorate
• Start date: October 01, 2025
• End date: September 30, 2029
• Field of knowledge: Agronomical Sciences - Veterinary Medicine - Animal Reproduction
• Principal Investigator: Juliano Coelho da Silveira
• Grantee: Camila Azzolin de Souza
• Host Institution: Faculdade de Zootecnia e Engenharia de Alimentos (FZEA). Universidade de São Paulo (USP). Pirassununga , SP, Brazil
• Associated research grant: 21/06645-0 - Extracellular vesicles as a platform for diagnostic and manipulation of the in vitro embryo production system: the next generation in animal reproduction, AP.JP2

Abstract

Assisted reproductive technologies have the potential to accelerate genetic improvement and enhance both productive and reproductive efficiency in livestock, in addition to serving as a crucial tool in the treatment of human infertility. However, only a small proportion of the cumulus-oocyte complexes (COCs) matured in vitro reach the blastocyst stage, and these embryos generally exhibit lower quality compared to those produced in vivo. This limitation is closely associated with the inability to fully mimic the physiological processes occurring within the follicular environment, which is directly linked to the success of reproductive biotechnologies.In light of this, recent studies have proposed the delivery of biological materials to cumulus cells in vitro in an attempt to simulate a more dynamic follicular environment during in vitro maturation (IVM), aiming to improve oocyte quality. Moreover, it is known that both systemic challenges and the follicular microenvironment itself can impact developmental competence. Therefore, the present project aims to investigate whether microRNAs (miRNAs) present in extracellular vesicles (EVs) from follicular fluid (FF) are capable of modulating the molecular content of the oocyte and influencing the acquisition of developmental competence in the female gamete.To address this question, three experiments will be conducted. The first experiment aims to explore the endocytosis pathways and intracellular transport mechanisms of EVs by cumulus cells, as well as the delivery of miRNAs into the oocyte cytoplasm. The second experiment will focus on identifying miRNAs that serve as biomarkers of follicular environment quality, both in vitro and in vivo. The third experiment will assess the impact of supplementing in vitro embryo production systems with EVs synthetically enriched with miRNAs associated with follicular and oocyte quality, using oocytes from animals with a history of gestational failure due to poor oocyte quality.The resulting data will first be analyzed to verify compliance with assumptions of homoscedasticity and normality. Subsequently, for each experiment, the most appropriate statistical tests will be applied according to the number of groups compared, adopting a significance level of p ¿ 0.05, using GraphPad Prism and R Studio software.Overall, this project aims to contribute to the understanding of still underexplored physiological processes that may represent important tools to improve in vitro embryo production, both in animal and human contexts. (AU)