Extracellular vesicles and lipid metabolism in bovine cumulus oocyte complexes and embryos cultured in vitro

• Grant number: 21/06760-3
• Support Opportunities: Regular Research Grants
• Start date: October 01, 2022
• End date: March 31, 2025
• Field of knowledge: Agronomical Sciences - Veterinary Medicine - Animal Reproduction
• Principal Investigator: Cláudia Lima Verde Leal
• Grantee: Cláudia Lima Verde Leal
• Host Institution: Faculdade de Zootecnia e Engenharia de Alimentos (FZEA). Universidade de São Paulo (USP). Pirassununga , SP, Brazil
• Associated research grant(s): 23/01524-5 - Morphological, molecular, and functional analysis of fetal bovine serum-derived extracellular vesicles on the lipid metabolism of cumulus-oocyte complexes and embryos, AP.R

Abstract

In vitro production (IVP) of embryos is a widely used reproductive biotechnique, but quality of embryos is still suboptimal; such embryos show greater sensibility to cryopreservation and increased cytoplasmic lipid accumulation. In vitro culture (IVC) of embryos with extracellular vesicles (EVs) from bovine oviductal fluid (ofEVs), as well as the use of fetal calf serum (FCS) depleted from its EVs (dFCS), improved embryo quality and cryotolerance. Sequential IVC with ofEVs followed by EVs from uterine fluid (ufEVs) resulted in embryos with lower lipid amounts and modulated lipid metabolism related genes and lipase protein. Addition of EVs isolated from follicular fluid (ffEVs) and supplemented to in vitro maturation (IVM) medium, also improved embryo development and quality, but lipid metabolism effects were not studied in cumulus-oocyte complexes (COCs) or embryos. Therefore, the aim of the present study is to investigate the role of EVs from different origins on COCs and embryos lipid metabolism. In the first set of experiments, we will investigate whether the removal of EVs from FCS improves embryo quality through effects on lipid metabolism. In the second set, effects of ffEVs during IVM on COCs lipid metabolism and oocyte maturation and subsequent embryo development will be assessed. The third set of experiments will determine the effects of addition of EVs during IVC (ofEVs followed by ufEVs) on embryo development, quality and lipid metabolism. Finally, in the last set, embryos will be produced using EVs throughout the entire culture sequence (ffEVs during IVM, ofEVs and ufEVs during IVC) and effects on development and quality will be assessed. Knowledge on bovine COCs and embryo lipid metabolism and the role of EVs may contribute to improve quality of IVP embryos. (AU)