Hatching is modulated by microRNA-378a-3p derived from extracellular vesicles secreted by blastocysts

Area of Science:

• Reproductive Biology
• Molecular Biology
• Extracellular Vesicle Research

Background:

• Hatching from the zona pellucida is critical for embryo implantation but is often impaired in vitro.
• Embryonic extracellular vesicles (EVs) and their microRNA (miRNA) cargo are released into culture media, but their role in hatching is unclear.
• Challenges in isolating miRNAs from limited embryo culture media have hindered research.

Purpose of the Study:

• To optimize the isolation of miRNAs from EVs secreted by individual bovine embryos.
• To investigate the role of embryonic EV-derived miRNAs in promoting blastocyst hatching.
• To identify specific miRNAs involved in regulating the hatching process.

Main Methods:

• Optimized a protocol for isolating miRNAs from extracellular vesicles (EVs) in conditioned media from individually cultured bovine embryos.
• Quantified miRNA expression in EVs secreted by blastocysts.
• Assessed the functional role of identified miRNAs in blastocyst hatching.

Main Results:

• Successfully optimized EV-miRNA isolation from low-volume embryo culture media.
• Identified miR-378a-3p as significantly upregulated in EVs secreted by blastocysts.
• Demonstrated that miR-378a-3p promotes blastocyst hatching in vitro.

Conclusions:

• Embryonic EVs contain regulatory miRNAs that influence key developmental processes like hatching.
• miR-378a-3p is a novel regulator of blastocyst hatching, acting via secreted EVs.
• This finding enhances understanding of embryo quality and implantation potential.