Dynamic microdevice culture during bovine oocyte maturation decreases lipid accumulation and improve blastocyst cell numbers

Assisted reproductive technology (ART) enhances livestock fertility and genetic quality while reducing disease transmission. In vitro embryo production (IVEP) is a crucial technique that requires optimization. Microfluidics has emerged as a promising platform for IVEP by offering a controlled environment with a continuous nutrient supply. This study introduces a novel non-toxic and reusable microdevice with reversible sealing designed for the in vitro maturation (IVM) of bovine cumulus oocyte complexes (COCs). The microdevice is constructed from PMMA and PDMS_LAM on a glass slide, coated with Pluronic 167 F.The use of the microdevice for bovine IVM resulted in similar maturation rates (polar body extrusion rates) compared to the control (4-well-plate) (p = 0.73). Oocytes matured in the microdevices showed reduced lipid droplet accumulation (p = 0.0001), increased reactive oxygen species (ROS) levels (p = 0.0024), and higher glutathione (GSH) levels (p = 0.000002) compared to control. The expression of genes related to lipid metabolism and cellular stress was assessed in cumulus cells from COCs matured in microdevices or control plates, revealing the downregulation of SREPB1 in microdevice-matured COCs. Control and microdevice-matured oocytes were parthenogenetically activated to evaluate embryo development. Although no differences were found in cleavage and blastocyst rates, blastocysts from microdevice-matured COCs had a higher total cell count than controls (p = 0.0031). These findings suggest that microfluidics influence oocytes' lipid metabolism, potentially enhancing early embryo development and increasing blastocyst cell numbers.