A novel technique for in vitro maturation of sheep oocytes in a liquid marble microbioreactor.

Abstract

The aim of this work was to develop a microbioreactor using liquid marble (LM) as a novel system for oocyte in vitro maturation (IVM) in small volumes. Cumulus-oocyte complexes (COCs) obtained from slaughterhouse sheep ovaries were in vitro matured in a LM system prepared by placing a drop (30μl containing 10 COCs) suspended in TCM 199 supplemented with 10% (v/v) oestrus sheep serum (OSS) and 0.1IU FSH and LH onto a polytetrafluoroethylene (PTFE) particle bed (LM group). As a control group (CTRL group), COCs were in vitro matured in standard volume and conditions (600μl of IVM medium in a four-well dish). After 24-h culture at 38.5°C in 5% CO2 in air, COCs were released from LM and the following parameters were evaluated: (a) percentage of MII oocytes, (b) oocyte developmental competence following in vitro fertilization (IVF) or parthenogenetic activation (PA) and embryo culture for 8days in synthetic oviductal fluid (SOF) medium at 38.5°C in 5% O2, 5% CO2, and 90% N2. The results indicated similar percentage of MII oocytes in LM and CTRL groups (88.0 vs. 92.0%). No differences were observed in blastocyst rate after IVF (LM 47.5% vs. CTRL 50.2%, P=0.637) or PA (LM 44.4% vs. CTRL 48.3%, P=0.426). The results indicate that LM microbioreactor is a viable technique that provides a suitable microenvironment to induce oocyte in vitro maturation.