Effect of BMP15 and GDF9 in the IVM medium on subsequent oocyte competence and embryo development of prepubertal goats

Abstract

Oocyte-secreted factors (OSFs), such as BMP15 and GDF9, are soluble paracrine factors that drive cumulus cell differentiation and function, sustaining oocyte competence acquisition and embryo development. This study aimed to assess the effect of BMP15 and GDF9 on IVM medium of prepubertal goat oocytes. COCs were in vitro matured in absence (control group) or presence of 100 ng/mL of BMP15, GDF9, or both. To determine cumulus-oocyte communication, transzonal projections (TZP) density at 0h, 6h, 12h and 24h of IVM were evaluated. After IVM, mitochondrial activity, intracellular ROS and glutathione (GSH) levels, the epidermal growth factor receptor (EGFR) expression in oocytes and cumulus cells, and cumulus expansion were assessed. Blastocyst production and quality were evaluated after parthenogenetic activation (PA) and IVF. IVM supplementation with BMP15 increased the TZP density during the first 6 h of culture. After IVM, BMP15 increased mitochondrial activity, EGFR expression in oocytes and cumulus cells, and cumulus expansion compared to control, but ROS and GSH levels were similar to control. BMP15 improved blastocyst production following PA (15.5 % vs 6.3 %) and the number of cells in the blastocyst inner cell mass. No differences were observed on blastocyst production or quality following IVF. IVM supplementation with GDF9 did not improve results from control group in any parameters studied. Additionally, GDF9 in combination with BMP15 only improved mitochondrial activity and cumulus expansion over control. In conclusion, IVM medium supplementation with BMP15 (100 ng/ml) improves COCs quality parameters and PA-blastocyst production and quality of prepubertal goat oocytes. However, GDF9 (100 ng/mL) did not have any beneficial effect in this study and was possibly antagonistic to BMP15.