Improvement of developmental competence of aged porcine oocytes by means of the synergistic effect of insulin-like growth factor-1 (IGF-1) and epidermal growth factor (EGF)

Abstract

There is a constant increase in demand for large numbers of high-quality oocytes of domestic mammals for various reproductive biotechnologies. Prolonged in vitro culture represents one of the many possible ways of meeting this demand. However, oocytes further cultured in vitro after reaching the stage of metaphase II undergo the complex process called "ageing", which decreases the quality of oocytes. The aim of the present study was to improve the culture conditions for in vitro matured porcine oocytes by supplement of the epidermal growth factor (EGF) or the insulin-like growth factor 1 (IGF-1) in order to reduce the adverse effects of ageing. Supplement of either EGF or IGF-1 had no significant effect on the ageing of porcine oocytes. Significant effects were demonstrated when the oocytes were cultured with both EGF and IGF-1. A combination of 10 µg EGF/ml with 25 ng IGF-1/ml was the most effective. Oocytes aged under these conditions retained very good developmental competence. We observed development to the morula (21%) or blastocyst (25%) stage in oocytes aged for 1 day with EGF and IGF-1. Porcine oocytes matured in vitro are more resistant to the ageing when cultured in the presence of both EGF and IGF-1 and these conditions retain an elevated developmental competence for a certain time.

Keywords

• epidermal growth factor
• insulin-like growth factor 1
• oocyte
• ageing
• pig