Effect of serum-containing and serum-free culture medium-mediated activation of matrix metalloproteinases on embryonic developmental competence

In this study, we examined whether serum-free and serum-containing media affect matrix metalloproteinase (MMP) activity with respect to embryonic development, and whether MMP expression is correlated with the development of in vitro fertilized eggs. When oocytes were cultured in serum-free medium (containing polyvinylpyrrolidone) and serum (foetal bovine serum)-containing medium, the generation of meiosis 2 (MII) oocytes was 76% and 87.5%, respectively (P < 0.05). After in vitro fertilization using mature oocytes, we observed 39.72% and 64.05% of cleaved oocytes in serum-free and serum-containing groups, respectively (P < 0.05). Our analysis revealed differential expression and activity of MMPs. The serum-containing group showed high MMP-9 activity during oocyte maturation and development of in vitro produced embryos, with particularly high activity in the inner cell mass zone of the embryos. Therefore, this study suggests that the presence or the absence of serum will affect the activity of MMPs, which can be used to measure the rate of embryonic development.