In vitro versus In vivo: Development-, Apoptosis-, and Implantation-Related Gene Expression in Mouse Blastocyst

Abstract

<strong>Background:</strong> While mammalian embryos can adapt to their environments, their sensitivity overshadows their adaptability in suboptimal <em>in vitro</em> conditions. Therefore, the environment in which the gametes are fertilized or to which the embryo is exposed can greatly affect the quality of the embryo and consequently its implantation potential.<br /> <strong>Objectives:</strong> Since providing an optimal culture condition needs a deep understanding of the environmental effects, and regarding the fact that normal morphology fails to be a reliable indicator of natural embryo development, the current study aimed at comparing <em>in vivo</em>- and <em>in vitro</em>-derived blastocysts at the molecular level.<br /> <strong>Materials and Methods:</strong> <em>In vivo</em> and <em>in vitro</em> mouse blastocysts were obtained by flushing the uterine horns and <em>in vitro</em> fertilization/culture, respectively. Normal blastocysts of both groups were evaluated in terms of hatching rate and expression of three lineage-differentiation-, apoptosis-, and implantation-related genes.<br /> <strong>Results:</strong> The hatching rate was lower in <em>In vitro</em> fertilization (IVF)-produced blastocysts in comparison with that of the <em>in vivo </em>counterparts. More importantly, the study results indicated significant changes in the expression levels of eight out of ten selected genes, especially <em>Mmp-9</em> (about -10.7-fold). The expression of <em>Mmp-9 </em>in trophoblast cells is required for successful implantation and trophoblast invasion.<br /> <strong>Conclusions:</strong> The current study, in addition to confirming that the altered gene expression pattern of <em>in vitro</em>-produced embryos resulted in normal morphology, provided a possible reason for lower implantation rate of <em>in vitro</em>-produced blastocysts regarding the <em>Mmp-9</em> expression.