New Gene Markers Regulating the Process of Vascularization in Pig Preovulatory Oocytes during Growth and Maturation

Abstract

Background: A frequent reason for in vitro fertilization failure is insufficient oocyte competence and difficulties in mimicking optimal in vivo conditions at the stage of in vitro maturation. This study aimed to identify the expression profile of genes associated with “vasculature development”, “circulatory system process”, “hemopoiesis”, “patterning of blood vessels” and “hemopoietic or lymphoid organ development” ontological groups during in vitro maturation of domestic pig oocytes. The goal was also to describe new genetic markers that can be used in assisted reproduction techniques. Methods: Porcine oocytes were subjected to in vitro maturation, and the expression of selected genes was compared before and after maturation. Microarray and reverse transcription quantitative polymerase chain reaction (RT-qPCR) analysis were performed on total RNA isolated from the samples. Additionally, immunocytochemical staining was performed and the histological morphology of ovaries was examined. Results: Regardless of the individual processes, the gene expression pattern remained the same and all 32 gene ontology biological process term-genes were represented in down-regulated gene sets. The greatest change in expression was shown by the Vascular Endothelial Growth Factor A (VEGFA) and the smallest by myoferlin (MYOF). Moreover, the expression of VEGFA was confirmed by immunohistochemical analysis of ovaries. Conclusions: The potential contribution of chosen genes to oocyte performance during in vitro maturation can enhance comprehension of the underlying processes in oocytes and their microenvironment. It may also improve the effectiveness of in vitro fertilization.