Circulating miRNAs in the maternal serum during early pregnancy in the pig

Recently, microRNAs (miRNAs) have emerged as new players in the fine tuning of embryo development and implantation in mammals via posttranscriptional gene regulation mechanisms. There is also a growing body of evidence showing that miRNA profiles in body fluids may reflect biological processes taking place in the organism. Applying custom made multispecies arrays we aimed to analyze expression profile of circulating microRNAs in serum samples to answer the question whether some of the miRNAs found to be expressed in porcine embryos and trophoblasts or pregnant endometria could be detected in maternal serum. miRNA expression profiles were analyzed in serum samples collected from pregnant and non-pregnant animals on Days 12, 16 and 20 of either pregnancy or the estrous cycle. Each group was represented by four samples.