Characteristics of the Main Molecular Processes in the Tissues of Placentas of Various Gestational Ages

The aim of the research was assessment of molecular events in the third trimester placentas of different gestational ages and clinical scenarious, based on immunohistochemical findings in the placental tissues. As the appearance of various factors correlate placental tissue changes in situ with gestational age, anthropological, morphological and basic clinical parameters, they are suggested to be original. In the samples from 53 post-delivery placentas of 22 till 40 weeks of gestation were evaluated amounts of cells or extracellular structures, containing the following factors of the molecular processes: growth factors and their receptors IGF1, IGFR1, HGF, bFGF and FGFR1, cytokines IL-10, IL-1α, IL-6 and TNFα, proteins of the basement membrane Collagen IV and Laminin, tissue degrading enzymes MMP2 and MMP9 and products of the homeobox gene HoxB3. Findings were evaluated semi-quantitively and ranked in the ascending order by the modified competition ranking method. Rank values were statistically correlated among themselves, as well as with the gestational age and weight of placenta, maternal and neonatal anthropological data and basic clinical parameters. Visually detectable amounts of bFGF, IL-6 and MMP2 positive cells and Laminin containing structures were not found; all the other factor positive cells or structure of extracellular matrix were seen in various amounts. Amount of IGFR1 and IL-10 positive cells significantly decresed with advanced gestation, suggesting decrease of their impact approaching the term. Significantly higher amount of apoptotic cells in preterm placentas suggested switch to other types of cellular disposal in later gestation. Positive structures of Collagen IV were significantly more in term placentas. Correlations of the other molecular factors with gestational age were not significant. There were found several correlations among the molecular factors, providing insight into interactions between processes in the tissues and suggesting their impact on the course and outcome of pregnancy.