Expression of selected cytokeratins in human placenta - a preliminary observational study

Every human body is made up of billions of cells, and every cell consists of thousands of microscopic structures. Thanks to the presence of the cytoskeleton, which is built by microfilaments, microtubules, and intermediate filaments, cells are able to fulfill their main function. Dozens of genes encode a large family of cytoskeletal proteins, which form 10-nanometer-long microfilaments, called cytokeratins.

The study was carried out on seven mature human placentas without significant pathology - all eligible mothers were healthy. The collection of basic anthropometric data preceded the dissection of the placentas. Paraffin blocks were made in the usual manner, and hematoxylin and eosin-stained slides were made afterward. Immunohistochemical reactions were performed and the expression of the studied markers was evaluated independently by two observers.

Evaluation of microscopic material revealed the absence of expression of antibodies for cytokeratin 5/6 in placental tissues. Moreover, strong expression of cytokeratin 7 was demonstrated in the villi trophoblast in all types of villi. Immunohistochemical reactions were observed in the mesenchyme within the blood vessel wall, as well as in the extravascular tissue.

The human placenta is an organ that only exists during the intrauterine period of human development and undergoes rapid changes and dynamic growth during pregnancy. These types of processes define selected placental cells as ‘pseudo-tumorigenic tissue’ because of the numerous similarities trophoblast cells have to tumor cells. The use of tissue microarray (TMA) in combination with immunohistochemistry (IHC) may be a valuable approach to validate the predictive and diagnostic utility of various biomarkers in non-cancerous tissues like placental tissue.