MORPHOLOGICAL AND MOLECULAR FEATURES OF DECIDUAL ENDOMETRIAL CELLS IN CASE OF MISCARRIAGES

Decidualization is a dynamic, multi-step process that differentiates elongated endometrial stromal cells into round, epithelioid-like decidual cells in response to rising progesterone levels. Decidual stromal cells play an important role throughout pregnancy by creating a tolerant microenvironment, the decidua, to suppress the maternal immune response and prevent rejection of the allogeneic fetus. Along with this, decidualization plays an important role not only in the establishment and maintenance of pregnancy, prevention of early losses, modulation of the immune response, but also in the control of the onset of labor, regulation of trophoblast invasion, and embryo selection. They have immunomodulatory properties in relation to cells of innate and adaptive immunity. Pregnancy maintenance requires selective elimination of pro-inflammatory senescent decidual cells by activated uterine NK cells. Data on various populations of decidualizing endometrial stromal cells are presented and three subtypes of them with different functional characteristics are distinguished: predecidual, decidual, transitional and senescent subpopulations. An increase in the number of the latter with a pro-inflammatory phenotype leads to pregnancy losses. This review analyzes the literature data on decidualization and its role in the genesis of miscarriage and highlights the important contribution of decidual stromal cells to the microenvironment and their direct or indirect influence on the recruitment, distribution and function of immune cells, on the remodeling of the extracellular matrix and the formation of the placenta. When preparing the review, a search was made for publications in the scientific databases of the RSCI, Scopus, Pubmed, Web of Sience and Google Scholar for the period 2013-2023.