Effect of progesterone on human mesenchymal stem cells.

Progesterone is considered to be a major reproductive steroid hormone which supports the successful development of pregnancy. One of the basic targets of progesterone are stromal cells in endometrium which are triggered to undergo decidualization in preparation to accept the embryo. However, the endometrial stroma consists of different subpopulations of cells with varying characteristics and functions as one of the subpopulations are the endometrial mesenchymal stem cells (MSCs) which seem to be located both in the basal layer and in the functional layer of the endometrium. In all cases, these cells have the features of typical MSCs such as adherence and differentiation in multiple cell lineages. The endometrial MSCs are stimulated by progesterone to increase the expression and secretion of immunomodulatory proteins such as HLA-G and PIBF.