Abstract
Decidual stromal cells (DSCs) are the most abundant cellular component of human decidua and play a central role in maternal-fetal immune tolerance. Antigen phenotyping and functional studies recently confirmed the relationship of DSCs with mesenchymal stem/stromal cells (MSCs) and pericytes, the latter two cell types being closely related or identical. The present study investigated the effect of decidualization, a process of cell differentiation driven by progesterone (P4) and other pregnancy hormones, on the MSC/pericyte characteristics of DSCs. To this end we isolated undifferentiated DSC (preDSC) lines that were decidualized in vitro (dDSC) by the effect of P4 and cAMP. Using flow cytometry, we found significant downmodulation of the expression of the MSC/pericyte markers α-smooth muscle actin, nestin, CD140b, CD146 and SUSD2 in dDSCs. The dDSCs did not differ, compared to preDSCs, in the expression of angiogenic factors (characteristic of pericytes) HGF, FGF2, ANGPT1 or VEGF according to RT-PCR results, but had significantly increased PGF expression. In migration assays, preDSC-conditioned media had a chemotactic effect on the THP-1 monocytic line (characteristic of pericytes), and this effect was significantly greater in dDSC-conditioned media. Media conditioned with dDSC, but not with preDSC, induced apoptosis in 4 out of 6 different tumor cell lines (characteristic of MSCs) according to propidium iodide staining and flow cytometry results. Our findings show that decidualization induces phenotypic and functional changes in the MSC/pericyte properties of DSCs that may have a role in the normal development of pregnancy.