Crossing the placental barrier: Preferential migration of microchimeric cells from maternal blood into fetal organs in mice

as in the 1st trimester trophoblast cell line HTR-8/SVneo. Isolated blood monocytes where cultured and differentiated in the presence of IL-34 for six days. When analyzed with flow cytometry, they showed high expression of CD14, CD163 (scavenger receptor), CD206 (mannose receptor) and CD209 (DC-SIGN), markers expressed on decidual macrophages. Taken together, our results show that IL-34 is produced both by placental and decidual cells and is able to induce macrophages with a phenotype resembling that of decidual macrophages. The findings suggest a role for IL-34 in the regulation of decidual macrophages during early pregnancy.