Macrophages modulate the growth and differentiation of rhesus monkey embryonic trophoblasts.

PROBLEM: Immune cells within the endometrium at implantation are thought to play an important role in implantation, although their exact role is not well understood. METHOD OF STUDY: A co-culture system of rhesus monkey embryos and maternal immune cells was established. Blastocysts obtained by in vitro fertilization were co-cultured with peripheral blood cells or decidual macrophages. Culture media were collected to assess secretions. Embryo growth was monitored, and trophoblasts were evaluated for proliferation, apoptosis, and differentiation. RESULTS: Embryonic trophoblast outgrowths were visible within 6 days of culture, and the area of embryo outgrowth was reduced when blastocysts were cultured with peripheral-derived or decidual macrophages. Trophoblast proliferation was not significantly affected with macrophage co-culture while chorionic gonadotropin secretion was increased. Trophoblast expression of CDH 11 and GJA1 was increased, suggesting that macrophages accelerate differentiation of peri-implantation trophoblasts. CONCLUSIONS: These results indicate an important role of macrophages in placentation and pregnancy success.