Platelet-derived soluble factors induce human extravillous trophoblast migration and differentiation: platelets are a possible regulator of trophoblast infiltration into maternal spiral arteries

Abstract

In early pregnancy, human extravillous trophoblasts (EVTs) invade and remodel maternal arteries. We have previously demonstrated that CCR1 is expressed on perivascular/endovascular trophoblasts and that CCR1 ligands promote EVT migration. In this study, we examined the physiologic roles of platelet-derived chemoattractants on EVT invasion. By immunohistochemistry, maternal platelets were localized among endovascular trophoblasts within the lumen of spiral arteries. Extracellular matrices (ECMs) were also detected among endovascular trophoblasts and platelets, suggesting that the platelets in these arteries were activated by ECMs. In vitro, platelets attached to EVTs isolated from human villous explant cultures and expressed P-selectin on the cell surface. Platelets significantly enhanced migration of EVTs without affecting proliferation of EVTs or secretion of MMP-2 or MMP-9. The invasion-enhancing effect of platelet-derived culture medium on EVTs was neutralized by anti-CCR1 antibody. Heat treatment completely abrogated the invasion-promoting effects of platelet-derived culture medium, but charcoal stripping did not. Platelets also induced endovascular trophoblast-like morphologic changes and integrin ␣1 expression in EVTs during 48-hour culture. These findings suggest that maternal platelets activated in the spiral arteries can regulate trophoblastic vascular infil IntroductionIn the human placenta, cytotrophoblasts show 2 distinct patterns of differentiation. In floating villi, cytotrophoblasts differentiate into syncytiotrophoblasts and form the syncytial layer while, at villousanchoring sites, cytotrophoblasts differentiate into extravillous trophoblasts (EVTs) and form the stratified structure called the cell column. After EVTs lose proliferative activity and acquire migratory activity in the cell column, 1 the cells begin to migrate into the decidual tissue (interstitial trophoblasts) or toward maternal blood vessels. Interestingly, EVT migration is directed preferentially to the uterine spiral arteries. 2 EVTs that migrate around the blood vessels (perivascular trophoblasts) destroy the muscular linings, and those that migrate along the vascular lumen (endovascular trophoblasts) replace the endothelium. Thus, the maternal arteries are remodeled into low-resistance tubes that are unable to constrict. This process ensures adequate placental perfusion and contributes to the successful establishment of pregnancy. 3 In fact, insufficient physiological remodeling has been reported in cases of preeclampsia and intrauterine fetal growth retardation. 4 In contrast to other organ constructions in the embryo and placenta, this extraembryonic tissue remodeling occurs in maternal tissues and requires both maternal and embryo-derived cells for cooperative tissue construction. From this perspective, this process is more complex than those involved in organ development during embryogenesis.Vascular infiltration of EVTs at the implantation site is mainly observed in humans and primates. 2 Therefore, analysis of the mech...

Platelet reactivity changes significantly throughout all trimesters of pregnancy compared with the nonpregnant state: a prospective study

“…Platelets have a role in placentation and there is evidence to suggest that the release of a number of growth factors and cytokines induce extravillous trophoblast migration at the feto-maternal interface. 13,14 The process of maternal vascular remodelling taking place in early pregnancy exposes subendothelial collagen to platelets on a continual basis. This study reconciles these two processes; a reduced platelet response to collagen in the first trimester allows vascular remodelling without fibrinogen deposition and clot formation yet the platelets are free to circulate in the microvasculature releasing the necessary soluble factors for trophoblast invasion.…”

Eph–ephrin A system regulates murine blastocyst attachment and spreading

“…Frozen sections of endometrial specimens were prepared and indirect immunofluorescence staining was performed as previously described (Sato et al, 2005) with minor modification. Frozen sections were fixed with acetone at Ϫ20°C for 5 min.…”

p45NF-E2 represses Gcm1 in trophoblast cells to regulate syncytium formation, placental vascularization and embryonic growth

“…Mice lacking p45NF-E2 display severe thrombocytopenia caused by a megakaryocyte maturation defect (Shivdasani et al, 1995). Megakaryocytes can be detected in the embryonic compartment as early as 7.5 days post-coitum (dpc) (Xu et al, 2001), and platelets may alter placental development through various mechanisms (Ohlsson et al, 1999;Sato et al, 2005). Hence, it is generally assumed, but remains to be shown, that the IUGR of p45NF-E2-deficient embryos results from the absence of embryonic platelets.…”