Intersection of regulatory pathways controlling hemostasis and hemochorial placentation

Abstract

Hemochorial placentation is characterized by the development of trophoblast cells specialized to interact with the uterine vascular bed. We utilized trophoblast stem (TS) cell and mutant rat models to investigate regulatory mechanisms controlling trophoblast cell development. TS cell differentiation was characterized by acquisition of transcript signatures indicative of an endothelial cell-like phenotype, which was highlighted by the expression of anticoagulation factors including tissue factor pathway inhibitor (TFPI). TFPI localized to invasive endovascular trophoblast cells of the rat placentation site. Disruption of TFPI in rat TS cells interfered with development of the endothelial cell-like endovascular trophoblast cell phenotype. Similarly, TFPI was expressed in human invasive/extravillous trophoblast (EVT) cells situated within first-trimester human placental tissues and following differentiation of human TS cells. TFPI was required for human TS cell differentiation to EVT cells. We next investigated the physiological relevance of TFPI at the placentation site. Genome-edited global TFPI loss-of-function rat models revealed critical roles for TFPI in embryonic development, resulting in homogeneous midgestation lethality prohibiting analysis of the role of TFPI as a regulator of the late-gestation wave of intrauterine trophoblast cell invasion. In vivo trophoblast-specific TFPI knockdown was compatible with pregnancy but had profound effects at the uterine–placental interface, including restriction of the depth of intrauterine trophoblast cell invasion while leading to the accumulation of natural killer cells and increased fibrin deposition. Collectively, the experimentation implicates TFPI as a conserved regulator of invasive/EVT cell development, uterine spiral artery remodeling, and hemostasis at the maternal–fetal interface.

Modeling Trophoblast Cell-Guided Uterine Spiral Artery Transformation in the Rat

“…Global-LOF Junctional zone dysgenesis and failed intrauterine trophoblast cell invasion [176] Ahr Global-LOF Maternal AHR regulates TCDD-induced endovascular trophoblast cell invasion [125] Tfpi Trophoblast-LOF Inhibition of endovascular and interstitial trophoblast cell invasion [48] a LOF, loss of function.…”

“…The first wave of trophoblast cell invasion is restricted to endovascular trophoblast cell colonization of uterine spiral arteries/arterioles, which is initiated at the earliest stages of placentation and is a prominent feature of the midgestation mesometrial decidua [ 34 , 35 , 46 ]. Endovascular trophoblast cells mimic and supplant endothelial cells [ 34 , 35 , 47 , 48 ], destabilize vascular smooth muscle [ 49 ], and become embedded in fibrin [ 12 ]. A second wave of trophoblast cell invasion begins after gestation day 13.5, as endovascular trophoblast cells penetrate blood vessels beyond the decidua-myometrial boundary and interstitial trophoblast cell invasion is initiated [ 34 , 35 , 36 , 46 ].…”

“…NK cells are most prevalent after embryo implantation until midgestation and then diminish in number as gestation advances concomitant with increases in intrauterine trophoblast cell invasion [ 34 , 81 ]. The reciprocal relationship between NK cells and intrauterine trophoblast cell invasion is also demonstrated by the retention of NK cells within the uterine-placental interface in rat pregnancies with compromised intrauterine trophoblast cell invasion [ 48 , 51 , 82 , 83 ]. An exception is NK cell expansion in failed conceptus sites [ 84 ].…”

“…It is important to appreciate that all in vitro analyses are artificial and potentially misleading without complementary in vivo physiological assessments [ 5 ]. Invasive trophoblast cells can be effectively tracked in vivo [ 46 , 173 ] and the importance of a gene in a physiological context can be evaluated using lentiviral-mediated trophectoderm gene manipulation [ 174 , 175 ] and global genome edited rat models [ 48 , 64 , 125 , 176 ]. Roles for phosphoinositide 3-kinase (PI3K)/AKT/fos-related antigen 1 (FOSL1)/JUNB proto-oncogene (JUNB), HIF/KDM3A/MMP12, achaete-scute family bHLH transcription factor 2 (ASCL2), and tissue factor pathway inhibitor (TFPI) as conserved regulators of the invasive trophoblast cell lineage have been demonstrated using this strategy [ 47 , 48 , 64 , 176 , 177 , 178 , 179 , 180 ] ( Table 2 ).…”

“…Invasive trophoblast cells can be effectively tracked in vivo [ 46 , 173 ] and the importance of a gene in a physiological context can be evaluated using lentiviral-mediated trophectoderm gene manipulation [ 174 , 175 ] and global genome edited rat models [ 48 , 64 , 125 , 176 ]. Roles for phosphoinositide 3-kinase (PI3K)/AKT/fos-related antigen 1 (FOSL1)/JUNB proto-oncogene (JUNB), HIF/KDM3A/MMP12, achaete-scute family bHLH transcription factor 2 (ASCL2), and tissue factor pathway inhibitor (TFPI) as conserved regulators of the invasive trophoblast cell lineage have been demonstrated using this strategy [ 47 , 48 , 64 , 176 , 177 , 178 , 179 , 180 ] ( Table 2 ). PI3K/AKT signaling regulates FOSL1, which cooperates with JUNB, to form a heterodimer and a functional activator protein 1 (AP-1) transcription factor that facilitates endovascular trophoblast cell development during early stages of placentation [ 177 , 178 , 179 , 180 ].…”