Nonetheless, placentae exhibit venous thrombosis in uteroplacental circulation associated with neonatal death

Nonetheless, placentae exhibit venous thrombosis in uteroplacental circulation associated with neonatal death. placental development and embryonic survival. Nonetheless, placentae exhibit venous thrombosis in uteroplacental circulation associated with neonatal death. In contrast, maternal EPCR deficiency results in clinical and histological features of placental abruption and is ameliorated with concomitant Par4 deficiency. Our findings unveil a causal link between maternal thrombophilia, uterine hemorrhage, and placental abruption and identify Par4 as a potential target of therapeutic intervention. INTRODUCTION The placenta plays key roles in supporting fetal development and preserving maternal health during pregnancy and parturition. Maternal thrombophilia is a suspected risk factor for placenta-mediated pregnancy complications that include recurrent pregnancy loss, intrauterine growth restriction, stillbirth, placental abruption, and preeclampsia (<< 0.001, 2 test of independence). These were normal in appearance and showed placental development comparable to littermate EPCR+/+ controls (Fig. 2, A to F). In this genetic experiment, the mother lacked Par4 and the fetuses (and their extraembryonic tissues) were heterozygous for Par4. Par4 is expressed on a Rabbit Polyclonal to IPPK variety of cell types that include trophoblast cells (<< 0.001, 2 test of independence). EPCR?/? placentae appeared normal and unremarkable upon histological examination (Fig. 2, G to L). Reverse genetic crosses (pregnancies of EPCR+/? females sired Varespladib methyl by Par3?/? EPCR+/? males) did not produce any live EPCR?/? embryos at 11.5 dpc and exhibited a high abortion rate [7 EPCR+/+, 7 EPCR+/?, 0 EPCR?/?, 10 aborted, 3 pregnancies analyzed, = 0.030, 2 goodness of fit (GOF)]. These results suggested that thrombin-mediated activation of maternal platelets plays a key role in placental failure of EPCR-deficient embryos. Table 1 Pregnancy outcomes from EPCR+/? intercrosses.Outcomes of intercrosses with and without inactivation of Par4, Par3, IIb, or FVIII in the mother, father, or both parents are shown. GOF, goodness of fit. * denotes significant values <0.05. value,= 0.85, 2 GOF test; 50% EPCR?/? expected, 46.0% observed, 95% confidence interval (CI) = 31.8 to 60.7%]. These results confirm that epiblast-specific deletion of EPCR (Meox2Cretg/? EPCR/; abbreviated henceforth as EPCR/) allows embryonic development and survival comparable to EPCR-expressing littermate controls. Thus, though the absence of Par4, Par3, or IIb in the mother protected EPCR-deficient (EPCR?/?) embryos from midgestational death, longer-term survival of these mice that lack EPCR expression on extraembryonic trophoblast cells was markedly reduced, compared to the survival of EPCR-deficient mice generated by maintaining expression on trophoblast cells (EPCR/). To investigate the time and cause of death of EPCR?/? embryos/pups, we examined pregnancy outcomes at late gestation and within the first 24 hours of birth. Frequencies of late-gestation EPCR?/? embryos (analyzed at 18.5 dpc) and neonates (collected within 24 hours of delivery) from pregnancies of Par4?/? EPCR+/? dams sired by EPCR+/? males did not deviate significantly from expected (Table 1, rows 10 and 11). EPCR?/? offspring were also present in expected Mendelian frequency at 18.5 dpc in pregnancies of Par3?/? EPCR+/? dams sired by EPCR+/? males (Table 1, row 12) but were markedly reduced among 1-day-old neonates (Table 1, row 13, = 0.058, 2 GOF). EPCR-deficient mice were fewer at late gestation in pregnancies of IIb ?/? EPCR+/? mothers sired by EPCR+/? males, but the reduction in their frequency was not statistically significant (Table 1, row 14; 15.5% observed, 25% expected, = 0.276, 2 GOF). In each of these crosses, 100% of EPCR?/? mice that survived past the first week of birth exhibited normal life spans (>1 year of Varespladib methyl age). Thus, EPCR?/? pups are vulnerable in the perinatal period, and many died within the first few days of birth. We examined EPCR?/? Varespladib methyl neonates from each of these genetic crosses but did not discover any obvious potential cause of death. However, we observed that EPCR?/? embryos in pregnancies of Par3?/? EPCR+/? dams were significantly smaller than their littermates at 18.5 dpc. The reduction in size was also observed for their corresponding placentae. A similar reduction was noted in placental sizes for EPCR?/? concepti in pregnancies of Par4?/? EPCR+/? and IIb?/? EPCR+/? dams and in sizes of EPCR?/? embryos in pregnancies of IIb?/? EPCR+/? dams (Fig. 3, A to J). Histological examination of late-gestation placentae in each of these genetic crosses notably revealed thrombi in the junctional zone of EPCR?/? placentae. EPCR Varespladib methyl is highly expressed in the spongiotrophoblast cells of the junctional zone in normal mouse placentae (Fig. 3, K and M). The junctional zone is Varespladib methyl traversed by trophoblast-lined venous sinuses that drain maternal blood from the.