Patients and study samples
Eighty-five placentas were obtained from women who underwent cesarean delivery at the General Hospital of Ningxia Medical University between 2017 and 2021. PE was defined as a systolic blood pressure ≥140 mmHg and a diastolic blood pressure ≥90 mmHg in two consecutive measurements taken at least 6 h apart, along with proteinuria (≥0.3 g/24 h) after 20 weeks of gestation. Placentas from non-PE pregnancy volunteers (pregnant controls (PCs), n=40), with no medical history or medication usage, served as controls.Placentas in the PE pregnancy group (n=45) were obtained from pregnant patients who delivered with early-onset PE (<34 weeks gestation). The exclusion criteria included multiple gestations, fetal congenital malformations/chromosomal abnormalities, recent infection, antiphospholipid antibodies, trauma, drug/alcohol abuse during pregnancy, hypertension that had been discovered before 20 weeks, thrombophilia with a history of PE, receiving anticoagulant/antiaggregation therapy, smoking, and incomplete data from pregnant women’s obstetric examinations. Placentas were collected from the central part within 10 min of cesarean delivery, avoiding macroscopic areas of infarction and calcification. After rinsing briefly in saline, the samples were frozen at -80°C or fixed in polyformaldehyde until further analyses. All experiments were conducted following the protocol approved by the Clinical Research Ethics Committee of Ningxia Medical University (NO. 2017-083), and informed consent was obtained from all patients.