Animal experiments
All the animal experiments were performed in Sprague‒Dawley (SD) rats (aged 13 –14 weeks) housed at Ningxia Medical University Laboratory Animal Center (Yinchuan, China). These rats were housed in a temperature-controlled room (22–24°C) with a 12-h light/dark cycle and had free access to food and water. Following a week of acclimatization, they were mated with healthy male SD rats at a 2:1 ratio. The onset of gestation was identified by the presence of vaginal sperm plugs on gestational day 1. The most reliable animal model of PE is the surgically induced reduced uterine perfusion pressure (RUPP) model. This model has been shown to induce hypertension, proteinuria, renal dysfunction, an antiangiogenic state, inflammation, oxidative stress, cardiac dysfunction and intrauterine growth restriction (IUGR), similar to PE in humans. Thus, on the 14th day of gestation, the rats underwent surgical RUPP under pentobarbital anesthesia. Briefly, through a midline incision, the abdominal cavity was opened to expose the lower abdominal aorta. Silver clips (0.203 mm) are placed around the aorta above the iliac bifurcation to the RUPP by approximately 40%. Simultaneously, silver clips (0.100 mm) are used to decrease the degree of ovarian collateral circulation of the bilateral uterine arteries at the ovarian ends of the uterine arch. The sham group underwent the same procedure as the RUPP group but without clip placement. Recombinant adeno-associated virus (AAV) serotype 9 vectors carrying TP53BP2 short hairpin RNA (shRNA) (AAV-shTP53BP2), recombinant AAV serotype 9 vectors carrying DNMT1 shRNA (AAV-DNMT1), recombinant AAV serotype 9 vectors carrying G9a shRNA (AAV-shG9a), or recombinant AAV9 vectors carrying a negative control (AAV-shNC) were manufactured by GeneChem (Shanghai, China). Ten microlitres of virus (1.5E+11) was injected into the placenta. On the 20th day of gestation, the rats were euthanized with pentobarbital, and the pups were removed and weighed. The placentas were washed with ice-cold physiological salt solution and preserved at -80°C for subsequent analysis. The animal experiments were approved by the Committee on the Ethics of Animal Experiments of Ningxia Medical University (NO. 2021–250).