IL1B and preeclampsia: Exosomes derived from human umbilical cord mesenchymal stem cells reduce the systolic blood pressure and 24-hour urinary protein levels of preeclamptic rats by expressing it, increase the placental weight, reduce the levels of inflammatory factors (such as TNF-α, IL-1β, and IL-6) in the serum and placental tissue, and inhibit cell apoptosis, ultimately suppressing the progression of preeclampsia