Investigating placental structural and cellular alterations in maternal-fetal communication associated with congenital heart defects

In the United States, Congenital heart defects (CHDs) are the most common birth anomalies, affecting nearly 1% of all births annually and serve as the leading cause of fetal mortality and morbidity. Recent evidence highlights the critical importance of the placenta in fetal cardiovascular health in utero, as it regulates nutrient and oxygen availability essential for optimal development and growth. This study characterized placental structure at delivery and analyzed maternal and umbilical cord blood at mid-gestation across various CHD subtypes to identify disrupted placental architecture and cell-cell communication pathways. We hypothesize that placentas of fetuses with CHD will show immature villous vasculature and altered levels of placenta-derived extracellular vesicles (EVs) compared to uncomplicated controls. Patients were recruited and consented at the Women’s Medical Plaza Clinic at the University of Florida and Cincinnati Children’s Hospital Medical Center under IRB approval. Clinical data and maternal blood were obtained between 24 and 28 weeks of gestation and at time of delivery. Cord blood and placenta were obtained at time of delivery. Controls were matched for gestational age, maternal age, and fetal sex. EVs were isolated by cell sorting using antibodies against cell of origin and size/number assessment performed. Placental maturation was analyzed following hematoxylin and eosin (H&E) staining. Villous blood vessel density was assessed following immunohistochemistry (IHC) against CD31. Statistical analysis was performed using the student’s t-test (Prism GraphPad). Data is presented as a mean ± standard of the mean. P value <0.05 was considered significant. Placental morphology from pregnancies complicated by CHD revealed a significant reduction in terminal villi (11.3±2.6, p<0.001, n=21) and vasculo-syncytial membrane numbers (3.2±1.07, p < 0.001, n=21) compared to uncomplicated control (21.3±3.9, p < 0.001, 10.4 ± 2.5, p < 0.001 respectively, n=18). IHC with CD31 confirmed a decrease in the number of fetoplacental blood vessel CHD (28 (7-41)) versus control (69(51-81), p<0.001). Maternal serum exhibited higher total EV counts at both mid-pregnancy and delivery in CHD cases compared to controls (p < 0.01, n = 75 CHD, 27 controls), with a significant increase in total EV observed in CHD pregnancies with female fetuses compared to male fetuses (p = 0.03). Additionally, EVs from activated platelets in maternal plasma were significantly increased (p <0.0001). Interestingly, there were significant changes in total umbilical cord blood EVs (p = 0.04), endothelial EVs (p < 0.0001), and platelet EVs (p = 0.03) in male fetuses compared to female fetuses. Our findings highlight placentas from pregnancies complicated by a spectrum of CHD subtypes exhibit an abnormal villous vasculature, indicating disrupted angiogenesis. The fetal sex specific difference in EV profiles suggests that EV profiling by fetal sex could serve as a non-invasive biomarker for assessing placental health in CHD pregnancies. Detections of dysfunctional placental health at mid-gestation may enable more targeted interventions to improve the outcome of the affected pregnancy. Porter Physiology Development Fellowship This abstract was presented at the American Physiology Summit 2025 and is only available in HTML format. There is no downloadable file or PDF version. The Physiology editorial board was not involved in the peer review process.