Beyond the Placenta: Spatial Genomic Atlas Traces Cross-Tissue Dysregulation in Severe Preeclampsia

Preeclampsia is not simply elevated blood pressure, nor can it be fully explained by a single placental abnormality. A study led by University College London (UCL) broadened its scope to multiple tissues at the fetal–maternal interface and found that severe cases simultaneously exhibit placental stress, abnormal vascular remodeling, and widespread immune activation, creating a more multidimensional pathological picture of this pregnancy complication that can threaten the lives of both mother and baby.

Published in *Science Advances*, the study enrolled 20 pregnant women, including 10 patients with severe preeclampsia and 10 controls, at 25 to 37 weeks of pregnancy. The team combined single-cell and spatial genomic analyses to examine the placenta, myometrium, and chorioamniotic membranes. This approach identified the molecular activity of different cells while preserving information about their locations within tissues, allowing the researchers to distinguish changes in maternal cells from those in fetal cells.

After adjusting for differences in gestational age, placentas from severe preeclampsia cases still showed hypoxia, dysregulated angiogenic signaling, fibrosis, and metabolic abnormalities. Some cells that should help remodel maternal blood vessels also failed to function normally. This remodeling is crucial for increasing placental blood flow; if the process is disrupted, it may deepen placental hypoxia and stress, creating a self-reinforcing vicious cycle.

The abnormalities did not stop at the placenta. Researchers detected signals of immune activation in the myometrium, chorioamniotic membranes, and maternal blood, including interferon responses and mitochondrial dysfunction. These cross-tissue findings support a more comprehensive explanation: signals released by the stressed placenta may interact with the maternal immune response, causing what begins as a localized placental problem to expand into a systemic disease.

These cells and pathways could serve as starting points for drug research, such as designing intervention strategies targeting placental stress, dysregulated angiogenesis, or specific immune responses. The research team also believes that severe early-onset cases may particularly require early intervention. However, this work identified potential targets; it has not yet demonstrated that inhibiting any pathway can improve clinical outcomes for pregnant women or fetuses, and it did not test any candidate therapies.

The greatest limitation is that the samples came from only 20 donors, making it difficult to reliably capture subtle differences in rare cells and potentially failing to encompass the highly diverse clinical manifestations of preeclampsia. The next step is to reproduce the findings in larger, more diverse populations of pregnant women with longitudinal data and determine which changes cause disease and which are merely molecular traces left by severe illness. Only then can this atlas be advanced toward usable biomarkers or treatments.