Biologists discover 'molecular fingerprint' of preeclampsia

Researchers at HSE University employed a new method to model hypoxia in placental cells during pregnancies complicated by preeclampsia and identified molecular markers of tissue hypoxia. Since hypoxia is one of the key mechanisms underlying preeclampsia, these findings are important for a more accurate and timely diagnosis of the disease and for the development of effective treatment methods. The paper has been published in Placenta.

Preeclampsia is a dangerous pregnancy complication affecting 2–8% of pregnancies worldwide and one of the leading causes of maternal and perinatal mortality. Because the disorder does not manifest immediately, timely diagnosis is often difficult. Symptoms include elevated blood pressure, protein in the urine, and impaired organ function. The early-onset form of preeclampsia, which develops before the 34th week of pregnancy, is particularly dangerous.

Despite many years of research, the mechanisms underlying the disease are still not fully understood, but scientists believe that its origins lie in the early stages of placental development. Direct studies of the placenta are difficult because of technical and ethical limitations, so biologists rely on cellular models to reproduce these processes in the laboratory.

Hypoxia, or oxygen deficiency in placental tissues, is considered one of the key mechanisms underlying preeclampsia. Researchers from the HSE Faculty of Biology and Biotechnology reproduced a hypoxic state using a placenta-on-a-chip model and compared the results with clinical data obtained from women with early- and late-onset preeclampsia. This allowed them to identify molecular changes characteristic of the disease and discover potential biomarkers. 

First, the scientists analysed real-world RNA sequencing data from single placental cells collected from women with early- and late-onset preeclampsia, as well as from women with normal pregnancies. This made it possible to determine which placental cells change their activity during the disease. The researchers compared different types of trophoblast cells—specialised embryonic cells that form the placenta. The results showed that signs of hypoxia are most pronounced in early preeclampsia. Particularly strongly affected are the extravillous trophoblast cells, which are responsible for remodelling the uterine vessels during pregnancy. 

The researchers then identified nine genes whose activity consistently increased across all cell types in preeclampsia, establishing a kind of molecular signature for the disease.

To assess how reliably this molecular signature can be reproduced in the laboratory, the researchers compared two approaches for modelling preeclampsia in a placenta-on-a-chip model based on the BeWo b30 cell line. The first was the conventional method of inducing hypoxia using cobalt chloride. The second was an alternative approach involving an oxyquinoline derivative. They found that the latter more accurately replicated the molecular profile of preeclampsia. Unlike cobalt chloride, which induced numerous non-specific cellular changes, the oxyquinoline-based compound triggered a more targeted and physiologically relevant response.

'We wanted to test how closely the laboratory model resembles real preeclampsia. This is very important because we cannot continuously take placental samples from pregnant women, we cannot experiment on patients, and, generally, the placenta is a unique, complex, and highly variable organ,' explains the lead author of the paper, Evgeny Knyazev, Head of the HSE Laboratory of Molecular Physiology. 'We have shown that the widely used cobalt chloride model does not always adequately reflect the processes occurring in the placenta during preeclampsia. In some cases, it even produces opposite changes in the activity of key genes.'

A comparison of the sequencing data with the on-chip cellular model confirmed the key role of hypoxia in triggering changes associated with early-onset preeclampsia. The scientists were able to identify potential molecular factors involved in this process. Of particular interest were the EBI3 and COL17A1 genes, which were identified as universal markers of placental stress. In addition, the researchers discovered hypoxia-associated microRNAs, including miR-27a-5p and miR-193b-5p, as well as several isoforms of microRNA molecules. 

'This is the first time we have conducted such a detailed comparative analysis of real patient samples and laboratory models, which has allowed us to obtain a "molecular fingerprint" of early-onset preeclampsia. Changes in the EBI3 and COL17A1 genes, as well as in certain microRNA molecules, clearly indicate placental dysfunction and can be considered molecular markers of the disease,' emphasises Knyazev.

According to the authors, these findings may contribute to the development of methods for early diagnosis of preeclampsia. In addition, a more accurate cellular model based on oxyquinoline derivatives may help more reliably identify new disease biomarkers and potential therapeutic targets.

The study was conducted with support from the HSE Basic Research Programme as part of the Centres of Excellence project, as well as with support from the Russian Science Foundation (grant 24-14-00382).