About halfway through a pregnancy, an expectant mother may notice the first symptoms of serious complications. For example, abnormally high blood pressure and dark urine around 20 weeks could indicate preeclampsia, while excessive thirst and frequent urination starting at 24 weeks may signal gestational diabetes. These complications, if left untreated, can negatively impact the health of both the mother and the baby, and may lead to long-term consequences after birth.
Medical professionals typically monitor pregnant women for changes in blood pressure and glucose levels to detect complications. However, these symptoms often appear after the damage has already occurred. Detecting complications earlier could lead to better outcomes, which has driven researchers to develop more reliable screening tools. One such effort focuses on placental extracellular vesicles (EVs) found in maternal blood plasma.
EVs are small particles released by cells, including those in the placenta. These vesicles carry molecules that can provide insights into the health of the originating cells. Although the precise role of EVs in health and disease is still being studied, changes in their quantity and composition have been linked to various pregnancy complications. Researchers at the University of Queensland, led by Carlos Palma, have developed a sensor to detect placental EVs and potentially predict complications before they become clinically apparent.
To develop their sensor, Palma’s team collected blood plasma samples from 201 pregnant women at 13 weeks into their pregnancies. The group was split into two: one half had normal pregnancies, while the other half developed serious complications like preeclampsia, gestational diabetes, and preterm birth. The researchers isolated the EVs from the samples and measured the amounts of specific proteins associated with the placenta and EVs. They identified two key proteins—placental alkaline phosphatase (PLAP) and cluster of differentiation 9 (CD9)—that were most predictive of complications.
Using these findings, Palma’s team created a sensor capable of detecting EVs bearing PLAP and CD9. The sensor used tiny magnetic beads coated with PLAP antibodies to capture the EVs. The beads also had metallic properties that allowed them to catalyze a color change in a dye solution without the need for biological enzymes. After the beads were incubated in blood plasma and isolated, the researchers applied the dye and observed a color shift. The intensity of the color change was proportional to the number of placental EVs in the sample. A spectrophotometer was then used to measure the color, and the data were input into an algorithm that predicted the likelihood of complications.
This sensor proved particularly effective in identifying women at risk for gestational diabetes. Andy Powell, a biochemist at Liverpool John Moores University, praised the technology, noting its potential to function similarly to a pregnancy test but using blood instead of urine. He also commended the decision to use an artificial enzyme for the color change, which may offer more stability compared to biological proteins.
However, Powell and his colleague Iain Dykes expressed concern about the lack of specificity in the biomarkers used. While the technology showed promise, neither PLAP nor CD9 is uniquely tied to any particular pregnancy complication. This raised questions about the potential for false positives or inconsistent results across different diseases. The researchers may need to investigate additional disease-specific biomarkers to improve the accuracy of the test for different complications.
Surendra Sharma, an obstetrician and molecular biologist, echoed similar concerns. He pointed out that while the sensor is an excellent starting point, further research is needed to refine the approach and identify more specific biomarkers for conditions like preeclampsia or gestational diabetes. Despite these challenges, the development of such a sensor holds great promise for early detection of pregnancy complications, ultimately leading to better outcomes for both mothers and babies.
