New blood filtering treatment safely extends pregnancy in severe preeclampsia

Cedars-Sinai Health Sciences University investigators have developed and successfully tested a new treatment for pregnant women with severe early preeclampsia, a leading cause of premature birth as well as maternal and fetal death.

The early-stage international study, published in the journal Nature Medicine, focused on removing a harmful protein from a mother's blood.

Preeclampsia is marked by high blood pressure that can quickly become life-threatening. In its most severe early form-before 34 weeks of pregnancy-physicians frequently must deliver babies prematurely to protect the mother, even though early delivery can pose significant risks for the infant. The method tested by investigators was found to safely extend pregnancy, giving babies more time to develop before birth.

Even a few extra days in the womb can make a meaningful difference in outcomes for premature infants. We found a way to potentially buy that time safely. Our approach could shift how we manage very early preeclampsia."

Ananth Karumanchi, MD, co-corresponding study author, professor of Medicine, director of the Renovascular Research Center and the Medallion Chair in Vascular Biology at Cedars-Sinai

The approach focuses on a protein called sFlt-1, which is produced by the placenta and known to damage blood vessels and drive preeclampsia symptoms. Investigators engineered a specialized immune protein that binds to sFlt-1 and incorporated it into a blood-filtering device. Using a process called extracorporeal apheresis-similar to kidney dialysis-they were able to filter the mother's blood and remove excess sFlt-1 without affecting other essential blood components.

The treatment was evaluated in 16 women. Their blood pressure improved, their babies continued to grow normally during treatment, and they remained pregnant for an average of 10 additional days-more than double the time seen in untreated patients.

"Right now, the only way to cure preeclampsia and protect the life and health of the mother is to deliver the baby," said Sarah Kilpatrick, MD, PhD, an expert in maternal-fetal medicine and chair of the Department of Obstetrics and Gynecology at Cedars-Sinai. "That puts very premature infants at high risk. This approach could give clinicians more flexibility in managing these high-risk cases."

Researchers say the treatment is notable also because it removes a harmful factor rather than introducing new drugs, potentially reducing the risk of side effects. However, they note that despite the small study's positive results, the treatment is experimental and needs to be tested in larger clinical trials.

"Our goal was to directly target one of the root causes of preeclampsia," said the study's co-corresponding author Ravi Thadhani, MD, MPH, executive vice president of Clinical Affairs, chief medical officer for Cedars-Sinai Medical Center and Cedars-Sinai Health System. "By lowering sFLt-1, we were able to stabilize patients and extend pregnancy-a meaningful and exciting step forward."