Nanotech-Based Blood Test Detects Risk of Placental Complications During Pregnancy

By Marilynn Larkin

August 16, 2021

NEW YORK (Reuters Health) - A new blood test based on NanoVelcro chip technology can detect placenta accreta as early as the first trimester, researchers say.

The chip is a postage stamp-sized device with nanowires that are 1,000 times thinner than a human hair and coated with antibodies that can recognize specific cells. It was originally created to detect circulating tumor cells in the blood of cancer patients.

Dr. Hsian-Rong Tseng of the University of California, Los Angeles told Reuters Health by email, "We repurposed the NanoVelcro chip to detect and quantify single and clustered circulating trophoblast cells (cTBs) as a new diagnostic solution for noninvasive detection of placenta accreta spectrum (PAS). The intellectual property was licensed from UCLA to CytoLumina Technologies Corp in 2011, and the devices are commercially available for research use at this stage."

Coauthor Dr. Yalda Afshar, also of UCLA, added in the same email, "This screening test gives physicians a chance to intervene to reduce the risk of complications. Knowing who is at risk for PAS early in the pregnancy is a quick and easy way to improve clinical care. I'm looking forward to translating this technology to the patient's bedside so it can be accessible to all."

As reported in Nature Communications, the new blood test detects abnormally high levels of cTBs or trophoblast clusters, both of which indicate an elevated risk of PAS.

For a feasibility study, the team collected blood samples from 168 pregnant women and 15 non-pregnant women in four cohorts: PAS cohort: 65 prenatally suspected and subsequently pathologically confirmed PAS patients (mean age, 36); placenta previa cohort: 59 clinically diagnosed placenta previa patients (mean age, 35); normal placentation cohort: 44 pregnant women with clinically confirmed normal placentation (mean age, 37); and 15 healthy non-pregnant female donors (mean age, 29).

The counts of single and clustered cTBs, as well as the number of cTB clusters, were significantly higher in women with PAS than in those with placenta previa and normal placentation throughout gestation, and also in the subpopulations of both earlier and late gestational age.

The team constructed a logistic regression model using a training cohort, and then cross-validated and tested it in an independent cohort. The combined cTB assay (for single and clustered cTBs, as well as cTB clusters) achieved an Area Under ROC Curve of 0.942 throughout gestation and 0.924 during early gestation for distinguishing PAS from non-PAS.

The authors conclude, "The enumeration of cTBs and cTB-clusters holds great promise for the early detection of PAS, and augments ultrasound screening, with implication to low resource settings."

Dr. Peter Bernstein, Director, Maternal Fetal Medicine at Montefiore Health System in New York City, commented in an email to Reuters Health. "This does seem like an important and potentially extremely useful tool to identify patients with placenta accreta."

"The ability of our current techniques to identify patients with this potentially life-threatening condition is far from perfect," he said. "If this high-risk condition can be reliably detected, the care of affected patients can be centralized in specialized care centers where outcomes have been shown to be better."

"This was a small study that needs to be repeated," he noted. "I would also be interested in knowing how difficult and expensive it would be to make this widely available."

"I would like to see larger studies, particularly prospective ones, which would help to identify which patients should be offered the test," he said. "In addition, since patients with the most severe versions of this condition are typically identified with our current tools, this approach may be most useful for patients with less obvious placenta accreta."

"I would want to know how accurate this approach will be for identifying patients with less severe forms of placenta accreta," Dr. Bernstein concluded.

SOURCE: Nature Communications, online August 3, 2021.