Enrichment of circulating trophoblasts from maternal blood using laminar microscale vortices

Objective Enrichment of circulating trophoblasts (CTs) from maternal blood at week 11–13 of gestation, using laminar microscale vortices, and evaluation of the performance of the VTX‐1 Liquid Biopsy System in terms of CT recovery and purity. Method Eight mililiter of blood was collected from 15 pregnant women and processed with the VTX‐1 Liquid Biopsy System. Y‐chromosome specific quantitative PCR was performed to estimate the number of enriched male CTs. To evaluate the VTX‐1 performance, the target cell recovery was characterized by spiking experiments with a trophoblast cell line. Furthermore, the total quantity of DNA after enrichment was used to calculate the number of retained maternal cells. Results Successful recovery of male CTs was established in 7 out of 10 first trimester samples from pregnant women carrying a male fetus. The number of CTs, recovered from 8 ml of blood, was estimated between two and six. Spiking experiments resulted in a CT recovery of ±35 % with ±1524 retained maternal blood cells. Conclusion CTs can be enriched from maternal blood with high purity, using laminar microscale vortices, starting from 8 ml of blood. Key Points What's already known about this topic? Cell‐free noninvasive prenatal testing (cfNIPT) is an established, clinically validated method for the prenatal screening of large chromosomal aberrations. The isolation of circulating trophoblasts (CTs), allowing cell‐based NIPT, has been accomplished by means of marker‐based enrichment, although approximately 30‐40 ml of maternal blood is required. Size‐based enrichment of CTs was published in 2012, but was never repeated nor confirmed. What does this study add? Laminar microscale vortices allow size‐based enrichment of circulating trophoblasts, starting from only 8 ml of maternal blood. CT recovery and purity after enrichment using the VTX‐1 Liquid Biopsy System are reported.