A Systemic Approach to Isolate, Retrieve, and Characterize Trophoblasts from the Maternal Circulation Using a Centrifugal Microfluidic Disc and a Multiple Single-Cell Retrieval Strategy.

Rare cells in the blood often have rich clinical significance. Although their isolation is highly desirable, this goal remains elusive due to their rarity. This paper presents a systemic approach to isolate and characterize trophoblasts from the maternal circulation. A microfluidic rare cell disc assay (RaCDA) was designed to process an extremely large volume of up to 15 mL of blood in 30 min, depleting red blood cells (RBCs) and RBC-bound white blood cells (WBC) while isolating trophoblasts in the collection chip. To minimize cell loss, on-disc labeling of cells with fluorescent immuno-staining identified the trophoblasts. Retrieval of trophoblasts utilized an optimized strategy in which multiple single cells were retrieved within the same micropipette column, with each cell encapsulated in a fluid volume (50 nL) separated by an air pocket (10 nL). Further, whole-genome amplification (WGA) amplified contents from a few retrieved cells, followed by quality control (QC) on the success of WGA via housekeeping genes. For definitive confirmation of trophoblasts, short-tandem repeat (STR) of the WGA-amplified content was compared against STR from maternal WBC and amniocytes from amniocentesis. Results showed a mean recovery rate (capture efficiency) of 91.0% for spiked cells with a WBC depletion rate of 99.91%. The retrieval efficiency of single target cells of 100% was achieved for up to four single cells retrieved per micropipette column. Comparison of STR signatures revealed that the RaCDA can retrieve trophoblasts from the maternal circulation.

Noninvasive prenatal diagnosis.

Prenatal examination plays an important role in present medical diagnosis. It provides information on fetal health status as well as the diagnosis of fetal treatment feasibility. The diagnosis can provide peace of mind for the perspective mother. Timely pregnancy termination diagnosis can also be determined if required. Amniocentesis and chorionic villus sampling are two widely used invasive prenatal diagnostic procedures. To obtain complete fetal genetic information and avoid endangering the fetus, noninvasive prenatal diagnosis has become the vital goal of prenatal diagnosis. However, the development of a high-efficiency separation technology is required to obtain the scarce fetal cells from maternal circulation. In recent years, the rapid development of microfluidic systems has provided an effective method for fetal cell separation. Advantages such as rapid analysis of small samples, low cost, and various designs, greatly enhance the efficiency and convenience of using microfluidic systems for cell separation. In addition, microfluidic disks can be fully automated for high throughput of rare cell selection from blood samples. Therefore, the development of microfluidic applications in noninvasive prenatal diagnosis is unlimited.