Current prenatal diagnostic methods are invasive in nature and carry significant risks of causing a miscarriage; therefore, they are not performed on all pregnant women. As a result, a large number of fetal genetic abnormalities, such as Down syndrome, are missed. Reliable methods of noninvasive prenatal diagnosis have long been sought in perinatal medicine. The presence of fetal nucleated red blood cells (NRBCs) in the maternal blood is well-established, and they are currently considered the best target for noninvasive prenatal screening and diagnosis. However, the detection of these cells remains problematic due to their low abundance in maternal circulation, and the presence of similar NRBCs that are of maternal origin. Current approaches for identification of fetal NRBCs rely on mechanical separation methods, such as flow-activated cell sorting (FACS) or magnetic-activated cell sorting (MACS), subsequent analysis of cellular morphology, and fluorescence in situ hybridization (FISH)- or PCR-based analyses of molecular or genetic biomarkers. However, according to the National Institute of Child Health and Human Development Fetal Cell Isolation Study (NIFTY) none of these methods have been shown to obtain fetal cells from maternal blood with sufficient reliability for routine prenatal diagnosis. Thus, the development of an efficient method for separating fetal NRBCs from maternal blood is necessary to enable the routine detection of a small numbers of these cells for noninvasive prenatal diagnosis. We hypothesize that the unique morphology of fetal NRBCs, and subsequently their unique dielectric properties, can facilitate separation of these cells by dielectrophoresis. This proposal describes an integrated design and development plan leading to a novel miniaturized Dielectrophoresis Activated Cell Sorting (DACS) system for recovery of fetal NRBCs from maternal peripheral blood. Isolation of fetal NRBCs with the DACS system will enable accurate, early diagnosis and screening for chromosomal and genetic abnormalities without risk of miscarriage. In addition, the DACS system can be adapted to separate other types of morphologically distinct cell populations from peripheral blood, such as those from a tumor or a pre-neoplastic lesion.
Successful development of the DACS technology will result in a highly sensitive and specific method for noninvasive identification and isolation of fetal NRBCs, allowing timely identification of chromosomal and genetic abnormalities in the fetus without the risks associated with standard procedures. Some of the identified prenatal conditions can then be treated to improve the outlook for the unborn baby. For example, biotin dependence and methylmalonic acidemia, both life-threatening inherited disorders, have been diagnosed by amniocentesis and treated in the womb, resulting in the births of healthy babies. When a fetus has a condition for which prenatal treatment is not yet possible, prenatal diagnosis permits parents to prepare themselves emotionally, and to plan the safest timing, hospital facility, and method of delivery. ? ? ?
