SBIR-STTR Award

Fetal cells that enter the maternal blood stream can be recovered by the newly-developed charge flow separation (CFS) method. By this method, maternal blood is separated into fractions according to the movement of the different cell types in an electric field and a buffer counter-flow gradient. This enables significant enrichment of fetal nucleated red blood cells (NRBCs), selected as the best targets for the present project, and obviates the risks associated with amniocentesis and chorionic villus sampling, currently used to obtain fetal cells for prenatal diagnosis. The aims of the project are: (i) to optimize and further validate CFS-mediated enrichment of fetal NRBCs; and (ii) to determine the frequency of fetal NRBCs in maternal blood at different stages of pregnancy. For analysis of results, the enriched fractions will be tested by FISH for Y-chromosomal sequences, found in pregnancies involving male fetuses. In addition, the enriched fractions will be tested for common fetal aneuploides such as trisomy 13,18, 21 and X. In all cases, the fetal chromosome complement will be compared with that identified after amniocentesis or chorionic villus sampling. The CFS method has significant commercial potential. Because the different cell types exhibit consistent migration patterns, the method is consistent and reproducible. The CFS unit is automated and can process plus/minus 60,000 cells per second. Pretreatment with antibody is unnecessary and the recovered cells are fully viable, raising the question of further enrichment in cell culture.Proposed commercial application:The CFS method would be available to 3-4 million pregnant women annually in the USA of which 15-20% are over 35 years of age, and thus at risk for fetal aneuploidy. This represents a market in excess of several hundred million dollars.National Institute of Human Development (NIHD)

Fetal cells that enter the mother's blood stream during pregnancy can be recovered by charge flow separation (CFS), a method that obviates the risks associated with amniocentesis and chorionic villus sampling. The long-term objective of this project is development of a commercial system for prenatal screening and diagnosis based on recovery by CFS of fetal nucleated red blood cells (NRBC). The aims of the project are: (I) to increase further the speed and efficiency of CFS, and to decrease disposable costs: (II) to test CFS in the screening of common aneuploidies such as trisomy 13, 18, and 21, and to evaluate the specificity and sensitivity of the screening method; (III) to ascertain the life span of fetal NRBC in the maternal circulation; (IV) to culture CFS-processed fetal NRBC, and to discriminate between female fetal NRBC and maternal NRBC after recovery. For analysis of results, the processed fractions will be tested by FISH and primed in situ labeling (PRINS) for sex- chromosome-complement and the common aneuploidies; the results will be compared with those obtained after conventional cytogenetic analysis. Cultures will be evaluated for paternal DNA sequences and for karyotype. With further development, CFS could enable early diagnosis of a broad spectrum of congenital abnormalities, without risk to fetus or mother. Because the different cell types exhibit characteristic surface charge densities and distinctive mobilities in moving fluids, results with CFS are consistent and reproducible, facilitating experimental design and interpretation. Pretreatment of maternal blood samples with antibody is unnecessary. The method is rapid. The recovered cells are viable and the numbers of fetal NRBC obtained are substantially greater than the numbers obtained after separation by other methods.