To isolate fetal cells from maternal blood, we developed a new method based on galactose-bearing conjugation. Nucleated red blood cells (NRBCs), which highly express galactose on their surface, were selectively attached to a substrate coated with a galactose-containing polymer via soybean agglutinin (SBA), a galactose-specific lectin. Cord blood samples were used to evaluate enrichment efficacy of NRBCs by this method. Blood samples were obtained from 131 pregnant women between 6 and 27 gestational weeks. After preliminary condensation of fetal cells by Ficoll gradient centrifugation, NRBCs were enriched using galactose-positive selection by adjusting SBA concentration. We isolated one to several hundred NRBCs (mean+/-SD, 7.8+/-8.5) in 2.3 ml of peripheral blood samples from 96% of pregnant women. The isolated NRBCs were analyzed by a Y-chromosome FISH probe in eight cases carrying male fetuses. Y-signals were detected in all eight cases and more than half of the NRBCs were off fetal origin. The study demonstrates that our new method using galactose-specific lectin provides effective enrichment of fetal NRBCs allowing non-invasive prenatal diagnosis.

Copyright 2002 John Wiley & Sons, Ltd.