New technique using galactose‐specific lectin for isolation of fetal cells from maternal blood

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Abstract
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 severalhundred NRBCs (mean±SD, 7.8±8.5) in 2.3 ml of peripheral blood samples from 96% of pregnantwomen. 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 wereoffetal 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.