Identification Of Fetal Cells Research Articles

Simultaneous immunophenotyping and FISH on fetal cells from maternal blood.

Current methods for the prenatal diagnosis of genetic disorders from fetal cells in the maternal circulation are restricted by maternal cell contamination and therefore must rely on the presence of features (such as Y-specific DNA sequences) absent from maternal cells. We have used density gradient centrifugation and magnetic-activated cell sorting to enrich maternal blood samples for fetal nucleated red cells. Mouse monoclonal antibodies for CD45 and CD32 were used to reduce the proportion of leukocytes. Unequivocal identification of fetal cells was achieved using an immunophenotypic test for fetal hemoglobin that allowed the simultaneous application of a diagnostic FISH analysis with chromosome-specific DNA probes. A positive diagnosis of female fetal sex (among other diagnoses) is thus possible even in the presence of an excess of maternal cells. The method, which appears to represent an advance over previous techniques, has considerable application in the development of noninvasive prenatal diagnosis from maternal blood.

Fetal cells in the maternal circulation during first trimester in pregnancies.

To investigate the presence of fetal cells in the maternal circulation during early pregnancy, the polymerase chain reaction was used to test the presence of human Y chromosome-specific ZFY and SRY gene DNA sequences in maternal peripheral blood specimens from 19 women carrying male fetuses and 12 women carrying female fetuses. The presence of fetal cells was suggested as early as 6 weeks gestation in 1 of the 19 women bearing male fetuses. Fetal cells were present in the maternal circulation of 15 of the 19 women by 9 weeks gestation, and in only 1 of the 19 were fetal cells not detected until the 12th week after conception. These results suggest that identification of fetal cells in the maternal circulation is possible with a properly designed and executed polymerase chain reaction. However, there was considerable variation with respect to when these fetal cells first became detectable during pregnancy. These fetal cells are potentially a valuable source of material for biochemical and genetic studies of the fetuses.

Magnetic cell sorting and the transferrin receptor as potential means of prenatal diagnosis from maternal blood

We wanted to test whether the recently described method of using the transferrin receptor system for fluorescence-activated cell-sorter enrichment of nucleated red blood cells can be used for prenatal diagnosis from maternal blood. Instead of the laborious, expensive fluorescence-activated cell-sorter system, we used the newly described magnetic-activated cell sorter. An effective enrichment could be achieved with separation of lymphocyte subsets. With the transferrin receptor, however, the enrichment was very inefficient because of the poor specificity of the antibody itself. Even in umbilical cord blood only 25% of nucleated red blood cells were labeled as demonstrated by immunogold silver enhancement of transferrin receptor-labeled cells. In spite of the availability of a fast and effective separation method (magnetic-activated cell sorter) the use of the transferrin receptor antigen alone is not likely to enable a reliable identification of fetal cells in maternal circulation.