Fetal Cells in Maternal Blood: Technical and Clinical Aspects

Currently, common used methods to obtain fetal material for prenatal diagnosis are potentially dangerous for fetus and mother; this has led to the effort by many groups to develop methods to recover fetal cells by non-invasive means, such as their enrichment from the peripheral blood of pregnant women. The fetal cell types studied by numerous investigators worldwide include fetal leukocytes, i.e. fetal lymphocytes and granulocytes, fetal nucleated red blood cells (NRBCs) and trophoblast cells. Fetal NRBCs have been the most commonly studied cell type, for this reason: the frequency of NRBCs in the fetus early in gestation is relatively high; these cells are also fairly well differentiated and likely to have a limited life span in the maternal circulation and finally, there are specific markers for the enrichment of these cells. However, the fetal cells in maternal blood are rare and a sophisticate technique is required for their enrichment; currently, the most commonly employed techniques are fluorescent activated cell sorting (FACS), magnetic cell sorting (MACS), and charge flow separation. Then, if the fetal cells can eventually be isolated, possible clinical applications will be included screening for fetal chromosome abnormalities via fluorescence in-situ hybridization (FISH) and for gene abnormalities by polymerase chain reaction (PCR).