Intact fetal cells can be isolated from every maternal blood sample. Amplified DNA from isolated fetal cells enabled genetic analysis by array comparative genomic hybridization and next-generation sequencing. © 2016 John Wiley & Sons, Ltd.

Introduction: Circulating fetal cells in maternal blood provide a tool for risk-free, non-invasive prenatal diagnosis. However, fetal cells in the maternal circulation are scarce, and to effectively isolate enough of them for reliable diagnostics, it is crucial to know which fetal cell type(s) should be targeted. Materials and Methods: Fetal cells were enriched from maternal blood by magnetic-activated cell sorting using the endothelial cell marker CD105 and identified by XY fluorescence in situ hybridization. Expression pattern was compared between fetal cells and maternal blood cells using stem cell microarray analysis. Results: 39 genes were identified as candidates for unique fetal cell markers. More than half of these are genes known to be expressed in the placenta, especially in extravillous trophoblasts (EVTs). Immunohistochemical staining of placental tissue confirmed CD105 staining in EVTs and 76% of fetal cells enriched by CD105 were found to be cytokeratin-positive. Discussion: The unique combination of mesodermal (CD105) and ectodermal (cytokeratin) markers in EVTs could be a potential marker set for cell enrichment of this cell type in maternal blood and could be the basis for future cell-based non-invasive prenatal diagnosis.

The marker set identifies fetal cells with specificity high enough to make cell-based noninvasive prenatal diagnosis realistic.

Aneuploidy and subchromosomal aberrations can be detected using fetal cells harvested from maternal blood. The method has the future potential of being offered as a cell-based NIPT with large high genomic resolution.