How useful is the in vitro expansion of fetal CD34+ progenitor cells from maternal blood samples for diagnostic purposes?

Abstract

Fetal cells present in the maternal circulation are a potential source of fetal DNA that can be used for the development of a prenatal diagnostic test. Since their numbers are very low, amplification of fetal cells has been discussed for a long time. So far, most studies have focused on culturing fetal erythroid cells. In this study, we evaluated whether limiting numbers of fetal haemopoietic progenitor cells present in an excess of maternal cells were able to overgrow the maternal component. Therefore, we used a model system in which limiting numbers of male CD34+ umbilical cord blood cells were diluted in 400 000 female CD34+ peripheral blood cells. The number of XY positive cells derived from umbilical cord blood was determined using two-colour in situ hybridization with X and Y chromosomal probes. We demonstrated a 1500-fold relative expansion of male umbilical cord blood cells over the peripheral blood component after three weeks of liquid culture, which also corresponded to the extent of expansion of CD34+ cells derived from 20-week fetal blood. However, application of the same culture protocol to maternal blood samples obtained at 7-16 weeks of gestation showed no preferential growth of fetal haemopoietic progenitor cells. This study, therefore, suggests that fetal primitive haemopoietic progenitor cells do either not circulate in maternal blood before 16 weeks of gestation, or require different combinations/concentrations of cytokines for their in vitro expansion.

Implications of fetal stem cell trafficking in pregnancy

“…Fetal HSC have been demonstrated in maternal blood during pregnancy, but they are difficult to distinguish from maternal cells [3,13]. With few exceptions [38], fetal haemopoietic progenitors have not been identified or expanded in maternal blood before 16-weeks gestation, and selective amplification of fetal over maternal HSC has not been successful in actual maternal samples [20,37,[39][40][41].…”

Intact fetal cell isolation from maternal blood: improved isolation using a simple whole blood progenitor cell enrichment approach (RosetteSep™)

“…(d) compares CD34 expression in the three populations of cells. and expansion and detection of fetal cells have not been demonstrated in all studies (17,18,(20)(21)(22)(23). Less than salutary results probably reflect not only rarity of fetal progenitor cells, but specific enrichment strategies and culture conditions.…”

“…Our results suggest merit in enriching for progenitor cells and in particular for cells of myeloid lineage (Table 1). Although fetal progenitor cells have also been shown to exist in first and second trimester maternal blood samples (1, 16–18), little effort has been made toward targeting these cells for non‐invasive prenatal diagnosis. One reason is the fear that fetal cells such as lymphocytes or CD34 + cells could persist from prior pregnancies.…”

Harvesting Fetal Cells From the Maternal Circulation

“…CD34+ fetal haemopoietic progenitor cells can be found in very low numbers in maternal blood 65 and some groups have had a degree of success in using micromanipulation and PCR to confirm that colonies of fetal cells can be established from maternal blood. It was hoped that the culture of fetal erythroid progenitor cells obtained from maternal blood might overcome the universal problem of low target cell number as large populations of fetal cells would be generated for analysis.…”