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Antepartum Fetal Assessment

Poster Session 1

(360) A novel method for placental evaluation: Isolation of intact circulating trophoblast cells from maternal circulation

Tuesday, February 13, 2024
10:30 AM – 12:00 PM  
Location: Prince George's Exhibit Hall CDE, Lower Atrium Level
Objective: We are developing a program to test the hypothesis that gene expression profiles of placental cells in maternal circulation can be used as a biomarker to predict risk of stillbirth and other adverse pregnancy outcomes. As a foundational step in this effort, we developed a method to isolate individual, intact circulating trophoblasts (CTB) from maternal circulation.

Study Design: After informed consent, buffy coats were isolated from third trimester pregnancy blood samples using the AccuCyte® sample preparation system. Following immunomagnetic bead enrichment, cells were spread to slides. A 4-parameter manual immunofluorescence (IF) assay was developed with the following markers: Hoechst (nucleus), pan-cytokeratin (CK, trophoblast marker), TMX (supportive trophoblast marker) and CD45 (exclusion marker). Slides were stained and then imaged on the CyteFinder® imaging system. CTBs were defined as nucleated, CK positive, TMX agnostic, and CD45 negative cells. CTBs were then isolated using the CytePicker® Retrieval Module.

Results: The method was developed using the JEG-3 cell line in spike-in experiments. We then evaluated clinical samples from uncomplicated pregnancies (N=3 to date). CTBs were identified in all clinical samples and successfully retrieved from slides. A representative image of a CTB is shown (Figure 1).

Conclusion: Identification and isolation of intact CTB from maternal circulation was demonstrated reproducibly from third trimester samples. This methodology is a critical component of our efforts to evaluate CTB gene expression to identify risk of stillbirth and other adverse pregnancy outcomes.