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ObjectivesWe aimed to compare cell-based NIPT (cbNIPT) to chorionic villus sampling (CVS) and to examine the test characteristics of cbNIPT in the first clinical validation study of cbNIPT compared to cell-free NIPT (cfNIPT).Material and MethodsStudy 1: Women (N = 92) who accepted CVS were recruited for cbNIPT (53 normal and 39 abnormal). Samples were analyzed with chromosomal microarray (CMA). Study 2: Women (N = 282) who accepted cfNIPT were recruited for cbNIPT. cfNIPT was analyzed using sequencing and cbNIPT by CMA.ResultsStudy 1: cbNIPT detected all aberrations (32/32) found in CVS: trisomies 13, 18 and 21 (23/23), pathogenic copy number variations (CNVs) (6/6) and sex chromosome aberrations (3/3). cbNIPT detected 3/8 cases of mosaicism in the placenta. Study 2: cbNIPT detected all trisomies found with cfNIPT (6/6) and had no false positive (0/246). One of the three CNVs called by cbNIPT was confirmed by CVS but was undetected by cfNIPT, two were false positives. cbNIPT detected mosaicism in five samples, of which two were not detected by cfNIPT. cbNIPT failed in 7.8% compared to 2.8% in cfNIPT.ConclusionCirculating trophoblasts in the maternal circulation provide the potential of screening for aneuploidies and pathogenic CNVs covering the entire fetal genome.

Purpose Proof of concept of the use of cell-based non-invasive prenatal testing (cbNIPT) as an alternative to chorionic villus sampling (CVS) following preimplantation genetic testing for monogenic disorders (PGT-M). Method PGT-M was performed by combined testing of short tandem repeat (STR) markers and direct mutation detection, followed by transfer of an unaffected embryo. Patients who opted for follow-up of PGT-M by CVS had blood sampled, from which potential fetal extravillous throphoblast cells were isolated. The cell origin and mutational status were determined by combined testing of STR markers and direct mutation detection using the same setup as during PGT. The cbNIPT results with respect to the mutational status were compared to those of genetic testing of the CVS. Results Eight patients had blood collected between gestational weeks 10 and 13, from which 33 potential fetal cell samples were isolated. Twenty-seven out of 33 isolated cell samples were successfully tested (82%), of which 24 were of fetal origin (89%). This corresponds to a median of 2.5 successfully tested fetal cell samples per case (range 1–6). All fetal cell samples had a genetic profile identical to that of the transferred embryo confirming a pregnancy with an unaffected fetus, in accordance with the CVS results. Conclusion These findings show that although measures are needed to enhance the test success rate and the number of cells identified, cbNIPT is a promising alternative to CVS. Trial registration number N-20180001

Introduction Circulating fetal extravillous trophoblasts may offer a superior alternative to cell-free fetal DNA for noninvasive prenatal testing. Cells of fetal origin are a pure source of fetal genome; hence, unlike the cell-free noninvasive prenatal test, the fetal cell-based noninvasive prenatal test is not expected to be affected by maternal DNA. However, circulating fetal cells from previous pregnancies may lead to confounding results.Material and methods To study whether fetal trophoblast cells persist in maternal circulation postpartum, blood samples were collected from 11 women who had given birth to a boy, with blood sampling at 1-3 days (W0), 4-5 weeks (W4-5), around 8 weeks (W8) and around 12 weeks (W12) postpartum. The existence of fetal extravillous trophoblasts was verified either by X and Y chromosome fluorescence in situ hybridization analysis or by short tandem repeat analysis. To exclude technological bias in isolating fetal cells, blood samples were also collected from 10 pregnant women between a gestational age of 10 and 14 weeks, the optimal time frame for cell-based noninvasive prenatal test sampling. All the samples were processed according to protocols established by ARCEDI Biotech for fetal extravillous trophoblast enrichment and isolation.Results Fetal extravillous trophoblasts were found in all the 10 samples from pregnant women between a gestational age of 10 and 14 weeks. However, only 4 of 11 blood samples taken from women at 1-3 days postpartum rendered fetal extravillous trophoblasts, and only 2 of 11 samples rendered fetal extravillous trophoblasts at 4 weeks postpartum.Conclusions In this preliminary dataset on few pregnancies, none of the samples rendered any fetal cells at or after 8 weeks postpartum, showing that cell-based noninvasive prenatal testing based on fetal extravillous trophoblasts is unlikely to be influenced by circulating cells from previous pregnancies.