High-purity isolation of rare single cells from blood using a tiered microchip system

Exploration of a Novel Noninvasive Prenatal Testing Approach for Monogenic Disorders Based on Fetal Nucleated Red Blood Cells

BACKGROUND

Due to technical issues related to cell-specific capture methods, amplification, and sequencing, noninvasive prenatal testing (NIPT) based on fetal nucleated red blood cells (fNRBCs) has rarely been used for the detection of monogenic disorders.

METHODS

Maternal peripheral blood was collected from 11 families with hereditary hearing loss. After density gradient centrifugation and cellular immunostaining for multiple biomarkers, candidate individual fetal cells were harvested by micromanipulation and amplified by whole-genome amplification (WGA). Whole-exome sequencing/whole-genome sequencing (WGS) and Sanger sequencing were performed on the identified fNRBCs to determine the fetal genotype. The impact of single-cell and pooled WGA products on the sequencing quality and results was compared. A combined analysis strategy, encompassing whole-exome sequencing/WGS, haplotype analysis, and Sanger sequencing, was used to enhance the NIPT results.

RESULTS

fNRBCs were harvested and identified in 81.8% (9/11) of families. The results of cell-based-NIPT (cb-NIPT) were consistent with those of invasive prenatal diagnosis in 8 families; the coincidence rate was 88.9% (8/9). The combined analysis strategy improved the success of cb-NIPT. The overall performance of pooled WGA products was better than that of individual cells. Due to a lack of alternative fetal cells or sufficient sequencing data, cb-NIPT failed in 3 families.

CONCLUSIONS

We developed a novel fNRBC-based NIPT method for monogenic disorders. By combining multiple analysis strategies and multiple fetal cell WGA products, the problem of insufficient genome information in a single cell was remedied. Our method has promising prospects in the field of NIPT for the detection of monogenic disorders.

Isolation and Enrichment of Circulating Fetal Cells for NIPD: An Overview

Prenatal diagnosis plays a crucial role in clinical genetics. Non-invasive prenatal diagnosis using fetal cells circulating in maternal peripheral blood has become the goal of prenatal diagnosis, to obtain complete fetal genetic information and avoid risks to mother and fetus. The development of high-efficiency separation technologies is necessary to obtain the scarce fetal cells from the maternal circulation. Over the years, multiple approaches have been applied, including choice of the ideal cell targets, different cell recovering technologies, and refined cell isolation yield procedures. In order to provide a useful tool and to give insights about limitations and advantages of the technologies available today, we review the genetic research on the creation and validation of non-invasive prenatal diagnostic testing protocols based on the rare and labile circulating fetal cells during pregnancy.

Overview and recent developments in cell-based noninvasive prenatal testing

Investigators have long been interested in the natural phenomenon of fetal and placental cell trafficking into the maternal circulation. The scarcity of these circulating cells makes their detection and isolation technically challenging. However, as a DNA source of fetal origin not mixed with maternal DNA, they have the potential of considerable benefit over circulating cell-free DNA-based noninvasive prenatal genetic testing (NIPT). Endocervical trophoblasts, which are less rare but more challenging to recover are also being investigated as an approach for cell-based NIPT. We review published studies from around the world describing both forms of cell-based NIPT and highlight the different approaches' advantages and drawbacks. We also offer guidance for developing a sound cell-based NIPT protocol.