Detecting monogenic disorders in utero non-invasively based on fetal nucleated red blood cells highly-purified by multi-functional magnetic nanoparticles.

BACKGROUND: Fetal monogenic disorders cause gestation anomalies, birth defects or infant mortality. Implementing non-invasive prenatal testing (NIPT) of these diseases benefits timely intervention while avoids high risk of inducing maternal complications and fetal injuries. However, fetal materials used for current NIPT (e.g., blood-borne cell-free fetal DNA (cffDNA)) are inevitably interfered by tremendous maternal interference in peripheral blood, leading to difficulty of exactly analyzing fetal monogenic mutations. Fetal nucleated red blood cells (FNRBCs) in maternal peripheral blood possess the entire fetal genome, which is encapsulated inside the cells and is away from maternal interference. Therefore, FNRBCs are promising and superior for NIPT of fetal genetic disorders after they are highly purified from huge maternal blood cells and subsequently analyzed.

RESULTS: We synthesized multi-functional magnetic nanoparticles (MMNs) by coating erythrocyte-leukocyte hybrid membrane on Fe3O4 magnetic nanoparticles and grafting specific antibody (anti-CD147) to highly purify FNRBCs from maternal peripheral blood. Fetal origin of all the isolated cells were confirmed by short tandem repeat (STR) to validate their sufficient purity for downstream analysis. Potential maternal factors that would influence FNRBC counts were evaluated based on clinical samples. Utilizing Sanger sequencing and droplet digital PCR (ddPCR), FNRBCs were analyzed to non-invasively assess the risk of five kinds of fetal monogenic disorders, which was challenging for current NIPT.

SIGNIFICANCE: It is anticipated that this MMN-based strategy will create possibilities for overcoming limitations of NIPT when detecting fetal monogenic disorders nowadays.