Maternal Folic Acid Supplementation Ameliorates Outflow Tract Malformations in Tbx1 Hypomorphic Mice via Notch and Midkine Signaling.

BACKGROUND

Congenital heart disease involving outflow tract (OFT) malformations remains a major clinical challenge, particularly in 22q11.2 deletion syndrome. Although folic acid (FA) reduces the incidence of neural tube defects, its mechanistic role in cardiac OFT development is not fully understood.

METHODS AND

RESULTS

Using Tbx1neo/neo hypomorphic mice as a model of 22q11.2 deletion syndrome, we investigated the effects of maternal FA supplementation on cardiac development. Pregnant dams received FA through diet or intraperitoneal injection and embryonic cardiac morphology was assessed at E15.5 and E18.5. Maternal FA administration significantly improved the persistent truncus arteriosus (PTA) phenotype, with 60% of Tbx1neo/neo embryos exhibiting a partially septated PTA (Van Praagh type A1) vs. complete PTA (type A2) in controls. Neural crest cell (NCC) migration from the neural tube into the OFT was enhanced. GFP lineage tracing confirmed the presence of increased NCCs in the OFT and reduced ectopic neuronal differentiation. Single-cell RNA-sequencing and immunohistochemistry revealed activation of the Notch and Midkine signaling pathways in NCCs following FA treatment.

CONCLUSIONS

Maternal FA supplementation improved cardiac OFT malformations in Tbx1neo/neo embryos by enhancing NCC migration and fate specification, possibly mediated by Notch and Midkine signaling activation. Our findings provide mechanistic insights into the observed reduction in congenital heart defects with FA and suggest its potential as a minimally invasive prenatal intervention.