Diverging Roads To The Heart

Insight into early cardiac lineage diversification is essential to unravel the origins of congenital heart defects, which are among the most frequent birth anomalies. Congenital heart defects commonly affect specific regions of the heart or cardiac cell types ( 1 ). Moreover, directed differentiation of pluripotent stem cells into specific cardiac lineages is a pivotal step in modeling heart disease, drug testing, and regenerative therapies. On page 1177 of this issue, Lescroart et al. ( 2 ) used single-cell RNA sequencing to generate two high-resolution snapshots of gene expression in nascent cardiovascular mesoderm in the early mouse embryo. Their findings capture the transcriptional complexity of precardiac mesoderm and reveal how different lineages contributing to the heart first arise during embryogenesis.