Primordial cardiomyocytes orchestrate myocardial morphogenesis and vascularization but are dispensable for regeneration.

Primordial cardiomyocytes are essential for heart development but not necessary for regeneration in zebrafish, with only 15% capable of regeneration after injury.

• Why it matters: Understanding the distinct roles of cardiomyocyte subpopulations is crucial for developing regenerative therapies, as their functions during development and repair may differ significantly.
• What they did: Using single-cell RNA sequencing, the study identified a unique phlda2+ cardiomyocyte population involved in heart morphogenesis and performed genetic ablation to assess their roles in development and regeneration.
• The result: Primordial CMs are vital for proper heart formation but do not contribute to regeneration, highlighting a fundamental difference between developmental processes and regenerative capacity in the vertebrate heart.