Characterizing Neonatal Heart Maturation, Regeneration, and Scar Resolution Using Spatial Transcriptomics.

The neonatal mammalian heart exhibits a remarkable regenerative potential, which includes fibrotic scar resolution and the generation of new cardiomyocytes. To investigate the mechanisms facilitating heart repair after apical resection in neonatal mice, we conducted bulk and spatial transcriptomic analyses at regenerative and non-regenerative timepoints. Importantly, spatial transcriptomics provided near single-cell resolution, revealing distinct domains of atrial and ventricular myocardium that exhibit dynamic phenotypic alterations during postnatal heart maturation.

Coordination of endothelial cell positioning and fate specification by the epicardium.

The organization of an integrated coronary vasculature requires the specification of immature endothelial cells (ECs) into arterial and venous fates based on their localization within the heart. It remains unclear how spatial information controls EC identity and behavior. Here we use single-cell RNA sequencing at key developmental timepoints to interrogate cellular contributions to coronary vessel patterning and maturation.

Pre-existing fibroblasts of epicardial origin are the primary source of pathological fibrosis in cardiac ischemia and aging.

Serum response factor (SRF) and the SRF co-activators myocardin-related transcription factors (MRTFs) are essential for epicardium-derived progenitor cell (EPDC)-mobilization during heart development; however, the impact of developmental EPDC deficiencies on adult cardiac physiology has not been evaluated. Here, we utilize the Wilms Tumor-1 (Wt1)-Cre to delete Mrtfs or Srf in the epicardium, which reduced the number of EPDCs in the adult cardiac interstitium. Deficiencies in Wt1-lineage EPDCs prevented the development of cardiac fibrosis and diastolic dysfunction in aged mice.