Transcriptomic profiling of the postnatal mouse cardiac conduction system

The cardiac conduction system (CCS) comprises a network of highly specialized cells, including sinoatrial node, atrioventricular node, His bundle, bundle branches and Purkinje fibers. To uncover the transcriptomic landscape across the postnatal CCS and comparative profiling of different CCS components, we conducted scRNA-seq in purified postnatal CCS cells and spatial transcriptomic analysis in the postnatal CCS reporter mouse heart. Overall design: The postnatal cardiac conduction cells were isolated from the CCS reporter (Cntn2-Cre;Rosa26tdTomato) mice, purified by FACS, labelled using MULTI-seq, and subjected to 10x Genomics scRNA-seq. Additionally, different regions of the CCS were captured through cryosectioning of the CCS reporter heart and subsequently analyzed using the NanoString GeoMX Digital Spatial Profiler (DSP). For GeoMx DSP: two ROIs were selected for the SA node (SAN), lower nodal bundle (LNB), His bundle (HIS), proximal left and right bundle branch (PLBB/PRBB), distal left and right bundle branch (DLBB/DRBB), and left and right Purkinje fibers (LPF/RPF). One ROI was collected for the compact AV node (cAVN). One ROI was collected ffor non-CCS regions adjacent to each CCS region, including the right atrial appendage (RAA), left endomyocardium (LENDO), left epimyocardium (LEPI), basal interventricular septum (IVS-Base), apical interventricular septum (IVS-Apex), and right ventricle (RV).