Modulate spatial restriction of injury responses for cardiac repair

Intrinsic molecular strategy at the organ level to injury stimuli remains elusive. Identifying and modulating such potential molecular strategy for systemic adaptations to injury is theoretically fascinating and therapeutically promising. Here, using integrative single-cell and spatial transcriptomic analysis, we reported that lysozyme 2 (Lyz2), a long-established myeloid marker, surprisingly indicated global injury status (across cell types and anatomic divisions) and influenced cardiac function after injury. We correlated the Lyz2 regulon of the lysosome-matrisome (particularly endocardial lysosomal-degrading Hspgs) with anatomical and functional relevance to cardiac injury and determined that such spatial model is consensus across various injury types, both mouse and human. Modulation of spatial model mediated by Lyz2 via genetic deletion or chemical inhibition in adult mice with myocardial infarction remarkably achieved immediate protective effects, a rare therapeutic benefit among current interventions for heart failure. These results provided the first molecular evidence for the unprecedented molecular strategy adopted by the heart with unparalleled therapeutic promising for organ repair. We leveraged single cell transcriptomics to overview molecular organization with anatomical divisions during cardiac regeneration. For single cell sequencing, heart tissue from the apical region of the ventricular was collected and pooled from 4 to 6 hearts. The study included six different time points, namely P1+(1dpr, 1dps, 4dpr, 4dps, 7dpr, 7dps) and P7+(1dpr, 1dps, 4dpr, 4dps, 7dpr, 7dps). Subsequently, the collected tissue underwent enzymatic digestion using the Neonatal Heart Dissociation Kit (Miltenyi Biotec) to obtain single cells. These single cells were then utilized for single cell RNA sequencing, specifically for the generation of single cell RNA-seq libraries. The Single Cell 3′ Reagent Kits v2 (10×Genomics) were employed in accordance with the manufacturer's instructions. After completing the capture and lysis procedures, cDNA synthesis and amplification were carried out according to the guidelines provided by the manufacturer (10X Genomics). The amplified cDNA obtained from each channel of the Chromium System was utilized for the construction of a sequencing library. This library was subsequently subjected to paired-end 150 bp sequencing on Hiseq X-ten (Illumina). As a result, a combined dataset consisting of 69,303 single cells and encompassing 30,905 genes was generated.