Integrated Spatial Transcriptomics and Single-Cell RNA Sequencing Reveal Lars2-Mediated Spatiotemporal Dynamics of Myocardial Remodeling in a Mouse Model of Transverse Aortic Constriction (TAC)

Multi-omics approaches have emerged as a cornerstone in medical biology, offering an integrative perspective on tissue and cellular composition, gene expression patterns, functional states, and metabolic dynamics. In this study, we employed multi-omics methodologies, combining spatial transcriptomics (ST) and single-cell RNA sequencing (scRNA-seq), to perform large-scale bioinformatics analysis on heart samples from Transverse Aortic Constriction (TAC) mouse models at various stages of disease progression. The aim was to investigate the spatial and temporal characteristics of cellular distribution, gene composition, and associated functional changes within the myocardium in response to pressure overload. For the first time, the pathophysiology of myocardial hypertrophy in this model is described through the integrated lens of spatial and single-cell transcriptomics. The spatial transcriptomics analysis revealed a uniform cellular distribution across the heart tissue in TAC mice at different disease stages. However, substantial shifts in cellular composition were observed, with the most significant alterations occurring in cluster 1, which primarily involved changes in fibroblasts and macrophages. Single-cell RNA sequencing further demonstrated that the most notable changes in cellular composition occurred at the TAC-4W stage, characterized by a reduction in fibroblast and macrophage populations and an increase in immune cell subsets, such as neutrophils and T cells. By TAC-6W, the cellular composition returned to a state comparable to that observed at TAC-2W. Further analysis integrating both spatial and single-cell transcriptomes highlighted cluster 1 as the site of the most prominent microenvironmental changes, predominantly involving T cells and macrophages. Notably, the genes Lef1, Ccr7, Sell, and Lars2 were identified as significantly differentially expressed in these cells—an observation not previously reported. In particular, the expression of Lars2 exhibited dynamic modulation throughout disease progression. While its expression at TAC-2W did not differ significantly from controls, Lars2 expression peaked at TAC-4W, only to decline at TAC-6W. This study provides a comprehensive characterization of myocardial hypertrophy in the TAC mouse model, leveraging the power of spatial transcriptomics and single-cell RNA sequencing. The findings offer novel insights into the spatial and temporal dynamics of cellular distribution and gene expression, advancing our understanding of the molecular mechanisms underpinning cardiac remodeling in response to pressure overload. Overall design: Eight-week-old male C57BL/6J mice (25–27 g) were randomly assigned to sham or transverse aortic constriction (TAC) groups. Hearts were harvested at 2, 4, and 6 weeks after surgery. Cardiac tissues were processed for both spatial transcriptomics (10x Genomics Visium) and single-cell RNA sequencing (10x Genomics Chromium 3' v3.1). Sequencing was performed on the Illumina NovaSeq 6000 platform. This design enabled the integration of temporal, spatial, and single-cell transcriptomic data to characterize myocardial remodeling under pressure overload.