# Integrated spatial transcriptomics and single-cell RNA sequencing reveal Lars2-mediated spatiotemporal dynamics of myocardial remodeling in a mouse model of transverse aortic constriction

## TL;DR

This study combines spatial and single-cell RNA sequencing to track heart cell changes in mice with a heart condition, identifying Lars2 as a key gene involved in disease progression.

## Contribution

The study introduces an integrated spatial and single-cell approach to uncover Lars2's role in myocardial remodeling dynamics.

## Key findings

- Spatial transcriptomics showed preserved cardiac cell distribution despite changes in composition during disease stages.
- TAC-4w stage showed the most significant changes in immune cell populations, including increased neutrophils and T cells.
- Lars2 was identified as a gene with peak expression at TAC-4w, declining by TAC-6w, suggesting its role in disease progression.

## Abstract

Pressure overload-induced myocardial hypertrophy is associated with complex spatial and temporal remodeling of cardiac cell populations. However, the spatial organization of these changes and their dynamic transcriptional programs remain incompletely understood. Integrating spatial transcriptomics with single-cell RNA sequencing enables a comprehensive characterization of cardiac remodeling at high cellular and spatial resolution.

Heart tissues were obtained from transverse aortic constriction (TAC) mouse models at different stages of disease progression (TAC-2w, TAC-4w, and TAC-6w). Spatial transcriptomics and single-cell RNA sequencing were performed, followed by large-scale bioinformatics analyses to evaluate spatial cellular distribution, alterations in cellular composition, and gene expression dynamics associated with pressure overload.

Spatial transcriptomics revealed a largely preserved spatial distribution of major cardiac cell populations across TAC stages, despite substantial changes in cellular composition. The most prominent alterations were observed in cluster 1, primarily involving fibroblasts and macrophages. Single-cell RNA sequencing demonstrated that most notable changes in cellular composition occurred at the TAC-4w stage, characterized by reduced fibroblast and macrophage populations and increased immune cell subsets, including neutrophils and T cells. By TAC-6w, cellular composition partially returned to a pattern similar to that observed at TAC-2w. Integrated spatial and single-cell analyses identified cluster 1 as a key microenvironment undergoing dynamic remodeling, driven predominantly by T cells and macrophages. Several genes, including Lef1, Ccr7, Sell, and Lars2, were identified as significantly differentially expressed in these cells. Notably, Lars2 expression peaked at TAC-4w and declined at TAC-6w.

This study provides a spatially resolved and cell-specific transcriptomic characterization of myocardial hypertrophy in the TAC mouse model. The findings highlight dynamic immune-stromal interactions during pressure overload-induced remodeling and identify Lars2 as a gene associated with disease progression.