Border-zone cardiomyocytes and macrophages contribute to remodeling of the extracellular matrix to promote cardiomyocyte invasion during zebrafish cardiac regeneration

About this publication:

Florian Constanty and colleagues investigate the involvement of border-zone cardiomyocytes and macrophages in the remodeling of the extracellular matrix (ECM) to facilitate cardiomyocyte invasion during cardiac regeneration in zebrafish. The study reveals that these border-zone cardiomyocytes and macrophages actively contribute to modifying the ECM environment, which promotes the invasion of neighboring cardiomyocytes. This process is essential for efficient cardiac regeneration in zebrafish, shedding light on the intricate cellular interactions involved in tissue repair and regeneration in the heart.

Publication Summary

This publication provides insight into cardiac regeneration, and more specifically, how regenerating cardiomyocytes eventually replace collagen-containing fibrotic tissue following injury. Here, the authors provide an in-depth analysis of the process of cardiomyocyte invasion using live-imaging and histological approaches, macrophage ablation models, and single-cell sequencing.  The data indicates that defects in ECM remodeling at the border zone and subsequent cardiomyocyte protrusion can be partly attributed to a population of resident macrophages. Single-cell RNA-sequencing analysis of cells at the wound border revealed a population of cardiomyocytes and macrophages with fibroblast-like gene expression signatures, including  the expression of genes encoding ECM structural proteins and ECM-remodeling proteins.  Altogether, the data provide insights into the process of cardiomyocyte invasion and how resident macrophages contribute to ECM remodeling to promote wound healing. 

Sample Clean-Up Using Levitation Technology

When working with limited sample quantities such as injured zebrafish hearts, removal of dead cell populations is essential to maximize the resolution of the targeted populations of interest. The cell suspensions were depleted for dead cells using the LeviCell system,  and were counted and diluted to obtain 10,000 single-cell data points per sample. The versatility of sample types that can be run using Levitation Technology(™) enabled the researchers to simultaneously enrich viable cells from limited quantities of fish cardiac tissue, while removing detrimental debris and dead/dying cells. This step helped to ensure that the samples were of the highest quality for their downstream analysis, enabling the researchers to identify key roles for macrophages in cardiac repair.