# Dynamic microRNA Signatures as Biomarkers for Cardiac Ischemia and Remodeling

## TL;DR

This study identifies specific microRNAs that change over time after a heart attack, offering potential noninvasive biomarkers for monitoring heart injury and recovery.

## Contribution

The study reveals dynamic miRNA signatures associated with cardiac ischemia and remodeling in a time-dependent manner.

## Key findings

- Early depletion of circulating miRNAs was observed 24 hours post-occlusion.
- Transient upregulation of cardiac tissue miRNAs and fibrotic gene expression occurred at 72 hours post-occlusion.
- Candidate miRNAs like miR-107, miR-122-5p, and miR-221-3p were identified as time-dependent indicators of myocardial stress.

## Abstract

Myocardial infarction (MI) triggers complex pathological processes, including inflammation, hypoxia, and fibrotic remodeling. MicroRNAs (miRNAs) have emerged as promising biomarkers for cardiovascular injury; however, their expression dynamics along processes remain underexplored. We used an in vivo rat model of permanent coronary occlusion to study the molecular alterations associated with MI and its resolution in a temporal mode, including five experimental groups with five animals in each: sham, PO 24 h, PO 72 h, PO 7 d, PO 1 month. Histological analysis, serum biomarkers, and miRNA/gene expression profiles were analyzed in a time-dependent manner post-occlusion. Subsequent analysis revealed early depletion of selected circulating miRNAs (PO 24 h). Transient upregulation in cardiac tissue miRNAs, inflammatory and fibrotic gene expression (Fibronectin, Collagen, Vimentin, E-Cadherin) were observed at PO 72 h. These molecular alterations correlated with histological evidence of myocardial injury and repair. Taken together, our findings delineate the molecular timeline of MI progression and resolution and identify candidate miRNAs as sensitive and time-dependent indicators of myocardial stress, including miR-107, miR-122-5p and miR-221-3p. This integrative approach supports the use of miRNA signatures for noninvasive monitoring of cardiac injury and resolution and unveils potential therapeutic targets to reduce pathological remodeling.