Cellular Interactions of Cardiac Repair After Myocardial Infarction.

When blood flow to a part of the myocardial muscle is reduced or blocked, it leads to tissue ischemia in that region. Myocardial infarction (MI) occurs when the ischemic insult is of sufficient duration in time to induce cardiomyocyte death and subsequent activation of the innate immune response. MI initiates a complex cascade of cellular and molecular events within the left ventricle. Inflammatory cells rapidly infiltrate the infarcted area to remove necrotic tissue, setting the stage for reparative wound healing processes. Over the ensuing days, various cell populations-including leukocytes, fibroblasts, and endothelial cells-are attracted to the infarcted site by inflammatory cytokines and chemokines. The activated cells at the site of injury contribute to tissue remodeling and scar formation through the deposition of extracellular matrix components, particularly collagen. While scar formation is essential for structural stabilization of the infarct region to replace the loss of cardiomyocytes, scar tissue also increases myocardial stiffness and impairs cardiac contractile function. This review summarizes our knowledge regarding cellular dynamics, inflammatory signaling, and cardiac remodeling that govern MI healing. We identify the current gaps in the field and provide a foundational resource for those seeking to understand the biological underpinnings of cardiac repair following MI.