Cardiomyocytes Cellular Phenotypes After Myocardial Infarction

Abstract

Despite the increasing success of interventional coronary reperfusion strategies, mortality related to acute myocardial infarction (MI) is still substantial. MI is defined as sudden death of myocardial tissue caused by an ischemic episode. Ischaemia leads to adverse remodelling in the affected myocardium, inducing metabolic and ionic perturbations at a single cell level, ultimately leading to cell death. The adult mammalian heart has limited regenerative capacity to replace lost cells. Identifying and enhancing physiological cardioprotective processes may be a promising therapy for patients with MI. Studies report an increasing amount of evidence stating the intricacy of the pathophysiology of the infarcted heart. Besides apoptosis, other cellular phenotypes have emerged as key players in the ischemic myocardium, in particular senescence, inflammation, and dedifferentiation. Furthermore, some cardiomyocytes in the infarct border zone uncouple from the surviving myocardium and dedifferentiate, while other cells become senescent in response to injury and start to produce a pro-inflammatory secretome. Enhancing electric coupling between cardiomyocytes in the border zone, eliminating senescent cells with senolytic compounds, and upregulating cardioprotective cellular processes like autophagy, may increase the number of functional cardiomyocytes and therefore enhance cardiac contractility. This review describes the different cellular phenotypes and pathways implicated in injury, remodelling, and regeneration of the myocardium after MI. Moreover, we discuss implications of the complex pathophysiological attributes of the infarcted heart in designing new therapeutic strategies.

Keywords: apoptosis; autophagy; cardioprotection; dedifferentiation; inflammation; myocardial infarction; senescence.

Figure 1

Schematic representation of different cellular phenotypes and intracellular pathways involved in the pathophysiology of the infarcted heart. Besides different forms of cell death (apoptosis, necrosis, and necroptosis), other cellular phenotypes have emerged as key players in the ischemic myocardium, including autophagy, inflammation, senescence, and dedifferentiation.

Figure 2

In addition to reperfusion therapy, cardioprotective strategies are necessary to reduce the infarct size and repair the injured myocardium. A combination of different approaches, including stem cell- and progenitor cell-derived extracellular vesicles, pharmacologic treatments, and AAVs for gene therapy, holds great promise for heart regeneration through limiting cell death and stimulating cardiomyocytes proliferation and blood vessel growth.