Apoptosis in Human Acute Myocardial Infarction

TLDR

After reperfusion of the infarct-related artery, cardiomyocyte death continues, and the mechanisms of this cell death remain debated. The study aimed to determine whether apoptosis occurs in human acute myocardial infarction and to suggest it as a potential cardioprotective target. The authors examined myocardial tissue from eight autopsy cases of AMI with patent infarct arteries, six of whom had undergone successful thrombolysis. DNA strand breaks and internucleosomal fragmentation revealed that apoptosis occurs predominantly in border zones of infarcted myocardium, indicating that apoptosis accompanies necrosis during ischemia‑reperfusion injury.

Abstract

After reopening of the infarct-related coronary artery, cardiomyocytes continue to die during reperfusion. The mechanisms of cell death have been subject to debate. We studied whether an apoptotic type of cell death occurs in human acute myocardial infarction (AMI).We studied myocardial samples of eight patients who died of AMI and had patent infarct-related arteries at autopsy. Six of the patients had received initially successful thrombolysis. Extensive formation of DNA strand breaks, the typical biochemical feature of apoptosis, was detected with the use of the in situ DNA end-labeling method. Apoptotic cardiomyocytes were observed particularly in the border zones of histologically infarcted myocardium, whereas very few apoptotic cells were present in the remote noninfarcted myocardium. Internucleosomal fragmentation was confirmed by agarose gel electrophoresis of DNA isolated from the representative myocardial areas.This study provides evidence that in addition to overt necrosis, a subset of myocytes undergo apoptosis during ischemia-reperfusion injury. Apoptosis may provide a new target for cardioprotection during evolving AMI in humans.