Matrixmetalloproteinases and tissue inhibitors of metalloproteinases: Immunhistochemical markers in the diagnosis of lethal myocardial infarctions?

Matrixmetalloproteinases (MMP) 2 and 9 as well as tissue inhibitor of metalloproteinases (TIMP) 1 were tested as markers of myocardial early ischemia/infarctions. Experiments with an animal model, the isolated Langendorff heart, and analysis of human tissue samples drawn during autopsies were performed. Results of the experiments with the Langendorff model implied that the detectable amount of the markers might increase early after the onset of ischemia, in less than one hour, under ideal conditions. The results of the examined human cases showed that MMP-2 is constantly detectable in human myocardial tissue with an increased amount in case of an infarction with longer survival times. MMP-9 and TIMP-1 were negative in control cases, distinct positive staining results were obtained mainly in cases of infarctions with longer survival times and only rarely in those with a short survival time. According to these results MMPs and TIMPs do not qualify as first choice markers of myocardial infarctions. As an interesting side finding in the Langendorff experiments, positive staining results for all three markers were seen in myocardial areas that were mechanically traumatized by ECG-electrodes or ligation of blood vessels. These findings make the markers interesting for forensic wound age estimation.