Thrombomodulin is a transmembrane
glycoprotein that is ubiquitously expressed on the surface of vascular endothelial cells.
Thrombomodulin exerts its
anticoagulant effects by combining with
thrombin, activating
protein C, and inactivating the
coagulation factors FVa and FVIIIa. Clinically,
thrombomodulin is also known as a marker of
vascular injury because it circulates freely in response to endothelial injury. In this study, myocardial tissue from cases of
ischemic heart disease was subjected to immunohistochemistry by
thrombomodulin. We examined 40 neutral-
formalin-fixed,
paraffin-embedded myocardial tissue samples from autopsy cases that were diagnosed with
ischemic heart disease (within 48 h postmortem).
Thrombomodulin expression was observed in vascular endothelial cells between myocardial cells and in mesothelial cells of the epicardium. In necrotic myocardium, diffusion of
thrombomodulin, which reflected endothelial injury, was observed. Upregulated
thrombomodulin expression was observed around myocardial cells under ongoing remodeling, which suggested endothelial proliferation in these locations. Completed fibrotic foci of the myocardium did not show upregulated
thrombomodulin expression. In a mouse model of acute
myocardial infarction, the same phenomena as that found in human samples were observed by immunohistochemistry of
thrombomodulin. Immunostaining of
thrombomodulin, as a marker for endothelial injury or myocardial remodeling, may be useful for supplementing conventional staining techniques in the diagnosis of
ischemic heart disease in forensic pathology.