Forensic pathological investigation of myocardial hypoxia-inducible factor-1α, erythropoietin and vascular endothelial growth factor in cardiac death

The present study investigated the immunohistochemical distributions and mRNA expressions of myocardial hypoxia-inducible factor (HIF)-1α and its downstream factors, erythropoietin (Epo) and vascular endothelial growth factor (VEGF), in cardiac deaths. Medico-legal autopsy cases (n = 114, within 48-h postmortem) of cardiac deaths (n = 58) and control cases (n = 56) were examined. Immunohistochemical positivities of HIF-1α, Epo and VEGF were patchily observed in cardiomyocytes in the acute ischemic lesions of myocardial infarction (n = 37), showing a relationship to morphological cardiomyocyte damage: the staining was intense in the regions with early ischemic changes and weak in the necrotic regions. Immunopositivities were sporadically detected in cardiomyocytes in some cases of sudden cardiac death without infarction (SCD, n = 13). In chronic congestive heart disease (CHD, n = 8), weak positivities were diffusely observed in the cardiomyocytes. However, there were no such findings in cases of mechanical asphyxiation (n = 16) or drowning (n = 18). HIF-1α, Epo and VEGF mRNA expressions, as measured by real-time reverse transcription-polymerase chain reaction (RT-PCR), showed localized elevations related to acute myocardial infarction (AMI) lesions, whereas such findings were mild in recurrent myocardial infarction (RMI) and SCD cases. CHD showed significant elevations of these mRNAs irrespective of the sampling site. The mRNA expressions were significantly lower in cases of drowning. These findings suggest that focal immunopositivities and increased mRNAs of these factors are indicative of short and substantial duration of myocardial ischemia, respectively. The combined analyses may not only be useful for investigating the site, phase and severity of acute myocardial ischemia and the severity of chronic ischemic stress, but also contribute to differentiating cardiac deaths from asphyxiation and drowning or interpreting the possible contribution of cardiac disease in traumatic death.