Immunohistochemical analysis of thrombomodulin expression in myocardial tissue from autopsy cases of ischemic heart disease

HIF-1α expression by immunohistochemistry and mRNA-210 levels by real time polymerase chain reaction in post-mortem cardiac tissues: A pilot study

INTRODUCTION

The postmortem diagnosis of acute myocardial ischemia (AMI) represents a challenging issue in forensic practice. Immunohistochemical studies and gene expression studies are becoming a promising field of research in forensic pathology. The present study aims to evaluate HIF-1α expression through immunohistochemistry (IHC), and mRNA-210 level using real-time polymerase chain reaction (RT-PCR), in order to define if HIF-1α and mRNA-210 in post-mortem myocardium could be adopted in the diagnosis of AMI.

MATERIALS AND METHODS

Thirty-five deceased individuals, who underwent forensic autopsy at the Legal Medicine Service of the University of Parma, between 2010 and 2018, were investigated. The cohort was divided into two groups according to the cause of death (sudden deaths caused by AMI vs control cases). Cardiac specimens were collected during autopsy, then samples were processed for morphological evaluation using haematoxylin-eosin staining, for IHC, and for RT-PCR. HIF-1α expression and mRNA-210 levels were investigated.

RESULTS

Statistical evaluation demonstrated statistically significant differences in terms of number of IHC positive vessels, leukocytes, and cardiomyocytes between the two groups. Moreover, in the majority of cases, immunostaining positivity was observed only in myocardial and subendocardial samples. With reference to mRNA-210, the difference between the two groups proved to be statistically significant.

CONCLUSIONS

The present study indicates that HIF-1α and mRNA-210 in post-mortem cardiac specimens could represent appropriate biomarkers in the diagnosis of AMI. The current study was primarily limited by the scarcity of the cohort, so further research is required to confirm these preliminary observations.

The influence of fixing condition on myoglobin stainability of striated muscle as a tool for forensic diagnosis

It is reported that immunostaining of Myoglobin (Mb) is useful for forensic diagnosis. In this study, we investigated the condition of fixation of striated muscle in 10 % neutral-buffered formalin to obtain appropriate stationarity of Mb in immunostaining. Firstly, criteria for staining intensity and definition of the stainability of examined were determined for sheep muscle tissue. Sheep myocardial tissue was fixed using 10 % neutral-buffered formalin under the 21 different conditions based on combinations of the following: three ratios of volume of formalin (mL) to weight of myocardium (g) (RFM) of 1, 4 or 9, 7 durations of fixation (DF) of 0.5, 3 or 6 h, and 1, 2, 5 or 7 days. Secondly, detection of Mb diffused form skeletal muscle from autopsy cases into formalin during fixation were confirmed by ELISA. Finally, the evaluation of stainability of Mb of striated muscle in routine autopsy examinations was confirmed using sheep staining intensity standards. From this experimental investigation, it has been demonstrated that the most suitable formalin fixation condition for using Mb staining in forensic diagnosis is RFM4 with a fixation time of at least DF 3 h up to 1 day. It was evident that staining intensity decreases with fixation durations exceeding 2 days, irrespective of the RFM. Thus, the fixation time was deemed the most influential factor affecting the staining properties of Mb staining in skeletal muscle tissue. When conducting Mb staining using striated muscle as an evaluation sample, particular attention should be paid to the fixation time.

The Role of Protein Degradation in Estimation Postmortem Interval and Confirmation of Cause of Death in Forensic Pathology: A Literature Review

It is well known that proteins are important bio-macromolecules in human organisms, and numerous proteins are widely used in the clinical practice, whereas their application in forensic science is currently limited. This limitation is mainly attributed to the postmortem degradation of targeted proteins, which can significantly impact final conclusions. In the last decade, numerous methods have been established to detect the protein from a forensic perspective, and some of the postmortem proteins have been applied in forensic practice. To better understand the emerging issues and challenges in postmortem proteins, we have reviewed the current application of protein technologies at postmortem in forensic practice. Meanwhile, we discuss the application of proteins in identifying the cause of death, and postmortem interval (PMI). Finally, we highlight the interpretability and limitations of postmortem protein challenges. We believe that utilizing the multi-omics method can enhance the comprehensiveness of applying proteins in forensic practice.

Investigation of impacts of decellularized heart extracellular matrix and VEGF on cardiomyogenic differentiation of mesenchymal stem cell through Notch/Hedgehog signaling pathways

OBJECTIVE

Decellularization is the process to obtain natural scaffolds with tissue integrity and extracellular matrix components, and recellularization is used to produce tissue-like constructs with specific cell types. In this study, rat bone marrow-derived mesenchymal stem cells (rBM-MSCs) were cultured on decellularized heart extracellular matrix. These cells were then induced to differentiate into cardiomyogenic cells under the stimulatory effect of vascular endothelial growth factor (VEGF) and other chemicals. This study aimed to investigate the effect of the cardiac extracellular matrix and VEGF on cardiomyogenic differentiation in the context of the Notch and Hedgehog signaling pathways.

METHODS

Heart samples extracted from rats were decellularized by serial application of detergent to remove cells from the tissue, and then recellularized with rBM-MSCs. The recellularized tissue matrices were then analyzed for cardiomyogenesis. Cardiomyogenic differentiation was performed on decellularized heart extracellular matrix (ECM; three-dimensional scaffolds) and culture plates (two-dimensional cell culture system) for 28 days to understand the effects of the heart extracellular matrix. In addition, differentiation was induced with and without the stimulatory effect of VEGF to understand the effect of VEGF on cardiomyogenic differentiation of rBM-MSCs.

RESULTS

Immunofluorescence staining showed that decellularization of the heart was performed effectively and successfully. After decellularization process, the heart extracellular matrix was completely free of cells. It was observed that rBM-MSCs transplanted onto the heart extracellular matrix remained viable and proliferated for 21 days after recellularization. The rBM-MSCs promoted cardiomyogenic differentiation in the conventional differentiation medium but were inversely affected by both VEGF and heart extracellular matrix proteins. Lower expression of connexin43 and cardiac troponin I genes was observed in cells induced by either matrix proteins or VEGF, compared to cells differentiated by chemical agents alone.

CONCLUSION

In this study, we investigated the effect of decellularized heart extracellular matrix and VEGF on cardiomyogenic differentiation of rBM-MSCs. On the decellularized cardiac extracellular matrix, rBM-MSCs maintained their viability by adhering to the matrix and proliferating further. The adhesion of the cells to the matrix also produced a physical stimulus that led to the formation of histological structures resembling myocardial layers. Chemical stimulation of the decellularized heart extracellular matrix and cardiomyogenic differentiation supplements resulted in increased expression of cardiomyogenic biomarkers through modulation of the Notch and Hedgehog signaling pathways.

Immunohistochemical analysis of vimentin expression in myocardial tissue from autopsy cases of ischemic heart disease

Vimentin is a type III intermediate filament cytoskeletal protein that is expressed mainly in cells of mesenchymal origin and is involved in a plethora of cellular functions. In this study, myocardial tissues from patients with ischemic heart disease and a mouse model of acute myocardial infarction were subjected to immunohistochemistry for vimentin. We first examined 26 neutral formalin-fixed, paraffin-embedded myocardial tissue samples from autopsies of patients that were diagnosed with ischemic heart disease within 48 h postmortem. Myocardial cells were negative for vimentin, whereas non-myocardial cells, including vascular endothelium, vascular smooth muscle, fibroblasts, nerve fibers, adipocytes and mesothelial cells, showed positivity. Elevated vimentin expression was observed around myocardial cells undergoing remodeling, suggesting fibroblastic and endothelial proliferation in these locations. By contrast, myocardial foci that were completely fibrotic did not show upregulated vimentin expression. Inflammatory foci including macrophages and neutrophils were clearly visualized with vimentin immunostaining. The same vimentin expression phenomena as those found in human samples were observed in the mouse model. Our study indicates that immunostaining of vimentin as a marker for myocardial remodeling and the dynamics of all non-myocardial cell types may be useful for supplementing conventional staining techniques currently used in the diagnosis of ischemic heart disease.

Immunohistochemical analysis of von Willebrand factor expression in myocardial tissues from autopsies of patients with ischemic heart disease

von Willebrand factor (VWF) plays a crucial role in hemostasis and thrombosis. VWF is involved in platelet attachment to the subendothelium, serving as a carrier protein for coagulation factor VIII. In this study, myocardial tissues from deceased patients with ischemic heart disease and a mouse model of acute myocardial infarction were subjected to immunohistochemistry to determine VWF expression. We examined 28 neutral formalin-fixed, paraffin-embedded myocardial tissue samples obtained from the autopsies of patients who were diagnosed with ischemic heart disease within 48 h postmortem. Most myocardial cells were negative for VWF, although some cells showed nonspecific positivity. Elevated VWF expression was observed around myocardial cells undergoing remodeling, suggesting that endothelial proliferation occurred at these sites. In contrast, completely fibrotic myocardial foci did not show upregulated VWF expression. Positivity in fibrin deposition and hemorrhagic sites was observed. The same VWF expression characteristics as those observed in the human samples were observed in the mouse model. VWF immunostaining as an endothelial marker may be a useful supplementation to conventional staining techniques that are currently used in the diagnosis of ischemic heart disease in terms of examining the timing of myocardial remodeling in detail and highlighting the remodeling process.