The Proliferation And Differentiation Of CSCS In Early Myocardial Ischemia Sudden Death And The Significance In Forensic Pathology

Background and ObjectiveSudden cardiac death is one of the most common types in sudden death cases,caused by cardiac factor with or without cardiac disease. Coronary heart disease is acommon cardiovascular diseases, myocardial ischemia due to coronary artery stenosisand ischemic necrosis of myocardial cell damage and even myocardial infarction, whichcan lead to the occurrence of sudden cardiac death and myocardial ischemia was one ofthe causes of sudden cardiac death. In the process of forensic pathologic justification,focal myocardial infarction can be diagnosed by gross or microscopic observation.Nevertheless, early myocardial infarction is usually tough to observe typicalpathological change, as the most difficult issue in forensic justification. Some surveyshave reported that early myocardial infarction or myocardial infarction can inducecardiac stem cells (CSCs) proliferation and differentiation in order to repair injuredmyocardial cells.CSCs are pluripotent stem cell, which possess the ability of proliferation anddifferentiation in adult myocardial tissue., and CSCs have the ability of myocardialregeneration and repair. High mobility group box protein1(HMGB1), as a signal oftissue damage, plays a critical role in the early and late period of myocardial infarction. Based on coronary artery stenosis to cause myocardial ischemia and infarction, theexpression of HMGB1protein change at different degrees in damaged myocardial cells.There were reports showing that exogenous HMGB1can induce CSCs proliferation anddifferentiation, associated with the expression of miRNA-206. Therefore, this studyinvestigated the proliferation and differentiation of CSCs and the expressions ofHMGB1and miRNA-206in early myocardial ischemia provide forensic pathologicevident for early period diagnosis of myocardial ischemia.Materials and methods1. Myocardial paraffin blocks of60cases selected in Clinical and pathologicalResearch Center in Liaoning province Dalian Medical University forensic experttestimony from the year of2011to2012were divided into3groups based on medicalhistory, the extent of coronary artery stenosis and myocardial change under amicroscope: a. group of25cases of early myocardial ischemia, coronary artery lumenstenosis of the main branch of the Group rated at3to4levels, rare through the typicalpathological changes in myocardial infarction, cardiac muscle cells have poor; b. groupof15cases of myocardial infarction, this group through main branches of coronaryartery lumen stenosis grade3to grade4, microscopically typical changes and oldmyocardial infarction scar; c. normal myocardium group of20patients, coronary arterystenosis-free, no heart disease and death caused by non-cardiac. Slice in all group casewax blocks, HE stained.2. The expression of surface maker c-kit+and HMGB1protein in every group wasassessed by immunohistochemistry.3. The expression of miRNA-206extracted from blocks in every group wasinvestigated by RT-PCR.4. The proliferation and differentiation of CSCs and expression of HMGB1andmiRNA-206were analyzed by the software of SPSS13.0.Results1.The expression of HMGB1protein in different groupsHMGB1-positive expression was detected in the myocardial nuclei in the cases of 3groups. Cell cytoplasm of both early myocardial ischemia group and myocardialinfarction group is visible in the brown-yellow, expression of HMGB1is positive,normal myocardium cell cytoplasm is negative. Early myocardial ischemia testedpositive was96%, positive rates of myocardial infarction was100%, normalmyocardium tested positive was10%.The positive expression of HMGB1is ofsignificant difference between the first two experimental groups and control group（P＜0.05).2. The expression of c-kit+in different groupsc-kit+-positive expression was detected in cell membranes and cytoplasm of bothearly myocardial ischemia group and myocardial infarction group, but less in the normalmyocardial group. Results showed positive rates of early myocardial ischemia groupwas76%,and positive rates of myocardial infarction group was87%. There is no bigdifference between the two groups. Normal myocardium tested positive was20%.Thepositive expression of c-kit+in both early myocardial ischemia group and myocardialinfarction group is significantly different compared to the control（P＜0.05).3. The expression of miRNA-206in different groupsmiRNA-206-positive rate was observed by RT-PCR, finding that positive rate ofmiRNA-206in both early myocardial ischemia group and myocardial infarction groupis significantly different compared to the control（P＜0.05).4. Correlation analysis of the expression of HMGB1and c-kit+in early myocardialischemia group and myocardial infarction groupThe expression of HMGB1was positively correlated with the one of c-kit+in thecases of both early myocardial ischemia group and myocardial infarction groupConclusion1.Groups myocardial tissue of part of the cardiomyocyte cell membrane andcytoplasmic expression of c-Kit+, description exists in the myocardial tissue has cardiacstem cells or some of cardiomyocytes that has characteristics of cardiac stem cells.2.The expression of HMGB1in the cytoplasm of early myocardial ischemia groupand myocardial infarction group was higher compared to normal myocardial, and the positive expression of HMGB1in normal myocardial was only in the nuclei.3.The expression of c-kit+in the cytomembrane of early myocardial ischemia groupand myocardial infarction group was higher compared to normal myocardial, andc-kit+expression in myocardial infarction group is higher than the early myocardialischemia group.4.The expression of miRNA-206in the cytoplasm of early myocardial ischemiagroup and myocardial infarction group was higher compared to normal myocardial, andthe expression of miRNA-206in myocardial infarction group is higher than the earlymyocardial ischemia group.5.The high expression of HMGB1, c-kit+and miRNA-206in early myocardialischemia group and myocardial infarction group and the positive correlation betweenHMGB1and c-kit+suggested to be a forensic pathologic justification examinationapproach for the diagnosis of sudden death caused by early myocardial ischemia.