Establishment Of A Model Of Doxorubicin Myocardial Fibrosis And Its Mechanism

Background and Objective: Doxorubicin(DOX)is utilized for anti-neoplastic treatment for several decades.But it has limited clinical application due to severe cardiotoxicity.Though several mechanisms have been shown to be involved in cardiotoxicity the precise mechanism is still elusive.The most serious consequence of doxorubicin on myocardial tissue is the apoptosis and necrosis of normal myocardial tissue.As a result,the cardiomyocytes are replaced by fibrous tissue to form myocardial fibrosis characterized by myofibroblast growth.Myocardial fibrosis is the main content of myocardial remodeling.Endothelial to mesenchymal transition(EndoMT)refers to the transformation of endothelial cells into stromal cells after injury.Recent studies have shown that Endothelial to mesenchymal transition plays a big role in fibrotic diseases.The present our study:1.aimed to establish a model of myocardial fibrosis in SD rats by the chemotherapy drug doxorubicin-induced.2.To reveal that EndoMT is involved in the formation of doxorubicin-induced myocardial fibrosis in SD rats,and to explore a new mechanism of doxorubicin cardiomyopathy,and provide a new strategy for the prevention and treatment of doxorubicin cardiotoxicity.Method: A total of 40 male and female SD rats,aged 6 weeks,weighing about 180 g.All rats were randomly divided into the experimental group and the control group.The rats in the experimental group were intraperitoneally injected with the dose of doxorubicin hydrochloride 2mg/kg/W.The control group was given the same amount of normal saline,respectively,the experimental components were grouped as doxorubicin 1W,2W and 6W according to the time,after the injection then obtain the corresponding material.1.HE is staining and Masson trichrome staining were used to detect the pathological changes of myocardial tissue in SD rats.2.Primers were designed by NCBI Primer-Blast method,and the expressions of fibrosis-related genes Col1?,Col3? and TGF-?1 were evaluated by RT-qPCR.3.Immunohistochemistry was used to exam the expression of TGF-?1 in myocardial tissue.4.The hydroxyproline(HYP)content in the heart tissue of SD rats induced by doxorubicin was detected by hydroxyproline kit assay.5.Immunofluorescence staining confirmed the EndoMT phenomenon of myocardial tissue caused by the side effects of doxorubicin.Results: 1.After intraperitoneal injection of doxorubicin(2mg/kg once a week)in rats,all rats showed hair thinness,abdominal distension,and poor hair color condition.About one-third of the rats died due to acute arrhythmia.2.With the prolongation of doxorubicin action,pericardial effusion and peritoneal effusion appeared in the doxorubicin 6W group.HE staining and Masson's trichrome staining showed significant ventricular enlargement,thinning of the heart wall,myocardial fibrosis,myocardial vascular endothelial injury and increased permeability in rats with Adriamycin-induced cardiomyopathy accompany other pathological changes.The myocardial fibrosis was significantly higher in the experimental group compared with the control group(P<0.05).3.RT-qPCR showed that the expressions of fibrosis-related factors Col1?,Col3? and TGF-?1 were increased in the experimental group compared with the control group(P<0.05).4.With the prolongation of the action time of doxorubicin,the content of HYP in the myocardium gradually increased.Compared with the 1W and 2W levels in the 6W group,the experimental group was significantly more significant than the control group(P<0.05).5.Endothelial interstitial transformation occurs in cardiac vascular endothelial cells of rats with Adriamycin-induced myocardial fibrosis.Conclusion: 1.Doxorubicin can induce irreversible myocardial fibrosis in SD rats.This study successfully constructed a doxorubicin-induced myocardial fibrosis model.2.Endothelial to mesenchymal transition participates in the formation of doxorubicin-induced myocardial fibrosis in SD rats and plays an important role in the formation of doxorubicin-induced myocardial fibrosis.Prevention or treatment of Endothelial to mesenchymal transition may be an effective means of treating doxorubicin-induced myocardial fibrosis.