Ad-HGF Promotes The Proliferation And Differentiation Of The C-kit~+ Cardiac Stem Cells In The Infarcted Aged Heart And Its Mechanism Study

BackgroundIschemic heart disease causes great attention because of its severe mortality and poor prognosis.In China,mortality rate of ischemic heart disease shows a clear upward trend,reaching an average of 62.5/100,000 people,which has become the main cause of death in male aged more than 50 years old and in female over 70 years of age.According to statistics,the Chinese population of 65 years of age and above in 2015 is 144.34 million.Nearly 10 years,population of 65 years of age and above increased year by year;the peak of population aging is coming,which Will lead to the further increase in the incidence of ischemic heart disease,especially myocardial infarction(MI)in the elderly.So to explore the myocardial regeneration and repair strategy in the elderly after MI is particularly important.The discovery of c-kit+cardiac stem cells(CSCs)provided us with new therapeutic targets to repair the damaged heart.However,the precise mechanisms regulating CSC proliferation and differentiation in the aged heart remained elusive.Our previous studies have confirmed the protective effects of hepatocyte growth factor(HGF)on the heart following MI.However,it remains unclear whether and how HGF promotes endogenous c-kit+ CSC proliferation and differentiation in the aged heart following MI.Necroptosis,a type of regulated cell death,has recently been shown to occur following MI;however,its effect on c-kit+ CSCs remains unknown.ObjectiveWe investigated the effects of HGF and necroptosis on the proliferation and differentiation of endogenous c-kit+ CSCs in aged rat hearts following MI.Methods1.The c-kit+ CSCs and HGF/p-Met expression levels in neonatal,adult and aged rats were compared using immunofluorescence and Western blotting.2.Immediately after MI,adenovirus carrying the HGF gene(Ad-HGF)was injected into the left ventricular wall surrounding the infarct areas of the aged rat heart.3.The proliferation and differentiation of the endogenous c-kit+ CSCs were studied using immunofluorescence.4.The signaling pathways were analyzed via Western blotting and ELISA.Results1.HGF/p-Met expression levels and c-kit+ CSC abundance gradually decreased with age.2.Ad-HGF promoted c-kit+ CSC differentiation into precursor cells of cardiomyocyte,endothelial and smooth muscle cell lineages and enhanced cardiomyocyte proliferation and angiogenesis in aged rats;these effects were reversed by the inhibition of necroptosis.3.Ad-HGF administration induced necroptosis by increasing the expression of receptor interacting protein kinase(RIP)1 and receptor interacting protein kinase(RIP)3 proteins in the infarcted heart.4.Moreover,Ad-HGF-induced necroptosis increased high-mobility group box 1 protein(HMGB1)levels and enhanced the abundance of c-kit+ cells in the bone marrow,which may partly account for the beneficial effect of necroptosis on the c-kit+ CSCs.ConclusionAd-HGF-induced necroptosis facilitated aged heart repair and cardiac remodeling after MI by promoting c-kit+ CSC proliferation and differentiation.These findings may lead to the development of new methods for the treatment of ischemic heart disease in aged populations.