CS-IGF-1C Hydrogel Enhances The Efficacy Of Mesenchymal Stem Cells In The Treatment Of Acute Myocardial Infarction

Effect of CS-IGF-1C hydrogel on biological characteristics of mesenchymal stem cells and neonatal mouse cardiomyocytes and evaluation of molecular imagingBackground:In this study,chitosan(CS)was modified with C domain peptide of insulin-like growth factor-1 to prepare bioactive CS-IGF-1C hydrogel.It can maintain the activity of stem cells by simulating the microenvironment in which stem cells live.Therefore,the purpose of our study was to evaluate the cytocompatibility of hydrogels and the effects of proliferation,anti-apoptosis and angiogenesis on the placental mesenchymal stem cell(PMSCs)in vitro,and the effect of hydrogel on anti-apoptosis and anti-hypoxia of neonatal mouse cardiomyocytes.We further explore the mechanism of stem cell enhancement in order to provide a new theoretical basis for tissue engineering to promote cardiac repair.Methods:A cell line stably expressing green fluorescent protein and firefly luciferase was constructed,neonatal mouse cardiomyocytes were extracted,and bioactive CS-IGF-1C hydrogels were prepared.The biocompatibility,cell proliferation and anti-apoptosis ability of CS-IGF-1C hydrogels to PMSCs were detected by bioluminescence imaging(BLI).Calcein-AM/PI staining was used to evaluate the effect of CS-IGF-1C hydrogel on anti-apoptosis and anti-hypoxia of neonatal mouse cardiomyocytes.The ability of CS-IGF-1C to promote angiogenesis of HUVECs cells was evaluated by scratch test.The expression of proliferation and anti-apoptosis related genes in PMSCs were detected by Real-time quantitative RT-PCR.Results:PMSCs cultured in vitro had strong proliferation ability and stable expression of GFP,and in vitro BLI analysis showed that there was a positive correlation between the number of cells and bioluminescence intensity(R2=0.99).In vitro,BLI results showed that CS-IGF-1C could promote the proliferation of PMSCs cells and significantly up-regulate the expression of proliferation-related genes,antagonize the apoptosis induced by H2O2.In addition,it could down-regulate the expression of apoptosis related genes.It can also up-regulate the expression of angiogenesis related genes in PMSCs.In vitro culture,Calcein-AM/PI staining results showed that CS-IGF-1C could promote the anti-apoptosis,anti-hypoxia and other biological characteristics of neonatal mouse cardiomyocytes.The results of scratch test showed that CS-IGF-1C could promote angiogenesis and the expression of related genes in HUVECs cells in vitro.Conclusions:CS-IGF-1C hydrogel has good biocompatibility and can promote the proliferation of PMSCs inhibit apoptosis and promote angiogenesis in vitro.Neonatal mouse cardiomyocytes were cultured in vitro with CS-IGF-1C hydrogel combined with PMSCs and it can improve the anti-apoptosis and anti-hypoxia ability of neonatal mouse cardiomyocytes.CS-IGF-1C hydrogel combined with PMSCs can promote angiogenesis of HUVECs cells.Efficacy of CS-IGF-1C hydrogel enhanced mesenchymal stem cells in the treatment of acute myocardial infarctionBackground:Mesenchymal stem cell(MSCs)is one of the ideal donors for stem cell transplantation in acute myocardial infarction(AMI).However,the low retention rate and survival rate of transplanted cells limit the successful application of MSCs in the treatment of AMI.In this study,CS-IGF-1C hydrogel was used to simulate the microenvironment on which stem cells depended to maintain the activity of stem cells,to evaluate whether CS-IGF-1C could improve the survival rate of PMSCs in vivo,and to explore the mechanism of enhancing the therapeutic effect of stem cells.It provides a new theoretical basis for the use of tissue engineering to promote cardiac repair.Methods:A PMSCs cell line stably expressing Fluc and GFP was constructed,and a bioactive CS-IGF-1C hydrogel was prepared.AMI mouse model was constructed and CS-IGF-1C hydrogel loaded PMSC was injected into the myocardium around infarction to evaluate the survival effect of transplanted PMSCs in vivo by bio luminescence imaging(BLI).CD31 immunofluorescence was used to evaluate the effect of CS-IGF-1C hydrogel on the differentiation of PMSCs into vascular endothelial cells.Four weeks after operation,the cardiac function was measured by echocardiography,and the infiltration of inflammatory cells and myocardial fibrosis were observed by HE staining and Masson staining.Real-time quantitative RT-PCR was used to detect the expression of genes related to inflammation,angiogenesis and fibrosis.Results:In vivo,BLI results showed that CS-IGF-1C hydrogel could significantly promote the survival of PMSCs after transplantation(P<0.05).Immunofluorescence analysis showed that CS-IGF-1C hydrogel combined with PMSCs transplantation was beneficial to angiogenesis,thus promoting histological and functional repair.On the other hand,CS-IGF-1C hydrogel combined with PMSCs transplantation can reduce inflammatory response.In addition,it could down-regulate the expression of apoptosis related genes.The results of echocardiography showed that CS-IGF-1C combined with PMSCs transplantation could improve left ventricular ejection fraction(LVEF)(P<0.01).The results of Masson staining 4 weeks after injury showed that CS-IGF-1C hydrogel combined with PMSCs transplantation could significantly reduce collagen deposition and the expression of fibrosis-related genes was down-regulated.Conclusions:Injection of CS-IGF-1C hydrogel combined with PMSCs into the damaged heart can improve the survival of PMSCs,enhance neovascularization,reduce inflammation and reduce the degree of fibrosis,so as to improve cardiac function and accelerate heart repair.Evaluation of Left Ventricular Volumes and Ejection Fraction by Gated SPECT and Gated PET in Patients with Prior Myocardial InfarctionBackground:This study aimed to compare the accuracy of gated-SPECT(GSPECT)and gated-PET(GPET)in the assessment of left ventricular(LV)end-diastolic volumes(EDV),end-systolic volumes(ESV)and ejection fraction(LVEF)among patients with prior myocardial infarction(MI).Methods:One hundred and sixty-eight consecutive patients with MI who underwent GSPECT and GPET were included.Of them,76 patients underwent CMR in addition to the two imaging modalities.The measurements of LV volumes and LVEF were performed using Quantitative Gated SPECT(QGS),Emory Cardiac Toolbox(ECTB)and 4D-MSPECT(4DM).Results:The correlation between GPET,GSPECT and CMR were excellent for LV EDV(r=0.855-0.914),ESV(r=0.852-0.949)and LVEF(r=0.618-0.820),as calculated from QGS,ECTB and 4DM.In addition,subgroup analysis revealed that EDV,ESV and LVEF measured by GPETwere accurate in patients with different extent of total perfusion defect(TPD),viable myocardium and perfusion/metabolic mismatch.Furthermore,multivariate regression analysis identified that mismatch score was associated with the difference in EDV(P<0.05)measurement between GPET and CMR.Conclusions:In patients with MI,LV volumes and LVEF measured by both GSPECT and GPET imaging were comparable with those determined by CMR,but should not be interchangeable in individual patients.