Telomerase And The Role Of Tert In The Experimental Mice, Cvb3 Myocarditis And Astragaloside Intervention Study

PartⅠKinetic changes of stem cell and telomerase expression in the circulation and myocardium of mice with Coxsackie virus B3-induced myocarditisObjective To investigate kinetic changes of stem cell and telomerase expression in the circulation and myocardium of mice with Coxsackie virus B3-induced myocarditis. Methods Groups of mice were administered Eagle's minimal essential medium (control group, CON) or virus solution (virus group, VIR). The animals were further divided into six subgroups based on the following time points post-inoculation: 1, 3, 7, 14, 21, and 28 days. Ten animals were studied in each subgroup. Circulating blood mononuclear cells were collected from the heart and analyzed using flow cytometry, TaqMan real-time RT-PCR, Western blot, and ELISA to measure myocardial TERT mRNA, TERT protein, and telomerase activity, respectively. Myocardial inflammation and expression of stem cell marker were detected by H&E staining, histology, and immunofluorescence. Myeloperoxidase (MPO) and reactive oxygen species (ROS) were evaluated according to the manufacturer's instructions.Results H&E staining revealed inflammative cells infiltration and bleeding by day three post-infection. MPO and ROS levels peaked by day three, and were followed by myocyte loss and collagen deposition. Circulating mesenchymal stem cells also peaked by 3 day. In contrast, hematopoietic stem cells did not increase significantly until day 14. Fluoroscence microscopy also showed a marked increase in cardiac stem cells by day 14. The kinetics of this increase was consistent with a rise in proliferating cells expressing nuclear and cytoplasmic proteins that are typical of cardiomyocyte or vascular endothelial cells. TERT mRNA and protein expression and telomerase activity increased significantly between days seven and 14, and decreased by day 21.Conclusion These results demonstrate the rapid kinetics of stem cell and telomerase expression during viral myocarditis and suggest that the optimal time to administer cell therapy to induce heart repair is within two weeks after viral infection.PartⅡThe Effect of Astragaloside on Telomerase in the Viral Myocarditis with CVB3Objective To investigate the effect of astragaloside (Astr) on telomerase activity and telomerase reverse transcriptase (TERT) expression in viral myocarditis mice.Methods Viral myocarditis was induced by intraperitoneally injection of Eagle's minimal essential medium (EMEM) solution. The animals were randomly received with saline, low-dose Astr (1%), and high-dose Astr (9%) treatment, respectively. Two weeks later, mortality were analysized by statistics; Telomerase activity of peripheral blood mononuclear cells were evaluated by TRAP-ELISA; The effect of astragaloside (Astr) on TERT expression was examined by RT-PCR.Results The mortality was found significantly reduced in high-dose Astr treated infected animals. High-dose Astr treatment led the highest telomerase activity and up-regulated TERT expression.Conclusion The results showed that enhancing telomerase activity and up-regulating TERT expression could be one of the therapic mechanisms of astragaloside for CVB3-induced myocarditis.