| Background Owing to the primary and secondary prevention, the death rate of CAD has been decreased dramatically in recent years. The coronary artery disease is still one of the three major causes of deaths,giving rise to heavily burdens on patients,family and society. In order to improve survival rate of patients with CAD, a lot of new methods have been introduced into clinical practice.EPO is one of the members of class I cytokines super family with molecular weight of 30.4kDa which fold into a compact globular structure consisting of 4α-helical bundles. Therapy with recombinant human EPO has become a standard for correction of renal and non-renal anemias for decades. Although EPO is traditionally viewed as a hematopoietic hormone, the finding of EPO-Rs outside the hematopoietic tissue prompted the search for nonhematopoietic effects of EPO. Experimental studies show the protective effect of exogenous EPO treatment in different tissues. For example systemic administration of EPO in the rat model of focal brain ischemia reduced the infarct volume by 50% to 75%. Other reports documented the benefit of EPO administration in the setting of cardiac infarction. In addition, some small-scale prospective clinical trials have proved the benefit of EPO in the treatment of cerebral ischemia too. However it is still lack of data regarding the efficacy, stability and mechanism of EPO treatment. We hypothesized that the protective effect of systemic rhEPO administration that resulted in improvement of brain cell survival after cerebral ischemia may also occur in the ischemic heart model too.Objective To observe the anti-apoptosis and neovascularization effect with EPO treatment, and to clarify the mechanism of EPO protection in ischemia-reperfusion injury. Methods1,the expression of EPO receptors in cardiomyocytes were investigated by RT-PCR and western blot. Cardiomyocyte apoptosis was induced by H2O2 , and Tunel stain was applied to observe the antiapoptosis of EPO. The signal pathways that involved in the anti-apoptosis were investigated by specific intracellular signaling pathway blocker. The supernate of cardiomyocytes at different time points were collected and concentrated to check the expression of VEGF with the administration of EPO.2,The langendroff reperfusion system was applied to investigate the protect function of EPO in the ischemia-reperfusion condition. The effects of EPO on extracellular matrix were observed by western blot and signal pathway blocker. The time course of MMPs activities were investigated in rat ischemic reperfusion model by Zymography Assay.Results: We confirmed that there are EPO receptors in cardiomyocytes. EPO can inhibit the apoptosis of cardiomyocytes, decrease the expression of pro-apoptosis protein and increase the expression of anti-apoptosis protein induced by H2O2. Erk and PI3K-Akt were involved in the anti-apoptosis process of EPO. The secretion of VEGF in cardiomyocytes was increased after EPO treatment. EPO promotes the proliferation of HUVEC. With Langendroff reperfusion system,EPO was observed to improve the hemodynamic parameters in the reperfused rat heart. The infarction area was decreased at the same time. EPO was found to activate the Jak2-Erk signal pathway, increased the expression of CollagenI/III and decreased the expression of MMP2 and MMP9. The MMPs activity was found to decrease for a week by zymography assay too. In cultured rat cardiac fibroblast the expression of MMPs was decreasede by EPO and this function was inhibited by the MEK inhibitor. EPO was observed to increase the expression ofα-smooth muscle by cardiac fibroblast too.Conclusion1. There is EPO receptor in cardiomyocytes. EPO can inhibit the apoptosis of cardiomyocyte by Erk and Akt signal pathway. 2. EPO can increased the secretion of VEGF in cardiomyocyte3.EPO play a role in the metabolism of extracellular matrix by Erk signal pathway.
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