Preparation of nanoparticles loaded with membrane-impermeable peptide AC3-I and its protective effect on myocardial ischemia and reperfusion

Purpose: It is well known that inhibition of Ca2+/calmodulin-dependent protein kinase II (CaMKII) provides cardiac protection in cases of myocardial ischemia–reperfusion injury. However, there are currently no cytoplasm-impermeable drugs that target CaMKII. The aim of this study was to develop curcumin albumin nanoparticles (HSA-CCM NPs) containing AC3-I and investigate their protective effects on hypoxia–reoxygenation (H/R)-induced injuries in adult rat cardiomyocytes and ischemia–reperfusion (I/R) injuries in isolated rat hearts. Methods: HSA-CCM NPs were synthesized using β-ME methods, while the membrane-impermeable peptide AC3-I was covalently linked via a disulfide bond to synthesize AC3-I@HSA-CCM NPs (AC3-I@NPs). Nanoparticle stability and drug release were characterized. To assess the cardiomyocyte uptake of AC3-I@NPs, AC3-I@NPs were incubated with cardiomyocytes under normoxia and hypoxia, respectively. The cardioprotective effect of AC3-I@NPs was determined by using a lactate dehydrogenase kit (LDH) and PI/Hoechst staining. The phosphorylation of phospholamban (p-PLB) was detected by Western blotting in hypoxia–reoxygenation and electric field stimulation models. To further investigate the protective role of AC3-I@NPs against myocardial ischemia–reperfusion injury, we collected coronary effluents and measured creatine kinase (CK) and LDH release in Langendorff rat hearts. Results:AC3-I@NPs were successfully prepared and characterized. Both HSA-CCM NPs and AC3-I@NPs were taken up by cardiomyocytes. AC3-I@NPs protected cardiomyocytes from injury caused by hypoxia–reoxygenation, as demonstrated by decreased cardiomyocyte death and LDH release. AC3-I@NPs reduced p-PLB levels evoked by hypoxia–reoxygenation and electrical field stimulation in adult rat cardiac myocytes. AC3-I@NPs decreased the release of LDH and CK from coronary effluents. Conclusions: AC3-I@NPs showed protective effects against myocardial injuries induced by hypoxia–reoxygenation in cardiomyocytes and ischemia–reperfusion in isolated hearts.