Cardiac gene therapy using SHP-1 siRNA and deoxycholic acid-modified polyethyleneimine to heart ischemia-reperfusion myocardial infarction in rat model

Abstract

The apoptotic cell death of cardiomyocytes was found to play a critical role in the development of myocardial injury after ischemia and reperfusion. Thus, alteration of the major apoptosis-regulatory factors during myocardial ischemia-reperfusion is expected to have favorable cardioprotective effects. In the present study, we report ischemic-reperfused myocardial infarction repair with therapeutic siRNA against the Src homology region 2 domain-containing tyrosine phosphatase-1 (SHP-1), which is known as a key factor involved in regulating the progress of apoptosis in many cell types. Herein, a low molecular weight polyethyleneimine modified with deoxycholic acid (PEI1.8-DA)-based delivery strategy was suggested for the cardiac application of SHP-1 siRNA to overcome the poor gene delivery efficiency to the myocardium due to the highly charged structures of the compact cardiac muscles. The PEI1.8-DA conjugates formed stable self-assembled nanocomplexes with the SHP-1 siRNA via electrostatic and hydrophobic interactions. The PEI1.8-DA /SHP-1 siRNA polyplexes dramatically reduced the SHP-1 gene expression in rat cardiomyocytes, leading to a significant inhibition of cardiomyocyte apoptosis induced by exposure to hypoxia. In comparison to conventional gene carriers that rapidly disappeared from the injected heart region, relatively large amounts of the siRNA molecules remained after treatment with the PEI1.8-DA/SHP-1 siRNA polyplexes. Cardiac administration of the PEI1.8-DA/SHP-1 siRNA polyplexes resulted in substantial improvement in SHP-1 gene silencing, which can be explained by the enhancement of in vivo cardiac gene delivery efficiency of the PEI1.8-DA conjugates. In addition, in vivo treatment with the PEI1.8-DA/SHP-1 siRNA polyplexes induced a highly significant reduction in myocardial apoptosis and infarct size in rat models of myocardial ischemia-reperfusion. These results demonstrate that the PEI1.8-DA/SHP-1 siRNA polyplex formulation is not only a useful system for efficient gene delivery into the compact myocardium, but also provides a fundamental advantage in treating ischemic-reperfused myocardial infarction. In this study, deoxy cholic acid-modified low molecular weight polyetyleneimine/SHP-1 siRNA polyplex delivery system might be appropriate for myocardium gene therapy as clinical applications possibility of siRNA therapy.