ISCHEMIC REPERFUSED MYOCARDIUM CAN EXPRESS RECOMBINANT PROTEIN FOLLOWING DIRECT DNA OR RETROVIRAL INJECTION/

A non-contracting scar following myocardial infarction can adversely a ffect ventricular topography and hemodynamic function. Gene transfer h as the potential to prevent or alter such pathophysiological processes . Normal myocardium is a proven target for delivery of DNA or viral ve ctors but the potential for gene therapy in ischemic myocardium has no t been evaluated. In an initial series of experiments, we determined w hether the direct injection of reporter genes into hearts subjected to coronary artery occlusion followed by reperfusion could result in gen e expression comparable to the levels observed in non-occluded normal hearts. Anesthetized rats were subjected to 15 min or 60 min of proxim al coronary occlusion or sham operation. Luciferase gene under control of the Rous sarcoma virus promoter was injected directly into the ant erior left wall. At 1 week, high expression of luciferase was observed in both the ischemic/reperfused and non-ischemic tissue. Thus DNA tra nsfer by direct injection is possible after ischemic injury and uptake and expression are not impaired. In a second series of experiments, m yocardial infarcts in dogs were injected with a beta-glactosidase expr essing retroviral vector, LNPOZ. Six to 11 days later frozen sections revealed macroscopically visible expression of beta-galactosidase acti vity. Not only can foreign genes be taken up by direct injection of DN A or retroviruses into ischemic/reperfused myocardium but they can be transcribed and the protein synthetic machinery of the injured cells c an produce recombinant polypeptides that retain enzymatic activity. Th ese results open the way for the investigation of gene therapy in mode ls of ischemia. (C) 1996 Academic Press Limited