EFFICIENT IN-VIVO GENE-TRANSFER INTO THE HEART IN THE RAT MYOCARDIAL-INFARCTION MODEL USING THE HVJ (HEMAGGLUTINATING VIRUS OF JAPAN) - LIPOSOME METHOD

The lack of efficient treatment for myocardial infarction remains an u nresolved problem in the field of cardiovascular disease. Gene therapy may be a potential therapeutic strategy for the treatment of myocardi al infarction. However, current methods of in vivo gene transfer into the heart are limited by their low efficiency and/or potential toxicit y. In the present study. we developed an efficient technique of gene t ransfer into the intact heart in vivo using the Sendai virus (HVJ: Hem agglutinating Virus of Japan)-liposome method. We used the beta-galact osidase gene, luciferase gene and human angiotensin converting enzyme (ACE) gene as markers. In vivo gene transfer into the rat heart was pe rformed as follows: (1) direct injection into the rat heart, (2) incub ation within the pericardium, and (3) infusion into a coronary artery. Direct injection of the HVJ-liposome complex containing the beta-gala ctosidase vector into the rat heart resulted in limited staining of be ta-galactosidase 3 days after transfection. To compare transfection ef ficiency between ''naked'' plasmid DNA transfection and the HVJ-liposo me method, we also transfected the luciferase reporter gene into the h eart. Luciferase activity was significantly higher in hearts transfect ed by the HVJ-liposome method than that in hearts transfected by direc t ''naked'' plasmid transfection (P < 0.01). To confirm the successful gene in the protein level, we measured ACE activity in the hearts. Ca rdiac ACE activity was significantly increased in hearts transfected w ith human ACE gene as compared to hearts transfected with control vect or (P < 0.01). On the other hand. incubation of HVJ-liposome complex, containing beta-galactosidase vector, within the pericardium resulted in widespread staining of cardiac myocytes and fibroblasts, mainly loc ated in several surface layers beneath the pericardium. More important ly, widespread stained areas of beta-galactosidase were also observed in the middle of the myocardium around the vasa vasorum. We also exami ned the efficiency of gene transfer by the HVJ-liposome method in a ra t myocardial infarction model. In the infarction model, using the peri cardium incubation approach, staining for beta-galactosidase was obser ved in the viable cells around the infarction area. Finally, direct in fusion of the HVJ complex. containing the beta-galactosidase vector, i nto coronary artery also resulted in widespread staining of beta-galac tosidase in cardiac myocytes around the microvasculature. Using direct injection, we found significant injury to the myocardium and severe f ibrosis at the injection site, whereas no apparent injury was observed using pericardium incubation and coronary infusion. There was no evid ence of cytotoxicity or inflammation caused by the HVJ-liposome comple x itself. Overall, we have established an efficient in vivo gene trans fer method into the heart using the HVJ-liposome method. Direct infusi on into the coronary artery resulted in widespread transfection withou t damaging the myocytes; incubation within the pericardium demonstrate d the usefulness of the HVJ-liposome method for studying cardiac funct ion and as a means of gene therapy for cardiovascular diseases. (C) 19 97 Academic Press Limited.