A New Cationic Liposome DNA Complex Enhances the Efficiency of Arterial Gene Transfer In Vivo

Abstract

An important goal of gene therapy for cardiovascular diseases and cancer is the development of effective vectors for catheter-based gene delivery. Although adenoviral vectors have proven effective for this purpose in animal models, the ability to achieve comparable gene transfer with nonviral vectors would provide potentially desirable safety and toxicity features for clinical studies. In this report, we describe the use of a new cationic DNA–liposome complex using an improved expression vector and lipid, N-(3-aminopropyl)-N,N-dimethyl-2,3-bis(dodecyloxy)-1-propaniminium bromide/dioleoyl phosphatidylethanolamine (GAP-DLRIE/DOPE) to optimize catheter-mediated gene transfer in porcine arteries. The efficiency of this vector was compared to DNA alone, DNA with a previously described cationic liposome complex, ( ± )-N-(2-hydroxyethyl)-N,N-dimethyl-2,3-bis(tetradecyloxy)-1-propanaminium bromide (DMRIE/DOPE), and a replication-defective adenoviral vector in a porcine artery gene transfer model. When used in optimal ratios, GAP-DLRIE/DOPE liposomes provided a 15-fold higher level of gene expression in arteries compared to DNA alone or DMRIE/DOPE. Gene expression was observed in intimal and medial cells. However, when compared to adenoviral vectors (10¹⁰ pfu/ml), gene expression following GAP-DLRIE/DOPE transfection was ~20-fold lower. Following intravenous injection of GAP-DLRIE/DOPE in mice, biochemical, hematological, and histopathological abnormalities were not observed. Significant improvements in the efficacy of arterial gene expression can be achieved by optimization of transfection conditions with DNA–liposome complexes in vivo that may prove useful for arterial gene delivery in cardiovascular diseases and cancer. GAP-DLRIE/DOPE, a new cationic liposome preparation, is an efficient liposomal vector that increases gene expression in arteries compared to naked DNA or previously described cationic DNA–liposome complexes by more than 15-fold. Although less efficient than adenoviral gene transfer, these levels of gene expression represent a significant improvement in liposome transfection in vivo and approach levels observed with clinically acceptable doses of adenoviral vectors. The improvement in gene expression, together with the relative safety associated with liposomal gene transfer, suggests that such nonviral vectors may be appropriate for human gene therapy protocols which utilize catheter-based gene delivery.