Abstract 17094: “Trojan Horse” Monocytes: a New Approach for Gene Delivery to Angioplastied Arteries

Abstract

Introduction: Monocyte-derived macrophages are implicated in sustained inflammation typical of atherosclerotic and restenotic arteries. Since the role of macrophage-mediated inflammatory reactions in the progression of atherosclerosis and post-angioplasty restenosis is firmly established, multiple approaches have been devised to decrease the number and/or functionality of mononuclear phagocytic cells residing in atherosclerotic and stented arteries. However, no prior research has exploited the capability of monocytes to target sites of vascular injury in order to introduce pro-healing “therapeutic” genes into diseased vasculature. Here we report preliminary results demonstrating feasibility of this concept. Methods and Results: Monocytes were isolated from heparinized rat blood by sequential Ficoll and Percoll gradient centrifugation. The cells labeled with CM-DiI dye (5x10 5 cells/ml) were suspended in complete RPMI1640 medium and administered via tail vein to rats that underwent balloon denudation injury of carotid arteries 4 days prior to cell therapy. The animals were euthanized on day 8 after balloon injury (day 4 after monocyte delivery). The CM-DiI-labeled cells were found in the nascent neointima and adventitia of balloon-injured arteries (373±90 and 77±37 per mm 2 of tissue, respectively). Comparison of CM-DiI labeling with immunohistochemical staining results (CD 68) has demonstrated that up to 30% of all macrophages in the neointimal tissue of rats treated with ex vivo modified monocytes derive from the delivered cells. To verify functional competence of delivered cells, monocytes isolated as above were transduced with adenovectors driving synthesis of firefly luciferase and administered to rats that underwent Fogarty balloon injury 4 days prior to the cell delivery. One day later, luciferase expression in balloon injured arteries was confirmed by bioluminescence imaging. Conclusions: These pilot studies demonstrate the feasibility of using ex vivo transfected autologous or syngeneic monocytes as a means to introduce prohealing factors to diseased vasculature.