We will investigate a novel approach to improve the therapeutic efficacy of stent angioplasty. It is hypothesized that biodegradable nonpolymeric magnetic nanoparticles (MNP) can be used to render ex vivo cultured circulating endothelial progenitor cells (EPC) magnetically responsive and thus able to deliver a therapeutically relevant transgene with magnetic targeting to a deployed stent thereby enabling enhanced regeneration of injured and diseased arteries.
Aim 1 : To formulate and characterize the components of a magnetic targeting complex including: Biodegradable nonpolymeric MNP, EPC and Helper Dependent Adenoviral Vectors (HD-Ad). MNP used in these gene delivery experiments can be rendered magnetically responsive by inclusion of magnetite in their composition without compromising their biocompatibility. EPC will be harvested from peripheral blood and investigated under conditions of MNP loading for magnetic responsiveness and viability. HD-Ad vectors, that result in sustained transgene expression without genomic integration will be constructed in collaboration with Dr. Phillip Ng, Baylor College of Medicine, with both reporter constructs (green fluorescent protein, GFP, and luciferase, Luc), as well as inducible nitric oxide synthase (iNOS) as our lead therapeutic gene.
Aim 2 : To study magnetic cell targeting in vivo with reporter constructs to establish an optimal range of delivery conditions. GFPHD-Ad transduced EPC preloaded with MNP will be investigated in rat carotid stent procedures comparing EPC targeted to 304 steel stents versus controls to determine optimal delivery conditions and the distribution of the GFP expressing EPC in the targeted arterial segment. Longer term studies, up to 28 days, will follow Luc expression in 304 stents targeted with EPC transduced with LucHD-Ad, following transgene expression over time with Luc optical imaging.
Aim 3 : To investigate in vivo the antirestenotic efficacy of MNP-modified EPC transduced with iNOSHD-Ad. Having established protocols for optimal cell preparation and delivery per Aim 2 results, we will investigate the antirestenotic effect of magnetically targeted EPC modified with iNOSHD-Ad in both the rat carotid stenting model and pig femoral stent angioplasties.

Public Health Relevance

The use of stents for treating vaso-occlusive disease has been associated with both therapeutic benefit and significant complications, including reobstruction post-stenting, termed instent restenosis. Drug eluting stents have been shown to ameliorate instent restenosis in coronary disease (not peripheral vascular disease), but with significant risks. This proposal will investigate magnetic cell targeting of endothelial progenitor cells to stented arteries as a novel approach for regenerating diseased blood vessels.

National Institute of Health (NIH)
National Heart, Lung, and Blood Institute (NHLBI)
Exploratory/Developmental Grants (R21)
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Bioengineering, Technology and Surgical Sciences Study Section (BTSS)
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Buxton, Denis B
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Children's Hospital of Philadelphia
United States
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