Stent-Mediated Gene Delivery for Site-Specific Transgene Administration to the Airway Epithelium and Management of Tracheobronchial Tumors
Authors: Kruklitis Robert J. , Fishbein Ilia , Singhal Sunil , Kapoor Veena , Levy Robert J. , Sterman Daniel H. 
Published: November 2014

<b><i>Background:</i></b> Gene therapy is currently under investigation as a means of managing a variety of pulmonary diseases. Unfortunately, gene transfer to bronchial epithelium has been hampered by the lack of stable and efficient transduction. Recent studies have shown that gene vectors could be tethered to the metallic surfaces of intra-arterial stents. This approach enables efficacious and site-specific adenoviral gene delivery to the vascular endothelium. <b><i>Objectives:</i></b> We hypothesized that airway mesh stents impregnated with viral gene vectors could be used for local gene delivery to benign and malignant bronchial epithelium. <b><i>Methods:</i></b> Serotype 5 adenoviral vectors (Ad5, E1-/E3-) containing the reporter genes green fluorescent protein (Ad.GFP) or β-galactoside/<i>LacZ</i> (Ad.<i>LacZ</i>), or a therapeutic gene, Ad.INF-β, were coupled to either metallic mesh disks or stents via anti-Ad knob antibodies. These platforms were assessed for their ability to transfect bronchial epithelial cells from both rats and humans, as well as murine (L1C2) and human (A549) lung cancer cell lines. Gene transfer was quantified by fluorescent microscopy, scanning fluorimetry for Ad.GFP, and light microscopy studies assessing β-galactosidase staining for Ad.<i>LacZ</i>. Metallic mesh and stent-mediated gene transfer was also performed in a murine flank tumor model and in a rat endotracheal tumor model in order to evaluate the therapeutic potential. <b><i>Results:</i></b> In these studies, murine and human non-small cell lung cancer (NSCLC) cells were successfully transfected with reporter genes in vitro. Ad.<i>LacZ</i>-complexed mesh successfully transfected reporter genes into established murine flank NSCLC tumors. In addition, Ad.<i>LacZ</i>-tethered stents could effectively transfect both tracheobronchial epithelium and submucosal glands in rats. Similar epithelial transfection was achieved in ex vivo human bronchial epithelium. Pilot in vivo experimentation provided data supporting the concept that therapeutic genes could also be delivered with this technology. In additional pilot in vivo experiments, the growth of murine flank tumors was inhibited by placement of mesh disks coupled with Ad.muINF-β, and rats bearing endotracheal tumors demonstrated a trend towards prolonged survival with insertion of Ad.ratINF-β-tethered stents. <b><i>Conclusions:</i></b> Stent-mediated gene delivery successfully enabled site-specific vector administration to target rat and human airway cells in cell culture, organ culture and in vivo. Local tracheobronchial gene delivery via stents could provide a viable clinical solution for overcoming the difficulties encountered with vector delivery within the lungs, in particular by lowering requisite vector titers and by directing desired vectors to areas of interest. This strategy may prove valuable for treating tumors involving the tracheobronchial tree, as well as other nonmalignant tracheobronchial disorders.