DNA delivery from an intravascular stent with a denatured collagen-polylactic-polyglycolic acid-controlled release coating: mechanisms of enhanced transfection

We previously demonstrated that DNA-polylactic-polyglycolic acid (PLGA)-coated stents can deliver genes to the arterial wall with reporter expression involving 1% of neointimal cells. The present study investigated a novel formulation utilizing denatured collagen in DNA-stent coatings; denatured collagen was hypothesized to enhance gene transfer due to adhesion molecule interactions and actin-related mechanisms. Arterial smooth muscle cells (SMCs) cultivated on denatured collagen had significantly greater plasmid DNA (beta-galactosidase) transfection than SMC grown on native collagen (18.3+/-1.2 vs 1.0+/-0.1%, P<0.001). The denatured-collagen effect was completely blocked with anti-alpha(v)beta(3) integrin antibody. SMCs cultivated on native collagen supplemented with tenascin-C (TN-C), a protein recognized by alpha(v)beta(3) integrins, showed a 33-fold increase in transfection compared to control (P<0.001); this effect was also blocked with anti-alpha(v)beta(3) antibody. We observed that cells grown on denatured collagen had marked F-actin-enriched stress fibers and intense perinuclear G actin, compared to those grown on native collagen, which demonstrated F-actin-enriched focal adhesions without perinuclear G-actin localization. Cytochalasin-D, an F actin depolymerizing agent, caused significantly increased SMC transfection in cells cultivated on native collagen compared to control cells (18.0+/-1.8 vs 3.02+/-0.9%, P<0.001) further supporting the view that actin-related cytoskeletal changes influence transfection. A denatured-collagen-PLGA composite vascular stent coating similarly resulted in increased plasmid DNA green fluorescent protein (GFP) expression compared to controls (P<0.001) in SMC cultures; the increased transfection was blocked by anti-alpha(v)beta(3) antibody. Pig coronary studies comparing denatured-collagen-PLGA-coated stents containing plasmid DNA (encoding GFP) to coated stents without DNA demonstrated 10.8% of neointimal cells transfected; this level of expression was almost an order of magnitude greater than previously reported with a DNA delivery stent. It is concluded that denatured collagen incorporated into plasmid DNA-stent coating formulations may increase the level of gene expression in vitro and in vivo because of integrin-related mechanisms and associated changes in the arterial smooth muscle cell actin cytoskeleton.

Localized adenovirus gene delivery using antiviral IgG complexation

Gene therapy with viral vectors has progressed to clinical trials. However, the localization of viral vector delivery to diseased target sites remains a challenge. We tested the hypothesis that an adenoviral vector could be successfully delivered by complexation with a specific antibody that is bound to a biodegradable matrix designed for achieving localized gene transduction. We report the first successful delivery system based upon antibody immobilization of virions in a type I collagen-avidin gel using a polyclonal biotinylated IgG specific for the adenovirus hexon. In vitro stability studies demonstrated retention of viral vector activity with antibody-complexed adenovirus collagen gel preparations, in comparison to loss of vector activity from collagen gels prepared with nonspecific biotinylated IgG. Cell culture investigations using this antibody-controlled release system for adenoviral vector transduction of rat aortic smooth muscle cells (A10) demonstrated a significantly more localized reporter expression (beta-galactosidase) compared with non-antibody-complexed controls. Herpes simplex thymidine kinase (HSVtk) adenoviral vectors were immobilized on avidin-collagen gels via this antibody-complexation approach, and ganciclovir was added to rat smooth muscle cells (A10) in culture with the gels. With complexed HSVtk adenovirus, only cells either in contact with the virus-containing gel or within 50 microm were killed. By comparison, at the same adenovirus and ganciclovir dose, non-antibody-complexed HSVtk adenoviral delivery with ganciclovir resulted in the death of virtually all cells. Myocardial gene transfer studies in pigs demonstrated significantly more efficient right ventricular adenoviral GFP expression with anti-hexon antibody-complexed matrix injections, compared with direct vector injections. Thus, our results show that matrix formulations based on antibody-complexation delivery of adenovirus resulted in site-specific localization of transgene expression that enhances the efficiency of therapeutic vector strategies and provides a potent means for localization, to avoid distal side-effects. This approach has therapeutic potential as an implantable preparation that through the means of antibody-complexation, can localize and optimize viral vector gene therapy.

Gene delivery from a DNA controlled-release stent in porcine coronary arteries

Expandable intra-arterial stents are widely used for treating coronary disease. We hypothesized that local gene delivery could be achieved with the controlled release of DNA from a polymer coating on an expandable stent. Our paper reports the first successful transfection in vivo using a DNA controlled-release stent. Green fluorescent protein (GFP) plasmid DNA within emulsion-coated stents was efficiently expressed in cell cultures (7.9% +/- 0.7% vs. 0.6% +/- 0.2% control, p < 0.001) of rat aortic smooth muscle cells. In a series of pig stent-angioplasty studies, GFP expression was observed in all coronary arteries (normal, nondiseased) in the DNA-treated group, but not in control arteries. GFP plasmid DNA in the arterial wall was confirmed by PCR, and GFP presence in the pig coronaries was confirmed by immunohistochemistry. Thus, DNA-eluting stents are capable of arterial transfection, and could be useful as delivery systems for candidate vectors for gene therapy of cardiovascular diseases.

Treatment of painful diabetic polyneuropathy with mixed gangliosides

We studied 18 patients with painful diabetic neuropathy in a double-blind study of 40 mg per day of mixed gangliosides. Diabetes control was maintained throughout by analysis of serum glucose and glycosylated hemoglobin levels. Median motor and sensory, and peroneal motor conductions we evaluated in placebo and treated groups before and after a treatment period of three months. All conductions were performed by one technician on a TECA-4 EMG machine with surface temperature controlled at 37 degrees C. There was a definite improvement in nerve conductions in the treated group, particularly noted in the median sensory conductions. We have demonstrated a difference between right and left-sided conductions in the same patients confirming that this illness, at least from an electrophysiological point of view is asymmetric. Clinical improvement was variable but when present was dramatic. Side effects of this drug were minimal. Half of the patient complained of a transient increase in pain during the first two weeks of treatment. No patient stopped the drug because of this complaint. We conclude that in this three-month study mixed gangliosides caused a significant improvement in some nerve conductions without significant side effects. Further studies seem warranted to determine the nature and extent of this effect.