Adenoviral Gene Vector Tethering to Nanoparticle Surfaces Results in Receptor-Independent Cell Entry and Increased Transgene Expression

Abstract

The present studies investigated the hypothesis that affinity immobilization of replication-defective adenoviruses (Ad) on the surfaces of biodegradable nanoparticles (NP) can improve transduction through uncoupling cellular uptake from the coxsackie–adenovirus receptor (CAR). Ad was tethered to the surfaces of polylactide-based NP that were surface-activated using a photoreactive polyallylamine–benzophenone–pyridyldithiocarboxylate polymer, which enabled (via thiol chemistry) the covalent attachment of Ad-binding proteins, either the recombinant D1 domain of CAR or an adenoviral knob-specific monoclonal antibody. Gene transfer by NP–Ad complexes was studied in relation to cellular uptake as a function of cell type and the character of NP–Ad binding. NP–Ad complexes, but not Ad applied with or without control nonimmune IgG-modified NP, significantly increased green fluorescent protein reporter expression in endothelioma and endothelial and arterial smooth muscle cells (SMC) in direct correlation to the extent of NP–Ad internalization. CAR-independent uptake of NP–Ad was confirmed by demonstrating inhibition of free Ad- but not NP–Ad complex-mediated transduction by knob protein. Complexes formulated with an Ad encoding inducible nitric oxide synthase inhibited growth of cultured SMC to a significantly greater extent than those with GFPAd or NULLAd or free vector. It is concluded that Ad-specific affinity tethering to biodegradable NP can significantly increase the level of gene expression via a CAR-independent uptake mechanism.