Abstract
DNA nanostructures hold great potential for drug delivery. However, their specific targeting is often compromised by recognition by scavenger receptors involved in clearance. In our previous study in cell culture, we showed targeting specificity of a 180 nm, 4-layer DNA-built nanocarrier called 3DNA coupled with antibodies against intercellular adhesion molecule-1 (ICAM-1), a glycoprotein overexpressed in the lungs in many diseases. Here, we examined the biodistribution of various 3DNA formulations in mice. A formulation consisted of 3DNA whose outer-layer arms were hybridized to secondary antibody-oligonucleotide conjugates. Anchoring IgG on this formulation reduced circulation and kidney accumulation vs. non-anchored IgG, while increasing liver and spleen clearance, as expected for a nanocarrier. Anchoring anti-ICAM changed the biodistribution of this antibody similarly, yet this formulation specifically accumulated in the lungs, the main ICAM-1 target. Since lung targeting was modest (2-fold specificity index over IgG formulation), we pursued a second preparation involving direct hybridization of primary antibody-oligonucleotide conjugates to 3DNA. This formulation had prolonged stability in serum and showed a dramatic increase in lung distribution: the specificity index was 424-fold above a matching IgG formulation, 144-fold more specific than observed for PLGA nanoparticles of similar size, polydispersity, ζ-potential and antibody valency, and its lung accumulation increased with the number of anti-ICAM molecules per particle. Immunohistochemistry showed that anti-ICAM and 3DNA components colocalized in the lungs, specifically associating with endothelial markers, without apparent histological changes. The degree of in vivo targeting for anti-ICAM/3DNA-nanocarriers is unprecedented, for which this platform technology holds great potential to develop future therapeutic applications.