Polymeric particles conjugated with a ligand to VCAM-1 exhibit selective, avid, and focal adhesion to sites of atherosclerosis

The increased expression of VCAM-1 on endothelial segments within plaque regions could be used as a target to deliver polymeric drug carriers selectively to sites of atherosclerosis. We probed me hypothesis that polymeric particles conjugated with a ligand for VCAM-1 exhibit selective and avid adhesion to sites of atherosclerosis. Particles made from polystyrene or the biodegradable polymer poly(sebacic acid)-block-polyerthylene glycol (PSA-PEG) were conjugated with an antibody to VCAM-1 (α-VCAM-1) or IgG (negative control). The particles were injected into the jugular vein of ApoE^-/- (a murine model of atherosclerosis) or wild type mice and their adhesion to the aorta determined. α-VCAM-1 particles exhibited sig-nificantiy greater adhesion to ApoE^-/- mouse aorta [32 ± 5 (mean ± SEM) particles/mm² for polystyrene particles and 31 ±7 particles/mm² for PSA-PEG particles] compared to the level of adhesion to wild type mouse aorta (18 ± 1 particles/mm² for polystyrene particles and 6± 1 particles/mm² for PSA-PEG particles). Within ApoE^-/- mice, the α-VCAM-1 particles exhibited significantly greater adhesion to the aorta (32 ± 5 particles/mm² for polystyrene particles and 31 ±7 particles/mm² for PSA-PEG particles) compared to the adhesion of IgG particles (1 ± 1 particles/ mm² for polystyrene particles and 2 ± 1 particles/mm² for PSA-PEG particles). Detailed analysis of the adhesion revealed that α-VCAM-1 particles exhibited focal adhesion to plaque regions, in particular the periphery of the plaques, within the ApoE^-/- mouse aorta. Combined the data demonstrate that polymeric particles conjugated with a ligand to VCAM-1 exhibit selective, avid and focal adhesion to sites of atherosclerosis providing strong evidence that VCAM-1 ligand bearing polymeric particles could be used for targeting drues selectively to atherosclerotic tissue.