Hypercholesterolemia aggravates in-stent restenosis in rabbits: a mitigating effect of stent surface modification with CD47-derived peptide

Background Hypercholesterolemia (HC) has previously been shown to augment restenotic response in several animal models and humans. However, the mechanistic aspects of in-stent restenosis (ISR) on a hypercholesterolemic background, including potential augmentation of systemic and local inflammation precipitated by HC are not completely understood. CD47 is a transmembrane protein known to abort crucial inflammatory pathways. Our present studies have examined the interrelation between HC, inflammation, and ISR and investigated the therapeutic potential of stents coated with a CD47-derived peptide (pepCD47) in the hypercholesterolemic rabbit model. Methods and Results PepCD47 was immobilized on metal foil coupons and stents using polybisphosphonate coordination chemistry and pyridyldithio/thiol conjugation. The relative abundance of the surface-associated cells on bare metal (BM) and pepCD47 foils exposed to whole rabbit blood showed a 40% inhibition of cell attachment on pepCD47-modified surfaces. Likewise, M1 cytokine expression analyzed in buffy coat-derived cells cultured over the BM and pepCD47-derivatized foils demonstrated a>80% decrease in TNFa and MCP1 levels with the pepCD47 coating. Rabbits with diet-induced hypercholesterolemia and normocholesterolemic counterparts underwent bilateral implantation of BM and pepCD47 stents in the iliac location. Hypercholesterolemia increased neointimal area and percent of luminal stenosis in comparison with normocholesterolemic animals at 4 weeks post-stenting (2.07±0.52 vs 0.64±0.15 mm2 and 54.32±13.01 vs 23.30±4.36%, respectively). These untoward outcomes were mitigated (54% and 50% for neointimal area and percent of luminal stenosis) in the arteries of hypercholesterolemic rabbits treated with pepCD47-derivatized stents. Compared to NC animals, TNFa immunopositivity and MΦ infiltration of peri-strut areas increased in HC group animals 1.81- and 2.58-fold, respectively, and was attenuated in the arteries of hypercholesterolemic rabbits treated with pepCD47 stents. Conclusions Augmented inflammatory responses triggered by HC underlie severe ISR morphology in hypercholesterolemic rabbits. Blockage of initial platelet and leukocyte attachment to stent struts through CD47 functionalization of stents mitigates pro-restenotic effects of HC. ### Competing Interest Statement The authors have declared no competing interest.