Prohealing Endothelial Progenitor Cell Capture Stents

Since the early days of percutaneous transluminal angioplasty, it has been recognized that balloon inflation disrupts the endothelial monolayer and injures normal arterial segments.1 This initiates a repair process that is mediated by platelets, inflammatory cells, and circulating progenitor cells that are recruited to sites of injury. There has been recent interest in the prohealing properties of endothelial progenitor cells (EPCs). Early studies identified these cells by expression of the surface antigen CD34 and demonstrated that they promoted reendothelialization after balloon injury.2,3 Because of the fact that these cells are relatively rare in the circulation (0.005%–0.01% of the total white blood cell count), it is not surprising that a stent was designed to capture circulating EPCs and sequester the cells to promote rapid reendothelialization, to decrease thrombogenicity, and to prevent restenosis.4 To accomplish this, the stent incorporated a monoclonal CD34 antibody in a proprietary polysaccharide intermediate coating that was adhered to a stainless steel stent; in 2010, the stent platform was changed to cobalt chromium.5The safety and efficacy of the EPC capture stent have been studied extensively in clinical registries and randomized trials. The Healthy Endothelial Accelerated Lining Inhibits Neointimal Growth (HEALING) registries established a safety profile for the stent but demonstrated what would become a common theme; the stent did not decrease late lumen loss (LLL) to the same degree observed for drug-eluting stents (DES). This finding was attributed initially to variation in the number of circulating EPCs because of differences in the use …