Post‐angioplasty restenosis: coronary adventitial fibroblasts are not a major constituent of the neointima in swine

Abstract

Adventitial fibroblasts are thought to be a major constituent of the neointima following coronary balloon angioplasty. However, approximately 90% of neointimal cells express smoothelin, a marker of differentiated smooth muscle cells not found in adventitial fibroblasts. The aim of this study was to determine if proliferating cells in the adventitia following coronary balloon angioplasty migrate to form the neointima. BrdU (30mg/kg), a marker of proliferating cells, was given intravenously at 12 and 24 or 36 and 48 hours following balloon angioplasty. For each time point, one animal was euthanized 24 hours following the last injection to identify the location of proliferating cells. A second animal for each group was euthanized 25 days following angioplasty to determine if the proliferating cells migrated to the neointima. Our results demonstrate that BrdU labeled cells were located primarily in the adventitia with both injection protocols following balloon angioplasty. Furthermore, on day 25, the BrdU labeled cells remained in the adventitia and did not migrate to form the neointima in either experiment. In conclusion, our results demonstrate that coronary adventitial fibroblasts do not migrate to form the neointima following coronary balloon angioplasty, suggesting the neointima is primarily composed of smooth muscle cells. Supported by: NIH HL52490