Summary of smooth muscle cell response to stent injury in coronary arteries.

<p>Alpha-smooth muscle actin immunoreactivity was found solely in the luminal side of the neointima and absent from areas surrounding stent struts and external elastic region of neointima (A-B) in stented coronary arteries with an injury score greater than 2. The neointima region that is positive to alpha-smooth muscle actin also stained green in the Movat’s pentachrome stain, indicating the presence of proteoglycans (C). Spindle shaped smooth muscle cells that are positive to alpha-smooth muscle actin are concentrated around the lumen of stented coronary arteries with an injury score greater than 2 (D-E) and those cells stained red in Movat’s pentachrome stain indicating the presence of muscle cells (F). Alpha-smooth muscle actin is absent from neointimal cells surrounding stent struts in stented coronaries with an injury score greater than 2 (G), however, those cells are positive for a synthetic smooth muscle cell marker, vimentin (H). There was a lack of green stain (proteoglycans) and possible necrotic cells surrounding the stent strut (I). These are representative histological slides from N = 3 in each injury score group.