Fibrous Cap Smooth Muscle Cells in Atherosclerotic Coronary Arteries Do Not Express Pluripotent Stem Cell Markers

Rupture of the coronary artery fibrous cap is a common cause of myocardial infarction, and bone marrow derived cells could play a role in preventing plaque rupture. It is currently unknown whether smooth muscle cells within coronary artery fibrous cap formation are of mature phenotype. Objective . To characterize cells expressing bone marrow stem cells of embryonic type (ESC) markers in coronary artery fibrous cap formation. Design . New Zealand White rabbits were fed a diet supplemented with 0.5% cholesterol + 1% methionine + 5% peanut oil for 4 weeks and then a normal diet for 9 weeks. The left main coronary artery was excised from the heart, processed for paraffin and immunohistochemistry was performed by standard techniques. Results . Oct-4, SSEA 1, 3, and 4 were all present within in atherosclerotic plaque core, codistributed with RAM-11, and were sparingly found in the fibrous cap, but TRA-1-60 and TRA-1-81 positive cells were scarce. Core but not fibrous cap smooth muscle (SMCα actin+) cells also showed codistribution with ESC markers. Conclusions . These results suggest that smooth muscle cells present in the fibrous cap do not express ESC markers, indicative of a mature cell.