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 (SMC 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.