Therefore, we tested the effect of injecting stem cells into hypercholesterolemic rats to pinpoint the efficacy of replacement of SMCs in atherosclerotic lesions with stem cells, and to address the consequent effects on the potential players in the mechanisms of atherosclerosis including foam cells, adhesion molecules [vascular cell adhesion molecule (VCAM-1) and intracellular adhesion molecule (ICAM-1)], chemokines such as M-CSF-1, inducible enzymes such as iNOS and COX-2, and oxidative stress. This evidence concerns the gene NOS2 and atherosclerosis.