Other possible sources of VSMC are adventitia and bone marrow derived precursor cells in the circulation.32 Recently, in vivo studies have shown that mature medial VSMC may become activated and transdifferentiate to macrophage-like cells.33In order to identify proliferating cells (e.g., VSMC) within developing early atherosclerotic lesions, aorta and coronary arteries of HCD and treated groups were analyzed with PCNA monoclonal antibody technique. This evidence concerns the gene PCNA and heavy chain disease.