Expression of fibroblast activation protein in human coronary vessels

Fibroblast Activation Protein (FAP) is a cell surface glycoprotein expressed exclusively by myofibroblastic cells in areas of active tissue remodeling. Role of FAP expression by smooth muscle cells in atherosclerotic plaque and possible role in plaque rupture resulting in acute coronary syndromes remains unclear.

The aim of our study was to analyze FAP expression by smooth muscle cells in sections of human coronary arteries without atherosclerosis and with atherosclerotic plaque. Additionally, FAP expression in human atherosclerotic plaque was compared with other markers of activated smooth muscle cells.

Hybrid cells (cF19) producing anti human FAP were grown in suspension. A crude anti-human FAP IgG have been obtained in 4 consecutive days process. Monoclonal anti-human FAP antibody were used with immunochemistry staining and immunofluorescence to identify FAP distribution in human atherosclerotic plaque in normal coronary arteries without atherosclerosis from heart transplant patients and in coronary arteries from patients with advanced atherosclerotic plaques.

Analysis of FAP expression in human coronary vessels showed absence of FAP in sections without atherosclerosis and expression of FAP in human atherosclerotic plaque. Immunofluorescence staining of advanced atherosclerotic plaque showed distinct distribution of FAP expression in advanced atherosclerotic plaque as compared with other markers of activated vascular smooth muscle cells.

FAP is expressed in advanced atherosclerotic plaque. Comparison of FAP expression with other markers of activated myocytes suggests that FAP may identify different specific subpopulation of activated smooth muscle cells in atherosclerotic plaque.