EXPRESSION OF PLATELET-DERIVED GROWTH-FACTOR-B CHAIN AND BETA-RECEPTOR IN HUMAN CORONARY-ARTERIES AFTER PERCUTANEOUS TRANSLUMINAL CORONARY ANGIOPLASTY - AN IMMUNOHISTOCHEMICAL STUDY

Objective-To evaluate whether expression of platelet derived growth fa ctor B (PDGF-B) protein is associated with expression of its protein i n receptor human coronary arteries after angioplasty and to identify c ells involved. Background-PDGF is considered an important growth facto r in the repair process of the vessel wall after angioplasty. In situ hybridisation has revealed expression of PDGF-A and -B chain messenger ribonucleic acid (mRNA) in human coronary arteries at sites of postan gioplasty injury. Methods-Target and non-target sites of eight coronar y arteries were studied immunohistochemically for PDGF-B and PDGF-beta receptor proteins in relation to macrophages, T lymphocytes, smooth m uscle cells, and HLA-DR positive cells. Results-The PDGF-B and PDGF-be ta receptor proteins were expressed in areas with distinct repair, con taining alpha actin negative spindle cells, macrophages and, at later stages, alpha actin positive smooth muscle cells as well. When the neo intima was composed mainly of alpha actin smooth muscle cells, PDGF-B expression was rare and PDGF-beta receptor expression was negative. Co nclusions-There is expression of PDGF-B and PDGF-beta receptor protein s at sites of postangioplasty repair in human coronary arteries. The a ssociated cells are mainly macrophages and alpha actin negative spindl e cells; the latter may be dedifferentiated smooth muscle cells. A lin k between PDGF expression and the postangioplasty time interval sugges ts a relation with cell differentiation as part of the maturation of t he repair tissue. Mutual expression of both the growth factor and its receptor protein strongly suggests that in humans a PDGF mediated repa ir process occurs, with involvement of smooth muscle cells and macroph ages.