Expression of platelet derived growth factor B chain and β receptor in human coronary arteries after percutaneous transluminal coronary angioplasty: An immunohistochemical study

Abstract

Objective - To evaluate whether expression of platelet derived growth factor B (PDGF-B) protein is associated with expression of its protein in receptor human coronary arteries after angioplasty and to identify cells involved. Background - PDGF is considered an important growth factor 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 postangioplasty injury. Methods - Target and non-target sites of eight coronary arteries were studied immunohistochemically for PDGF-B and PDGF-β receptor proteins in relation to macrophages, T lymphocytes, smooth muscle cells, and HLA-DR positive cells. Results - The PDGF-B and PDGF-β receptor proteins were expressed in areas with distinct repair, containing α actin negative spindle cells, macrophages and, at later stages, α actin positive smooth muscle cells as well. When the neointima was composed mainly of α actin smooth muscle cells, PDGF-B expression was rare and PDGF-β receptor expression was negative. Conclusions - There is expression of PDGF-B and PDGF-β receptor proteins at sites of postangioplasty repair in human coronary arteries. The associated cells are mainly macrophages and α actin negative spindle cells; the latter may be dedifferentiated smooth muscle cells. A link between PDGF expression and the postangioplasty time interval suggests a relation with cell differentiation as part of the maturation of the repair tissue. Mutual expression of both the growth factor and its receptor protein strongly suggests that in humans a PDGF mediated repair process occurs, with involvement of smooth muscle cells and macrophages.