EXPRESSION OF STEM-CELL FACTOR IN HUMAN AORTIC ENDOTHELIAL AND SMOOTH-MUSCLE CELLS

It has been confirmed that the receptor protein encoded by the c-kit p roto-oncogene is expressed by cells of the hematopoietic, gonadal, pig ment, and mast cell lineages and that its ligand, stem cell factor (SC F), is mainly expressed in their microenvironment. In a previous study we investigated the expression of the c-kit gene in human aortic endo thelial cells (EC). In the present study we investigated the expressio n of SCF in human aortic EC and smooth muscle cells (SMC). Reverse tra nscription (RT)-PCR and Northern blot analyses showed that both human arterial EC and SMC expressed mRNA specific for the SCF gene. In addit ion, tissue-specific expression of the SCF gene was confirmed by in si tu hybridization in the EC and the SMC. Western blot analysis and immu nocytochemistry showed evidence of production of SCF protein in both t he EC and the SMC. These results indicate the existence of mast cell-S MC interaction and of an autocrine loop of c-kit and its ligand on the surface of EC, suggesting that the interaction between c-kit protein and SCF may play an important role in metabolism of arterial wall and in the pathogenesis of atherosclerosis in the arterial intima. (C) 199 7 Elsevier Science Ireland Ltd.