Expression of local hepatocyte growth factor system in vascular tissues.

Since endothelial cells (EC) are known to secrete various anti-proliferative and vasodilating factors, an agent that promotes seeding or regeneration of EC may have potential therapeutic value against vascular smooth muscle cell (VSMC) proliferation. For the above purpose, we have found that hepatocyte growth factor (HGF) fulfills such conditions. However, the local HGF system has not yet clarified. Therefore, we investigated endogenous HGF production and its specific receptor (c-met) in vascular tissues. Our results revealed the expressions of HGF and its receptor (c-met) mRNA in endothelial cells, VSMC and neointimal VSMC of rat assessed by RT-PCR. HGF and c-met mRNA were also detected in human aortic endothelial cells and VSMC. Endothelial cells and VSMC of both rat and human produce and secrete immunoreactive HGF as assessed by ELISA. Of importance, the existence of local HGF system (HGF and c-met) was also observed in vivo in intact abdominal aorta of SD and Wistar rats. Overall, this study demonstrated that HGF is expressed and secreted from endothelial cells and VSMC of both rat and human in vitro as well as in vivo. Since HGF has characteristics of an endothelium-specific growth factor, locally synthesized HGF in endothelial cells and VSMC may have a role in vascular functions in autocrine-paracrine manner.