| Co-Investigator(Kenkyū-buntansha) |
TAKAI Shinji Osaka Medical College, Faculty of Medicine, Associate Professor, 医学部, 助教授 (80288703)
JIN Denan Osaka Medical College, Faculty of Medicine, Assistant Professor, 医学部, 講師 (90319533)
村松 理子 大阪医科大学, 医学部, 助手 (30330096)
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| Budget Amount *help |
¥13,500,000 (Direct Cost: ¥13,500,000)
Fiscal Year 2006: ¥4,800,000 (Direct Cost: ¥4,800,000)
Fiscal Year 2005: ¥8,700,000 (Direct Cost: ¥8,700,000)
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| Research Abstract |
Chymase is a chymotrypsin-like serine protease in mast cell granule and generates angiotensin (AII). Previously, we have reported that chymase induced angiogenesis in an animal model, but AII receptor blocker (ARB) did not completely inhibit its angiogenesis. Involvement of substrates except AII in chymase-induced angiogenesis was suggested, however, it remains unclear what it is. In this study, we wanted to clarify the role of chymase in angiogenesis and to investigate the possible application by chymase-dependent angiogenesis. In in vitro experiments, in endothelial tube formation assay, chymase increased tube area by supporting the effects of vascular endothelial cell growth factor (VEGF) on endothelial cell proliferation and migration but it was not inhibited by an ARB. Since not only VEGF but also matrix-degrading proteases are essential in this assay, the effect of chymase on matrix metalloproteinase (MMP) was studied. When chymase was added to the cultured HT-1080 cells secreting MMP-2, chymase generated active MMP-2 from its intermediate form. In in vivo experiments, in a hamster hindlimb ischemia model produced by ligation of femoral vessels, purified hamster chymase directly into ischemic tissue enhanced angiogenesis accompanied with the improvement of blood flow. These results suggested that not only AII but also MMP-2 might be for chymase as a substrate in vivo angiogenesis.
Next, we clarified the role of chymase in angiogenesis after myocardial infarction (MI). In hamster and dog models, the left coronary artery was legated. Chymase activity was significantly increased 1 day after MI. Angiotensin-converting enzyme activity was increased 3 days after MI. On the other hand, MMP-9 and MMP-2 activities were significantly increased 1 and 3 days after MI, respectively. These findings demonstrate the mechanism of angiogenesis by chymase via activation of AII and MMP-9. Now, we evaluate the effect of chymase administration in angiogenesis just after MI.
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