Masataka Majima (1), Masako Isono (1), Yasuhiro Ikeda (1), Izumi Hayashi
(1), Ko Hatanaka (1), Yoshiteru Harada (1), Osamu Katsumata (2), Shohei
Yamashina (2), Makoto Katori (1) and Shouzo Yamamoto (3)
(1) Department of Pharmacology and (2) Department of Anatomy, Kitasato
University School of Medicine, Kanagawa 228, Japan
(3) Department of Biochemistry, Tokushima University School of Medicine,
Tokushima 770, Japan
Abstract: Angiogenesis in rat sponge implants, as determined
from the concentration of hemoglobin in the sponge granuloma tissues, was
gradually increased over a 14-day experimental period. The inducible cyclooxygenase
COX-2 was detected in the sponge granuloma tissues at day 4 by Western blot
analysis using specific mouse COX-2 antibody. Angiogenesis in the sponge
implants was enhanced by daily topical injections of human recombinant basic
fibroblast growth factor (bFGF) or human recombinant epidermal growth factor
(EGF) (100 or 1000 ng/sponge/day) for 4 days. These treatments clearly enhanced
the expression of COX-2 in the sponge granuloma tissues. In immunohistochemical
studies, COX-2-positive staining was mainly observed in the endothelial
cells of the neovasculature and in the fibroblasts of the granuloma capsule.
Administration of the selective COX-2 inhibitor NS-398 (p.o., 3 mg/kg, 3
times a day) for 14 days significantly inhibited the angiogenesis. The angiogenesis
enhanced with bFGF or EGF (day 4) was inhibited by administration of indomethacin
or NS-398, both in the above regimen, and fell to the level obtained without
growth factor treatment. These results suggest that COX-2 induced in the
sponge granuloma tissues may participate in neovascularization through prostaglandin
formation.
Keywords: Angiogenesis, Cyclooxygenase (COX)-2, Sponge implant, Growth
factor, Immunohistochemistry