Omentum and basic fibroblast growth factor in healing of chronic gastric ulcerations in rats

Omentum was shown to exhibit angiogenic activity, but its role in healing of chronic gastric ulcers is unknown. This study was designed to compare the effects of omentum and basic fibroblast growth factor (bFGF), a potent angiogenic factor, on healing of chronic gastric ulcers in rats. Several series of rats with gastric ulcers were used: series A with intact omentum (control), series B with omentum resected, and series C with omentum placed on the serosal side of the ulcer. Series A–C were divided into four groups treated with vehicle (I); indomethacin (II), an inhibitor of prostaglandin formation, difluoromethylornithine (DFMO) (III); an inhibitor of polyamine biosynthesis or bFGF (IV). Seven days after ulcer induction, the animals were anesthetized, the gastric blood flow (GBF) was determined by laser Doppler flowmetry (LDF), and the ulcer area was measured by planimetry. Biopsy samples of the ulcer margin were taken for determination of the number of capillaries and myofibroblasts in the granulation tissue. Attachment of omentum significantly accelerated ulcer healing, whereas omentectomy delayed this process. LDF revealed the decrease in the GBF at the ulcer margin to 45% and at the ulcer bed to 18% of the value recorded in the intact adjacent mucosa. Attachment of the omentum significantly increased the blood flow at the ulcer margin and increased the number of capillaries and myofibroblasts in the granulation tissue. Indomethacin (1 mg/kg/day) that inhibited mucosal PGE₂ by about 85% delayed significantly ulcer healing without affecting the blood flow in the ulcer area. DFMO (200 mg/kg intraperitoneally) suppressed ODC activity in the mucosa but did not influence the ulcer healing. bFGF given subcutaneously accelerated dose-dependently ulcer healing and stimulated angiogenesis to a similar extent as the attached omentum. We conclude that omentum enhances the ulcer healing in similar way as bFGF and that this effect is accompanied by the increased angiogenesis and blood flow in the ulcer area.