Omental flap closure of refractory wounds: rat model.

Omental flaps, with their associated rich and pliable vascular arcades, are frequently used in clinical practice for the reconstruction of complex and irregular defects. There is little experimental evidence, however, to prove that omental flaps can be a useful tool for the defects. Using a gastric-wall defect model, we performed histological and immunocytochemical examinations. We created an omental flap lining a 2.0-mm defect perforating the center of the anterior wall of a rat stomach. We examined the tissue response during gastric wall regeneration by H&E and Masson trichrome stains. We also performed immunocytochemical studies for the detection of proliferating cell nuclear antigen (PCNA), factor VIII-related antigen, fibroblast growth factor-2 (FGF-2) and vascular endothelial growth factor (VEGF). One day after the operation, the omental flap was found to firmly adhere to the gastric serosa surrounding the defect. An extensive inflammatory response occurred from Day 1 to 3 with dilated vessels in the omentum. From Days 3 to 7, a significant number of PCNA-positive cells, FGF-2-positive cells and VEGF-positive cells were observed at the edge of the mucosa and within the granulation tissue. On Day 4, in place of extensive inflammation, an exuberant granulation tissue response was observed from the omentum. The defect had been covered by stratified villi by Day 7. This study demonstrated that an omental flap came to rapidly adhere to the defect serving as a source of extensive inflammation and granulation for the rich and pliable vascular arcades.