Effect of recombinant vascular endothelial growth factor on experimental otitis media with effusion.

CONCLUSION

This study demonstrates that rVEGF in the middle ear cavity contributes significantly to the development of OME by increasing the vascular permeability of the middle ear mucosa.

OBJECTIVE

Vascular endothelial growth factor (VEGF) has been detected in otitis media with effusion (OME). It has a very strong effect on increasing vascular permeability, and is much more potent than platelet-activating factor, arachidonic acid metabolites or histamine. The purpose of this study was to investigate whether recombinant VEGF (rVEGF) can increase vascular permeability in the middle ear mucosa of rats.

MATERIAL AND METHODS

rVEGF was injected transtympanically at doses of 0.01, 0.1 and 1.0 microg in the experimental groups; normal saline was injected in the control group. Twenty-four h after the injection of rVEGF, middle ear fluid was aspirated and the vascular permeability of the middle ear mucosa was measured by means of the Evans Blue vital dye technique.

RESULTS

Extravasation of Evans Blue dye was found in all specimens injected with rVEGF, and was quantified using a spectrophotometer. Middle ear fluid developed in all ears injected with 0.1 or 1.0 microg of rVEGF and histopathology of the middle ear mucosa revealed severe inflammatory cellular infiltration, subepithelial edema and vascular dilatation. Rats injected with 1.0 microg of rVEGF showed a significant increase in middle ear vascular permeability in comparison with the control group (p < 0.05).