EFFECTS OF TUMOR-NECROSIS-FACTOR-ALPHA AND VASCULAR-PERMEABILITY FACTOR ON NEOVASCULARIZATION OF THE RABBIT EAR FLAP

Objective: The survival of compromised skin flaps depends on neovascul arization for their nutrition and metabolic waste removal. Our study i nvestigated the effectiveness of angiogenic factors in accelerating pe ripheral neovascularization and in increasing skin flap viability. Des ign: We elevated pedicled dorsal skin flaps on the ears of 23 New Zeal and white rabbits, and the vascular pedicle was ligated to achieve par tial flap necrosis. Fifteen flaps were treated with 0.1 mu g/mL vascul ar permeability factor, and eight flaps were treated with 1.0 mu g/mL tumor necrosis factor alpha. The ear flaps that were not treated with growth factor functioned in each rabbit as a normal saline control. Ma in Outcome Measures: The viability of skin flaps was observed visually and was measured by Cartesian planimetry using templates. Neovascular ization was documented by microangiography and by histologic analysis of the flaps. Results: Although the angiogenic factors accelerated neo vascularization, increased flap survival was demonstrated only in thos e animals treated with vascular permeability factor that was supplied by an absorbable gelatin sponge. Conclusion: This experimental model, despite different levels of controls, contains multiple variables, inc luding the use of an absorbable gelatin sponge, seroma formation, bioa ctivity of the angiogenic factors, optimal dosages and dosimetry, the need for a ''blinded'' format, and the validity of the histologic anal ysis. Additional investigation must be done and the experimental model itself must be improved before these apparently positive results may be accepted as clinically useful.