A FREEZE-INJURED SKIN-GRAFT MODEL FOR THE QUANTITATIVE STUDY OF BASICFIBROBLAST GROWTH-FACTOR AND OTHER PROMOTERS OF ANGIOGENESIS IN WOUND-HEALING

A new in vivo model has been developed for the quantitative study of p romoters and potential promoters of angiogenesis. Full thickness rat s kin autografts received a reproducible and uniform freeze injury, befo re being applied to full thickness wounds, in order to delay revascula risation. Blood how in the grafts was measured during the healing peri od using noninvasive (laser Doppler flowmetry) and invasive (Xe-133 cl earance) techniques. The increase in blood flow over a period of 10-14 days was taken as an index of angiogenesis. These measurements were c orroborated by histological assessment of the graft vasculature, using a laminin stain to highlight vascular basement membrane. Freeze injur y delayed but did not ultimately prevent full graft revascularisation (p < 0.01 for laser Doppler flowmetry and Xe-133 clearance). Applicati on of the angiogenic agent basic fibroblast growth factor (bFGF), in s low release pellet form, stimulated angiogenesis in cryoinjured grafts in a dose-related fashion. Doses of 500 and 5000 ng bFGF produced sig nificant stimulation (500 ng bFGF, p < 0.001, and 5000 ng bFGF, p < 0. 01, for both laser Doppler flowmetry and Xe-133 clearance;increased ve ssel profile counts, p < 0.05, at each time point tested for both dose s) while 50 ng bFGF had no significant effect. By contrast, 500 ng bFG F had no measurable effect on uninjured grafts. In addition, bFGF-stim ulated angiogenesis in cryoinjured grafts was antagonised by a neutral ising antibody to bFGF, demonstrating the specificity of action of bFG F in this model.