The effect of basic fibroblast growth factor on scarring.

Granulation-tissue myofibroblasts are important in wound contraction, disappearing in normal scars but persisting in hypertrophic scars. While transforming growth factor beta 1 (TGF-beta 1) is implicated in excessive scarring and induces the accumulation of myofibroblasts, the role of basic fibroblast growth factor (FGF-2) on scarring remains unreported. Four linear full-thickness incisions, each 20 mm long, were made dorsally on 25 adult male Hooded Lister rats. In each animal, one wound was unmanipulated (control), one was injected with TGF-beta 1 (positive control), one with vehicle alone and one with FGF-2 (test). The wounds were injected daily for 5 days. Animals were sacrificed in groups of five on days 5, 10, 15, 20 and 30 after wounding. Wounds were subjected to tensiometry. Sections were stained for collagen fibres, immunostained for myofibroblasts and studied under light microscopy and electron microscopy. Myofibroblasts were present in the granulation tissue on day 5, reached their maximum number on day 10 and disappeared from all wounds by day 30. Treatment with FGF-2 inhibited this transient phenotypic change of granulation-tissue fibroblasts into myofibroblasts, relative to controls (15.23% versus 58.71%, 15.23% versus 54.71% and 15.23% versus 53.15%; P<0.003 on day 10, paired t-test). Test collagen-fibre orientation resembled that of the normal dermis, in contrast to that of the control wounds. Test wound breaking strength was unreduced. These results suggest a possible anti-scarring effect of FGF-2 during wound healing.