TRANSFORMING-GROWTH-FACTOR BETA-3 (TGF-BETA-3) ACCELERATES WOUND-HEALING WITHOUT ALTERATION OF SCAR PROMINENCE - HISTOLOGIC AND COMPETITIVEREVERSE-TRANSCRIPTION POLYMERASE CHAIN-REACTION STUDIES

Background: Transforming growth factor (TGF) beta 3 is a new isoform, of the TGF beta superfamily and is presumed to play an important role in wound repair and scarring. Objective: To examine the effects of TGF beta 3 on wound healing and on reducing scarring. Design and interven tions: Dermal ulcers were created on the ears of 75 anesthetized young female rabbits. Either TGF beta 3 or vehicle was applied topically to the wounds. Wounds were bisected and analyzed histologically at postw ounding day 7. A second group of wounds was treated with topical TGF b eta 3 and TGF beta 2 or vehicle at days 0 and 3 and harvested at days 21 through 42 as an excessive scarring model. The third group of wound s was treated with TGF beta 1, TGF beta 2, and TGF beta 3 and vehicle. The granulation tissue was harvested at day 7, and. cellular RNA was extracted for performing competitive reverse-transcription polymerase chain reaction. Main Outcome Measurement: The amount of new epithelium and granulation tissue was measured in TGF beta 3- and vehicle-treate d wounds. The hypertrophic index was calculated for scarring wounds tr eated with TGF beta 2 and TGF beta 3 or vehicle. Levels of TGF beta 1 messenger RNA were measured in those wounds that were treated with TGF beta 1, TGF beta 2, and TGF beta 3 and in their controls. Results: Th e use of TGF beta 3 (0.3-0.75 mu g per wound) increased granulation ti ssue formation by more than 100% (P<.005). Epithelialization showed a biphase, either increasing 30% (P<.04) or decreasing 25% (P<.001) depe ndent on dose. No significant difference in the hypertrophic index was noted in TGF beta 3-treated wounds compared with controls. Levels of TGF beta 1 messenger RNA increased (7.1- to 14.9-fold) in those wounds treated with TGF beta s compared with controls at day 7. Conclusions: Exogenous TGF beta 3 displays substantial vulnerary properties in wou nd healing and may be useful in treating nonhealing wounds. However, t he observation that TGF beta 3 can reduce scarring was not confirmed i n this study, and the messenger RNA level in response to TGF beta 3 su ggests that it behaves similarly to TGF beta 1.