Differentiation of myofibroblasts in wounds after topical use of metronidazole: an experimental study.

ABSTRACT Objective: to assess the effects of topical administration of metronidazole on fibroblast differentiation and on wound contraction during experimental secondary intention wound healing in rats. Methods: we submitted 108 rats to a circular wound on the back, 2cm in diameter, and divided them into six groups: control group, with application of saline solution on the wound and five experimental groups, divided according to the concentration of metronidazole solution used (4%, 6%, 8%, 10% and 12%). We changed the dressings daily throughout the trial period, which comprised three stages of analysis: three, seven and 14 days. We evaluated wound contraction by digital planimetry, and identified myofibroblasts and protomyofibroblasts using CD34 and α-SMA immunohistochemistry techniques. Results: wound contraction was not different between the experimental and the control groups. Protomyofibroblasts were significantly more numerous at seven days (p=0.022) in the 4%, 6% and 8% metronidazole groups. After 14 days, in the same groups, myofibroblasts predominated significantly (p=0.01). Conclusion: the topical administration of metronidazole solution in skin wounds healing by secondary intention was able to improve the differentiation of fibroblasts. The contraction phase of wound healing remained unchanged, without significant reduction of the contraction evaluated by digital planimetry. These results can be used in favor of the wound healing process.