The effects of collagenase ointment on the prevention of hypertrophic scarring in a rabbit ear scarring model: A pilot study

Collagen synthesis and degradation are important in scar maturation. Collagenase has been used for debridement of wounds and treatment of Dupuytrenĝ€™s disease but its effects on scar prevention are unknown. Objective. The objective of this study was to determine the effect of collagenase ointment on hypertrophic scar prevention by using a rabbit ear-scarring model. Methods. Four 7-mm, full-thickness dermal punches were made on the inner surface of each ear of 8 young adult New Zealand white rabbits. The wounds from one ear were treated with collagenase in petrolatum or petrolatum alone, while the wounds from the other ear of the same rabbits were not treated, serving as control. Tissues were collected at 28 days after surgery and histological analysis was performed. Total area of new scar and scar elevation index were determined. A paired two-tailed Studentĝ€™s t test was performed to compare treated scars with their own controls and a non-paired Studentĝ€™s t test was performed to compare collagenase-treated with petrolatum-treated scars. Results. Collagenase-treated wounds developed scars with less hypertrophy than untreated scars. The total area of new scar was smaller in collagenase-treated wounds than in untreated wounds (531 ± 32 vs. 617 ± 51; P ≤ 0.03). The scar elevation index was lower in collagenase-treated wounds than in untreated wounds (2.08 ± 0.15 vs. 2.45 ± 0.20; P ≤ 0.015). The adjusted scar elevation index was lower in collagenase-treated wounds than in petrolatum-treated wounds, and the difference showed a trend toward statistical significance (0.88 ± 0.04 vs. 1.03 ± 0.07; P ≤ 0.10). Conclusion. Treatment with collagenase ointment reduces hypertrophic scar formation in a rabbit ear model.