Evaluation of the effect of fractional CO 2 laser on histopathological picture and TGF ‐ β 1 expression in hypertrophic scar

Summary Background and Aims Hypertrophic scar is a form of abnormal wound healing process in which tissue repair regulating mechanism is disrupted. Transforming growth factor β 1 has a particular importance in the fibrotic scarring response. Treatment of hypertrophic scar included many chemical, physical, and surgical options. Fractional CO 2 laser devices have gained acceptance as a way for managing hypertrophic scar. Aims of this study are: (a) to determine the clinical and histopathological effects of fractional CO 2 laser on hypertrophic scar, (b) to evaluate the expression pattern of transforming growth factor‐ β 1 ( TGF ‐ β 1) as an important fibrogenic factor before and 6 months after fractional CO 2 laser treatment. Patients and Methods Forty patients of hypertrophic scar were selected, each patient was treated by four sessions with 1 month apart with fractional CO 2 laser. Vancouver Scar Scale ( VSS ) was used to assess the patients before and after laser treatment. Skin biopsy was taken from eight cases before and 3 months after four fractional CO 2 laser sessions and four normal skin control biopsies. All were assessed by hematoxylin‐eosin (H&E), Masson's trichrome, Van Gieson and immunohistochemical ( IHC ) staining with TGF ‐ β 1. The epidermal thickness was assessed before and after treatment by image analyzing system software. Results There was statistically significant difference in VSS before and after fractional CO 2 laser ( P  > 0.001). The epidermal thickness showed significant increase after laser treatment ( P  > 0.001), and there was also thinning in stratum corneum and replacement of the irregular collagen bands with organized new collagen fibrils as demonstrated by H&E and the other special stains. The study also showed significant decrease in TGF ‐ β 1 expression after laser therapy ( P  = 0.008). Conclusion Fractional CO 2 laser could be considered as a good way for hypertrophic scar management. It normalizes dermal collagen as imaged by histopathological picture and the change in TGF ‐ β 1 expression.