Journal of Cosmetic Dermatology, 13, 169--179 Evaluation of the effect of fractional CO2 laser on histopathological picture and TGF-b1 expression in hypertrophic scar Mohamed Makboul, MD, 1 Rania Makboul, MD, 2 Assem HK Abdelhafez, MD, 1 Safaa Said Hassan, MD, 3 & Sherif M Youssif, MSc 1 1 Faculty of Medicine, Plastic Surgery Department, Assiut University, Assiut, Egypt 2 Faculty of Medicine, Pathology Department, Assiut University, Assiut, Egypt 3 Faculty of Medicine, Histology Department, Assiut University, Assiut, Egypt 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 b1 has a particular importance in the fibrotic scarring response. Treatment of hypertrophic scar included many chemical, physical, and surgical options. Fractional CO2 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 CO2 laser on hypertrophic scar, (b) to evaluate the expression pattern of transforming growth factor-b1 (TGF-b1) as an important fibrogenic factor before and 6 months after fractional CO2 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 CO2 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 CO2 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-b1. 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 CO2 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-b1 expression after laser therapy (P = 0.008). Conclusion Fractional CO2 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-b1 expression. Keywords: fractional CO2 laser, histopathological picture, hypertrophic scar, TGF-b1 Introduction Hypertrophic scars are form of disturbance of wound healing producing abundant wound matrix responsible for erythematous, raised, hypopigmented and firm Correspondence: M Makboul, Plastic Surgery Department, Assiut University Hospital, Assiut 71526, Egypt. E-mail: plasticconsult@gmail.com Accepted for publication March 30, 2014 © 2014 Wiley Periodicals, Inc. 169 Original Contribution