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

<jats:title>Summary</jats:title><jats:sec><jats:title>Background and Aims</jats:title><jats:p>Hypertrophic scar is a form of abnormal wound healing process in which tissue repair regulating mechanism is disrupted. Transforming growth factor <jats:italic>β</jats:italic>1 has a particular importance in the fibrotic scarring response. Treatment of hypertrophic scar included many chemical, physical, and surgical options. Fractional <jats:styled-content style="fixed-case">CO</jats:styled-content>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 <jats:styled-content style="fixed-case">CO</jats:styled-content>2 laser on hypertrophic scar, (b) to evaluate the expression pattern of transforming growth factor‐<jats:italic>β</jats:italic>1 (<jats:styled-content style="fixed-case">TGF</jats:styled-content>‐<jats:italic>β</jats:italic>1) as an important fibrogenic factor before and 6 months after fractional <jats:styled-content style="fixed-case">CO</jats:styled-content>2 laser treatment.</jats:p></jats:sec><jats:sec><jats:title>Patients and Methods</jats:title><jats:p>Forty patients of hypertrophic scar were selected, each patient was treated by four sessions with 1 month apart with fractional <jats:styled-content style="fixed-case">CO</jats:styled-content>2 laser. Vancouver Scar Scale (<jats:styled-content style="fixed-case">VSS</jats:styled-content>) 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 <jats:styled-content style="fixed-case">CO</jats:styled-content>2 laser sessions and four normal skin control biopsies. All were assessed by hematoxylin‐eosin (H&E), Masson's trichrome, Van Gieson and immunohistochemical (<jats:styled-content style="fixed-case">IHC</jats:styled-content>) staining with <jats:styled-content style="fixed-case">TGF</jats:styled-content>‐<jats:italic>β</jats:italic>1. The epidermal thickness was assessed before and after treatment by image analyzing system software.</jats:p></jats:sec><jats:sec><jats:title>Results</jats:title><jats:p>There was statistically significant difference in <jats:styled-content style="fixed-case">VSS</jats:styled-content> before and after fractional <jats:styled-content style="fixed-case">CO</jats:styled-content>2 laser (<jats:italic>P</jats:italic> > 0.001). The epidermal thickness showed significant increase after laser treatment (<jats:italic>P</jats:italic> > 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 <jats:styled-content style="fixed-case">TGF</jats:styled-content>‐<jats:italic>β</jats:italic>1 expression after laser therapy (<jats:italic>P</jats:italic> = 0.008).</jats:p></jats:sec><jats:sec><jats:title>Conclusion</jats:title><jats:p>Fractional <jats:styled-content style="fixed-case">CO</jats:styled-content>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 <jats:styled-content style="fixed-case">TGF</jats:styled-content>‐<jats:italic>β</jats:italic>1 expression.</jats:p></jats:sec>