Quantitative evaluation of collagen and elastic fibers after intense pulsed light treatment of mouse skin

Background and Objective The aging of human skin includes intrinsic aging and photo‐aging, which are characterized by a decrease in collagen and the deposition of abnormal elastic fibers. Intense pulsed light (IPL) sources are widely used in medicine to treat various cosmetic problems, including photo‐damaged skin. Few studies have examined the microscopic changes produced by IPL. The objective of this study was to quantitatively evaluate the effects of IPL on collagen and elastic fibers in mice. Materials and Methods Forty female BALB/c mice were divided into four subgroups. Group 1 was the control group ( n = 10), and groups 2, 3, and 4 were treatment groups ( n = 10 in each group). Group 2 received one treatment, group 3 received two treatments, and group 4 received three treatments every 2 weeks. Skin tissue was obtained from irradiated areas 24 hours after the last treatment in each mouse. Collagen fibers were identified using the picrosirius red method. Elastic fibers were marked by Weigert‐oxone stain. All samples were analyzed and quantified by a light microscope using analyzer system images. Results Group 4, which received three IPL treatments, showed significant quantitative increases in both collagen fibers ( P < 0.05) and elastic fibers ( P < 0.01). Collagen fibers demonstrated a better parallel distribution in relation to the epidermis. Conclusion IPL treatment significantly increased the number of collagen and elastic fibers within the dermis and improved the parallel distribution of collagen fibers in relation to the epidermis. These results were evident after three IPL treatments. Lasers Surg. Med. 50:644–650, 2018. © 2018 Wiley Periodicals, Inc.