Abstract: Xu Liangheng*, Gu Hua, Guo Meihua, Liu Haiyang, Liu Fuhua, Tu Ying, Pang Qin, He Li. *First Affiliated Hospital of Kunming Medical University, Collaborative Innovation Center of Yunnan Province，Engineering and Technology Research Center of Yunnan Province， Kunming 650032, China Corresponding author: He Li, Email: heli2662@hotmail.com 【Abstract】 Objective To evaluate the restoring effect of dressings containing hyaluronic acid on impaired skin barrier function in BALB/c mice after laser irradiation. Methods The back of 63 BALB/c female mice were shaved with depilatory cream followed by exposure to Q-switched 1064-laser （frequency, 5 Hz; light spot, 3 mm; energy, 6 J）. Then, the mice were randomly and equally divided into three groups to be topically treated with dressings containing vehicle, vehicle + collagen protein and vehicle + hyaluronan acid respectively twice a day for 21 days. The dressings were only applied at one side of the back of these mice, and the other side was left untreated to serve as a negative control. Skin physiological parameters were measured on the back of these mice at 6 hours, 24 hours, 7 days, and 21 days after the beginning of treatment, and 3 mice were sacrificed in each group at every time points. Skin tissue specimens were obtained from the back of sacrificed mice followed by immunohistochemistry for the detection of proliferating cell nuclear antigen （PCNA）. Results On the 7th day, the vehicle + collagen protein group and vehicle + hyaluronan acid group showed lower TEWL values （（13.9 ± 0.9） and （12.6 ± 0.6） vs. （18.4 ± 0.4） and （18.4 ± 0.5） g?h-1?cm-2, all P < 0.05）, but increased water content in stratum corneum （33.6% ± 0.1% and 33.7% ± 0.1% vs. 25.4% ± 0.2% and 26.5% ± 1.3%, all P < 0.05） and PCNA expression compared with the vehicle group and negative control group （side）. However, no significant difference was observed between these groups in any of the above parameters at 24 hours, 1 day, or 21 days after the beginning of treatment （all P > 0.05）. Additionally, all the parameters returned to the preirradiation levels on the 21st day in all the three groups （all P > 0.05） with the recovery of skin barrier function. Conclusions The effects of dressings containing collagen protein and those containing hyaluronic acid are comparable on the restoration of impaired skin barrier function in BALB/c mice after laser irradiation.

Key words: Laser, Hyaluronic acid, Bandages, hydrocolloid, Skin, barrier, Animal experimentation