The Evaluation Of Mouse Skin Remodeling By Using A 1320nm Laser

The Evaluation of Mouse Skin Remodeling by Using a 1320nm LaserObjectives to evaluate the histological and physiological change of mouse skin after 1320nm laser irradiation and to compare the effect of different energy level, irradiate interval and time on dermal depth, hydroxyproline content and elasticity of mouse skin.Methods After hair removal by depilatory, skin on the back of KM mouse was irradiated with 1320nm Nd:YAG laser with energy level of 16, 20 and 24J/ cm2.The experimental animals were divided into 4 groups, the laser irradiation only performed once on Group 1 .For the second group, treatments were conducted at 7 days interval for four consecutive passes. Animals in the third group received laser irradiation four times at 3 days interval. Four weeks and eight weeks after the last irradiation, resonance running time of skin were tested on the animals in the first,second and third groups, and then skin biopsies were obtained from these animal. Skin depth and hydroxyproline content were detected. The forth group were treated by laser only once and resonance running time, melanin and hemoglobin content, transepidermal water loss, sebum content and moisture of skin were examined before treatment and at 1 hour, 3days, 7days, 15days, 30days after irradiation. The histological evaluation were performed at the same time.Results the fibres in dermal were tighened 1 hours after laser treatment . A mild fibroblastic proliferation and inflammatory infiltrate were observed at day 3. The number of fibroblast were increased notably 7 days after irradiation. At day 15, dermal depth and collagen were increased. Resonance running time, hemoglobin content,transepidermal water loss, sebum content and moisture of skin were changed temporarily after laser irradiation. But the laser has no effect on melanin content of mouse skin. The energy density of 20J/cm2 and 24J/cm2 have greater effect on dermal depth, hydroxyproline content and elasticity of skin,compared with 16 J/cm2.The second group have the greatest dermal change, and the least change was observed on group 1Conclusion The 1320nm Nd:YAG laser can induces fibreblast proliferation ,collagen formation and increased elasticity without epidermal ablation. But it also can effect the normal physiological state of skin temporarily. At the same energy level, more treatments have better results than one. The treatment interval is also very important. Too frequent treatment in a short period of time has no good results. The effect is related to energy level.