The effect of laser diode irradiation on wound healing of rat skin

Background: Light amplification by stimulated emission of radiation (LASER) diode irradiation (LDI) has some beneficial effects on the wound healing. However, little is known about the biochemical effect of LDI on wound healing. We have performed animal study to clarify the effect of LDI on wound healing based on microscopic findings. Methods: Eight-month-old male rats (NTacSam:SD, SamtakoBioKorea), weighting 250-300 g, were used. Round blade, of 1 cm diameter, was penetrated through the skin and subcutaneous level after elevating the skin just above the thoracic spine of the rats. Laser diode of 655, 785, and 850 nm wavelengths were irradiated to the skin wound for 9 days, 20 min a day. Eight rats were used in each four groups including non-irradiated group. Immunochemical staining was carried out to evaluate pan-cytokeratin and actin, and Masson's trichrome staining was carried to evaluate the cellular and protein components relating to wound healing. Wound size was measured on 9th postoperative day with computer system. Result: Collagen formation was graded as 2+, 3+, and 4+ in the order of non-radiation group, 655, 785, and 850 nm irradiation groups, respectively. Myofibroblast was formed more abundantly in LDI group than in non-irradiated group. The mean values of proliferating cell nuclear antigen (PCNA) were 67.8 +/- 5.0, 84.0 +/- 4.6, 78.0 +/- 6.8, and 74.2 +/- 4.0 nm in the order of non-radiation group, 655, 785, and 850 nm irradiation groups, respectively. Mean values of defect size were 2,840 +/- 124 um, 1,689 +/- 125 um, 1,254 +/- 94 um, and 1,423 +/- 113 in the order of non-radiation group, 65, 785, and 850 nm groups, respectively. Conclusion: LDI has beneficial effects on the formation of fibroblast and collagen, and results in better wound healing.