Fractional Photothermolytic Effect of Sellas Laser Device on Guinea Pig Skin

This study was designed to evaluate photothermolytic effects of a fractional laser device and to evaluate healing process after fractional laser treatment on guinea pig skin. Eleven guinea pigs received a single treatment with a prototype diode laser (Sellas ® ) emitting a wavelength of 1,550 ㎚, delivering 10 mJ and Excisional biopsies were done immediately after (0 day), 1, 3 and 7 days and analyzed by two blind pathologists using hematoxylin and eosin and Van Gieson stain. Definitive MTZs were observed in both 10 and 20 mJ energy with sparing normal tissue between MTZs. Average depths and diameters of microbeam produced were 308.46, 105.61 ㎛ in 10 mJ and 414.15, 130.57 ㎛ in 20 mJ, respectively. Degeneration of dermal collagen in MTZ is evident, revealing loss of collagen birefringence under polarizing microscope and lack of red staining on Van Gieson stain. One day after fractional laser treatment regeneration of epidermis was completed without disruption of stratum corneum. Microscopic epidermal necrotic debris (MENDs) were noted 1 day on the laser treated epidermis and disappear within 3 days after the treatment. Areas of each microscopic treatment zones were rapidly reduced by replacing newly formed collagen. Repair rate reached 30% at 1 day after laser treatment and at day 7 a wound healing process was almost completed. A single treatment with fractional laser device reveals fractional photothermolytic effects and wound healing responses in both epidermis and dermis.