FCT 10 : Effects of long-pulsed 1,064-nm Nd:YAG laser on chronic ultraviolet-induced skin damage in hairless mice: histological and molecular analysis

Background: Nonablative lasers are used for dermal collagen remodeling. Although clinical improvements have been reported using various laser devices the mechanism of dermal collagen remodeling remains unknown. Objectives: To investigate the effects of energy fluences of the long pulsed neodymium doped yttrium aluminum garnet (Nd:YAG) nonablative laser on dermal collagen remodeling and evaluate the dermal collagen remodeling mechanism. Methods: Hairless mice were pretreated with ultraviolet B irradiation to produce chronic photodamage. The laser treatment used a long pulse 1064 nm Nd:YAG laser at energy fluences of 10 20 and 40 J/cm2. The amount of dermal collagen and expressions of transforming growth factor beta (TGF β) matrix metalloproteinase 1 (MMP 1) and tissue inhibitor of metalloproteinase 1 (TIMP 1) of laser treated skin were compared with those of nontreated control skin. Results: The long pulse Nd:YAG laser treatment increased dermal collagen and significantly increased TGF βexpression. The expression of MMP 1 decreased with low energy fluence. The expression of TIMP 1 was not significantly different. Conclusion: Long pulsed 1064 nm Nd:YAG laser increases the dermal collagen in association with the increased expression of TGF β.