RESUMEN
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. OBJECTIVE: 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. MATERIALS AND METHODS: Hairless mice were pretreated with ultraviolet B irradiation to produce photo-damage. The laser treatment used a long-pulse 1,064-nm Nd:YAG laser at energy fluences of 20, 40, and 60 J/cm(2) . The amount of dermal collagen and expressions of transforming growth factor beta (TGF-ß), 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-ß expression. The expression of MMP-1 decreased with low energy fluence. The expression of TIMP-1 was not significantly different. CONCLUSION: Long-pulsed 1,064-nm Nd:YAG laser increases the dermal collagen in association with the increased expression of TGF-ß.