[Experimental study on the mechanism of nonablative skin photorejuvenation]

To explore the Mechanism of nonablative skin rejuvenation.

The Kunming mice be used as subjects and divided into three groups (A, B, C). A, B, C groups were irradiated with 1 320 nm cooltouch laser (20 J/cm2) in the skin of left back; B and C groups were irradiated two and three times respectively; the skin of right back of A, B, C groups was adopted as control. The expression of bFGF and TGF-beta1 in the mouse skin was examined by the immunohistochemistry . The fibroblasts were isolated from the foreskin and cultured. One group is a control and other three ones are low, intermediate and high energetic groups respectively. The fibroblasts were irradiated by laser with 15 J/cm2 ,20 J/cm2 and 24 J/cm2 energy for three times. We examined the levels of bFGF and TGF-beta1 by ELISA in 0, 24, 48 and 72 hours.

According to this research on immunohistochemistry result, there are significant differences in the expression of bFGF and TGF-beta1 between the group irradiated by three times and others (P < 0.01). The number of fibroblasts get increased after being irradiated by laser. The ELISA result indicates that the secretion of bFGF increased in the group of intermediate and high energetic level after laser irradiating and may reach the peak at 24 hours (P < 0.01). The amount of TGF-beta1 secretion, however, seems to get decreased in each group at all energetic levels, and at 24 hours it can reach the top level as well.

The direct influence of laser on the fibroblasts is to promote secretion of bFGF and to inhibit secretion of TGF-beta1, while its influence on the tissue is to promote the secretions of the both. Nonablative skin rejuvenation not only can induce fibroblasts to secrete more bFGF but also induce the blood vessels to release cytokines which stimulate endothelial cell to express more of bFGF and TGF-beta1. Furthermore, fibroblastic proliferation can accelerate by laser's irradiating.