Impacts Of The Intense Pulsed Light On Micronucleus Production, Cell Proliferation And Collagen Synthesis Of Fibroblasts

Background:Photorejuvenation technique is a kind of non-ablative treatment of photoaging skin using continuous wave-length intense pulsed light (IPL) at low energy density. Most research concentrated on clinic treatment with IPL and few reports concerned the basic research of the mechanism of IPL. After radiating by IPL, the fibroblasts are stimulated by the light heat and the photochemical effect and synthesize more collagen, but its detailed mechanism is still not very clear. Moreover there was one basal cell carcinoma case caused by using laser several times to treat Tattoo. The principle of IPL is similar to that of the laser; therefore it is worth paying attention to the security of the human skin with widespread application of IPL for a long time.Objective:To investigate the effects of IPL on the proliferation, micronucleus production and of human facial fibroblasts and Chinese hamster lung cells, especially on collagen synthesis of human facial fibroblasts.Methods:The primary human fibroblasts (a male aged 30 and a female aged 20), and Chinese hamster lung cells (CHL) were cultured and exposed to different dose of IPL. By culturing cells for some time after the irradiation of IPL, the proliferation activity was measured by MTT assay, the effect of IPL on chromosome was detected by micronucleus test and collagen synthesis were determined by immunohistochemical method. And at the same time, the negative control group (non IPL irradiation) and the positive control groups (UVA irradiation or mitomycin) were designed. Results:The proliferation activity of human fibroblasts and CHL cells after irradiated by IPL had no significant difference ( P>0.05) compared with negative control group after 24h,48h and 72h. But the proliferation activity of the positive control groups had been inhibited after 72h (p<0.001). The number of the micronuclei of the IPL group and the negative control group were less than 4‰after 24h and 48h while the number of the positive control group were 13‰and 21‰respectively. Contrasted with the positive control groups, the irradiation of IPL accelerated the synthesis of type I and III collagens after 48h(P<0.001), Moreover the quantities of the collagens type I and III of the lower energy group (20j/cm~2) increased more than that of high groups (40j/cm~2, 30j/cm~2).Conclusion:IPL neither stimulate micronucleus production of fibroblasts, nor promote the proliferation activity of fibroblasts. But it can enhance the collagen synthesis.