| Background:Skin aging is usually divided into natural aging and skin photoaging. Natural aging is characterized by slight wrinkles, sagging, rough and dry skin. Natural aging is caused by age growth in which the different individual genetic background are dominant factors. Photoaging is characterized by rough and deep wrinkles, reduced elasticity and pigmentation of the skin which mainly caused by ultraviolet radiation and other factors such as smoking, air pollution and so on. People with different skin colors show distinct symptoms when they get severe photoaging. Those who with light skin color are always accompanied with cutaneous telangiectasia, atrophy and actinic keratosis, while the dark one even have leather-like appearance in skin [1]. These symptoms of aging skin usually appears before age of thirty, which affect the appearance of the patients and cause serious psychological burden [2]. Recently, with the development of technology and economics in China, the demand for cosmetic skin rejuvenation are increased because of the improvement of living standard. In recent years, intense pulsed light, laser, red and blue light are used in the area of anti-aging of skin which acquire a certain therapeutic effect. Currently, photodynamic therapy (PDT) is a widely used and promising treatment in dermatology due to the advantages of security, simplicity, high tolerance, repeatable operation, few side effects and so forth. The skin rejuvenation effect of PDT was found in treatment of skin tumors such as actinic keratosis and other precancerous lesions, which encouraged people to explore the effectiveness of PDT for skin aging. Red light act as the main light source in PDT is widely used in China and Germany. Type I and type III collagen are major components of the dermis layer. Research have shown that TGF-?1 (transforming growth factor-betal)can increase gene expression of type I and type III collagen and further promote collagen synthesis and inhibit collagen degradation. In consideration of the tight relationship between type ?, type ? collagen and TGF-(31 with skin aging, they are main related factors of evaluating the effectiveness of skin aging treatments. Therefore, we carried out this research to investigate the effect of 5-aminolevulinic acid united with red light PDT on type I and type III collagen and TGF-?1, and to explore the suitable photosensitizer concentration and light dose of treatment in ICR rats.Objective:This experiment adopts different concentration of photosensitizer on mice and detects the changes of type ? ? collagen and TGF-?1 on the mice back skin, and aims to explore the role of 5-aminolevulinic acid combined with red light in the treatment of skin aging and the optimal photosensitizer concentration. This research intends to provide a new direction for the application of photodynamic therapy in the treatment of clinical skin aging.Methods:1 Used different concentrations of photosensitizer 5-aminolevulinic acid with red light on the back skin of ICR rats and observed two weeks,choose suitable photosensitizer concentrations and red light dose parameter of PDT according to the change of rat skin.2 Randomly divided 24 rats of 4 months old into control group, pure red light group, and ALA-R-PDT group. Each group have 8 mice. Each rat in ALA-R-PDT group was given 3%,5%,10% photosensitizer concentration in equivalent area on back skin. All rats in each groups were given one corresponding treatment every 2 weeks,3 times totally.3 Observed the changes of the mice back skin by HE dyeing on the first day, seventh day, fourteenth day and twenty-eighth day respectively after ICR rats get processed, and took 5 visions of same size randomly from back skin of the rats and make slides of immune organization by chemical dyeing. Calculated the percentage of type I and type III collagen positive area and the integral optical density of TGF-?1, then calculated the mean value of 5 visions for each slice.4 Statistical analyses of experimental data were performed using SPSS 13.0. All results were shown as means and standard deviations. All the quantitative data were conformed to Gaussian distribution and homogeneity of variance. One-way ANOVA was conducted to compare multi-sample means, and SNK test was used to multiple comparisons.Results:1 Took the dose of red light radiation 30J?60J?90J?120J with 3%, 5%,10% and 20% photosensitizer concentration in the back skin of ICR rats to find the suitable photodynamic parameters. Observed two weeks, severe bubble, exudation, crusting and other adverse reactions appeared on ICR rats' back skin with 120J red light and 20% photosensitizer concentration. Considered the individual difference of mice and effectiveness of experiment, we chose 90J red light with 3%,5% and 10% photosensitizer concentration in this study.2 On the seventh day, the expression of type I collagen in the mice back skin in the pure red light group and 3%,5%,10%ALA-R-PDT group were increased compared with the control group, and type I collagen in the photodynamic therapy group expressed significantly more than the pure red light group. The expression level of type I collagen growd with photosensitizer concentration increasing (P<0.05). On the fourteenth day, only the expression of type I collagen in the 10% ALA-R-PDT group increased significantly compared with the control group and red light group(P<0.05). The results showed that the effect of 10% ALA-R-PDT group for type I collagen were more obvious and lasting than pure red light group and the 3%, 5%ALA-R-PDT group.3 On the first day, the expression of type ? collagen in the mice back skin in the 5% ALA-R-PDT group was statistically significant compared with control group, however, the expression in rats were less. The comparison of type III collagen between pure red light group and control group on the 7th and 14th day had no significantly difference (P>0.05). it showed statistical significance (P<0.05) in the expression of type III collagen between 3%, 5%,10% ALA-R-PDT groups and the control group on the 7th,14th day.The difference of type III collagen in pure red light group and 3%,5%,10% ALA-R-PDT group comparing with the control group at 28th has statistical significance (P<0.05).The results suggest that increasing of type III collagen appears more earlier in PDT group than pure red light group, and the increasing expression of type III collagen in 10% PDT group was more obvious than other groups on the 14th,28th day (P<0.05).4 The IOD value of TGF-?1 in red light group and PDT group were increased significantly than the control group on the first and seventh day (P<0.05). The most obvious increasing value of TGF-?1 were in 10% ALA-R-PDT group on the 1st day, while in 3% photodynamic group on the 7th day. Then the value gradually fell to normal levels, and the difference of IOD value of TGF-?1 has no statistical significance for each group on the 14th day and 28th day (P>0.05).Conclusion:15-aminolevulinic acid with red light (ALA-R-PDT) promoted the expression of type I, type III collagen and TGF- ?1 and it plays a positive role in the improvement of skin aging.2 Optimal photosensitizer concentration is the key to skin aging treatment. This study showed that 10% PDT with 5-aminolevulinic acid can improve type I and type III collagen protein and TGF-?1 more significantly than 3%, 5% PDT and the pure red light group in most cases. It may be the appropriate concentration for skin aging treatment. |
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