Experimental Study On The Photodynamic Therapy Of Acne Using Different Concentration Of 5-Aminolevulinic Acid

Objective:To compare the efficacies of photodynamic therapy(PDT) treating experimental acne of rabbit's ear using 5%, 10%, 20% three kinds of concentration of 5-Aminolevulinic Acid(ALA). To investigate its mechanism of action, seek the suitable ALA concentration that ALA-PDT treating acne. To provide the theoretical basis and the guidance suggestion for ALA-PDT treating acne.Method:50 male 12-week-old white New Zealand rabbits of healthy were divided into normal group, model group, 5% ALA-PDT treatment group, 10% ALA-PDT treatment group, 20% ALA-PDT treatment group at random. The latter four groups established the experimental acne model of rabbit's ear. The latter three groups were irradiated just once for 45min with the semiconductor laser of wavelength 630nm, power density 25mW/cm~2 and energy density 25J/cm~2 after adopting ALA solution wet packing for 3h by the corresponding concentration. Each group were observed with naked eye and microscope by pathological changes of local skin before the treatment, after 2ds, 8ds, 15ds, 30ds and 45ds post the treatment. Adopt SPSS13.0 to deal with statistics of the mean value of diameter of sebaceous glands and the skin pathological comprehensive score result.Result:Macroscopic observation: After 1 day post ALA-PDT treatment, each treatment group appeared local reactions such as erythema, edema in various degrees. 20% ALA-PDT treatment group had the heaviest local reactions and the longest duration; 10% ALA-PDT treatment group took second place; and the local reactions of 5% ALA-PDT treatment group were slight. PDT treating experimental acne of rabbit's ear using 5%, 10%, 20% three kinds of concentration of ALA, the results showed that 5% ALA-PDT treatment group did not have obvious curative effect; 10% and 20% ALA- PDT treatment groups obtained obvious efficacy all, and there was no significant difference in curative effect between the two groups. And 10% ALA-PDT treatment group could reduce the local reactions by obtaining the likewise curative effect.Microscopic observation: The mean value of diameter of sebaceous glands of rabbit's ear was reduced with time, and the range of the reduction was different. The mean value of diameter of sebaceous glands decreased obviously in the the 10% and 20% ALA- PDT treatment groups, and there was no significance difference between the two groups. And there was no significance difference between the 5% ALA-PDT treatment group and the model group. The skin pathological comprehensive score result revealed: There was no significance difference among every groups before treatment; From after 15ds post the treatment, pathological comprehensive score of 20%, and 10% ALA-PDT treatment group began to reduce obviously, and there was significance difference between the two groups and the model group, and the difference sustained 45ds after treating, and there was significance difference between the 20% and 10% ALA-PDT treatment groups, but 5% ALA-PDT treatment group had no significance difference compared with the model group.Conclusion:The possible mechanism of action that ALA-PDT treating acne was as follows,(1) ALA-PDT damaged the sebaceous glands directly, reduced the secretion of sebum;(2) ALA-PDT lightened the degree of keratinization, reduced the hair follicle to block;(3) ALA-PDT Lightened local inflammation reaction.Under the shine of the same treat parameter of semiconduce laser, PDT using 10% concentration of ALA to treat acne could reduce the aches and local reactions and had the likewise effect, and it should be selected preferentially in treatment.