Protection Of Aloe Polysaccharide On HaCaT Cells Against Oxidative Damage From UVB Irradiation

Objective：To investigate the photoprotection effects of Aloe Polysaccharide （AP） on HaCaTcells against the oxidative damage of Ultraviolet B （UVB）.Methods:1. Cells culture:HaCaT cells with MEM-EBSS medium were seeded in flasks at37°C,5%CO₂humidified incubator.Cells were collected to prepare the cell suspension when cells are fusion at90%, then reseeding them at a1:3ratio.2. Determination of the optimal dose of UVB:HaCaT cells were exposed to UVB lamp（theVoltage is220V, the Power is8watts）. The culture plate center inoculated cell is far from of thelamp10cm when HaCaT cells is irradated.The radiation intensity is200uw/cm²by the UVradiometer determining. HaCaT cells is irridated corresponding time in accordance with theexperimental groups. The cells of morphology was observed by Inverted phase contrastmicroscope.MTT assay was used to record the cell proliferation and Trypan Blue staining wasused to calculate the cell viability. Finally Comprehensive analysis is determined to develop thebest dose of UVB program.3. Adding in AP and detecting indicators:In accordance with the best UVB irradiation dose ofcells for radiation150s, then AP is added immediately. Waiting for24h （cell after a latent periodto enter the logarithmic growth phase）,MTT assay was used to record cell proliferation. Theactivities of superoxide dismutase, glutathione peroxide were detected with colorimetricmethods;the level of maleic dialdehyde was detected with Thiobarbital methods（Biochemicalassay for measuring SOD, GSH-PX and MAD activity）.Results:1. Optimal radiation dose:It was found that the survival ratio of the HaCaT cells decreasedfollowing UVB irriation（30mj/cm²ï¼‰.The cells appeared typical damage morphology. Oxidativedamage model was established at the dosage of UVB of30mj/cm².2. The results of HaCaT cells proliferation and the Antioxidant index:OD value of the UVBirradiation group was significantly lower than untreated group（P<0.05）.The treatment group,though still lower than the blank control group, but significantly higher than the UVB irradiationgroup（P<0.05）. There are significant differences between the AP high and low dose group （P<0.05）. The ROS produced by UVB reduced SOD and GSH-Px of intracellular （P<0.05）, andthe AP can fight against this consumption.UVB caused MDA a significantly increased （P<0.05）.AP can reduce the production of MDA.Conclusions: 1. It was found that20mj/cm²of UVB radiation can activate cells and promote their growth,bythe contrast30,40,50mj/cm²can damage HaCaT cells.2. HaCaT cells is likely to be damaged by oxidative stress from UVB.AP can enhanced theactivity of antioxidant enzymes and antagonize the oxidative injury caused by UVB radiation ofHaCaT cells. AP can antagonize the cells photoaging by UVB radiation.