Effect Of The Aloe Vera Polysaccharide On Both Proliferation And Cytokine Secretion In Cultured Epidermal Cells

Objective:To investigate the effect of the Aloe vera polysaccharides on the proliferation and the cytokines secretion of epidermal cells cultured in vitro.Method:1. The epidermal cells of confluence culture were randomly divided into polysaccharide(25, 50, 100, 200, 400mg/L) and control groups. The cell proliferation was measured by MTT, cell count, conjugation time analysis and[~3H]-TdR incorporation. The cell cycle was detected by flow cytometry analysis. T he concentration of intracellular calcium was determined by the fluorescent calcium indicator Fura-2. The leakage rate of lactate dehydrogenase(LDH) was assayed for the evaluation of the cell injury. The changes in the cell morphology and ultrastructure were observed under inverted phase contrast microscope and transmission electron microscope(TEM), respectively.2. The levels of EGF, TGF-α, TGF-β1, IL-1β, IL-6, IL-8 and TNF in the supernatants of cultured epidermal cells in polysaccharide and control groups were measured by ELISA and RIA, and NO production was assayed by Green method.Result:1. There was no significant difference in the morphology of the epidermal cells among the groups under inverted phase contrast microscope. But under the TEM, the cells treated with polysaccharide were seen to have proliferated actively, with euchromatin dominant in the nuclei, while heterochromatin was dominant in the cellular nucleus in control group. The cell proliferation treated with polysaccharide reached the peak on the day 5 or day 6, while that in control was delayed by 1 to 2 days. The PD/day of cells increased dramatically and the confluence time of cells shortened 28 to 58 hours treated with polysaccharide compared with that in control group, with its[~3H]-TdR incorporation levels increased significantly in a dose-dependent manner(P<0.05).2. The levels of intracellular calcium of the epidermal cells treated with polysaccharide were higher than those in control group(P>0.05), and the percentage of cell cycle from phase G0/G1 to G2/M and S treated with polysaccharide increased significantly compared with that in control group(P<0.05). The leakage rate of the cells treated with polysaccharide was lower than those in control group(P<0.05).3. The levels of TGF-α, EGF, TGF-β1, IL-1β, IL-6, IL-8 and TNF in the supernatants of cultured epidermal cells were significantly higher treated with polysaccharide than that in control group in a dose-dependent manner(P<0.05). However, the Aloe vera polysaccharides markedly decreased NO production in a dose-dependent manner(P<0.01).Conclusion:These data indicate the Aloe vera polysaccharides may play an important role in the epithelial reconstruction during the phase of wound healing, through promoting both epidermal cell proliferation and the production of TGF-α, TGF-β1, EGF, and IL-1β, IL-6, IL-8, TNF, and regulating NO production.