OBJECTIVETo investigate the influence of polysaccharide from Aloe Vera (AP) on the proliferation of the human epithelial cells cultured in vitro.

METHODSThe human epithelial cells undergoing 3 to 4 passages of confluence culture were randomly divided into control and 25, 50, 100, 200 and 400 mg/L AP groups according to different dosage of the polysaccharide (AP) added into the culture medium. In the control group (C), equal volume of DK-SFM medium was added to the culturing cells. The conjugation time of epithelial cells, the changes in the cell morphology and ultrastructure were observed under inverted phase contrast microscope and transmission electron microscope, respectively. The cell proliferation was measured by MTT, cell count analysis and [(3)H]-TdR incorporation. Flow cytometry analysis was employed to detect the cell cycle. The leakage rate of lactate dehydrogenase (LDH) was assayed for the evaluation of the epithelial cell injury.

RESULTSThere was no significant difference in the morphology of the epithelial cells among the groups under inverted phase contrast microscope. But under the transmission electron microscope (TEM), the cells in 100 to 400 mg/L AP groups were seen to have proliferated actively, with euchromatin dominant in the nuclei, while heterochromatin was dominant in the cellular nucleus in control and 25 mg/L AP groups. The confluence time of epithelial cells in 50, 100, 200, 400 mg/L AP groups (154 +/- 12, 141 +/- 20, 130 +/- 19, 124 +/- 13) h preceded noticeably than that in control group (182 +/- 8) h, (P < 0.01). The cell proliferation in 100, 200, 400 mg/L groups reached the peak on the 5th day after AP treatment, while that in control and other groups was delayed by 1 to 2 days. The survival rate of the cells in 25 to 400 mg/L AP groups increased dramatically compared with that in control group, with its [(3)H]-TdR incorporation levels significantly increased in a dose dependent manner. The leakage rate of LDH in 200 and 400 mg/L AP groups was lower than that in control group (P < 0.01). The flow cytometric analysis of the cell cycle distribution revealed that the percentage of cell cycle from phase G0/G1 to G2/M and S in 25 to 400 mg/L AP groups increased significantly in a dose dependent manner compared with that in control group (P < 0.01).

CONCLUSIONAP might be beneficial to the protection of epithelial cells by promoting cell proliferation through inducing the progression of epidermal cells from phase G0/G1 into G2/M and S phases.