[Radioprotective effect of aloe polysaccharides on three non-tumor cell lines].

BACKGROUND OBJECTIVE: Our previous study showed that aloe polysacc harides (AP) could evidently decrease the mortality of irradiated mice mainly th rough increasing the amount of hemocytes and ameliorating immune function of mic e. Whether AP can protect the cells in vitro from irradiation damage is unknown. This study was to explore radioprotective effect of AP on 3 non-tumor cell line s, and its effect on cell cycle. METHODS: MTT assay was used to detect cytotoxic ities of AP to normal human liver cell line Chang Liver (C. Liver), normal human embryo kidney cell line 293, and normal human umbilicus vein endothelial cell l ine ECV304. The 3 cell lines were treated with AP before or after irradiation. A fter 7-10 days normal culture, survival rate of cells was calculated by clone fo rmation assay. Cell cycle was analyzed by flow cytometry (FCM) at different time points after irradiation. RESULTS: 293 cells were treated with AP at different time points before and after x-ray irradiation. Survival rate of 293 cells treat ed with AP 30 min before x-ray irradiation was the highest (64.2%) among all gro ups. Evident dosage-effect relationship of AP appeared in concentration range of 12.5-50 μg/ml. After treatment of 50 μg/ml of AP, survival rates of 293, ECV3 04, and C. Liver cells increased from 41.5%, 46.5%, and 40.9% to 49.4%, 72.1%, a nd 89.1%, respectively. Irradiation caused a distinct G2/M block and decreased G 0/G1 phase population in 293 and C.Liver cells. In C.Liver cells, pretreatment o f 50 μg/ml of AP increased G0/G1 phase population from 31.8% to 43.8%, decrease d G2/M phase population from 38.5% to 13.8% 6 h after irradiation; and decreased G2/M phase population from 22.9% to 8.7% 24 h after irradiation. In 293 cells, the same pretreatment increased G0/G1 phase population from 30.1% to 45.9% 6 h a fter irradiation, and from 40.4% to 45.2% 24 h after irradiation accompanied by decrease of G2/M population from 59.6% to 54.1%. CONCLUSIONS: AP has radioprotec tive effect on non-tumor cells. This effect might relate to alleviating of cell cycle turbulence.