Abstract: Objective To investigate the effects of superparamagnetic iron oxide covered by polyethylenimine(PEI) on human adipose mesenchymal stem cells (hADSCs).Methods The adipose tissue come from human subcutaneous,we extraction separation, culture and identification of hADSCs .The third passage of hADSCs were divided into four groups,and incubated in DMEM/F12 containing PEI -SPIO of 6,8,10,12mg/L.Detected by Prussian blue staining,Trypan blue staining,MTT test and inductions of multi-directional differentiation to evaluate the ability of SPIO on cell labeling efficiency,cell viability,proliferation and differentiation． Results 1.The labeling efficiency of SPIO (8,10,12mg/L) was 99%.However the labeling efficiency of SPIO(6mg/L)was 96%.2.In 6 ,8μg /ml group，the cell survival rate was 99%. But in10mg/L and 12mg/L group,the cell survival rate was(79.03±2.25)% and (70.23±1.36)%, Significantly lower than the control group(P<0.01).3.In 10，12 mg/L group，there were statistically significant differences in the viability，most of cells deceased in the procedure of multi-directional differentiation.Conclusions PEI-SPIO of 8mg/L can effectively label hADSCs，without influencing the cell viability，proliferation and the multiple differentiation ability．

Key words: Key words:Human adipose mesenchymal stem cells, Polyethylenimine, Superparamagnetic iron oxide, Biological characteristic