目的 检测和分选胃癌细胞系中的侧群细胞（side population，SP），并对其体外增殖能力进行初步分析。方法 选择3株不同分化程度的人胃癌细胞系MKN-28、SGC-7901、BGC-823，以Hoechst 33342 / 碘化丙啶（propidium iodidc，PI）荧光染料双染，维拉帕米拮抗对照，应用流式细胞仪荧光激活分选法检测SP细胞比例；通过细胞生长曲线（CCK-8法）对SP细胞体外增殖能力进行初步分析。结果 3株胃癌细胞中均存在含量极少的SP细胞，比例在0.8%～2.7%之间；SP细胞比例随着胃癌细胞分化程度降低而下降（2.20% vs 1. 57% vs 0.93%, P=0.023）人胃癌细胞系MKN-28来源的SP细胞体外培养1周、2周后的增殖倍数分别为22.67和290，明显高于非SP细胞培养后的13.68和124。细胞生长曲线显示，SP细胞体外增殖能力明显强于non-SP细胞及未经分选的MKN-28细胞（P=0. 044）。结论 胃癌细胞系中存在比例相对稳定的SP细胞，SP细胞比例随着胃癌细胞分化程度增高而上升。胃癌SP细胞体外增殖能力明显高于非SP细胞。

Objective To identify the side population (SP) isolated from cell lines of gastric cancer，

and to investigate proliferative capacity of the SP cells. Methods Side populations of three human gastric cancer cell lines with different differentiation grades were isolated by fluorescence-activated cell sorting after being stained by fluorochrome Hoechst 33, 342 and propidium iodide, then the capacity of proliferation was investigated with culture in vitro and analyzed by cell growth curve (CCK-8). Results Side population was detected in all of the three gastric cancer cell lines，with a proportion of 0.8% - 2.7%. Proportion of the well-differentiated cell MKN-28 was higher than the moderate-differentiated cell SGC-7901 and the poor-differentiated cell BGC-823 (2.20% vs 1.57% vs 0.93%, P=0.023). After cultured for 1 and 2 weeks, SP cells isolated from MKN-28 showed a proliferative multiple of 22.67 and 290, apparently higher than that of the non-SP cells (13.68 and 124). Cell growth curve indicated that proliferative capacity of the side population was better than the total cells without sorting and the non-SP cells (P=0.044). Conclusions Side population can be detected in the cell lines of gastric cancer，and the proportion of SP is related to the differentiation grade of the cell line. SP cells show a better proliferative ability in vitro than non-SP cells.