目的 明确能否以表面黏附分子CD133为干细胞标志物，使用免疫磁珠分选（magnetic cell separation，MACS）法分离小细胞肺癌细胞系H446细胞中的肿瘤干细胞。方法 以CD133为特异性分子标志物，使用MACS方法分选H446细胞，比较CD133阳性（CD133+）细胞与CD133阴性（CD133-）细胞在集落形成、自我更新、增殖分化、侵袭性、耐药性和成瘤性方面的不同。结果 CD133+细胞和CD133-细胞在集落形成能力、自我更新能力、增殖能力、分化能力、侵袭能力和耐药性方面基本相同。集落形成和成瘤性实验结果显示：CD133+或CD133-细胞中40%以上的细胞都能够形成含有100个细胞以上的大集落，增殖成为与未分选细胞相同的细胞群，并能在裸鼠身上成瘤。结论 表面黏附分子CD133不能作为分选小细胞肺癌H446细胞系中肿瘤干细胞的分子标志物，分选后的CD133+与CD133-细胞中含有相同的肿瘤干细胞。

Objective This study was designed to determine whether CD133 can be a stem cell marker to identify stem cell populations from small cell lung cancer cell line H446. Methods CD133+ and CD133- sub-populations were sorted from H446 by magnetic cell separation (MACS) and characterized for their in vitro stem cell-like properties. Results CD133+ cells and CD133- cells displayed similar abilities of colony formation, self-renewal, proliferation, differentiation and invasion, as well as resistance to chemotherapy drugs. Furthermore, colony formation assays showed that more than 40% of the cells in both CD133+ and CD133- sub-populations could form large colonies capable of regenerating the unsorted population and forming tumors in nude mice. Conclusions These results suggest that CD133 alone cannot be used as a stem cell marker for small cell lung cancer cell line H446, and both CD133+ and CD133- sub-populations contain similar amounts of cancer stem cells.