Isolation of Cancer Stem Cells by Side Population Method

The Hoechst side population (SP) method is a flow cytometry technique used to obtain stem cells based on the dye efflux properties of the ATP-binding cassette (ABC) transporters. The SP cells are characterized by their capability to efflux the fluorescent DNA-binding dye Hoechst 33342 through their ABC transporters and are enriched in stem cells, which are endowed with a self-renewal capacity and multilineage differentiation potential and express the stemness genes including ABC multidrug transporters. The protocols outlined in this book chapter describe the isolation method of the SP cells from human lung carcinoma cell lines by using Hoechst 33342. In addition, we refer to the propagation method of SP cells by successive rounds of fluorescence-activated cell sorting analysis for SP cells. These approaches will be helpful for the establishment of novel in vitro and in vivo models using cancer stem cells, which may play a key role during carcinogenesis and/or tumor progression.