Effective Detection of Hoechst Side Population Cells by Flow Cytometry

The side population (SP) cells are identified through Hoechst 33342 staining and analyzed using flow cytometry (FCM). The Hoechst SP method is utilized for the isolation of stem cells based on the dye efflux properties of ATP-binding cassette (ABC) transporters. The method was initially employed for the identification and isolation of hematopoietic stem cells (HSCs), but it has now evolved to primarily focus on the identification and isolation of cancer stem cells (CSCs). The traditional detection method of FCM uses a 355 nm laser to excite the dye to detect SP cells. Through this study, we have successfully identified alternative approaches for dye excitation that can effectively replace the detection of SP cells using a 355 nm laser. This is achieved through the utilization of high-power 375 nm or 405 nm lasers. This allows us to exercise enhanced selectivity in the detection of SP cells rather than being solely limited to the 355 nm laser flow cytometry.