Isolation and Functional Characterization of Side Population Stem Cells

The "side population" (SP) phenotype is a manifestation of primitive cells' ability to efficiently efflux the fluorescent DNA-staining dye Hoechst 33342 and can be used as the basis by which to isolate these cells using flow cytometry. In the bone marrow (BM), the SP defines a cell subset with a highly homogeneous content of hematopoietic stem cells (HSCs). In this chapter, we describe a protocol to reproducibly isolate murine BM SP cells, as well as analytic measures, such as single cell transplantation, that can be used to assess the functionality of SP-derived stem cells.