Flow Cytometric Detection of G0 in Live Cells by Hoechst 33342 and Pyronin Y Staining

Hoechst 33342 and Pyronin Y double staining can be used to measure DNA and RNA content in live cells by flow cytometry. Quiescent cells at G0 phase have the same amount of DNA as cells at G1 phase but lower RNA levels compared to proliferating cells. Therefore, resting cells in G0 phase can be distinguished from proliferating cells in G1, S, and G2 M phases. This chapter describes a protocol for double staining of live cells with Hoechst 33342 and Pyronin Y. Combined with immunophenotyping of intact and live cells Hoechst 33342 and Pyronin Y staining is a powerful noninvasive method for the analysis and isolation of quiescent cells from any defined cell population.