Does Hoechst 33342 stain dead cells?

Yes, Hoechst 33342 can stain dead cells, however Hoechst 33358 is the preferred dye that’s used for staining dead or fixed cells. Hoechst 33342 is generally used for staining live cells.

Hoechst dyes are a fluorescent stains that bind to AT-rich regions of the minor grove in DNA. This renders the dyes specific for nuclear chromatin. In healthy cells, the nuclei are usually spherical in shape with the DNA evenly distributed within. The DNA becomes condensed during apoptosis but not during necrosis. Because of its ability to bind to DNA, Hoechst dyes can be used to observe nuclear condensation, thereby distinguishing apoptotic cells from healthy cells as well as necrotic cells.