Fig. 6. Highly purified KTLS HSC isolated from the L2G85 transgenic line express detectable luciferase. All images are displayed at the same scale. (A) 7,500 freshly sorted HSC were imaged immediately after sorting was done. (B) 3,750 HSC were lysed in cell lysis buffer and a luciferase assay was performed according to the manufacturer’s guide (Promega) by using BLI to detect photon emission. (C) Iscove’s modified Dulbecco’s medium supplemented with 5% FCS was used to incubate 4,000, 1,000, 250, or 50 HSC at 37° C in for 7 h to allow recovery before they were imaged. Bioluminescent signals were detectable from as few as 50 highly purified HSC.