Hello everyone, I need help. I have a question concerning the cell membrane dye DIR for cell infusion during live imaging. rescently, we want to evaluate the ability of microglia to cross blood brain barrier, so we labeled the BV2 cell with DIR in vitro and then injected intravenously into mice. At time point 1 hour, 6 hours, 12 hours and 24 hours, we didn't see any signal in the mouse brain during live imaging. We tried more cell for infusion, higher concerntration of dye according to publlished papers, but it didn't work. Does anyone have some experience? Thank you very much.