CytoTell® UltraGreen is a fluorescent cell proliferation indicator developed for monitoring cell division and long-term tracking of live cells by flow cytometry and fluorescence microscopy. As cells divide, the dye is distributed equally between daughter cells, resulting in progressive halving of fluorescence intensity that enables visualization of successive cell generations. CytoTell® UltraGreen exhibits peak excitation around 492 nm and can be efficiently excited with the 488 nm blue laser line, making it compatible with standard FITC filter sets, fluorescence microscopes, flow cytometers, and high-content imaging systems.

CytoTell® UltraGreen was developed as an improved alternative to CFSE-based proliferation assays with enhanced intracellular retention, improved sensitivity, and simplified staining workflows. Compared to CFSE, CytoTell® UltraGreen exhibits reduced cytotoxicity, improved long-term stability, and minimized fluorescence intensity gaps between successive cell generations for improved proliferation analysis. The dye can be used for long-term tracking of labeled cells, and up to 9 generations may be visualized in suitable experimental systems. Two-parameter flow cytometry analysis may improve resolution between successive cell generations, particularly between undivided cells and first-generation daughter cells.