Objective

Fluorescent live-cell labelling dyes have proven beneficial for identifying and tracking sub-populations in mixed cell cultures. However, many are ill-suited for this purpose, limited by inconsistent or transient labelling, perturbation or passive intercellular transfer. Here, we describe experiments exemplifying the properties of new cell-labelling dyes (IncuCyte® CytoLight Rapid) designed to address these limitations.

Cells labelled with either CytoLight Rapid or competitor dyes were assessed for suitability for IncuCyte live-cell analysis. Only 4/20 competitor dyes yielded sufficiently bright and homogeneous cell labelling at concentrations that did not perturb cell proliferation. 2 of these 4 labelled cells transiently. In co-cultures, CytoLight Rapid, but not competitor dyes, exhibited little or no passive cell-to-cell transfer. Use of CytoLight Rapid was exemplified by immune/cancer cell interactions. Loss of fluorescence from CytoLight Rapid-labelled A549 cells was used to detect killing by activated immune cells, and direct interactions of CytoLight Rapid-labelled PBMCs with tumour cells expressing RFP were qualified through visualisation.

These findings demonstrate IncuCyte CytoLight Rapid dyes provide fast, bright and homogeneous cell-labelling for up to 48h without perturbing or transferring to adjacent cells. These dyes are suitable for live-cell analysis and labelling difficult to transfect cells, such as patient-derived tissues.