Assessment of islet cell viability using fluorescent dyes.

A rapid fluorometric method has been developed to evaluate the viability of isolated islet cells. The assay differentiates between viable and nonviable cells by the simultaneous use of the inclusion and exclusion dyes acridine orange and propidium iodide. When viewed by fluorescent microscopy, viable cells fluoresce green, while nonviable cells fluoresce bright red. Although the acridine orange and propidium iodide assay measures membrane integrity, the results of this assay correlate with other measures of cell viability. Compared to trypan blue exclusion, this assay is easier to read, more stable, and has fewer staining artifacts. The assay enables the rapid estimation of the viability of a population of islet cells prior to time-consuming experiments rather than retrospectively. This assay can also be used with intact islets. Stained islets can be divided into three distinct groups: green fluorescing islets contain insulin, red fluorescing islets contain little or no insulin and a third class of islets containing some non-viable cells fluoresce red, green, and yellow. The yellow colour is due to the superimposition of red and green fluorescing cells.