Flow cytometry and RNA studies.

RNA was less studied by flow cytometry (FCM) in comparison to other cellular components. Moreover, most of these studies were applied to the measurement of total RNA. Nevertheless, such a quantification, essentially by the use of acridine orange, but also other dyes or dye combinations, permitted the acquisition of important information about the general metabolism, and the characterization of different tumoral cell types. More recently, FCM has been used to quantify specific mRNA, in two different approaches: the first one employs the sorting followed by RNA extraction and/or detection by specific radiolabeled probes; in the second approach, the use of fluorescence in situ hybridization (FISH) on cells in suspension allowed the direct quantification of specific mRNA by FCM.