FLOW-CYTOMETRY STUDIES OF INTRACELLULAR ADRIAMYCIN IN MULTICELL SPHEROIDS INVITRO

Abstract

A marked gradient of adriamycin [an antitumor agent] uptake in cells [Chinese hamster V-79 lung fibroblasts] of tissue-like multicell spheroids in vitro was demonstrated by fluorescence photomicroscopy and flow microfluorimetry techniques. As expected, this gradient led to an increased net survival for cells from adriamycin-treated spheroids relative to monolayers and markedly greater clonogenicity of central spheroid cells than external cells selected by fluorescence-activated cell sorting. Growth of cells as spheroids seemed to impart an additional degree of drug resistance relative to cells grown as monolayers, in that equal toxicity required greater intracellular fluorescence (and thus more adriamycin) for the spheroid cells. The flow cytometry techniques thus provide a mechanism for quantification of adriamycin penetration into spheroids and provide a method of selection of cells from various depths within the spheroid.