Flow cytometric analysis of intracellular hematoporphyrin derivative in human tumor cells and multicellular spheroids.
Flow cytometry (FCM) has been used to investigate the intracellular fluorescence of hematoporphyrin derivative (HPD) in monolayer and spheroid cultures of WiDr cells. For exponentially-growing monolayer cultures mean cellular fluorescence was directly proportion to the external HPD levels in the range 5-100 micrograms ml-1 (r = 0.99). Heterogeneity of cellular fluorescence was quantified by determining the ratio of the fluorescence value below which were observed values for 98% of the cell population compared to the fluorescence value for 2%. In exponentially-growing cultures, decreasing levels of HPD in the medium led to an increase in the 98:2% ratio, i.e. an increase in heterogeneity of intracellular drug levels. The growth of cells as multicellular spheroids confers a spheroid-size-dependent resistance to photodynamic treatment. With increasing spheroid size (100, 250, 500, 750 and 1000 microns diam.) there was a decrease in mean intracellular HPD levels and a large linear increase in the 98:2% ratio (r = 0.94).
West
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CM
Moore
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JV
D000230:Adenocarcinoma / Q000032:analysis* / Q000378:metabolism / Q000473:pathology; D003110:Colonic Neoplasms / Q000032:analysis* / Q000378:metabolism / Q000473:pathology; D004351:Drug Resistance; D005434:Flow Cytometry; D017324:Hematoporphyrin Derivative; D006415:Hematoporphyrins / Q000032:analysis* / Q000378:metabolism; D006801:Humans; D010778:Photochemotherapy; D014407:Tumor Cells, Cultured
D006415:Hematoporphyrins; D017324:Hematoporphyrin Derivative