title: Flow cytometric analysis of intracellular hematoporphyrin derivative in human tumor cells and multicellular spheroids.
abstract: 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).
authors.forename: C M
authors.initials: CM
authors.lastname: West
authors.forename: J V
authors.initials: JV
authors.lastname: Moore
mesh_terms: 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
chemical_list: D006415:Hematoporphyrins; D017324:Hematoporphyrin Derivative