title: Flow cytometric technique for quantitating cytotoxic response to photodynamic therapy.
abstract: A simple flow cytometric technique for rapid measurement of multilog cytotoxic responses to photosensitization of cellular systems is described. This technique is particularly useful for cell lines with a low colony-forming efficiency, for which a nonclonogenic assay is required. The assay separates cell-sized objects from cellular debris by gating on forward scatter versus side scatter, identifies viable cells by positive calcein AM and negative ethidium homodimer-1 staining and measures cell concentration relative to an internal standard of polystyrene beads. Large numbers of cells can be analyzed rapidly. Two patient-derived small cell lung cancer cell lines, NCI-H209 and SV-E, were used to test the technique. Photordiation survival curves of the response of these cell lines to 5-aminolevulinic acid-induced protoprophyrin IX photosensitization correlated with the extent of photosensitizer accumulation. There was good agreement between the results obtained using the tritiated thymidine incorporation assay and the flow cytometric cytotoxicity assay. The technique can be used to measure cytotoxic responses to photosensitization of cell lines regardless of their plating efficiencies.
authors.affiliation: Department of Pathology, Queen's University, Kingston, Ontario, Canada.
authors.forename: D L
authors.initials: DL
authors.lastname: Campbell
authors.forename: M E
authors.initials: ME
authors.lastname: Fisher
authors.forename: J G
authors.initials: JG
authors.lastname: Johnson
authors.forename: F M
authors.initials: FM
authors.lastname: Rossi
authors.forename: B G
authors.initials: BG
authors.lastname: Campling
authors.forename: R H
authors.initials: RH
authors.lastname: Pottier
authors.forename: J C
authors.initials: JC
authors.lastname: Kennedy
mesh_terms: D000622:Aminolevulinic Acid / Q000378:metabolism; D018288:Carcinoma, Small Cell / Q000188:drug therapy* / Q000473:pathology; D002470:Cell Survival / Q000528:radiation effects; D005434:Flow Cytometry; D006801:Humans; D008175:Lung Neoplasms / Q000188:drug therapy* / Q000473:pathology; D010778:Photochemotherapy; D011524:Protoporphyrins / Q000378:metabolism; D014407:Tumor Cells, Cultured
chemical_list: D011524:Protoporphyrins; D000622:Aminolevulinic Acid; C028025:protoporphyrin IX