Selective killing of T lymphocytes by phototoxic liposomes.

Yemul, Shrishailam; Berger, Carole L.; Estabrook, Alison; Suarez, S. Israel; Edelson, Richard L.; Bayley, Hagan

doi:10.1073/pnas.84.1.246

Cited by 33 publications

(27 citation statements)

References 32 publications

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“…Uptake is increased when photosensitizers are conjugated to molecular delivery systems with affinity for the target of interest (6); examples include photosensitizers conjugated to monoclonal antibodies (7)(8)(9)(10)(11)(12), liposomes (13,14), low-density lipoproteins (15), combinations of monoclonal antibodies and liposomes (16), and microspheres (17). With all of these types of conjugates, photosensitization is enhanced.…”

mentioning

confidence: 99%

Photosensitized destruction of human bladder carcinoma cells treated with chlorin e6-conjugated microspheres.

Bachor

Shea

Gillies

et al. 1991

Proc. Natl. Acad. Sci. U.S.A.

111

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A photosensitizer conjugate, chlorin e6 (Ce6) covalently bound to 1-uim-diameter polystyrene microspheres, has been investigated in the photodynamic destruction of MGH-U1 human bladder carcinoma cells in vitro. The microspheres were taken up avidly by the carcinoma cells; confocal laser scanning fluorescence microscopy showed them to be localized in the cytoplasm, apparently within lysosomes, visualized by labeling with acridine orange. In contrast, fluorescence of unconjugated Ce6 was present within most cellular membranes. Use of Ce6-microsphere conjugates led to a 20- collected by centrifugation at 1000 rpm for 10 min, and the fluorescence of the supernatants was measured (model Fluorolog 2; Spex Industries, Edison, NJ). Cells not exposed to either form of Ce6, and cell-free dishes incubated in the presence of plain medium, unconjugated Ce6, or Ce6-microspheres served as controls. Standard solutions containing known concentrations of unconjugated Ce6 and Ce6-microspheres in DMF and unconjugated free Ce6 in medium were prepared and their fluorescence emission spectra (obtained with excitation at 406 nm) were recorded from 600 to 850 nm. After background and instrument correction for wavelength sensitivity, the integrated fluorescence of each standard solution was measured and a calibration curve relating integrated fluorescence to Ce6 concentration was determined. The integrated fluorescence from the supernatant of each cellular sample was then measured and the Ce6 concentration of the sample was ascertained from the calibration curve.Singlet Oxygen Generation. 02(1Ad) production was measured by trapping with histidine to form an endoperoxide; the change in absorbance at 440 nm of p-nitrosodimethylaniline as a consequence of reaction with the histidine endoperoxide was used to quantify the photosensitized generation of 02(1Ag) (28). One-milliliter aliquots of Ce6 solution or Ce6-microsphere suspension containing 10 ,uM histidine and 10 ytMp-nitrosodimethylaniline in 1.5-cm-diameter dishes were either kept in the dark or irradiated at 659 nm with 0.2-5 J/cm2 and studied by absorbance spectroscopy from 300 to 700 nm. The relative quantum yield Of 02('Ag) generation was calculated after correction for the molar extinction coefficient at 659 nm for unconjugated and bound Ce6 (21,400 and 25,000 liter'mol-1cm-1, respectively). RESULTS Absorption Spectra. In DMF both unconjugated Ce6 and Ce6-microspheres had a Soret band maximum at 404 nm and a Q-band maximum at 664 nm. In DPBS the unconjugated Ce6 had a Soret band maximum at 404 nm and a Q-band maximum at 655 nm; the corresponding maxima for Ce6-microspheres in DPBS were 408 nm and 665 nm (Fig. 1) Serial optical sectioning by confocal laser scanning microscopy showed that --90%o of the microspheres present in the dishes after rinsing were taken up intracellularly and resided within the cytoplasm (Fig. 2A). The number of microspheres per cell varied from 0 to 50 and averaged about 20. Fluorescence was strictly colocalized with the microspheres (Fig. 2B) in a ...

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confidence: 99%

Photosensitized destruction of human bladder carcinoma cells treated with chlorin e6-conjugated microspheres.

Bachor

Shea

Gillies

et al. 1991

Proc. Natl. Acad. Sci. U.S.A.

111

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“…Some precedence for the method can be found in the known selective cytotoxic effect of 1A402 formed upon irradiation of sensitizers that are immunochemically targeted to cells. Direct antibody-dye conjugates have been used for in vivo photodynamic therapy (15) and dye-labeled liposomes bound to antibodies exhibit selective in vitro killing of T lymphocytes (16).…”

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confidence: 99%

Luminescent oxygen channeling immunoassay: measurement of particle binding kinetics by chemiluminescence.

Ullman¹,

Kirakossian²,

Singh³

et al. 1994

Proc. Natl. Acad. Sci. U.S.A.

307

232

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A method for monitoring formation of latex particle pairs by chemilumnescence is described. Molecular oxygen is excited by a photosensitizer and an antenna dye that are dissolved in one ofthe particles. 1A02dlffse to the second particle and initiates a hi quantum yield chemilu ent reaction of an olefin that is dissolved in it. An alternative homogeneous method utilizes immunochemical aggregation of ligand-or receptor-labeled particles (latex agglutination) (3). Detection of agglutination by conventional light scattering requires formation of large aggregates and has limited sensitivity. Low-angle light scattering measurements provide higher sensitivity but require rigorously exclusion of adventitious particles (4,5).In the present study, nonenzymatic channeling of 1.02 is used to provide exquisitely sensitive real-time monitoring of particle-particle interactions. The prepared by adding concentrated ammonia to 500-kDadextran (Pharmacia) that had been activated by reaction with epichlorohydrin and Zn(BF4)2. The product was purified by precipitation with methanol. Fluorescein-biotin (Fl-biotin) was prepared by 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide (EDAC) coupling of Fl-5'-COOH to 1,12-diamino-4,9-dioxadodecane followed by reaction with biotinyl-6-aminohexanoic acid N-hydroxysuccinimide ester (biotin-LC-NHS, Pierce). Bis-(6-hydroxyhexyl) disulfide and 6-amino-

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“…In active target ing, incorporation of liposomes by the target organs and/or cells is accelerated by modulating their surfaces with antibodies (16) or ligands (17). In passive target (19), the probes that are also used for labeling lipophilic membranes (e.g., DiI and 3,3'-dioctadecyloxacarbocyanine) (20), and intracellular pH indicators (e.g., carboxyfluorescein and pyranine) (21,22). The fluorescence of DiI in this study was inde pendent of pH between pH 3.3 and pH 8.9, and the fluorescence in the cells was easily quantified by flow cytometry.…”

Section: Discussionmentioning

confidence: 99%

Fluorescent Probe-Labeled Lipid Microsphere Uptake by Human Endothelial Cells: A Flow Cytometric Study

Suzuki¹,

Takahashi

Matsuki³

et al. 1992

Japanese Journal of Pharmacology

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Lipid microspheres have been used as carriers of drugs such as prostaglandin E, (lipo PGE1) and corticosteroid (liposteroid). Lipo-PGE, is used for the treatment of chronic arterial occlu sive diseases because its activity is far greater than that of free PGE, in vivo. To verify the fact that the drug carriers, lipid microspheres, are preferentially taken up by endothelial cells, we labeled lipid microspheres with a fluorescent probe, DiI (DiI-LM), and observed them in some in vitro models. Stoichiometric fluorescence was obtainable, and the fluorescence was stable between pH 3.3 and pH 8.9. Human umbilical vein endothelial cells and cells of a human endothelial cell line, ECV304, showed increased uptake of DiI-LM, 81% and 61%, respectively. In contrast, uptakes were less than 7% in hu man skin fibroblasts, 3T3 cells, and human neutrophils. Prominent perinuclear fluorescence was also observed in endothelial cells by fluorescence microscopy. DiI-LM and flow cytometric analysis will be useful for studies to elucidate the precise mechanism of the selective accumulation of lipid microspheres by cells in blood vessel walls.

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Selective killing of T lymphocytes by phototoxic liposomes.

Cited by 33 publications

References 32 publications

Photosensitized destruction of human bladder carcinoma cells treated with chlorin e6-conjugated microspheres.

Photosensitized destruction of human bladder carcinoma cells treated with chlorin e6-conjugated microspheres.

Luminescent oxygen channeling immunoassay: measurement of particle binding kinetics by chemiluminescence.

Fluorescent Probe-Labeled Lipid Microsphere Uptake by Human Endothelial Cells: A Flow Cytometric Study

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