Quantitative in vitro demonstration of two-photon photodynamic therapy using photofrin and visudyne.
Photodynamic therapy (PDT), the combined action of a photosensitizer and light to produce a cytotoxic effect, is an approved therapy for a number of diseases. At present, clinical PDT treatments involve one-photon excitation of the photosensitizer. A major limitation is that damage may be caused to...
| Main Authors: | , , , , , |
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| Format: | Journal article |
| Language: | English |
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2007
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| _version_ | 1826302741377449984 |
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| author | Khurana, M Collins, H Karotki, A Anderson, H Cramb, D Wilson, B |
| author_facet | Khurana, M Collins, H Karotki, A Anderson, H Cramb, D Wilson, B |
| author_sort | Khurana, M |
| collection | OXFORD |
| description | Photodynamic therapy (PDT), the combined action of a photosensitizer and light to produce a cytotoxic effect, is an approved therapy for a number of diseases. At present, clinical PDT treatments involve one-photon excitation of the photosensitizer. A major limitation is that damage may be caused to healthy tissues that have absorbed the drug and lie in the beam path. Two-photon excitation may minimize this collateral damage, as the probability of absorption increases with the square of the light intensity, enabling spatial confinement of the photosensitizer activation. A potential application is the treatment of the wet-form of age-related macular degeneration, the foremost cause of central vision loss in the elderly. Herein, the commercial photosensitizers Visudyne and Photofrin are used to demonstrate quantitative in vitro two-photon PDT. A uniform layer of endothelial cells (YPEN-1) was irradiated with a Ti:sapphire laser (300 fs, 865 nm, 90 MHz) using a confocal scanning microscope. Quantification of the two-photon PDT effect was achieved using the permeability stain Hoechst 33258 and a SYTOX Orange viability stain. Visudyne was found to be around seven times more effective as a two-photon photosensitizer than Photofrin under the conditions used, consistent with its higher two-photon absorption cross-section. We also demonstrate for the first time the quadratic intensity dependence of cellular two-photon PDT. This simple in vitro method for quantifying the efficacy of photosensitizers for two-photon excited PDT will be valuable to test specifically designed two-photon photosensitizers before proceeding to in vivo studies in preclinical animal models. |
| first_indexed | 2024-03-07T05:52:09Z |
| format | Journal article |
| id | oxford-uuid:e942f896-9d8d-4f54-b6db-94821fecef7d |
| institution | University of Oxford |
| language | English |
| last_indexed | 2024-03-07T05:52:09Z |
| publishDate | 2007 |
| record_format | dspace |
| spelling | oxford-uuid:e942f896-9d8d-4f54-b6db-94821fecef7d2022-03-27T10:52:56ZQuantitative in vitro demonstration of two-photon photodynamic therapy using photofrin and visudyne.Journal articlehttp://purl.org/coar/resource_type/c_dcae04bcuuid:e942f896-9d8d-4f54-b6db-94821fecef7dEnglishSymplectic Elements at Oxford2007Khurana, MCollins, HKarotki, AAnderson, HCramb, DWilson, BPhotodynamic therapy (PDT), the combined action of a photosensitizer and light to produce a cytotoxic effect, is an approved therapy for a number of diseases. At present, clinical PDT treatments involve one-photon excitation of the photosensitizer. A major limitation is that damage may be caused to healthy tissues that have absorbed the drug and lie in the beam path. Two-photon excitation may minimize this collateral damage, as the probability of absorption increases with the square of the light intensity, enabling spatial confinement of the photosensitizer activation. A potential application is the treatment of the wet-form of age-related macular degeneration, the foremost cause of central vision loss in the elderly. Herein, the commercial photosensitizers Visudyne and Photofrin are used to demonstrate quantitative in vitro two-photon PDT. A uniform layer of endothelial cells (YPEN-1) was irradiated with a Ti:sapphire laser (300 fs, 865 nm, 90 MHz) using a confocal scanning microscope. Quantification of the two-photon PDT effect was achieved using the permeability stain Hoechst 33258 and a SYTOX Orange viability stain. Visudyne was found to be around seven times more effective as a two-photon photosensitizer than Photofrin under the conditions used, consistent with its higher two-photon absorption cross-section. We also demonstrate for the first time the quadratic intensity dependence of cellular two-photon PDT. This simple in vitro method for quantifying the efficacy of photosensitizers for two-photon excited PDT will be valuable to test specifically designed two-photon photosensitizers before proceeding to in vivo studies in preclinical animal models. |
| spellingShingle | Khurana, M Collins, H Karotki, A Anderson, H Cramb, D Wilson, B Quantitative in vitro demonstration of two-photon photodynamic therapy using photofrin and visudyne. |
| title | Quantitative in vitro demonstration of two-photon photodynamic therapy using photofrin and visudyne. |
| title_full | Quantitative in vitro demonstration of two-photon photodynamic therapy using photofrin and visudyne. |
| title_fullStr | Quantitative in vitro demonstration of two-photon photodynamic therapy using photofrin and visudyne. |
| title_full_unstemmed | Quantitative in vitro demonstration of two-photon photodynamic therapy using photofrin and visudyne. |
| title_short | Quantitative in vitro demonstration of two-photon photodynamic therapy using photofrin and visudyne. |
| title_sort | quantitative in vitro demonstration of two photon photodynamic therapy using photofrin and visudyne |
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