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Pires L, Khattak S, Pratavieira S, Calcada C, Romano R, Yucel Y, Bagnato VS, Kurachi C, Wilson BC. Femtosecond pulsed laser photodynamic therapy activates melanin and eradicates malignant melanoma. Proc Natl Acad Sci U S A 2024; 121:e2316303121. [PMID: 38551838 PMCID: PMC10998568 DOI: 10.1073/pnas.2316303121] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2023] [Accepted: 01/14/2024] [Indexed: 04/02/2024] Open
Abstract
Photodynamic therapy (PDT) relies on a series of photophysical and photochemical reactions leading to cell death. While effective for various cancers, PDT has been less successful in treating pigmented melanoma due to high light absorption by melanin. Here, this limitation is addressed by 2-photon excitation of the photosensitizer (2p-PDT) using ~100 fs pulses of near-infrared laser light. A critical role of melanin in enabling rather than hindering 2p-PDT is elucidated using pigmented and non-pigmented murine melanoma clonal cell lines in vitro. The photocytotoxicities were compared between a clinical photosensitizer (Visudyne) and a porphyrin dimer (Oxdime) with ~600-fold higher σ2p value. Unexpectedly, while the 1p-PDT responses are similar in both cell lines, 2p activation is much more effective in killing pigmented than non-pigmented cells, suggesting a dominant role of melanin 2p-PDT. The potential for clinical translational is demonstrated in a conjunctival melanoma model in vivo, where complete eradication of small tumors was achieved. This work elucidates the melanin contribution in multi-photon PDT enabling significant advancement of light-based treatments that have previously been considered unsuitable in pigmented tumors.
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Affiliation(s)
- Layla Pires
- Department of Cancer Biology and Imaging, Princess Margaret Cancer Center, University Health Network, Toronto, ONM5G 1L7, Canada
- Departamento de Fisica e Ciencia dos Materiais, São Carlos Institute of Physics, University of São Paulo, Sao Carlos13566-590, Brazil
| | - Shireen Khattak
- Departments of Ophthalmology & Vision Sciences, St. Michael’s Hospital, University of Toronto, Toronto, ONM5B 1W8, Canada
| | - Sebastiao Pratavieira
- Departamento de Fisica e Ciencia dos Materiais, São Carlos Institute of Physics, University of São Paulo, Sao Carlos13566-590, Brazil
| | - Carla Calcada
- Department of Cancer Biology and Imaging, Princess Margaret Cancer Center, University Health Network, Toronto, ONM5G 1L7, Canada
| | - Renan Romano
- Departamento de Fisica e Ciencia dos Materiais, São Carlos Institute of Physics, University of São Paulo, Sao Carlos13566-590, Brazil
| | - Yeni Yucel
- Departments of Ophthalmology & Vision Sciences, St. Michael’s Hospital, University of Toronto, Toronto, ONM5B 1W8, Canada
- Faculty of Medicine, Department of Ophthalmology, Ophthalmology and Visual Sciences, University of British Columbia, Vancouver, BCV5Z 3N9, Canada
| | - Vanderlei S. Bagnato
- Departamento de Fisica e Ciencia dos Materiais, São Carlos Institute of Physics, University of São Paulo, Sao Carlos13566-590, Brazil
- Department of Biomedical Engineering, Texas A&M University, College Station, TX77843
| | - Cristina Kurachi
- Departamento de Fisica e Ciencia dos Materiais, São Carlos Institute of Physics, University of São Paulo, Sao Carlos13566-590, Brazil
| | - Brian C. Wilson
- Department of Cancer Biology and Imaging, Princess Margaret Cancer Center, University Health Network, Toronto, ONM5G 1L7, Canada
- Faculty of Medicine, Department of Medical Biophysics, University of Toronto, Toronto, ONM5G 1L7, Canada
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