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Photodynamic therapy of ocular melanoma with bis silicon 2,3-naphthalocyanine in a rabbit model
R A Hill1, S Reddi, M E Kenney
1Department of Ophthalmology, University of California, Irvine 92717, USA.
Purpose:
To investigate bis (tri-n-hexylsiloxy) silicon 2,3-naphthalocyanine (SINc; 0.5 mg/kg) for photodynamic therapy of an experimental ocular melanoma in pigmented rabbits.
Methods:
SINc was dissolved in canola oil by heating, emulsified with Tween 80, and administered by ear vein. Pharmacokinetics were studied in frozen tumor sections by fluorescence microscopy using a charge coupled device, camera-based, low-light detection system with digital image processing at 1 and 24 hours. A Ti:sapphire laser and a microlens were used to deliver the light (770 nm; 40 mW/cm2; 20 J/cm2). A control rabbit received light without SINc.
Results:
Localization studies of SINc showed intravascular distribution shifting to a tumor stromal and perivascular distribution 24 hours after treatment. Tissue thermal damage after irradiation was minimal in the control. Exudative retinal detachments were not observed. Tumor destruction was observed, with sharp demarcation to a depth of 3.5 mm.
Conclusions:
Tumor light penetration was good at 770 nm, and thermal effects from the exciting light alone were minimal. Photodynamic therapy with SINc resulted in localized tumor destruction reflecting the light beam path without damage to adjacent tissue or intraocular complications.
Insights
Photodynamic therapy using bis(tri-n-hexylsiloxy) silicon 2,3-naphthalocyanine (SINc) effectively destroyed ocular melanoma in rabbits. This treatment showed good light penetration and minimal thermal damage, preserving adjacent tissues.
Area of Science:
- Ophthalmology
- Oncology
- Photodynamic Therapy
Background:
- Ocular melanoma is a significant challenge in ophthalmology.
- Photodynamic therapy (PDT) offers a targeted treatment approach.
Purpose of the Study:
- To evaluate bis(tri-n-hexylsiloxy) silicon 2,3-naphthalocyanine (SINc) for PDT in experimental ocular melanoma.
- To assess the efficacy and safety of SINc-mediated PDT in pigmented rabbits.
Main Methods:
- SINc was administered intravenously and its pharmacokinetics studied via fluorescence microscopy.
- Tumor irradiation was performed using a Ti:sapphire laser at 770 nm.
- A control group received light treatment without SINc.
Main Results:
- SINc localized to tumor stroma and perivascular areas within 24 hours.
- Irradiation resulted in minimal thermal damage and no exudative retinal detachments.
- Localized tumor destruction up to 3.5 mm depth was observed, correlating with the light beam path.
Conclusions:
- 770 nm light demonstrated good tumor penetration with minimal thermal effects.
- SINc-mediated PDT achieved localized ocular melanoma destruction without damaging surrounding tissues or causing intraocular complications.