Tumor Po₂ changes during photodynamic therapy depend upon photosensitizer type and time after injection

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• 作者：Pogue ; Brian W. ; O'Hara ; Julia A. ; Goodwin ; Isak A. ; Wilmot ; Carmen J. ; Fournier ; Gregory P. ; et. al.
• 关键词：Photodynamic ; EPR ; Benzoporphyrin derivative ; Po₂ ; Oxygen ; Photochemotherapy ; RIF-1 tumor ; Singlet oxygen
• 刊名：Comparative Biochemistry and Physiology - Part A: Molecular & Integrative Physiology
• 出版年：2002
• 出版时间：May, 2002
• 年：2002
• 卷：132
• 期：1
• 页码：177-184
• 全文大小：296 K

文摘

In this study, the vascular and tissue oxygen changes induced by photodynamic therapy in the RIF-1 tumor were examined, using electron paramagnetic resonance (EPR) oximetry. Two photosensitizers, including verteporfin (BPD-MA in a lipid-based formulation) and aminolevulinic acid-induced protoporphyrin IX (ALA-PPIX), were investigated with optical irradiation, sufficient to induce sub-curative damage in the tumor tissue, and the transient changes in Po₂ and vascular perfusion were examined. A large increase in tissue oxygenation (from 3 up to 9.5 mmHg) was observed when treated with ALA-PPIX based photodynamic therapy, which lasted during the treatment and a small residual increase that returned back to baseline levels by 48 h after treatment. With verteporfin-based photodynamic therapy, one group of animals was irradiated 15 min after injection and exhibited a small decrease in oxygenation relative to pre-irradiation levels. The second group was irradiated at 3 h after injection and exhibited a large increase in the average Po₂, (from 3 to 15 mmHg) by the end of the treatment. These observations indicate that photodynamic therapy significantly increases tissue Po₂ under certain treatment conditions, with the potential cause being either increased local blood flow or decreased local oxygen metabolic consumption due to cellular damage.