Calculation of singlet oxygen dose from photosensitizer fluorescence and photobleaching during mTHPC photodynamic therapy of MLL cells
Calculation of singlet oxygen dose from photosensitizer fluorescence and photobleaching during mTHPC photodynamic therapy of MLL cells
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DOI：
10.1562/2004-07-23-ra-244.1
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发表时间：
2005-01-01
影响因子：
3.3
通讯作者：
Patterson, MS
中科院分区：
文献类型：
--
作者：
Dysart, JS;Singh, G;Patterson, MS
预测光动力疗法（PDT）的治疗结果需要了解所产生的细胞毒性物质的量。已经提出了一种评估PDT疗效的隐式方法，其中使用治疗期间光敏剂（PS）荧光的变化来预测治疗结果。为了研究这一点，进行了体外实验，其中Mat-LyLu细胞在间四（羟基苯基）二氢卟酚（mTHPC）中孵育，然后用652 nm光照射。在治疗期间，独立控制和监测PS浓度、注量率和氧合。在处理期间监测mTHPC的荧光，并且在选定的能量密度水平下，使用集落形成测定法测定细胞活力。使用四种不同的模型计算单线态氧剂量，并与细胞存活率进行比较。对于基于单线态氧介导的PS光漂白的剂量度量，对于所有处理参数，发现细胞存活和单线态氧剂量之间的普遍关系。漂白的浓度依赖性分析表明，单重态氧在细胞内的寿命为0.05-0.25 μ s。每个细胞产生约9 × 10（8）个单重态氧分子，使存活分数减少1/e。
Predicting the therapeutic outcome of photodynamic therapy (PDT) requires knowledge of the amount of cytoxic species generated. An implicit approach to assessing PDT efficacy has been proposed where changes in photosensitizer (PS) fluorescence during treatment are used to predict treatment outcome. To investigate this, in vitro experiments were performed in which Mat-LyLu cells were incubated in meta-tetra(hydroxyphenyl)chlorin (mTHPC) and then irradiated with 652 nm light. PS concentration, fluence rate and oxygenation were independently controlled and monitored during the treatment. Fluorescence of mTHPC was monitored during treatment and, at selected fluence levels, cell viability was determined using a colony-formation assay. Singlet oxygen dose was calculated using four different models and was compared with cell survival. For the dose metric based on singlet oxygen-mediated PS photobleaching, a universal relationship between cell survival and singlet oxygen dose was found for all treatment parameters. Analysis of the concentration dependence of bleaching suggests that the lifetime of singlet oxygen within the cell is 0.05-0.25 mus. Generation of about 9 X 10(8) molecules of singlet oxygen per cell reduces the surviving fraction by 1/e.