The goal of this study is a comparative analysis of the efficiency of the PDT protocols for CT26 tumor model treatment in Balb/c mice employing red and blue light with both topical and intravenous administration of chlorin-based photosensitizers (PSs). The considered protocols include the doses of 250 J/cm² delivered at 660 nm, 200 J/cm² delivered at 405 nm, and 250 J/cm² delivered at both wavelengths with equal energy density contribution. Dual-wavelength fluorescence imaging was employed to estimate both photobleaching efficiency, typical photobleaching rates and the procedure impact depth, while optical coherence tomography with angiography modality (OCT-A) was employed to monitor the tumor vasculature response for up to 7 days after the procedure with subsequent histology inspection. Red light or dual-wavelength PDT regimes with intravenous PS injection were demonstrated to provide the most pronounced tumor response among all the considered cases. On the contrary, blue light regimes were demonstrated to be most efficient among topical application and irradiation only regimes. Tumor size dynamics for different groups is in good agreement with the tumor response predictions based on OCT-A taken in 24h after exposure and the results of histology analysis performed in 7 days after the exposure.

中文翻译：

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基于二氢卟酚类光敏剂的抗肿瘤光动力疗法中的红光和蓝光：通过光学成像方法辅助的对比动物研究

这项研究的目的是对PDT方案在Balb / c小鼠中使用红光和蓝光以及局部和静脉注射二氢卟酚类光敏剂（PSs）进行CT26肿瘤模型治疗的效率进行比较分析。所考虑的方案包括在660 nm处递送250 J / cm ²，在405 nm处递送200 J / cm ²以及250 J / cm ²的剂量以相同的能量密度贡献在两个波长下发射。采用双波长荧光成像来评估光漂白效率，典型的光漂白速率和手术影响深度，同时采用光学相干断层扫描和血管造影方法（OCT-A）监测手术后长达7天的肿瘤血管反应以及随后的组织学检查。在所有考虑到的病例中，静脉注射PS的红光或双波长PDT疗法被证明可提供最明显的肿瘤反应。相反，在局部施用和仅辐照方案中，蓝光方案被证明是最有效的。