Iron availability to cells may be modified in the tumour microenvironment, which may be involved in treatment response. Iron availability affects the conversion of protoporphyrin IX to heme, which likely determines the efficacy of aminolevulinic acid-based photodynamic therapy (ALA-based PDT). We compared photoinactivation efficacy in three oesophageal cell lines in culture media differing in iron content, DMEM and RPMI 1640, and in RPMI 1640 supplemented with iron to understand the importance of iron presence for ALA-based PDT outcome. ALA-based PDT was more efficacious in DMEM than in RPMI 1640 in all tested cell lines. Consistently, the highest protoporphyrin IX fluorescence signals, indicating the highest level of protoporphyrin IX production, were detected from cell colonies incubated in DMEM compared to those incubated in RPMI 1640 irrespective of iron presence. Components in the culture media other than iron ions are likely to be responsible for the observed differences in two culture media. Nevertheless, iron supplementation to RPMI 1640 showed that the presence of ferric ions in the concentration range 0–8 mg/l affected ALA-based PDT efficacy in a cell type-dependent manner. In poorly differentiated carcinoma cells, the increased efficacy of ALA-induced photoinactivation in the presence of 0.1 mg/l of supplemented iron was found. At the same iron concentration, the slightly different mitochondrial potential at no modifications of the iron labile pool was observed. The efficacy of ALA-based PDT in vitro depends on the choice of culture medium and the presence of iron ions in culture medium depending on intrinsic properties of cells.

在肿瘤微环境中可能会改变铁的细胞利用率，这可能与治疗反应有关。铁的可用性影响原卟啉IX向血红素的转化，这很可能决定了基于氨基乙酰丙酸的光动力疗法（基于ALA的PDT）的功效。我们比较了三种食道细胞系中铁含量不同的培养基，DMEM和RPMI 1640以及补充铁的RPMI 1640中的光灭活功效，以了解铁的存在对基于ALA的PDT结果的重要性。在所有测试的细胞系中，基于ALA的PDT在DMEM中比在RPMI 1640中更有效。一致地，原卟啉IX的荧光信号最高，表明原卟啉IX的产生水平最高，与在RPMI 1640中温育的细胞集落相比，在DMEM中温育的细胞集落中检测到的铁离子，与铁的存在无关。除铁离子外，培养基中的其他成分可能是两种培养基中观察到的差异的原因。但是，向RPMI 1640补充铁表明，浓度范围为0-8 mg / l的铁离子以细胞类型依赖性方式影响基于ALA的PDT功效。在低分化的癌细胞中，发现在添加铁0.1 mg / l的情况下，ALA诱导的光灭活的功效增强。在相同的铁浓度下，在不改变铁不稳定池的条件下，观察到了稍微不同的线粒体电位。