An In Vitro Investigation of 5-Aminolevulinic Acid Mediated Photodynamic Therapy in Bone Sarcoma

Photodynamic therapy (PDT) may eradicate residual malignant cells following sarcoma resection, through reactive oxygen species (ROS) mediated cytotoxicity, thus improve clinical outcomes. This study aims to assess the efficacy of 5-aminolevulinic acid (5-ALA) as a photosensitizer in combination with red light (RL) for PDT of bone sarcoma cells in vitro.

Three bone sarcoma cell lines underwent treatment with 5-ALA and RL or sham-RL (SL). 5-ALA uptake was assessed using flow cytometry. Production of ROS was measured using CellROX Green staining and fluorescence microscopy. Cell viability was assessed using Cell Counting Kit-8 assays.

All cell lines showed significant 5-ALA uptake in comparison to the 0 mM control (p < 0.05). Production of ROS was significantly increased in cells treated with 5-ALA and RL, compared to those treated with RL and no 5-ALA or SL (p < 0.05). Viability was significantly reduced in cells treated with 5-ALA and RL, compared to SL (p < 0.05). At 72 h post-treatment, cell viability ranged from 6%-12% in 0.5 mM 5-ALA and RL-treated cells vs. 90%-137% in 0.5 mM 5-ALA and SL-treated cells.

5-ALA-based PDT led to the desired increased production of ROS and reduction in cell viability in all cell lines. These preliminary in vitro results warrant further study with multicellular spheroid or animal models and suggest PDT has potential to be used as an adjuvant therapy to surgical resection in sarcoma management.