Effect of photodynamic therapy on glioblastoma cell lines

Abstract

Photodynamic therapy (PDT) utilises light-activated activation of 5-aminolevulinic acid (5-ALA) to reduce the viability of glioblastoma (GBM) cells. Primary patient-derived cell lines Ox5 core and G7 were exposed to light excitation at 410 nm, 528 nm & 810 nm wavelengths +/- 5-ALA (protoporphyrin IX). The primary objective is to evaluate whether PDT +/- 5-ALA is effective in reducing cell viability and clonogenic expansion, relative to the standard of care in (Temozolomide +/- Radiotherapy).

Results demonstrated significant cell death >70% in Ox5 after PDT/ 410nm + 5-ALA 50uM, and >23% in G7 cells utilising the MTT viability assay (n=4), p< 0.05, 0.001.

Clonogenic assays using G7 cells showed a severe inhibition of clonogenic potential upon PTD (PDT/410nm + 5-ALA 50uM) therapy. Apoptosis was detected in both, Ox5 core and G7 using immunohistochemistry for cleaved caspase-3. Additionally, the standard of care (TMZ monotherapy) was tested, and 4 biological repeats demonstrated no statistical significance, p>0.05, on the relative viability of Ox5 or G7 cells. Clonogenic assays treated with the standard of care regime (TMZ+/-Radiotherapy) demonstrated remaining colonies at the higher doses of radiation (4 & 6 Gy). Therefore, PDT/410nm + 5-ALA 50uM causes cell death in Ox5 and G7 cells offering a potential novel therapy in the treatment of GBM.