5-Aminolevulinic Acid-Mediated Photodynamic Therapy of Human Glioma Cells In Vitro

OBJECTIVE To investigate the effect of 5-aminolevulinic acid (ALA)-mediated photodynamic therapy (PDT) on U251 human glioma cells in vitro. METHODS U251 human glioma cells were routinely cultured and then treated with ALA, a type of photosensitizer, at various concentrations followed by light irradiation. The PDT-induced phototoxicity of the cells was determined by a MTT assay. In addition, cells were treated with ALA at a fixed concentration and subjected to various doses of light irradiation. RESULTS With the same light dosage (25.0 J/cm2), the cell survival rates were 70.16%+_5.02%, 50.19%+_4.79%, 34.97%+5.34%, 27.04%+-4.34%, and 24.26 % _+2.76 % at ALA concentrations of 0.25, 0.5, 1.0, 2.0, and 4.0 mM, respectively (F =279.88, P=0.0000). But the survival rates of the cells incubated with 2.0 mM ALA compared to those with 4.0 mM ALA (27.04%+-4.34 % vs 24.26%+2.76%) showed no significant difference (P=0.611). At a single ALA concentration, the cell survival rates were 83.48 % +- 6.79%, 68.09%+6.02%, 33.75%+- 6.70%, 23.34%+ 5.08 % and 15.14%+ 3.60 % fo