Effects of photodynamic therapy combined with methotrexate on C6 rat glioma cells: a preliminary study

This study was undertaken to determine if methotrexate (MTX) is effective against tumor cells surviving photodynamic therapy (PDT). C6 rat glioma cells were exposed to Photofrin and irradiated at 630 nm using power densities of 1.2 or 4.8 J/cm2 to simulate the conditions for cells in solid tumors which survive PDT. Cells were then treated with MTX at 5.0, 0.5, or 0.05 microM concentrations. MTT assay of cell proliferation was performed at 24, 48, 72, and 96 h postirradiation. During the first 48 h of incubation, MTX alone was more effective than PDT and MTX. After 48 h, the combination treatment was more effective. Further studies of combined PDT and chemotherapy are warranted.