5-aminolevulinic acid (ALA) mediated photodynamic therapy of bladder cancer cell lines

Topical application of 5-aminolevulinic acid (ALA) can be effectively used for photodynamic therapy and diagnosis of superficial bladder cancer. Administration of the heme precursor ALA leads to the selective accumulation of the photosensitizer protoporphyrin IX (PPIX) in certain types of tissue. The aim of this study was to determine the cellular PPIX concentration and the effect of photodynamic therapy mediated by ALA on two bladder cancer cell lines (RT4, J82) and a fibroblast cell line (N1). Following incubation with ALA the kinetics of cellular PPIX were examined using flow cytometry combined with extraction. The cancer cell lines showed considerably higher PPIX concentrations than the fibroblast cell line: RT4 1030, J82 710, and N1 110 ng PPIX/mg protein. Photodynamic therapy was performed with an incoherent light source (580 - 740 nm, 40 mW/cm2, 30 J/cm2). In contrast to the fibroblast cell line, which was resistant to photodynamic therapy, the cancer cell lines were effectively killed following the treatment as determined by MTT assay. This study suggests that ALA-mediated photodynamic therapy may be effective in transitional cell carcinoma of the bladder. Based on these findings, this therapeutic method should be further evaluated clinically.