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19 July 1994 Delta-aminolevulinic acid as a photosensitizer precursor for the treatment of hepatoma cells in vitro
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Delta-aminolevulinic acid ((delta) -ALA) has been recently proposed as a tumor photosensitizer precursor with increased selectivity and decreased toxicity for the treatment of neoplasms. We investigated the conversion and cytotoxicity of (delta) -ALA in a human hepatoma cell line to determine its clinical potential. SK-HEP-1 (ATCC) cells were plated on 35 mm coverslips in media for use in a digital fluorescence microscopic imaging system. (delta) -ALA was added to achieve final concentrations between 0-5 mM. Cells were excited with 450-490 nm light while a 610 nm long pass filter was used to assess fluorescence from conversion to protoporphyrin IX, the putative photosensitizer. After maximal fluorescence was obtained at each initial concentration of (delta) -ALA, cells were radiated with 10 J/cm2 of light from a xenon lamp fitted with a 515 nm band pass filter. After photoradiation, cell death was assessed by flow cytometry using propidium iodide labeling. Protoporphyrin IX accumulation was constant at Ksequals0.001 until a plateau was achieved 2 hours after the addition of (delta -ALA. Photoradiation with 10 J/cm2 at a concentration of 1 mM (delta ALA resulted in a linear increase in cell death over time with 5% cell death at 2 hours and 12% at 5 hours compared to controls. Interestingly, controls with (delta) -ALA alone demonstrated a cytoprotective effect with a logarithmic relationship between increasing cell survival and increasing dose of drug.
© (1994) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
Mark A. Laukka and Kenneth K. Wang "Delta-aminolevulinic acid as a photosensitizer precursor for the treatment of hepatoma cells in vitro", Proc. SPIE 2133, Optical Methods for Tumor Treatment and Detection: Mechanisms and Techniques in Photodynamic Therapy III, (19 July 1994);

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