Acute morphological sequelae of photodynamic therapy with 5-aminolevulinic acid in the C6 spheroid model

• Published in: Journal of neuro-oncology 2007-03, Vol.82 (1), p.49-60
• Main Authors: Zelenkov, Pitr, Baumgartner, Reinhold, Bise, Karl, Heide, Michael, Meier, Richard, Stocker, Susanne, Sroka, Ronald, Goldbrunner, Roland, Stummer, Walter
• Format: Article
• Language: English
• Subjects: Aminolevulinic Acid - pharmacology; Animals; Apoptosis - drug effects; Brain Neoplasms - drug therapy; Brain Neoplasms - pathology; Glioma - drug therapy; Glioma - pathology; Mice; Photochemotherapy; Photosensitizing Agents - pharmacology; Spheroids, Cellular - drug effects; Spheroids, Cellular - pathology; Tumor Cells, Cultured
• ISSN: 0167-594X; 1573-7373
• DOI: 10.1007/s11060-006-9252-8

Aminolevulinic acid (ALA)-mediated photodynamic therapy (PDT) may represent a treatment option for malignant brain tumors. We used a three-dimensional cell culture system, the C6 glioma spheroid model, to study acute effects of PDT and how they might be influenced by treatment conditions. Spheroids were incubated for 4 h in 100 microg/ml ALA in 5% CO(2) in room air or 95% O(2) with subsequent irradiation using a diode laser (lambda = 635 nm, 40 mW/cm(2), total fluence 25 J/cm(2)). Control groups were "laser only", "ALA only", and "no drug no light". Annexin V-FITC, a marker used for detection of apoptosis, propidium iodide (PI), a marker for necrotic cells and H 33342, a chromatin stain, were used for morphological characterization of PDT effects by confocal laser scanning and fluorescence microscopy. Hematoxylin-eosin staining and TdT-FragEL (TUNEL) assay were used on cryosections. Growth kinetics were followed for 8 days after PDT. PDT after incubation in 5% CO(2) provided incomplete cell death and growth delay in spheroids of >350 microm diameter. However, complete cell death and growth arrest occurred in smaller spheroids (