5-Aminolevulinic acid-based photodynamic therapy of chordoma: In vitro experiments on a human tumor cell line

Jan F Cornelius; Lennert Eismann; Lara Ebbert; Brigitte Senger; Athanasios K Petridis; Marcel Alexander Kamp; Rüdiger V Sorg; Hans Jakob Steiger

doi:10.1016/j.pdpdt.2017.09.011

5-Aminolevulinic acid-based photodynamic therapy of chordoma: In vitro experiments on a human tumor cell line

Photodiagnosis Photodyn Ther. 2017 Dec:20:111-115. doi: 10.1016/j.pdpdt.2017.09.011. Epub 2017 Sep 22.

Authors

Jan F Cornelius¹, Lennert Eismann², Lara Ebbert³, Brigitte Senger², Athanasios K Petridis⁴, Marcel Alexander Kamp⁴, Rüdiger V Sorg³, Hans Jakob Steiger⁴

Affiliations

¹ Department of Neurosurgery, Medical Faculty, Heinrich Heine University, Moorenstrasse 5, 40225, Düsseldorf, Germany. Electronic address: cornelius@hhu.de.
² Department of Neurosurgery, Medical Faculty, Heinrich Heine University, Moorenstrasse 5, 40225, Düsseldorf, Germany; Neuro-oncological Research Laboratory, Medical Faculty, Heinrich Heine University, Moorenstrasse 5, 40225, Düsseldorf, Germany.
³ Institute for Transplantation Diagnostics and Cell Therapeutics, Medical Faculty, Heinrich Heine University, Moorenstrasse 5, 40225, Düsseldorf, Germany.
⁴ Department of Neurosurgery, Medical Faculty, Heinrich Heine University, Moorenstrasse 5, 40225, Düsseldorf, Germany.

PMID: 28951177
DOI: 10.1016/j.pdpdt.2017.09.011

Abstract

Background: Chordomas are very rare tumors of the skull base and the sacrum. They show infiltrating and destructive growth and are known to be chemo- and radio-resistant. After surgical resection, the recurrence rate is high and overall survival limited. As current adjuvant treatments are ineffective, new treatment concepts are urgently needed. 5-aminolevulinic acid-based photodynamic therapy (5-ALA based PDT) showed promising results for malignant gliomas. However, it is unknown so far, whether chordomas accumulate protoporphyrin IX (PPIX) after application of 5-ALA and whether they are sensitive to subsequent 5-ALA based PDT.

Methods: The immortalized human chordoma cells U-CH2 were used as in vitro model. After incubation for 4h or 6h with different 5-ALA concentrations, PPIX accumulation was determined by flow cytometry. To assess sensitivity to PDT, chordoma cells were incubated at 30.000cells/well (high cell density) or 15.000cells/well (low cell density) with graded doses of 5-ALA (0-50μg/ml) in 96-well plates and subsequently exposed to laser light of 635nm wavelength (18.75J/cm²). Cell survival was measured 24h after exposure to laser light using the WST-1 assay.

Results: U-CH2 cells dose-dependently accumulated PPIX (ANOVA; p<0.0001). PPIX fluorescence was significantly higher, when cells were incubated with 5-ALA for 6h compared to 4h at higher 5-ALA concentrations (ANOVA/Bonferroni; p≤0.05 for≥30μg/ml 5-ALA). For both cell densities, a 5-ALA dose-dependent decline in viability was observed (ANOVA; p<0.0001). Viability was significantly lower at higher 5-ALA concentrations, when 30.000 cells/wells were treated compared to 15.000cells/well (ANOVA/Bonferroni; p≤0.001 for≥30μg/ml 5-ALA). LD50 was 30.25μg/ml 5-ALA.

Conclusion: The human UCH-2 cell line was a very useful in vitro model to study different effects of 5-ALA based PDT. For the first time, it could be shown that human chordoma cells may be destroyed by 5-ALA/PDT.

Keywords: 5-ALA; Adjuvant; Chordoma; PDT; Photodynamic therapy; Skull base.

MeSH terms

Aminolevulinic Acid
Cell Line, Tumor
Chordoma / pathology*
Chordoma / surgery
Dose-Response Relationship, Drug
Humans
Levulinic Acids / pharmacology*
Neoplasm Invasiveness
Neurosurgical Procedures / methods
Optical Imaging / methods*
Photochemotherapy / methods*
Photosensitizing Agents / pharmacology*
Protoporphyrins / pharmacokinetics*

Substances

Levulinic Acids
Photosensitizing Agents
Protoporphyrins
protoporphyrin IX