gms | German Medical Science

Objective: Chordoma is a locally aggressive, osteodestructive and metastasizing tumor. Current adjuvant treatment is ineffective. New effective treatment modalities have to be explored. 5-ALA PDT has shown promise in proof of principle- experiments with im-mortalized human chordoma cell lines. The objective was to confirm these findings in primary cells and to report interim results.

Methods: Tissue samples from 2 different chordoma patients were harvested and processed for cultivation according to a lab internal adapted protocol. Then cells were incubated with different 5-ALA concentrations for 6h and afterwards exposed to PDT (diode laser for 625 seconds at λ=635 nm with 15,6 J/cm2). Negative control groups were also realized. Cell viability was assessed by WST-1 assay.

Results: Cultivation of primary chordoma cells was successful. The higher the number of passage, the shorter the doubling-time of the two primary chordoma cell cultures. Initially, doubling-time was 28 days. Cells from the fifth passage reached a doubling- time of about 10 days. Light-microscopy confirmed typical morphology for chordoma cells, so-called physaliphorous cells (Figure 1 [Fig. 1], Figure 2 [Fig. 2]). Tumor cells were significantly destroyed by 5-ALA PDT. Cell viability of primary cells, established from tissue samples of the first chordoma was significantly lower at higher 5-ALA concentrations (ANOVA; p≤0.001 for ≥30 ug/ml ALA). Primary cells from tumor tissue of the second chordoma operation are currently in period of cultivation.

Conclusion: Two primary chordoma cell cultures based on intra-operatively resected tumor tissue could successfully be established. The presented in vitro-model allowed analysis of successful 5-ALA PDT in individual patient’s tissue. Further, experiments with different parameters like co-drugs, different incubation time and laser parameters are planned. This research avenue harbors great potential for future adjuvant therapy of chordomas.