Specific intensity imaging for glioblastoma and neural cell cultures with 5-aminolevulinic acid-derived protoporphyrin IX.

The fluorescence of protophorphyrin IX (PpIX) synthesized after incubation with 5-aminolevulinic acid (5-Ala) is used for the intraoperative visualisation of glioma cells in vivo. Such fluorescence may also be useful for the photodynamic therapy (PTD) of gliomas. A significant difference of fluorescence intensity in tumor cells compared to neurons is required for this application. To explore this, eight human glioma cell lines (LN-18, LN-428, U87MG, U373MG, D247MG, U251MG, LN-308, T98G) were compared with human astrocytes (SV-FHAS) and rat neurons after incubation for different periods of time in vitro with 5-Ala (1 mg/ml). Fluorescence intensity profiles were measured by a digital camera comparing glioma cell lines with control cells. All glioma cell lines could be discriminated from neural cells by their intensity of fluorescence by post-hoc tests for pairwise comparisons using Tukey's honestly significant difference test, at the global significance level of 5%. The glioma cell lines showed significant variation in this possibly limiting clinical use of fluorescence as a guide for resection.