In vitro photodynamic therapy on human U251 glioma cells with a novel photosensitiser ZnPcS4-BSA

Abstract

This article reports the phototoxicity effects of a novel photosensitiser ZnPcS4-BSA on human U251 glioma cells in vitro. The cellular uptake of ZnPcS4-BSA by U251 glioma cells was quantified by UV-spectra, and the optimal incubation time was determined. Human U251 glioma cells were incubated in ZnPcS4-BSA of various concentrations, and received laser irradiation of different energy densities. Cell survival rates were measured by CCK-8 assay. Flow cytometer was used to detect apoptosis. Expression of vascular endothelial growth factor (VEGF) gene was detected by real-time PCR in U251 cells after photodynamic therapy (PDT), and β-actin was used as an internal standard. The normal U251 cells severed as controls. Results indicate that the uptake of ZnPcS4-BSA by U251 glioma cells reaches maximum after incubation for 4 hours. ZnPcS4-BSA with different concentrations without light irradiation has no significant effects on cell survival rates. Without ZnPcS4-BSA incubation, cell survival rate of high-dose group (400 J/cm²) is the lowest, whereas no significant difference has been found between any other two groups. At laser irradiation of 150 J/cm², inhibition rates of the cells increase with ZnPcS4-BSA concentration, and half-inhibitory concentration (IC50) is 0.16 μmol/L. Apoptosis rate of the cells after PDT is significantly higher than that of the control group (p < 0.01). The VEGF expression in the cells increases 5.616 times after PDT. The novel ZnPcS4-BSA is a good photosensitiser for PDT towards U251 glioma cells. The ZnPcS4-BSA based PDT can induce effective apoptosis.

Key words:

• ZnPcS4-BSA
• U251 glioma cells
• photodynamic therapy

Acknowledgements

Financial support from the National Natural Science Foundation of China (No. 20604007) is gratefully acknowledged.