The second generation
photosensitizer mTHPC was approved by the European Medicines Agency (EMA) for the
palliative treatment of advanced
head and neck cancer in October 2001. It is known that
mTHPC possesses a significant
phototoxicity against a variety of human
cancer cells in vitro but also exhibits dark toxicity and can cause adverse effects (especially skin
photosensitization). Due to its poor water solubility, the administration of hydrophobic
photosensitizer still presents several difficulties. To overcome the administration problems, the use of nanoparticles as
drug carrier systems is much investigated. Nanoparticles based on
poly(lactic-co-glycolic acid) (PLGA) have been extensively studied as delivery systems into tumours due to their biocompatibility and biodegradability. The goal of this study was the comparison of free
mTHPC and
mTHPC-loaded PLGA nanoparticles concerning cytotoxicity and intracellular accumulation in human colon
carcinoma cells (HT29). The nanoparticles delivered the
photosensitizer to the colon
carcinoma cells and enabled drug release without losing its activity. The cytotoxicity assays showed a time- and concentration-dependent decrease in cell proliferation and viability after illumination. However, first and foremost
mTHPC lost its dark toxic effects using the PLGA nanoparticles as a
drug carrier system. Therefore, PLGA nanoparticles are a promising
drug carrier system for the hydrophobic
photosensitizer mTHPC.