Photosensitizer targeting: mitochondria-targeted photosensitizer enhances photodynamic effect and apoptosis

Using multiphoton laser scanning imaging microscopy the effects of subcellular localized PDT with the photosensitizer BPD-MA was studied in different cellular compartments including the mitochondria, the cytosol and the nucleus. Specifically, mitochondrial reactive oxygen species (mROS) and mitochondrial free calcium (mCa²⁺) were measured simultaneously during PDT with BPD-MA induced mitochondrial dysfunction. Intriguingly, PDT with BPD-MA-induced mROS formation and mCa²⁺ elevation as well as apoptotic death were found only when the mitochondrial compartment was illuminated. These data suggest that PDT with a mitochondria targeted photosensitizer can extensively enhance the efficacy of PDT via mROS and mCa²⁺-mediated apoptotic mechanisms.