Tetrahydroporphyrin-Tetratosylat (THPTS): A near-infrared photosensitizer for targeted and efficient photodynamic therapy (PDT) of human bladder carcinoma. An in vitro study

Efficacy of PDT in muscle-invasive bladder cancer is hampered by low tissue penetration of most photosensitizers by short excitation wavelength. THPTS is excitable at near-infrared (760nm) allowing tissue penetration up to 15mm. We examined the cellular effects of THPTS-PDT in human bladder cancer cells.

We used four human transitional carcinoma cell lines, epithelial bladder progenitors (HBLAK) and bladder smooth muscle cells (HBSMC). We used flow cytometry to examine pharmacokinetics of THPTS, confocal laser scanning microscopy to analyze subcellular localization and production of reactive oxidative species (ROS), examined cytotoxicity and cell death pathways (qRT-PCR).

Total uptake varied between cell lines and was significantly high in HBLAK and HBSMC. Lysosomal localization was mainly seen in cancer cells and HBLAK, while THPTS was distributed throughout the cytoplasm in HBSMC. Significant ROS production was detected 30min after THPTS-PDT. Growth arrest occurred within 4h and resulted in apoptotic and necrotic cytotoxicity after 24h. Cytotoxicity was dose-dependent and specifically high in cancer cells and HBLAK and significantly low in HBSMC.

THPTS-PDT induces cellular mechanisms leading to cellular growth arrest, apoptosis and necrosis in human bladder cancer cells. These effects are only partly dependent on the total amount of THPTS uptake and rather dependent on its subcellular compartmentalization. HBSMC are hardly affected by THPTS-PDT confirming tumor specificity and safety. THPTS is a promising new photosensitizer with the unique advantage of deep tissue penetration allowing the treatment of solid tumors and warranting further animal studies.

Photodiagnosis and photodynamic therapy. 2017 Mar 06 [Epub ahead of print]

Mandy Berndt-Paetz, Annett Weimann, Nadine Sieger, Stanislaw Schastak, Yasser M Riyad, Jan Griebel, Vinodh K A Arthanareeswaran, Jens-Uwe Stolzenburg, Jochen Neuhaus

Department of Urology, Research Laboratories, University of Leipzig, Leipzig, Germany. Electronic address: ., Department of Urology, Research Laboratories, University of Leipzig, Leipzig, Germany. Electronic address: ., Department of Urology, University Hospital Leipzig, Leipzig, Germany. Electronic address: ., Laser Medizin Zentrum Leipzig, Leipzig, Germany. Electronic address: ., Leibniz Institute of Surface Modification (IOM), Leipzig, Germany; Department of Chemistry, Faculty of Science, Al-Azhar University, Nasr City, 11884, Cairo, Egypt. Electronic address: ., Leibniz Institute of Surface Modification (IOM), Leipzig, Germany. Electronic address: ., Department of Urology, Jahn Ferenc South Pest Teaching Hospital, Budapest, Hungary. Electronic address: ., Department of Urology, University Hospital Leipzig, Leipzig, Germany. Electronic address: ., Department of Urology, Research Laboratories, University of Leipzig, Leipzig, Germany. Electronic address: .