[Photodynamic therapy of bladder cancer. A new option]. / Die photodynamische Therapie des Harnblasenkarzinoms. Eine neue Option.

BACKGROUND: Bladder cancer (BCa) is the third most common tumor in Germany. Currently, resection therapy for superficial BCa (Ta, CIS) includes photodynamic diagnostics (PDD) using HEXVIX® for improved assessment of tumor spread. Trials using these photosensitizers for photodynamic therapy (PDT) showed only limited success. Especially low tissue penetration due to short-wave excitation was a limiting factor. METHODS: This study which was funded by the German Research Foundation (DFG) examined the feasibility of the novel photosensitizer tetrahydroporphyrin-tetratosylate (THPTS) for PDT in a rat bladder cancer model. RESULTS: As THPTS is very effectively excitable at a near infrared wavelength of 760 nm it is within the so-called phototherapeutic window and allows tissue penetration of up to 15 mm. Thus THPTS can also be used for PDT of larger, solid tumors as was previously demonstrated for other tumor entities. Therefore, effective treatment of even muscle-invasive bladder cancer (≥T2) may become an option using THPTS. In this current study the effectiveness and safety of THPTS-PDT was examined in an orthotopic bladder cancer rat model.

Improved photoinactivation of gram-negative and gram-positive methicillin-resistant bacterial strains using a new near-infrared absorbing meso-tetrahydroporphyrin: a comparative study with a chlorine e6 photosensitizer photolon.

The antimicrobial activity of new tetracationic and water-soluble meso-substituted tetrahydroporphyrin tetratosylat (BL1065) and of dicationic water-soluble chlorine e6 Photolon (BLC1013) is described. The dark toxicity and photosensitizing potentials of both photosensitizers were tested on Gram-positive (Staphylococcus aureus and MRSA) and Gram-negative (Escherichia coli and Pseudomonas aeruginosa) bacteria in phosphate-buffered saline (PBS, pH 7.4), PBS + horse serum (HS) and PBS + sheep blood (SB). The results show that BLC1065 and BLC1013 did not inhibit the growth of S. aureus in the dark, but efficiently inactivated this Gram-positive bacterium after illumination. Contrary to BLC1013, BLC1065 has a photodynamic activity toward Gram-negative bacteria as well, at least in PBS. Results suggest that tetracationic BLC1065 can bind better to both Gram-positive and Gram-negative bacterial cell envelope than the dianionic chlorine BLC1013 resulting in better efficiency of photoinactivation.

Initiation of apoptosis by photodynamic therapy using a novel positively charged and water-soluble near infra-red photosensitizer and white light irradiation.

Our aim was to investigate the photophysical and photodynamic properties of a new, water-soluble positively charged and chemically stable photosensitizer: tetrahydroporphyrin tetratosylat (THPTS). Absorption, fluorescence and (1)H NMR spectra and the intracellular distribution of THPTS were measured. The apoptosis in choroidal melanoma cells was measured using cell death detection ELISA and caspase-8 activity assay. THPTS-PDT efficiency was studied in Balb/c mice bearing C26 colon carcinoma. Subcutaneously located tumors were irradiated with a white light source at a fluence rate of 100 mW/cm(2). THPTS was administrated 3 h before illumination. The tumoricidal effect was examined 24 h after THPTS-PDT by vital staining with 0.4-ml 1% Evans blue solution, intraperitoneally injected to each mouse. THPTS showed a strong absorption band at 760 nm. Its purity, measured by (1)H NMR, is better than 99%. At 24-h incubation period, CLSM revealed THPTS fluorescence in mitochondria and cell nucleus. THPTS possesses no toxic effect in preincubated CM cells without irradiation, and THPTS-PDT causes efficient apoptosis. THPTS-PDT using white light irradiation at a dose of 480 J/cm(2) caused necrosis with a depth of 8 mm in subcutaneously located C26 colon carcinoma in Balb/c-mice. In accordance with the present results, the THPTS seems to be of interest for further in vivo investigations with broad-band white light sources.