Biodistribution of Photofrin II® and 5-Aminolevulinic Acid-Induced Protoporphyrin IX in Normal Rat Bladder and Bladder Tumor Models: Implications for Photodynamic Therapy

Abstract

Photodynamic therapy (PDT) has been considered as a potential therapy for superficial bladder carcinomas. Cutaneous photosensitivity and reduction of bladder capacity are the two well-known complications following systemic administration of the commonly used photosensitizer, Photofrin II@ (PII). The objective of the present study was to evaluate whether intravesical (i.b.) instillation of photosensitizers for PDT of bladder cancer might be a more suitable treatment method. Female Fischer rats were utilized to develop orthotopic and heterotopic bladder tumor models. Rats bearing orthotopic bladder tumors were treated either intravesically or intravenously with graded doses of 5-aminolevulinic acid (ALA) or PII. Normal rats received the same doses of ALA or PII. As well, rats bearing heterotopic tumor were studied for comparison. The biodistribution times (times allowed for tissue uptake and bioconversion following drug administration) were 2, 4 or 6 h. Porphyrin fluorescence intensities within tumor, urothelium, submucosa, bladder muscularis and abdominal muscle were quantitated by confocal laser scanning microscopy. Following intravenous (i.v.) injection of ALA, tumor protoporphyrin IX (PpM) levels peaked at 4 h and diminished by 6 h. The PpIX ratios of tumor-to-bladder mucosa, submucosa and muscle layers were 3:1, 5 1 and 8:1, respectively, 4 h following 1000 mgkg ALA injection. After ALA instillation, the optimal biodistribution time appeared to be 4 h. Bladder instillation provided comparable tumor labeling with the i.v. route, but lost selectivity of PpIX accumulation between tumor and normal urothelium. The PpIX ratio of tumor-to-bladder muscularis was 5 1 . After i.b. instillation of PII, porphyrin fluorescence was detected only within tumor and urothelium, while porphyrin fluo-~ ~

Cellular Photodestruction Induced by Hypericin in AY-27 Rat Bladder Carcinoma Cells

“…The urinary bladder is one of the most suitable organs for PDT because endoscopic access is convenient and because early-stage urothelial cancer consists frequently of superficial multifocal lesions (2). At present, PDT is considered, after the failure of Bacille Calmette Guérin, as an alternative conservative treatment of urothelial carcinoma when cystectomy is not indicated.…”

“…The objective of the present study is to evaluate the sensitivity of urothelial carcinoma cells to PDT with hypericin and to highlight the background of hypericin-induced photocytotoxicity. For this purpose we selected AY-27 rat urinary bladder carcinoma cells that have been extensively used in vivo as a urinary bladder carcinoma model (2,14,15). In the present study several parameters crucial for the photocytotoxicity of hypericin are validated, including cellular uptake, incubation time and light fluence.…”

Optimization of differential photodynamic effectiveness between normal and tumor urothelial cells using 5-aminolevulinic acid-induced protoporphyrin IX as sensitizer

“…The heme precursor 5-aminolevulinic acid (5-ALA) has been used for local (e.g., urinary bladder, skin, esophagus and colon) and systemic (brain) applications in humans, resulting in an epithelium-selective accumulation of its photosensitizing metabolite protoporphyrin IX (PPIX). 1,2 Epithelial selectivity is an important pharmacological property since it targets cancer therapy to cells of interest, avoiding the direct damage of photodynamic therapy (PDT) in adjacent stromal cells, 3,4 as has been found with other photosensitizers. 5,6 In bladder tumors, 5-ALA has also proven useful for diagnostic purposes since a high sensitivity of tumor detection and flat tumor precursors were found on fluorescence endoscopy by applying a filtered lamp system and detecting red fluorescent lesions, caused by intracellular PPIX accumulation.…”

Photodynamic Therapy: Current Trends and Potential Future Role in the Treatment of Bladder Cancer

“…They showed, that the best penetration of hematoporphyrin was achieved two hours after instillation. The authors also described an orthotopic BC animal model in which the bladder surface was ablated and AY-27 tumor cells were administered, which allowed superficial bladder tumors located in the bladder wall to be reached [31]. The above technique was described in detail in a later publication of the study group in 2002 [32].…”