The morphological and functional changes in rat bladder following photodynamic therapy with phthalocyanine photosensitization

We have studied photodynamic therapy (PDT) in the rat bladder with a new photosensitizer, aluminium sulfonated phthalocyanine (AlSPc) given intravenously and intravesically. The microscopic distribution of photosensitizer fluorescence in the bladder wall was studied by laser fluorescence microscopy. Prior to PDT the bladder capacity and compliance were assessed by filling cystometry. Intravesical red light (675 nm.) from a copper vapour pumped dye laser was used to activate the photosensitizer using light doses of 20 to 200 J/cm2. Urodynamic and histologic changes were studied at intervals for up to three months. The fluorescence studies showed that AlSPc was eliminated from the deeper muscle layers more quickly than from the superficial layers of the bladder wall so that by 24 hours there was four times as much fluorescence from the mucosa and lamina propria compared to the deeper muscle. Control bladders illuminated with laser light alone showed no effects at these light doses. Animals treated 24 hours after sensitization showed a reduction in bladder capacity of up to 78% (20 J/cm2. light and 1.5 mg./kg.AlSPc). An initial reduction in compliance recovered in two weeks after low doses (0.5 mg./kg.) of AlSPc but was still abnormal at three months after higher doses (1.5 mg./kg.); though there was no long term histologic abnormality seen. Aluminium sulfonated phthalocyanine is a promising photosensitizer for bladder photodynamic therapy and using low doses of the drug it is possible to produce a superficial necrosis without muscle damage across a range of light doses. This heals by epithelial regeneration with no long term functional impairment. Direct absorption of this photosensitizer following intravesical administration seems unreliable.     

The effect of photodynamic therapy on rat urinary bladder with orthotopic urothelial carcinoma

OBJECTIVE: To assess the effect of whole-bladder photodynamic therapy (PDT) on a rat model with orthotopic superficial bladder cancer, as PDT is an alternative intravesical therapy for treating superficial bladder cancer, based on an interaction between a photosensitizer and light energy to induce oxygen radicals that destroy tissue by lipid peroxidation. MATERIALS AND METHODS: In all, 76 female Fischer F344 rats were inoculated intravesically with AY-27 tumour cells. After establishing superficial tumour, 24 rats were treated with PDT using aminolaevulinic acid (ALA)-induced protoporphyrin IX as a photosensitizer, and a continuous-wave argon pumped-dye laser (638 nm). At 4 h after intravenous (300 mg/kg) or intravesical (100 mg/mL) administration of ALA the bladders were intravesically exposed to a 40 J/cm(2) light dose; 12 rats received no ALA but were exposed to the same light dose. Before administering ALA, urine cytology samples were taken for analysis. At 3 or 21 days the treated rats were killed and morphological changes in the bladder walls analysed by light microscopy. Forty rats served as controls to examine the presence of tumour. RESULTS: The tumour established in 33 of 40 rats (83%) in the controls, but after PDT with intravesical ALA there was carcinoma in only in one of 12 (P < 0.001, Pearson's chi(2) test). After PDT with intravenous ALA there was carcinoma in five of 11 rats (P = 0.063, Pearson's chi2 test). In the control group of 12 rats receiving only light energy there was carcinoma in three (P = 0.001, Pearson's chi(2) test). Histologically, at 3 days after PDT there was only mild superficial damage in all six rats treated intravesically. Bladder wall destruction reached the muscular layer, with an abscess in one of six rats treated intravenously. After 3 weeks of PDT there was muscular necrosis with perforation and abscess from catheterization two of six rats treated intravesically and in three the bladder wall totally recovered. In the intravenous group the bladder walls were normal or had only mild superficial damage. Cytology of the urine sediment failed to detect half the tumours in the treatment groups. CONCLUSION: These results support the use of PDT with intravesical ALA-induced protoporphyrin X for treating superficial bladder carcinoma. Intravesical was better than intravenous ALA in eradicating bladder carcinoma with PDT.     

The morphological changes in rat bladder after photodynamic therapy with 5-aminolaevulinic acid-induced protoporphyrin IX

OBJECTIVE: To assess the optimum light energy needed to induce only superficial bladder wall damage during photodynamic therapy (PDT) as a treatment for bladder cancer. Materials and methods The urinary bladder (with normal epithelium) of 64 female rats was treated with PDT using a continuous-wave argon-ion laser as an energy source and aminolaevulinic acid (ALA)-induced protoporphyrin IX photosensitizer. Four hours after the intravenous administration of ALA (300 mg/kg) the bladders were intravesically exposed to light fluences of 20-80 J/cm2. The control rats received no ALA and were exposed to 20 J/cm2 light. After 1, 3, 7 and 21 days the animals were killed and the morphological changes in bladder wall analysed both macroscopically and using light and scanning electron microscopy. RESULTS: At the dose of ALA given, a fluence of 20-40 J/cm2 caused mainly superficial damage, whereas 80 J/cm2 produced full-thickness injuries to the bladder wall. The maximum effect of PDT occurred after 1 and 3 days of irradiation. After 3 weeks of PDT the histology showed few full-thickness injuries and only in those treated with 80 J/cm2 light. CONCLUSION: These results indicate that PDT can be used to safely induce a selective superficial removal of bladder mucosa with no fibrotic effects on detrusor musculature, when optimum photosensitizing drug and fluences are used. These findings support the use of PDT in the therapy of superficial bladder cancer.     

Photodynamic therapy of superficial bladder tumors

Photodynamic therapy (PDT), using hematoporphyrin derivative (HPD) and the red light (wavelength 630 nm) of an argon-dye laser as the source of excitation energy was performed on 46 patients with superficial bladder tumors. Two methods of laser irradiation, (1) focal PDT using a 400 micron quartz fiber through a cystourethroscope in 22 patients with superficial bladder tumors and (2) whole bladder wall total PDT using a motor-driven laser light scattering device in 24 patients with multifocal carcinoma in situ and/or dysplasia of bladder mucosa associated with multicentric concurrent superficial tumors, were used. The patients in (2) had been referred for total cystectomy, and 19 of these 24 patients had a history of several transurethral resections, hyperthermia and/or instillation therapy. HPD 2-4 mg/kg was i.v. injected 48 to 72 hours before PDT. Judging from the results of 60 protrusions treated by focal PDT, the light power should be 200 mW/cm2 for 5-10 minutes or more and the total light energy should be 100 J/cm2 or more in tumors up to 2 cm in size. With focal PDT, 4 of the 22 patients had no recurrence with the mean tumor free time of 20.8 months. In 6 of the 24 patients treated with total PDT using 10, 20 or 30 J/cm2 of light energy, there was no recurrence with a mean tumor-free time of 7.5 months and there was no significant relationship between the recurrence rate and total light energy used.     

Photodynamic modulation of wound healing with BPD-MA and CASP.

BACKGROUND AND OBJECTIVE: Wound healing is an intricate process requiring the orchestration of cells, growth factors, cytokines, and the extracellular matrix. Cytokines, specifically TGF-beta, are believed to be instrumental in sustaining the fibrotic process, which leads to scarring. Photodynamic therapy (PDT) uses potent photosensitizers, which induce a wide range of effects on cells and the extracellular matrix. The influences of PDT on wound healing are not well known. STUDY DESIGN/MATERIALS AND METHODS: Seven full-thickness incisional wounds were placed on each of 24 hairless Sprague Dawly rats, three wounds on one flank serving as dark controls and four on the contralateral side treated with PDT. Wounds were created two days before, one hour before, or one hour after red light exposure with an argon ion pumped dye laser. Twelve rats were injected with 0.25 mg/kg or 0.5 mg/kg of the PDT drug, BPD-MA, and the other 12 with 5 mg/kg or 10 mg/kg of the PDT drug, CASP, 3 and 24 hours prior to irradiation of light, respectively. At low doses of both photosensitizers, animals were irradiated with 1, 5, 10, and 20 J/cm2. At higher doses of BPD-MA and CASP animals were treated with 10, 20, 50, and 100 J/cm2 of light. Wounds were examined each day for 14 days and noted for edema, erythema, inflammation, necrosis, and quality of scarring. Wounds were also photographed at day 0, 2, 5, 8, and 14 post-irradiation. All animals were sacrificed 14 days after irradiation and the wounds were evaluated by light microscopy. RESULTS: Grossly, animals treated with 0.25 mg/kg BPD-MA showed no effect with PDT. Animals treated with 0.5 mg/kg BPD, and 5 and 10 mg/kg CASP showed responses that varied with both light and drug dose. Erythema, edema, inflammation, and necrosis attributed to PDT were all observed, but there was no apparent influence of PDT on either the rate or final appearance of wound healing. Histologically, there were no apparent differences between treated and untreated sites, regardless of the drug, dose of light, or time of irradiation. CONCLUSION: A single PDT treatment given before or after skin wounds does not apparently alter wound healing even when PDT caused brisk inflammatory reactions. PDT may have effects that were not detected. We conclude that PDT does not greatly influence incisional skin wound healing in the rat model.     

Effect of photodynamic therapy on urinary bladder function: an experimental study with rats

Photodynamic therapy (PDT) produces localized necrosis with light after prior administration of a photosensitizing drug. The problems with laser light dosimetry and complications relating to bladder function appear to be important limiting factors of PDT in urology. Photodynamic therapy on urinary bladder with normal epithelium of rats was performed using an argon ion laser as an energy source, with aminolevulinic acid (ALA)-induced protoporphyrin IX (PpIX) photosensitizer. Four hours after ALA intravenous administration, the bladders were intravesically radiated with light doses 20, 40, or 80 J/cm². Animals in the control group did not receive ALA and were radiated with 20 J/cm² light dose. Three weeks prior to PDT, the bladder capacity and pressure changes during filling cystometry were assessed. Cystometrics were repeated 1, 3, 7, or 21 days after laser therapy. The light dose 20 J/cm² and 40 J/cm² together with the used ALA dose caused no reduction in bladder capacity, whereas 80 J/cm² light dose produced up to 50% reduction in the capacity at 3 weeks postoperatively. In control group without ALA, the animals did not regain more than 34% of the capacity of their control values at 3 weeks. The light dose of 20 J/cm² and 40 J/cm² with ALA induced functional changes that subsided after day 1. Our results indicate that with proper dosing of photosensitizing drug and light energy, the functional impairment of urinary bladder may be reduced as transient. These findings support the use of PDT as safe therapy of superficial bladder cancer. Received: 10 April 2000 / Accepted: 16 November 2000     

Photodynamic activity of lutetium-texaphyrin in a mouse tumor system.

BACKGROUND AND OBJECTIVE: New photosensitizers proposed for photodynamic therapy (PDT) treatment of tumors need to be evaluated in animal models to determine the parameters needed for treatment. They also need to be compared with existing photosensitizers for efficacy. We examined the PDT response to lutetium-texaphyrin (PCI-0123) in a mouse mammary adenocarcinoma model and compared it with the PDT response seen when using Photofrin. STUDY DESIGN/MATERIALS AND METHODS: DBA/2 mice with SMT-F tumors were used to explore PCI-0123 toxicity, laser light dose, and drug dose effects on PDT response and to determine the most effective time for light application. The PDT response of PCI-0123-treated tumors was compared with that of Photofrin-treated tumors. RESULTS: Treatment of tumors with 150 J/cm2 of 740 nm laser light 5-6 hr after PCI-0123 administration (40 mg/kg) resulted in a 100% response rate and a 55% cure rate. Tumors treated with 150 J/cm2 of 630 nm laser light 24 hr after Photofrin administration (10 mg/kg) resulted in a 67% response rate and a 16% cure rate. CONCLUSION: PCI-0123 was found to be a more effective photosensitizer than Photofrin.     

PHOTODYNAMIC THERAPY IN THE TREATMENT OF SUBCUTANEOUSLY IMPLANTED HUMAN BLADDER TUMOUR

Photodynamic therapy (PDT) is an experimental treatment modality for malignant tumours. The effect of PDT with haematoporphyrin derivative (HpD) was studied using a human bladder tumour (BL-17) which was implanted subcutaneously (s.c.) into immunodeficient Balb/c nude mice. This model is only suitable for short-term investigation of PDT because of the high mortality that arises due to the immune deficiency of the animals. In a short-term observation (2 weeks post-treatment), HpD sensitized PDT was effective in the control of tumour growth, with 71 % of tumours cured. The effect of PDT was found to be highly dependent on doses of HpD and/or the activating laser light. The comparison of PDT effects of the gold metal vapour laser (GMVL) and argon ion pumped dye laser (AIPDL) indicated that no significant difference exists between these two different laser sources for PDT. The irradiation with laser light alone and the administration of HpD alone had no significant effect on tumour growth.     

Photodynamic therapy in the treatment of subcutaneously implanted human bladder tumour.

Photodynamic therapy (PDT) is an experimental treatment modality for malignant tumours. The effect of PDT with haematoporphyrin derivative (HpD) was studied using a human bladder tumour (BL-17) which was implanted subcutaneously (s.c.) into immunodeficient Balb/c nude mice. This model is only suitable for short-term investigation of PDT because of the high mortality that arises due to the immune deficiency of the animals. In a short-term observation (2 weeks post-treatment), HpD sensitized PDT was effective in the control of tumour growth, with 71% of tumours cured. The effect of PDT was found to be highly dependent on doses of HpD and/or the activating laser light. The comparison of PDT effects of the gold metal vapour laser (GMVL) and argon ion pumped dye laser (AIPDL) indicated that no significant difference exists between these two different laser sources for PDT. The irradiation with laser light alone and the administration of HpD alone had no significant effect on tumour growth.     

Photodynamic efficiency of liposome-administered tetramethyl hematoporphyrin in two human bladder cancer cell lines

The main problems presented by superficial bladder carcinoma, its high recurrence rate and multifocal appearance, require treatment of the bladder as a whole. Photodynamic therapy (PDT) is one such experimental treatment for superficial bladder carcinoma, involving the administration of a photosensitizer that accumulates in the tumor tissue, and subsequent irradiation of the tumor with light. Since the photosensitizers used in PDT suffer from several drawbacks, new photosensitizers are being sought. Drug delivery systems are also being investigated for the administration of hydrophobic photosensitizers and enhancement of photodynamic efficiency and tumor selectivity. In this study we examined a new photosensitizer, tetramethyl hematoporphyrin (TMHP), in two human bladder cancer cell lines. In the first pair of the experiments, TMHP was bound to unilamellar liposomes. Cellular uptake, dark toxicity and photodynamic efficiency were then studied. Fluorescence microscopy showed TMHP localization in the cytoplasm in a perinuclear region, sparing the nucleus. Dark toxicity occurred after incubation of cells with TMHP above a concentration of 20 g/ml. Irradiation was carried out using an argon-pumped dye laser emitting a wavelength of 630 nm at a fluence of 3.6 and 7.2 J/cm². Before irradiation, cells were incubated with TMHP at concentrations of 2.5 and 5 g/ml for 1 h. Cell survival rates after incubation with 5 g/ml TMHP and irradiation at 7.2 J/cm² were 15.7% of control cells for Rec and 4.5% for Waf cells. Uptake studies showed a higher intracellular TMHP concentration in Waf than in Rec cells. This correlates with the higher PDT efficiency seen in Waf cells. Our results show that TMHP can be encapsulated into unilamellar liposomes without losing its photodynamic efficiency. TMHP is taken up by human bladder carcinoma cells after an incubation time of only 1 h. This short incubation time seems to be appropriate for an intravesical instillation of the photosensitizer for PDT in bladder cancer patients. Intravesical instillation might demonstrate higher phototoxic efficiency with reduced side effects. TMHP acts as a potent photosensitizer and shows drug- and light-dose-dependent cell destruction. Thus, TMHP has the potential for use in PDT in bladder cancer.     

Photodynamic therapy of human ocular cancer

Photodynamic therapy (PDT), also known as photoradiation therapy, was employed in five patients with ocular tumors that had been photosensitized to hematoporphyrin derivative (HPD). In each case more conventional treatment had failed to control the tumor, or the patient was considered a poor candidate for surgical intervention because of advanced age or general health. Intravenous administration of 2.5-3.0 mg/kg HPD was followed by PDT 2-4 days later, using a dye laser tuned to a wavelength of 632 nm. Laser light was delivered either by a fiber optic probe maintained at a fixed distance, or via a slit lamp system, for intervals of up to 20 minutes. The levels of energy applied were mainly below 420 Joules/cm2, but for tumors less than 1 mm diameter energy levels were as high as 3000 J/cm2 with a conservative power value as low as 20 mW/cm2. Tumor response to PDT was disappointing. Although substantial superficial tumor necrosis occurred in several cases, it did not extend to the deeper levels of tumor tissue. In each instance surgical intervention became necessary. Deficiencies in the procedure are discussed.     

Influence of light fluence rate on the effects of photodynamic therapy in an orthotopic rat glioma model

OBJECT: Failure of treatment for high-grade gliomas is usually due to local recurrence at the site of resection, indicating that a more aggressive local therapy could be beneficial. Photodynamic therapy (PDT) is a local treatment involving the administration of a tumor-localizing photosensitizing drug, in this case aminolevulinic acid (ALA). The effect depends on the total light energy delivered to the target tissue, but may also be influenced by the rate of light delivery. METHODS: In vitro experiments showed that the sensitivity to ALA PDT of BT4C multicellular tumor spheroids depended on the rate of light delivery (fluence rate). The BT4C tumors were established intracranially in BD-IX rats. Microfluorometry of frozen tissue sections showed that photosensitization is produced with better than 200:1 tumor/normal tissue selectivity after ALA injection. Four hours after intraperitoneal ALA injection (125 mg/kg), 26 J of 632 nm light was delivered interstitially over 15 (high fluence rate) or 90 (low fluence rate) minutes. Histological examination of animals treated 14 days after tumor induction demonstrated extensive tumor necrosis after low-fluence-rate PDT, but hardly any necrosis after high-fluence-rate treatment. Neutrophil infiltration in tumor tissue was increased by PDT, but was similar for both treatment regimens. Low-fluence-rate PDT administered 9 days after tumor induction resulted in statistically significant prolongation of survival for treated rats compared with nontreated control animals. CONCLUSIONS: Treatment with ALA PDT induced pronounced necrosis in tumors only if the light was delivered at a low rate. The treatment prolonged the survival for tumor-bearing animals.     

Photodynamic therapy for superficial bladder cancer under local anaesthetic

OBJECTIVES: To evaluate the use of local anaesthesia (LA) in 5-aminolaevulinic acid (ALA) photodynamic therapy (PDT) for superficial transitional cell carcinoma (TCC) of the bladder, and to provide further toxicity and tolerability data on this new method within the context of a phase 1 trial. PATIENTS AND METHODS: ALA PDT was administered to 19 patients with recurrent superficial TCC (stage Ta/carcinoma in situ, grades 1-3) using escalating doses of ALA (3-6%) and 633 nm laser light (25-50 J/cm2) under various LA (lignocaine) protocols. Pain was assessed using a linear analogue scale from 0 to 10. The endpoints of tolerability and toxicity were assessed for the different LA, light and ALA doses, with lignocaine levels. RESULTS: ALA PDT is painful and requires some form of anaesthesia. The discomfort was immediate, associated with bladder spasm, and was a function of the ALA concentration rather than the total light dose given. Simple passive diffusion (PD) of 2% lignocaine instilled for 40 min before PDT gave adequate anaesthesia with 3% ALA (n=8; median pain score 1, range 0-2). With 6% ALA the pain was dramatically increased using PD (n=6; median pain score 8, range 5-10) and therefore the more potent LA technique of electromotive drug administration (EMDA) of 2% lignocaine was used, with excellent results (n=3; median pain score 1, range 0-2). All patients had transient bladder irritability that typically lasted 9-12 days, with no subjective/objective change in long-term bladder function. No other toxicity was reported. Serum lignocaine levels were minimal. CONCLUSION: Bladder ALA PDT is both safe and feasible under LA. At a dose of 3% ALA, the procedure was well-tolerated using PD of lignocaine. At higher doses (6% ALA) more effective anaesthesia is required and this can be obtained satisfactorily with EMDA of lignocaine. With refinement, ALA PDT may be feasible as an outpatient treatment for superficial bladder TCC.     

Preclinical comparison of mTHPC and verteporfin for intracavitary photodynamic therapy of malignant pleural mesothelioma

Efficacy and tumour selectivity of photodynamic therapy with two clinically approved sensitizers (mTHPC, verteporfin) were assessed for focal intracavitary photodynamic therapy (PDT) in rodents with malignant pleural mesothelioma (MPM) at recommended drug-light conditions and at escalating sensitizer dosages. MPM tumours were generated in 15 Fischer rats by subpleural mediastinal tumour cell injection followed after 5 days by intracavitary PDT with light delivery monitored by in situ dosimetry. Animals were intravenously sensitized either with mTHPC (0.1 mg/kg, n = 3; 0.2 mg/kg, n = 3) followed after 4 days by illumination with 20 J/cm(2) at 652 nm, or with verteporfin (0.6 mg/kg, n = 3; 1.2 mg/kg, n = 3) followed after 20 min by illumination with 100 J/cm(2) at 689 nm. Three untreated tumour-bearing animals served as controls. Histological evaluation of the treated tumour and of adjacent normal organs was performed 10 days after tumour implantation. The extent of PDT-induced tumour necrosis was compared to the non-necrosed area and expressed in percentage. A locally invasive growing MPM tumour (3.1 +/- 1 mm diameter) without spontaneous necrosis diameter was found in all animals. For both sensitizers, focal intracavitary PDT was well tolerated at drug-light conditions recommended for clinical applications. Mediastinal organs were spared for both sensitizers but verteporfin resulted in a higher extent of tumour necrosis (80%) than mTHPC (50%). Drug dose escalation revealed a higher extent of PDT-related tumour necrosis for both sensitizers (mTHPC 55%, verteporfin 88%), however, verteporfin-PDT was associated with a higher toxicity than mTHPC-PDT.     

Photodynamic Therapy on Rat Urinary Bladder with Intravesical Instillation of 5-Aminolevulinic Acid: Light Diffusion and Histological Changes

Purpose

Photodynamic therapy (PDT) has the potential to treat extensive premalignant lesions and microinvasive tumors in the bladder, but its use has been hampered by the risk of detrusor muscle damage and prolonged skin photosensitivity. We have shown that the rat urothelium can be sensitized by selectively using a 10 percent solution of 5-aminolevulinic acid (ALA) at pH 5.5 administered intravesically. This paper evaluates the photodynamic effects on sensitized bladders.

Materials and Methods

The bladders of Wistar rats were instilled with ALA solutions of different concentrations at pH 5.5 and subsequently treated with laser light at 630 nm. Bladders were harvested 1 to 7 days after PDT for histological assessment.

Results

Under optimum conditions (10 percent intralipid diffusion medium, light dose 50J) uniform urothelial necrosis was seen after 1 to 2 days; it healed in 7 days without damage to the underlying muscle layer although some increase in collagen was seen in the lamina propria. Overtreatment or poor light distribution resulted in muscle necrosis and scarring.

Conclusions

Selective urothelial necrosis is possible with PDT using intravesical ALA. There is now sufficient data for pilot clinical trials to start photodynamic therapy for management of superficial bladder cancer or carcinoma in situ.     

Tolerance of small bowel anastomoses in rabbits to photodynamic therapy with dihematoporphyrin ethers and 630 nm red light

Photodynamic therapy (PDT) is being evaluated in experimental clinical trials in patients with peritoneal malignancies. Some patients require partial small bowel resection with re-anastomosis prior to PDT because of bulky tumor or focal involvement of the small bowel by tumor. To assess the safety of PDT in this setting, the tolerance of small bowel anastomoses in New Zealand white rabbits to PDT with dihematoporphyrin ethers (DHE) and 630 nm light was studied. With conventional DHE doses of 1.5–2.5 mg/kg given 24 hours prior to surgery and light doses of 0–20 J/cm² of 630 nm light, no adverse effects were seen on the healing of small bowel anastomoses. Higher photosensitizer doses of 10 mg/kg and 20 mg/kg in conjunction with 20 J/cm², however, induced failure and breakdown of fresh anastomoses in 2/3 and 4/4 animals, respectively. © 1993 Wiley-Liss, Inc.     

Urodynamic effects of a novel EP(1) receptor antagonist in normal rats and rats with bladder outlet obstruction

PURPOSE: Prostaglandin E(2) and its EP(1) receptor were suggested as endogenous modulators of bladder function in the normal physiological state and under pathophysiological conditions. We investigated if the new EP(1) receptor antagonist PF-2907617-02 would influence the regulation of normal micturition in rats, and if it affects bladder function in animals with partial bladder outlet obstruction. MATERIALS AND METHODS: The study was performed in normal female Sprague-Dawley rats and in rats with moderate, experimentally induced bladder outlet obstruction 2 weeks in duration. All animals underwent continuous cystometry in the awake state. PF-2907617-02 was given intravenously at doses of 0.1 and 1.0 mg/kg(-1) in normal rats, and at 1.0 mg/kg(-1) in bladder outlet obstructed animals. In a group of normal rats detrusor overactivity was produced by intravesical instillation of prostaglandin E(2). RESULTS: In normal rats PF-2907617-02 (1 mg/kg(-1)) significantly increased bladder capacity, micturition volume and the micturition interval but it had no effect on other urodynamic parameters. The lower dose of PF-2907617 (0.1 mg/kg(-1)) showed no effect. Intravesical prostaglandin E(2) (50 muM) induced detrusor overactivity. The antagonist significantly decreased the stimulatory effects of prostaglandin E(2) at 0.1 and 1.0 mg/kg(-1). In obstructed animals PF-2907617-02 significantly increased the micturition interval but not bladder capacity and residual volume. The drug also decreased the frequency and amplitude of nonvoiding contractions. CONCLUSIONS: EP(1) receptor is involved in initiation of the micturition reflex in normal rats and in animals with bladder outlet obstruction. It may also contribute to the generation of detrusor overactivity after bladder outlet obstruction. Thus, EP(1) receptor antagonists may have potential as treatment for detrusor overactivity in humans.     

Intrathoracic photodynamic therapy: A canine normal tissue tolerance study and early clinical experience

Surgery with intraoperative photodynamic therapy (PDT) has the potential to improve the treatment of pleural malignancies. Before embarking on such treatment in humans, however, thoracic tissue tolerance to PDT was studied. For each of three (1 week, 1 month, and 6 month) study end-points, one control (no Photofrin II [PII]) and four treated animals underwent thoracotomy 72 hours after I.V. injection (6 mg/ kg) PII. Red light (630 nm) was delivered (5–40 J/cm²) to the pleural surface (1 cm diameter) of selected thoracic organs. No clinical differences were observed between PDT and control dogs. The control showed no histological changes; however, in the treated animals focal areas of coagulation necrosis were found at 1 week which progressed to fibrosis at 1 month. The extent and depth of injury was proportional to light dose. The lung was the most sensitive; the chest wall was the most resistant. Myocardium had superficial damage, whereas coronary arteries appeared normal. The results provide the basis for proceeding to phase I human trials in the evaluation of PDT as an intraoperative adjuvant treatment in the management of pleural malignancies. © 1994 Wiley-Liss, Inc.     

Green light photodynamic therapy in the human bladder

We conducted this pilot clinical study to investigate the safety, primarily acute toxicity, of green light (514.5 nm) whole bladder photodynamic therapy (PDT) in human bladders with transitional cell carcinoma. We enrolled five patients who were scheduled to undergo radical cystectomy and urinary diversion for locally muscle invasive bladder cancer. Four patients received intravenous injection of Photofrin at 1 mg/kg, while one patient received no drug, 48 hr before undergoing green light whole bladder photoactivation with light doses of 20-60 J/cm 2. Each patient underwent radical cystectomy on day 7 following light treatment. Post-PDT evaluation included daily monitoring of voiding symptoms, cystometric measurements of bladder capacity, and gross and histopathologic examination of the excised bladders. Our results show that the intensity of acute bladder irritation and acute post-PDT loss in bladder volume depended on the light dose and extent of bladder tumor with the associated inflammation. There was no transmural bladder injury and no treatment related morbidity. These data on acute toxicity suggest that green light whole bladder PDT treatment with 1 mg/kg of Photofrin and 20-40 J/cm 2 of laser power is safe.     

Fluorescence detection and photodynamic treatment of photosensitized tumours in special consideration of urology

Most methods of modern laser tumour therapy are physically based on the conversion of light to heat. Recently tumours have also been treated using ionizing processes for tissue ablation. Photodynamic laser therapy (PDT), however, involves light-induced non-thermal biochemical processes and the use of a photosensitizer.Several drugs are known to be stored selectively in tumours after systemic application. This transient marking can be used for diagnostic and therapeutic procedures. The marker most commonly used is dihaematoporphyrin ether/ester (DHE) intravenously injected at doses of 0.2–3.0 mg/kg bodyweight for diagnosis and therapy, respectively. The corresponding clearance intervals after injection of DHE range from 3–48 h to 25–75 h.Detection of photosensitized tumours might offer great advantages. The highly sensitive two-wavelength laser excitation method with computerized fluorescence imaging recently has been transferred to the hospital for clinical tests.Photoinduced production of singlet oxygen is claimed to be the initial process which leads to later tumour destruction and therapy. PDT has been applied to 20 patients suffering from superficial tumours (TIS GII–III) recurred after application of other treatments. The results after PDT were evaluated by three-monthly check-ups (endoscopy, cytology, bladder mapping, renal ultrasonography) as well as by computed tomography (CT) examination at 8–13 month intervals. In six patients treated by PDT no tumour recurrence has been found over the whole observation period of up to 5 years. Four patients have remained free of tumour (12 and 14 months) after repeated transurethral resection (TUR) and Nd-YAG laser therapy following PDT. Due to an initial application of insufficient irradiation four patients required a second PDT. In one patient a circumscribed dysplasia appeared at the left ostium 26 months following PDT and was treated successfully by means of thermal Nd-YAG laser irradiation following TUR. In six patients slight mucosal atypia persisted for a period of at least 2.5 years. One cystectomy had to be performed because of bladder shrinkage. The dissected bladder, however, was free of tumour.These preliminary results suggest that PDT is justified in patients who are in a worst-case situation with cystectomy recommended in case of recurrent superficial TIS bladder carcinoma and indicate the future potential of photodynamic therapy of tumours.Homogeneous irradiation of the area to be treated and a reliable light dosimetry are prerequisites for an effective tumour therapy. Standard instruments for a routine application do not exist, but are under development.