5-aminolevulinic-acid-hexyl-ester and Disease-Models--Animal

Hexyl aminolevulinate (HAL) is a long-chained 5-aminolevulinic acid-ester that has been proposed as a novel photosensitizing agent to methyl aminolevulinate (MAL) in topical photodynamic therapy (PDT). The more lipophilic HAL, may improve treatment outcome for non-melanoma skin cancer.. To compare the prophylactic and therapeutic effects of HAL- and MAL-PDT for ultraviolet-induced squamous cell carcinomas (SCCs) in hairless mice.. Mice (n = 249) were irradiated with solar UV-radiation (UVR) until SCC occurred. Before any skin changes developed, two prophylactic PDT treatments were given, using creams of HAL (2%, 6%, 20%) or MAL (20%) followed by illumination (632 nm, Aktilite, Photocure). Two therapeutic PDT-treatments were given by randomization to the first developed SCC of 1 mm. Primary end-points were time to first SCC of 1 mm and complete SCC clearance. Secondary end-points were time to SCC-recurrence, PpIX fluorescence and skin reactions to PDT.. The median time to first SCC was significantly longer for mice treated with prophylactic HAL-PDT (2%, 6% and 20% HAL, 264 days) and MAL-PDT (20% MAL, 269 days) than mice exposed to UVR (186 days) and UVR + placebo-PDT (199 days) (P < 0.0001). The therapeutic efficacy of HAL- and MAL-PDT showed cure rates of 23-61.5% (P = 0.11). Similar PpIX fluorescence intensity and severity of clinical reactions were seen for HAL- and MAL-groups, although mice developed more intense hyper-pigmentation when treated with 20% MAL-PDT compared with 2% HAL-PDT.. PDT with HAL (2%, 6% and 20%) and MAL (20%) is equally effective to prevent and treat UV-induced SCC in hairless mice.

Topics: Administration, Topical; Aminolevulinic Acid; Animals; Carcinoma, Squamous Cell; Disease Models, Animal; Dose-Response Relationship, Drug; Female; Mice; Mice, Hairless; Neoplasms, Radiation-Induced; Photochemotherapy; Photosensitizing Agents; Skin Neoplasms; Treatment Outcome; Ultraviolet Rays

This experimental study aimed to compare three illumination schemes to optimize hexaminolaevulinate (HAL)-PDT in a rat tumor model with advanced ovarian cancer.. Peritoneal carcinomatosis was induced by intraperitoneal 5×10(6)NuTu-19 cells injection in 60 female rats Fisher 344. Carcinomatosis was obtained 50 days post-tumor induction. Four hours post-intraperitoneal HAL (Photocure ASA, Oslo, Norway) injection, three different schemes of PDT were performed during 25 min on a 1cm(2) area. (A) Fractionated illumination (n=20) with an on-off cycle ("on": 2 min and "off": 1 min) at 30mW cm(-2) until a fluence of 30J cm(-2), (B) continuous illumination (n=20) at 30mW cm(-2) with a fluence of (45J cm(-2)C) continuous illumination (n=20) at 20mW cm(-2) with a fluence of 30J cm(-2). Laser light was generated using a 532nm KTP laser (Laser Quantum, Stockport, UK). Biopsies were taken 24h after treatment. Quantitative histology was performed. Necrosis value was determined: 0-no necrosis to 4-full necrosis. Depth of necrosis was then measured for each sample and correlated to Necrosis value.. HAL-PDT was efficient in producing necrosis irrespective of the scheme. Tumor destruction was superior with fractionated illumination compared to both continuous illumination schemes regarding to the depth of necrosis (213±113μm vs 154±133μm vs 171±155μm) (p<0.05) or to the full necrosis rate (50% vs 30% vs 10%) (p<0.0001).. Fractionated illumination during photodynamic therapy (PDT) was shown to improve tumor response. Fractionated illumination with short intervals should be considered for an effective PDT of advanced ovarian cancer.

Topics: Adenocarcinoma; Aminolevulinic Acid; Animals; Disease Models, Animal; Female; Ovarian Neoplasms; Peritoneal Neoplasms; Photochemotherapy; Photosensitizing Agents; Rats; Rats, Inbred F344

The hexylester of 5-aminolevulinic acid (HAL) is a very efficient precursor of the photosensitizer protoporphyrin IX (PpIX) for photodynamic therapy (PDT). Our previous study, performed in rat orthotopic bladder tumors, indicated an opposite effect of HAL/PpIX-PDT according to HAL concentration. The present study investigated possible reasons for this differential effect considering the impact of extracted amounts of PpIX in normal and tumor bearing bladders along with PpIX distribution in distinctive histopathological layers. High performance liquid chromatography (HPLC) analysis of tumor and normal bladder tissues after 8 mM and 16 mM HAL instillation showed that PpIX was the main porphyrin species. The PpIX production in tumor bladders instilled with 8 mM HAL was significantly higher than after 16 mM HAL. Fluorescence confocal microscopy demonstrated a punctuate bright fluorescence pattern in tumor zones of bladders instilled with 8 mM HAL, whereas a more diffuse cytoplasmatic fluorescence distribution was observed after 16 mM HAL instillation. Immunofluorescence staining together with transmission electron microscopy showed severe mitochondrial damage in tumor zones of bladders treated with 8 mM HAL/PpIX PDT, with intact mitochondria in tumor zones of bladders treated with 16 mM HAL/PpIX PDT. We conclude that the differential response to HAL/PpIX PDT in function of HAL concentrations could be attributed to diminished PpIX synthesis and differential intracellular localisation of PpIX. Mitochondria were shown to be the critical photodamaged sites of HAL/PpIX PDT and as such tissue sensitivity to treatment can be estimated through investigation of intracellular PpIX distribution.

Topics: Aminolevulinic Acid; Animals; Cell Line, Tumor; Chromatography, High Pressure Liquid; Disease Models, Animal; Female; Microscopy, Electron, Transmission; Photochemotherapy; Photosensitizing Agents; Protoporphyrins; Rats; Rats, Inbred F344; Urinary Bladder Neoplasms

This experimental study aimed to compare continuous and fractionated illumination to optimize hexaminolaevulinate (HAL)-photodynamic therapy (PDT) in a rat tumour model with advanced ovarian cancer.. Intraperitoneal 10(6) Nu Tu-19 cells were injected in 36 female rats Fisher 344. Peritoneal carcinomatosis was obtained 26 days post-tumour induction. Four hours post-intraperitoneal HAL (Photocure ASA, Oslo, Norway) injection, two schemes of PDT were performed at 30 mW cm(-2) on a 1cm(2) area: fractionated illumination (n=16) with a on-off cycle ("on": 2 min and "off": 1 min) until a fluence of 30 J cm(-2) was delivered, and continuous illumination (n=20) with a fluence of 45 J cm(-2). Laser light was generated using a 532 nm KTP laser (Laser Quantum, Stockport, UK). Biopsies were taken 24h after treatment. Semi-quantitative histology was performed. Necrosis value was determined-0: no necrosis to 4: full necrosis.. HAL-PDT was efficient in producing necrosis irrespective of the scheme (NV=3.34+/-0.91). Tumour destruction was superior with fractionated illumination compared to continuous illumination (3.67+/-0.70 vs. 3.10+/-0.94) (p<0.05).. Fractionated illumination during photodynamic therapy was shown to improve tumour response. Fractionated illumination with short intervals should be considered for an effective PDT of advanced ovarian cancer.

Topics: Aminolevulinic Acid; Animals; Disease Models, Animal; Female; Light; Neoplasm Staging; Ovarian Neoplasms; Peritoneum; Photochemotherapy; Rats

To optimize photodynamic therapy (PDT) we investigated the kinetics and biodistribution of hexylester 5-aminolevulinate (hALA) induced protoporphyrin IX (PpIX) and the therapeutic efficacy of PDT at different drug and light doses in an orthotopic rat bladder tumor model.. Healthy and tumor bearing rats were instilled intravesically with hALA (4, 8 and 16 mM) for 1 hour. Fluorescence was recorded spectroscopically in situ. PpIX fluorescence distribution and quantification across the bladders was visualized with fluorescence microscopy. PDT efficacy at different fluences (15 to 80 J/cm2) was histologically assessed 48 hours and 1 week after treatment.. Spectroscopic analysis in normal or tumor bearing rats showed the highest tumor-to-normal ratios 2 or 3 hours after the end of the 8 or 16 mM hALA instillation (5.4 and 5.7, respectively). Within the same tumor bearing animal the same fluorescence levels were observed in normal epithelium and transitional cell carcinoma, whereas the tumor-to-muscle ratio was 3. Tumor necrosis with an intact normal bladder wall was observed with a fluence of 20 J/cm2 for 8 mM hALA, while 15 J/cm2 was ineffective and 25 J/cm2 induced total wall necrosis. Although it induced comparable PpIX fluorescence, 16 mM hALA did not result in tumor eradication at any fluence.. An optimal PDT effect was obtained with 8 mM hALA and a fluence of 20 J/cm2. While different hALA concentrations ind uce identical PpIX fluorescence intensities, the PDT outcome was considerably different. Thus, fluorescence does not necessarily predict the therapeutic efficacy of PDT.

Topics: Aminolevulinic Acid; Animals; Carcinoma, Transitional Cell; Disease Models, Animal; Photochemotherapy; Rats; Tissue Distribution; Urinary Bladder Neoplasms

Although 5-aminolevulinic acid (ALA)-based photodynamic therapy (PDT) has proven to be clinically beneficial for the treatment of certain cancers, including a variety of skin cancers, optimal tissue localisation still remains a problem. An approach to improve the bioavailability of protoporphyrin IX (PpIX) is the use of ALA derivatives instead of ALA. In this work, we employed a subcutaneous murine mammary adenocarcinoma to study the tissue distribution pattern of the ALA hexyl ester (He-ALA) in comparison with ALA after their topical application in different vehicles. He-ALA induced porphyrin synthesis in the skin overlying the tumour (SOT), but it did not reach the tumour tissue as efficiently. Only 5 h after He-ALA lotion application, tumour porphyrin levels surpassed control values. He-ALA delivered in cream induced a substantially lower porphyrin synthesis in SOT, reinforcing the importance of the vehicle in the use of topical PDT. Porphyrin levels in internal organs remained almost within control values when He-ALA was employed. The addition of DMSO to ALA formulation slightly increased tumour and SOT porphyrin biosynthesis, but it did not when added to He-ALA lotion.

Topics: Administration, Topical; Aminolevulinic Acid; Animals; Disease Models, Animal; Esters; Female; Male; Mammary Neoplasms, Experimental; Mice; Mice, Inbred BALB C; Photosensitizing Agents; Porphyrins; Skin Neoplasms; Time Factors; Tissue Distribution