OBJECTIVES: In this study, we evaluated histologically the effects of hexyl 5-aminolevulinateinduced photodynamic treatment in the AY-27 tumor cell induced rat bladder cancer model.
MATERIAL & METHODS: The animals (fischer-344 female rats) were divided into 2 groups, half of which were orthotopically implanted with 400,000 syngeniec AY-27 urothelia1 rat bladder cancer
cells and half sham implanted. 14 days post implantation 6 rats from each group were treated with hexyl 5-aminolevulinate-induced photodynamic treatment (8mM HAL and light fluence of 20 J/cm2).
Additional groups of animals were only given HAL instillation, only light treatment, or no treatment.
All animals were sacrificed 7 days after the PDT/only HAL/only light or no treatment. Each bladder was removed, embedded in paraffin and stained with hematoxylin, eosin, and saferin for histological
evaluation at high magnification for features of tissue damage by a pathologist blinded to the sample source.
RESULTS: In all animals that were AY-27 implanted and not given complete PDT treatment, viable tumors were found in the bladder mucosa and wall. In the animals treated with complete HAL-PDT
only 3 of 6 animals had viable tumor. In the 3 animals with viable tumor it was significantly reduced in volume compared to the untreated animals. It was also noted that in the PDT treated animals there was a significantly increased inflammatory response (lymphocytic and mononuclear cell infiltration) in the peri-tumor area compared to implanted animals without complete HAL-PDT.
CONCLUSION: Our results suggest that hexyl 5-aminolevulinate-induced photodynamic treatment in a rat bladder cancer model involves both direct effects on cell death (necrosis and apoptosis) and
indirect effects to evoke the host immune-response, together contributing to tumor eradication.