Abstract
ObjectivePhotodynamic therapy (PDT) has become a well-established modality for the treatment of many cancers. Photodynamic eradication of tumor cells depends on the presence of a photosensitizer, oxygen and light. However, oxygen depletion during PDT is a well known problem. Modulation of light delivery could address this issue by counteracting tumor hypoxia, thereby improving tumor cell killing. This preclinical study was designed to validate an animal model incorporating 5-aminolaevulinic acid (5-ALA)-PDT using U87 glioblastoma cells. We aimed to evaluate the effects of light modulation for inducing specific tumoral lesions in this model (i.e., necrosis or apoptosis). Materials and methodsU87 glioblastoma cells were stereotactically engrafted into the brains of male fox1 rnu/rnu rats. Light delivery was studied after 5-ALA injection (100mg/kg i.p.). 26J of 635nm light was interstitially delivered to U87 tumor-bearing rats at a radiant power of either 30 mW (high fluence rate) or 4.8mW (low fluence rate). In each group, half of the population received illumination in 2 fractions with a refractory interval of 120s, whereas the other half received continuous illumination. ResultsTwenty-two animals received 5-ALA-PDT, and the level of necrosis was scored. In the high-fluence-rate group, we observed a greater degree of tumor necrosis in rats receiving fractionated delivery than in rats receiving continuous illumination. Similar differences were not observed in the low-fluence-rate group, which exhibited only sparse necrosis. Higher morbidity and mortality rates were observed in the high-fluence-rate group. ConclusionWe have developed a reproducible and reliable rodent model for interstitial 5-ALA PDT. We found that the effects of 5-ALA-PDT are dependent on light delivery conditions. Although the low-fluence-rate treatment was better tolerated, 5-ALA-PDT induced more necrosis using fractionated delivery at a high fluence rate. These results require confirmation with further studies involving larger populations and additional fractionation schemes.
Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
