Effects of low-fluence-rate PDT on glioma spheroids

Steen J. Madsen, Robin M. Rodenbush, Chung-Ho Sun, Bruce J. Tromberg, Henry Hirschberg, Thomas J. Dougherty
2002 Optical Methods for Tumor Treatment and Detection: Mechanisms and Techniques in Photodynamic Therapy XI  
The effectiveness of low-fluence rate PDT on human glioma spheroids incubated in 5-aminolevulinic acid (ALA), or hexyl-ALA, is investigated. Spheroid survival is monitored following PDT at representative drug concentrations, light fluences and fluence rates. It is shown that, for above threshold fluences, significant PDT response can be obtained at a fluence rate of 5 mW cm2. At this fluence rate, the response of human glioma spheroids to PDT with lipophilic ester derivatives, such as
more » ... is equivalent to that obtained with ALA, however, this equivalency is observed for ester concentrations 20 times lower than the parent compound. The efficacy of PDT is significantly reduced at a sub-threshold fluence of 25 J cm2. Spheroid response appears to be somewhat fluence rate dependent at sub-threshold fluencessurvival is marginally poorer at the higher fluence rate (25 mW cm2) investigated. In addition, the efficacy of PDT at 25 J cm2 depends significantly on photosensitizer concentration at the lowest fluence rate investigated (5 mW cm2).
doi:10.1117/12.469347 fatcat:uqwv7l6yibfdfdfllucohfwiiy