Issue 12, 2007

Light fractionation does not enhance the efficacy of methyl 5-aminolevulinate mediated photodynamic therapy in normal mouse skin

Abstract

Previous work demonstrated that fractionated illumination using two fractions separated by a dark interval of 2 h, significantly enhanced the clinical efficacy of photodynamic therapy (PDT) with 5-aminolevulinic acid (ALA). Considering the increasing clinical use of methyl 5-aminolevulinate (MAL) and the expected gain in efficacy by light fractionation we have investigated the response to MAL-PDT using a single and a two-fold illumination scheme and compared that with ALA-PDT. Our results show that fractionated illumination does not enhance the efficacy of PDT using MAL as it does using ALA despite the comparable fluorescence intensities at the end of the first light fraction and at the start of the second light fraction. Only the initial rate of photobleaching was slightly greater during ALA-PDT although the difference was small. Previously we hypothesized that cells surviving the first fraction are more susceptible to the second fraction. Since this is not true for MAL-PDT our data suggest that the distribution of MAL and ALA in tissues, and therefore the site of PDT induced damage, is an important parameter in the mechanism underlying the 2-fold illumination scheme.

Graphical abstract: Light fractionation does not enhance the efficacy of methyl 5-aminolevulinate mediated photodynamic therapy in normal mouse skin

Article information

Article type
Paper
Submitted
04 Jun 2007
Accepted
27 Jul 2007
First published
28 Aug 2007

Photochem. Photobiol. Sci., 2007,6, 1325-1331

Light fractionation does not enhance the efficacy of methyl 5-aminolevulinate mediated photodynamic therapy in normal mouse skin

H. S. de Bruijn, E. R. M. de Haas, K. M. Hebeda, A. van der Ploeg - van den Heuvel, H. J. C. M. Sterenborg, H. A. M. Neumann and D. J. Robinson, Photochem. Photobiol. Sci., 2007, 6, 1325 DOI: 10.1039/B708340H

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