title: Photodynamic treatment as a novel approach in the therapy of arthritic joints.
abstract: OBJECTIVE
  Minimal invasive local treatment of joints is a desirable option in the therapy of rheumatoid arthritis (RA). Aim of this study was to evaluate the effects of photodynamic treatment (PDT) with different doses of the photosensitizer meta-tetra(hydroxyphenyl)chlorin (m-THPC; or temoporfin) in a murine model of RA (antigen-induced arthritis, AIA). METHODS IN VIVO DISTRIBUTION: The distribution of native and liposomal m-THPC (including a formulation with polyethylene glycol [PEG] coating) was assessed by fluorescence spectrometry in arthritic joints, normal joints, and skin.
  
  
  METHODS
  AIA mice received different concentrations of pegylated liposomal m-THPC (0.1, 0.05, 0.01, or 0.005 mg/kg body weight; n = 5 per group) and subjected to PDT with a laser system 12 hours post-injection of the photosensitizer. Treatment effects were evaluated histologically in comparison to untreated AIA (n = 5).
  
  
  RESULTS
  Pegylated liposomal m-THPC showed the most favorable accumulation in arthritic joints compared to native m-THPC and to non-peg-liposomal m-THPC, therefore it was selected as photosensitizer for PDT treatment. In comparison to untreated AIA, PDT reduced the arthritic score with all doses of pegylated liposomal m-THPC; statistical significant effects were obtained with doses of 0.05 and 0.01 mg/kg.
  
  
  CONCLUSIONS
  Our study demonstrated that local PDT of arthritic joints is feasible. Application of pegylated liposomal m-THPC for PDT resulted in significant reduction of arthritis scores.
authors.affiliation: Institute of Diagnostic and Interventional Radiology, Friedrich Schiller University of Jena, Bachstrasse 18, D-07743 Jena, Germany. andreas.hansch@med.uni-jena.de
authors.forename: Andreas
authors.initials: A
authors.lastname: Hansch
authors.forename: Oliver
authors.initials: O
authors.lastname: Frey
authors.forename: Mieczyslaw
authors.initials: M
authors.lastname: Gajda
authors.forename: Graefe
authors.initials: G
authors.lastname: Susanna
authors.forename: Joachim
authors.initials: J
authors.lastname: Boettcher
authors.forename: Rolf
authors.initials: R
authors.lastname: Bräuer
authors.forename: Werner A
authors.initials: WA
authors.lastname: Kaiser
mesh_terms: D000818:Animals; D001172:Arthritis, Rheumatoid / Q000188:drug therapy*; D004195:Disease Models, Animal; D008297:Male; D008652:Mesoporphyrins / Q000494:pharmacology; D051379:Mice; D008810:Mice, Inbred C57BL; D008856:Microscopy, Fluorescence; D010778:Photochemotherapy / Q000379:methods*; D017319:Photosensitizing Agents / Q000494:pharmacology
chemical_list: D008652:Mesoporphyrins; D017319:Photosensitizing Agents; C072269:temoporfin