title: Effects of vascular photodynamic therapy in a newly adapted experimental rat aortic aneurysm model.
abstract: The hypothesis driving this study was that photodynamic therapy (PDT) may limit abdominal aortic aneurysm growth due to matrix changes. The aortas of 12 rats were incubated with elastase using a newly modified experimental aneurysm model (3.5 mg/ml). Rats were allocated to an elastase-only group (n = 6) to study the elastase-induced aneurysm growth and an elastase ± PDT group to evaluate if PDT limited aneurysm growth (n = 6). PDT was performed with the photosensitizer methylene blue, and thermoneutral laser light (660 nm) was applied (120 J/cm(2), 100 mW/cm(2)) using a diode laser. Four untreated rats served as controls. The arteries were analysed after 4 weeks based on histology, immunohistochemistry and morphometry. This modified rat elastase model led to reproducible aneurysm development with no elastase-induced mortality compared with control animals (circumference, controls: 2.9 ± 0.2 vs. elastase: 5.5 ± 0.9 mm; P < 0.01). PDT after elastase incubation did not inhibit inflammatory cell infiltration. No significant change in the circumference was observed between elastase incubation and PDT treatment after elastase incubation (circumference, elastase: 5.5 ± 0.9 vs. elastase and PDT: 6.1 ± 0.8 mm; P < 0.01). Despite a PDT-induced resistance to protease digestion, PDT did not reduce aortic dilatation in the elastase-treated rat aorta. These findings suggest that PDT may not be a useful modality to prevent aneurysm growth.
authors.affiliation: Department of Vascular Surgery,  University of Cologne, Cologne,  Germany.
authors.forename: Joerg
authors.initials: J
authors.lastname: Heckenkamp
authors.forename: Thomas
authors.initials: T
authors.lastname: Luebke
authors.forename: Thorsten
authors.initials: T
authors.lastname: Theis
authors.forename: Lukas
authors.initials: L
authors.lastname: Schumacher
authors.forename: Michael
authors.initials: M
authors.lastname: Gawenda
authors.forename: Roland
authors.initials: R
authors.lastname: Thul
authors.forename: Jochen W U
authors.initials: JW
authors.lastname: Fries
authors.forename: Jan
authors.initials: J
authors.lastname: Brunkwall
mesh_terms: D000818:Animals; D017544:Aortic Aneurysm, Abdominal / Q000139:chemically induced / Q000188:drug therapy* / Q000276:immunology / Q000473:pathology; D004195:Disease Models, Animal; D007150:Immunohistochemistry; D008297:Male; D008751:Methylene Blue / Q000494:pharmacology*; D010196:Pancreatic Elastase; D010778:Photochemotherapy; D017319:Photosensitizing Agents / Q000494:pharmacology*; D051381:Rats; D017207:Rats, Sprague-Dawley; D013997:Time Factors
chemical_list: D017319:Photosensitizing Agents; D010196:Pancreatic Elastase; D008751:Methylene Blue