Endovascular photodynamic therapy inhibits intimal hyperplasia after PTA in a rat model

Background: Vascular restenosis due to intimal hyperplasia (H) and negative vascular remodeling (shrinkage) attenuates long-term patency of interventions like bypass procedures, endarterectomies and PT(C)As. Endovascular photodynamic therapy (PDT) may be an adjuvant approach based on intracellular photoactivation of 5-aminolevulinic acid (ALA) induced protoporphyrin IX (PP IX) resulting in local cytotoxicity. Aim: To prevent restenosis by inhibiting ill with endovascular PDT. Methods: Male Wistar rats (n33) were subdivided into two groups; one experimental group; the PTA + PDT group (n18), in which illumination with either 0, 12.5 , 25 and 50 J I cm diffuser length was applied at 100 mW I cm diffuser length; one control group; the PTA group in which 114 was induced after balloon denudation ofthe right iliacal artery (n15). Results: Morfometric analysis showed that IH developed from 0.02 0.022 at 1 week to 0. 13 0.04 n2 at 4 weeks in the PTA group. In the PTA + PDT group with 50 J / cm diffuser length still no lB (0.002 0.003 ii2 ) developed after 4 weeks. Conclusion: Endovascular PDT prevents formation of H measured 4 weeks post PTA. An optimal light dosimetry of 50 J / cm diffuser length at 3 hours after ALA application was found in this lB model. Therefore, endovascular PDT is a promising therapy to prevent restenosis after vascular interventions. keywords: endovascular PDT, ALA, intimal hyperplasia, artery, angioplasty, rat model In Lasers in Surgery: Advanced Characterization, Therapeutics, and Systems X, R. Rox Anderson, et al., Editors, Proceedings of SPIE Vol. 3907 (2000) • 1605-7422/00/$15.00 575

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