Longer term assessment of photodynamic therapy for intimal hyperplasia: a pilot study

Purpose: To determine the potential long term (three or six months) effectiveness of photodynamic therapy (PDT) in reducing intimal hyperplasia in swine. s: Intimal hyperplasia in the abdominal aortae of swine was created by a combination of fat-supplemented diet and balloon catheter injury prior to PDT. Swine were randomly allocated into one of three groups which received either: (i) both drug and light (PDT), (ii) drug only, or (iii) light only. Twenty-four hours following administration of the photosensitizer PHOTOFRIN® (porfimer sodium) at 2.5 mg/kg, two distinct 1 cm spots on the posterior wall of the abdominal aorta were illuminated by an argon pumped dye laser tuned to 630 nm for an energy fluence of 120 J/cm2. After three or six months, swine were sacrificed, perfusion fixed, and had their aortae removed for light and electron microscopy. s: Intimal hyperplasia reduction following PDT persisted for the three or six months follow up period. Experimental vessels receiving PDT showed a 26.0 ± 4.5% (n=2, ie. four spots) and 30.8 ± 5.4% (n=1, ie. two spots) smaller percent intimal area after three or six months of recovery, respectively. Control groups receiving either light or drug only showed less than a 6% difference in percent intimal area. Medial and adventitial layers were unaffected in all groups. Electron microscopy demonstrated that the endothelium or endothelial-like cells had regenerated in both the posterior and adjacent areas of the abdominal aortae with no clear difference between them. sions: These findings suggest that PDT may be beneficial in reducing intimal hyperplasia for up to three or six months in swine.