UCL Discovery

Abstract

Objectives. Photodynamic therapy (PDT, the combination of light with a photosensitising drug in the presence of oxygen) inhibits restenosis after angioplasty without stenting. This study assesses the potential of PDT for prevention of in-stent restenosis.Design and methods. Normal rabbits were given the photosensitising agent 5-aminolaevulinic acid (ALA) 60 mg/kg, 3 h prior to endovascular illumination of the iliac artery (635 nm at 50 J/cm(2)) either immediately before or after deployment of an oversized Q turn diameter) stent. PDT treated arteries were retrieved 3 or 28 days later and assessed for cell counts and vascular morphometry. Control arteries (stent but no PDT) were examined at 28 days.Results. There were no adverse events and all vessels were patent at the end of the study. At 3 days there was (almost complete medial cell ablation when light was delivered before stent deployment (17 +/- 1 cells/hpf), with little effect when illumination followed stent deployment (184 +/- 17 cells/hpf, p < 0.0001). Twenty-eight days after PDT, the neointimal areas were 1.41 +/- 0.52 mm(2) (stent with no PDT), 1.24 +/- 0.54 mm(2) (light after stent) and 0.60 +/- 0.21 mm(2) (light before stent) (p = 0. 004).Conclusions. PDT before stent deployment caused almost complete medial cell ablation at 3 days with inhibition of in-stent restenosis at 28 days. PDT is worthy of further study as an adjuvant to percutaneous intervention in patients with vascular disease.