Background. Motexafin lutetium (Lu-Tex) is a photodynamic therapy (PDT) agent that localizes in atheromatous plaque in which it can be activated by farred light. Lu-Tex biolocalization was examined in graft coronary artery disease (GCAD) with a rodent allograft model. After photoactivation, the effect on intimal proliferation was assessed. Methods. A PVG to ACI rat heterotopic heart transplantation model was used. Lu-Tex (10 mg/kg) was intravenously administered 90 days after transplantation. Photoactivation was performed 24 hr after LuTex administration. A light-emitting diode, central wavelength of 742 nm, was used to illuminate the intraperitoneally placed allografts via a laparotomy (light fluence of 75 J/cm2 at a power density of 75 mW/cm2). Animals were divided into four groups according to postoperative treatments: PDT with Lu-Tex injection and light illumination (n=21), Lu-Tex injection and laparotomy (n=14), laparotomy with light only (n=14), and laparotomy only (n=16). GCAD was quantitatively assessed 14 days after treatments. Results. Lu-Tex localized in atherosclerotic plaque in vessels with GCAD. PDT significantly reduced both the percent of affected vessels and intimal proliferation compared to all other control study groups. α-Smooth muscle cell actin and anti-rat macrophage antibody-positive areas were significantly reduced within the neointima in allografts treated with PDT compared to all other study groups. Conclusions. PDT significantly reduced atherosclerotic lesions of GCAD. Lu-Tex-mediated PDT may, therefore, be a potential method for treating accelerated atherosclerosis associated with transplantation.
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