Photodynamic therapy inhibits experimental allograft rejection : a novel approach for the development of vascular bioprostheses

• Published in: Circulation (New York, N.Y.) N.Y.), 1995-10, Vol.92 (7), p.1919-1926
• Main Authors: LAMURAGLIA, G. M, ADILI, F, SCHMITZ-RIXEN, T, MICHAUD, N. A, FLOTTE, T. J
• Format: Article
• Language: English
• Subjects: Aluminum - therapeutic use; Animals; Aorta, Abdominal - transplantation; Aorta, Abdominal - ultrastructure; Biological and medical sciences; Bioprosthesis; Blood Vessel Prosthesis; Graft Rejection - pathology; Graft Rejection - prevention & control; Indoles - therapeutic use; Medical sciences; Microscopy, Electron, Scanning; Organometallic Compounds - therapeutic use; Photochemotherapy; Photosensitizing Agents - therapeutic use; Rats; Rats, Inbred ACI; Rats, Inbred Lew; Surgery (general aspects). Transplantations, organ and tissue grafts. Graft diseases; Transplantation, Homologous; Vascular surgery: aorta, extremities, vena cava. Surgery of the lymphatic vessels
• ISSN: 0009-7322; 1524-4539
• DOI: 10.1161/01.CIR.92.7.1919

Biological vascular allografts have proved unsatisfactory because of thrombosis, occlusion, and aneurysmal degeneration during chronic rejection. Photodynamic therapy (PDT), a technique that leads to the production of cytotoxic free radicals, was investigated as a novel method to prepare arterial allografts. Shortly after impregnation with the photosensitizer drug chloroaluminum sulfonated phthalocyanine, infrarenal aortas of ACI rats were PDT-treated and orthotopically grafted in Lewis rats (PDT). The transplanted grafts were sequentially analyzed at 2, 4, and 8 weeks by morphometry, immunohistochemistry, and scanning electron microscopy. Of 25 untreated allografts, 4 (16%) developed aneurysms compared with 0 of 33 in PDT or untreated isografts (ISO, P < .001). PDT treatment of allografts significantly inhibited intimal hyperplasia (P < .001) and resulted in intimal areas comparable to those in ISO. However, medial thickness in both control allografts and PDT grafts was markedly decreased compared with ISO. External graft diameters of control allografts at 8 weeks were significantly enlarged (P < .02) compared with PDT or ISO. At all time points, T lymphocytes were found in a substantially larger number in untreated control grafts than in PDT or ISO. Scanning electron microscopy at 4 weeks confirmed complete repopulation with endothelial cells in PDT, which was not seen in the control allografts. Our findings suggest that local PDT treatment of arterial allografts inhibits inflammatory infiltration, aneurysmal dilatation, and development of intimal hyperplasia and may be used to develop vascular bioprostheses for use in humans.