INHIBITION OF GRAFT-REJECTION PHOTODYNAMI C THERAPY OF ARTERIAL ALLOGRAFTS

To date, no synthetic prosthesis provides satisfactory long term resul ts as bypass graft for the coronary circulation or small diameter peri pheral vessels. Homologous and heterologous vascular grafts have been unsuitable so far for safe, long term replacement due to the associate d chronic rejection process which ultimately leads to aneurysm formati on. Since immunization of the host is most likely triggered by endothe lial and vascular smooth muscle cells in the biologic graft, this stud y was designed to determine if photodynamic therapy (PDT) induced dece llularization of vascular grafts inhibits chronic rejection. In a rat model, arterial allografts were investigated 2, 4, and 8 weeks after e x vivo-PDT treatment, by means of morphometric analysis, immunohistoch emistry, electronmicroscopy, and FACS analysis. Our findings suggest t hat chronic rejection of arterial allografts was completely inhibited by PDT.