Anti-Inflammatory Effects of Aav-Mediated Angiopoietin-1 and –2 Expression in Rat Cardiac Allografts

O277 Aims: Anti-inflammatory angiogenic growth factor angiopoietin-1 (Ang1) regulates endothelial functions through Tie2 receptor and promotes vessel stability by recruiting smooth muscle coverage. Ang2 also binds to Tie2 and has both agonistic and antagonistic properties. Our aim was to investigate the effect of overexpression of Ang1 and Ang2 in rat cardiac allografts. Methods: Heterotopic cardiac transplantations were performed from DA to WF rats receiving CyA 2.0mg/kg/d for the first week and CyA 1.0mg/kg/d thereafter as background immunosuppression. Adeno-associated-virus (AAV) vectors were injected intracoronary after harvesting to induce transgene expression in the graft. Allografts were perfused with reporter and control vector AAV-EGFP (n=11), AAV-Ang1 (n=8) or AAV-Ang2 (n=7) and harvested at 8 weeks for histological and immunohistochemical evaluation of vascular changes and graft inflammation. Data was analysed by log rank test and ANOVA. Results: Transgene expression was detected at 4 weeks remaining stable for the study period of 8 weeks. Graft survival was 82% in AAV-EGFP and 100% in AAV-Ang1 and AAV-Ang2 groups (p=NS). Intracoronary perfusion with AAV-Ang1 or AAV-Ang2 reduced graft infiltrating ED1+ macrophages and CD8+ cells (p<0.05) compared to AAV-EGFP. Intracoronary perfusion with AAV-Ang2 reduced the incidence of arterial lesions compared to AAV-EGFP (p<0.05). Conclusions: Intracoronary AAV mediated gene transfer produces delayed but stable transgene expression in allografts. Both Ang1 and Ang2 overexpression in the cardiac allografts had anti-inflammatory effects but Ang2 may also inhibit smooth muscle recruitment to arterial intima.