The cross talk between coagulation cascade and endothelial cells in a porcine limb ischemia reperfusion injury model and the protective role of C1-INH
M. Abdelhafez, J. Shaw, D. Sutter, J. Schnider, H. Jenni, E. Voegelin, M. Constantinescu, R. Rieben (Bern, Switzerland)
Time: 08:00 - 09:15
Objective: Ischemia reperfusion (I/R) injury is an inflammatory reaction of the tissue, probably caused by expression of ‘danger’ signals on the ischemic endothelium, and involves activation of the endothelium the plasma cascades and the innate immune system. Revascularization of traumatically amputated limbs within 6 hours is essential to avoid extensive reperfusion injury. We aimed to investigate the interactions between endothelial cells (EC) and the plasma cascades, in particular coagulation. We also used C1-easterase inhibitor (C1-INH) in this study because of its known inhibitory effects on activation of the plasma cascades to access its role in protecting against I/R injury in the porcine limb amputation model.
Methods: 15 wild type porcine forelimbs were amputated, exposed to 9 hours of cold ischemia at 4°C, and then ex vivo perfused for 12 hours with autologous blood using a purpose built extracorporeal perfusion circuit. The treated limbs were passively perfused with 500 ml hydroxyethyl starch solution (HAES) containing C1-INH (1 U/ml) after 2 hours of cold ischemia (treatment group, n=8), while the non-treated limbs (control group, n=7) were rinsed with HAES without C1-INH.
Results: As assessed by IF there was a significant decrease in tissue deposition of IgM (P=0.009), IgG (P=0.01), C3c (P=0.0011), C5b-9 (P=0.0059), fibrinogen like protein-2 (P=0.019) and fibrin (P<0.001) in the treatment group compared to the control group. There was a significant increase in thrombin deposition in the control group, but not in the treatment group, compared to baseline. On the other hand, there was no difference between the groups regarding tissue factor (TF) expression. Moreover the treatment group expressed higher levels of EC markers CD31 (P=0.0006) and VE-Cadherin (P=0.006) than the control group.
Conclusion: Activation of the coagulation cascade due to I/R injury of the skeletal muscle seems mediated by EC expression of fibrinogen like protein-2 (FGL-2) rather than the extrinsic TF pathway. FGL-2 is known for its prothrombinase activity that directly leads to thrombin formation and fibrin deposition. C1-INH was able to protect the vascular endothelium and the muscle tissue from fibrin deposition. It also led to a significant reduction of EC activation. C1-INH might therefore be useful to reduce reperfusion injury after replantation of traumatically amputated limbs.