Effect of TNF‐alpha blockade on coagulopathy, survival and endothelial activation in xenoperfused porcine kidneys

Abstract

Background: Following pig to primate kidney transplantation, endothelial cell activation and xenogenic activation of the coagulation (XAC) system of the recipient eventually leading to organ dysfunction and disseminated intravascular coagulation (DIC) can be observed (1). In this study we examined the effect of a TNF‐Receptor‐Fusionprotein (TNF‐RFP) on XAC and endothelial cell activation utilizing an appropriate ex‐vivo perfusion system.Methods: Using an ex‐vivo perfusion circuit based on C1‐Inhibitor (C1‐Inh) and low dose heparin administration, we have analysed XAC following contact of human blood with porcine endothelium. Porcine kidneys were recovered following in situ cold perfusion with HTK organ preservation solution and were immediately connected to a perfusion circuit utilizing freshly drawn pooled porcine or human AB blood. The experiments were performed in three individual groups: autologous perfusion (n = 5), xenogenic perfusion without any further pharmacological intervention (n = 10) or with addition of TNF‐RFP (n = 5). After perfusion tissue samples were obtained for QPCR and immunohistological analyses. Endothelial cell activation was assessed by measuring the expression levels of E‐Selectin, ICAM‐1 and VCAM‐1 in QPCR.Results: Kidney survival during organ perfusion with human blood, CI‐Inh, heparin but without any further pharmacological intervention was 126 ± 78 min. XAC was observed with significantly elevated concentrations of d‐Dimer, thrombin antithrombin complex (TAT), resulting in formation of multiple microthrombi. Endothelial cell activation was pronounced, as shown by increased expression of E‐Selectin and VCAM‐1. In contrast, pharmacological intervention with TNF‐RFP reduced the consumption of antithrombin and fibrinogen and prolonged organ survival to 240 min (±0). Additionally, formation of microtrombi was reduced compared to the xenogenic control without pharmacological intervention. Remarkably, also endothelial cell activation was significantly reduced in the TNF‐RFP group.Conclusions: We conclude that TNF‐RFP can interfere with XAC and is able to suppress endothelial cell activation in this ex vivo perfusion model, thus representing a potential candidate as an adjuvant immunosuppressive drug.Reference: 1. BÜhler L, Basker M, Alwayn IPet al. Coagulation and thrombotic disorders associated with pig organ and hematopoietic cell transplantation in nonhuman primates. Transplantation 2000; 9: 1323–1331.