Introduction We developed a novel normothermic ex vivo porcine liver perfusion model with whole blood in order to have alternatives for animal experiments in the research and development of new local haemostatic agents. This study aims to assess the construct and content validity of this model. Methods In this study we performed two ex vivo experiments using nine livers and one in vivo experiment using six female Norsvin Topigs pigs: (1) ex vivo liver perfusion for establishing physiological blood parameters of the perfused liver and controlled heparinization, (2) ex vivo liver perfusion with a surgical injury and (3) a surgical liver injury in anaesthetized pigs with and without heparin. Results Ex vivo coagulation parameters were comparable to in vivo with heparin. Blood gas values and metabolic parameters were comparable between ex vivo and in vivo with heparin, but significantly different compared with in vivo baseline, with the exception of (partial pressure of oxygen (PO2). Activated clotting time (ACT) values significantly differed depending on the heparin doses. The coagulation parameters fibrinogen, activated partial thromboplastin time, prothrombin time and ACT were rather constant during the 4 h ex vivo perfusion. Haemostatic efficacy of commercially available products was comparable between in vivo with heparin and the ex vivo liver perfusion experiment. Conclusion This novel ex vivo liver perfusion model demonstrates good construct and content validity for at least 4 h of perfusion. The model is an easily accessible, table-top, tunable and effective alternative for the in vivo testing of (new) haemostatic products on their haemostatic properties. Validité d'un nouveau modèle de perfusion hépatique porcin ex-vivo pour l'étude des produits hémostatiques Résumé

Background A new hemostatic sealant based on a N-hydroxy-succinimide polyoxazoline (NHS-POx) polymer was evaluated to determine hemostatic efficacy and long-term wound healing and adverse effects in a large animal model of parenchymal organ surgical bleeds. Methods Experiment 1 included 20 pigs that were treated with two NHS-POx patch prototypes [a gelatin fibrous carrier (GFC) with NHS-POx and an oxidized regenerated cellulose (ORC) with poly(lactic-co-glycolic acid)-NHS-POx:NU-POx (nucleophilically activated polyoxazoline)], a blank gelatin patch (GFC Blank), TachoSil® and Veriset™ to stop moderate liver and spleen punch bleedings. After various survival periods (1–6 weeks), pigs were re-operated to evaluate patch degradation and parenchymal healing. During the re-operation, experiment 2 was performed: partial liver and spleen resections with severe bleeding, and hemostatic efficacy was evaluated under normal and heparinized conditions of the two previous prototypes and one additional NHS-POx patch. In the third experiment an improved NHS-POx patch (GATT-Patch; GFC-NHS-POx and added 20% as nucleophilically activated polyoxazoline; NU-POx) was compared with TachoSil®, Veriset™ and GFC Blank on punch bleedings and partial liver and spleen resections for rapid (10s) hemostatic efficacy. Results NHS-POx-based patches showed better (GFC-NHS-POx 83.1%, ORC-PLGA-NHS-POx: NU-POx 98.3%) hemostatic efficacy compared to TachoSil® (25.0%) and GFC Blank (43.3%), and comparable efficacy with Veriset™ (96.7%) on moderate standardized punch bleedings on liver and spleen. All patches demonstrated gradual degradation over 6 weeks with a reduced local inflammation rate and an improved wound healing. For severe bleedings under non-heparinized conditions, hemostasis was achieved in 100% for Veriset™, 40% for TachoSil and 80–100% for the three NHS-POx prototypes; similar differences between patches remained for heparinized conditions. In experiment 3, GATT-Patch, Veriset™, TachoSil and GFC Blank reached hemostasis after 10s in 100%, 42.8%, 7.1% and 14.3%, respectively, and at 3 min in 100%, 100%, 14.3% and 35.7%, respectively, on all liver and spleen punctures and resections. Conclusions NHS-POx-based patches, and particularly the GATT-Patch, are fast in achieving effective hemostatic sealing on standardized moderate and severe bleedings without apparent long-term adverse events.

BACKGROUND: A new hemostatic sealant based on a N-hydroxy-succinimide polyoxazoline (NHS-POx) polymer was evaluated to determine hemostatic efficacy and long-term wound healing and adverse effects in a large animal model of parenchymal organ surgical bleeds. METHODS: Experiment 1 included 20 pigs that were treated with two NHS-POx patch prototypes (a gelatin fibrous carrier (GFC) with NHS-POx and an oxidized regenerated cellulose (ORC) with poly(lactic-co-glycolic acid)-NHS-POx:NU-POx (nucleophilically activated polyoxazoline)), a blank gelatin patch (GFC-Blank), TachoSil®, and Veriset™ to stop moderate liver and spleen punch bleedings. After various survival periods (1-6 weeks), pigs were re-operated to evaluate patch degradation and parenchymal healing. During the re-operation experiment 2 was performed; partial liver and spleen resections with severe bleeding, and hemostatic efficacy was evaluated under normal and heparinized conditions of the two previous prototypes and one additional NHS-POx patch. In the third experiment an improved NHS-POx patch (GATT-Patch; GFC-NHS-POx and added 20% as nucleophilically activated polyoxazoline; NU-POx) was compared with TachoSil®, Veriset™ and GFC-Blank on punch bleedings and partial liver and spleen resections for rapid (10 seconds) hemostatic efficacy. RESULTS: NHS-POx-based patches showed better (GFC-NHS-POx 83.1 %, ORC-PLGA-NHS-POx: NU-POx 98.3%) hemostatic efficacy compared to TachoSil® (25.0%) and GFC blank (43.3%), and comparable efficacy with Veriset™ (96.7%) on moderate standardized punch bleedings on liver and spleen. All patches demonstrated gradual degradation over 6 weeks with a reduced local inflammation rate and an improved wound healing. For severe bleedings under non-heparinized conditions, hemostasis was achieved in 100% for Veriset™, 40% for TachoSil, and 80-100% for the three NHS-POx prototypes; similar differences between patches remained for heparinized conditions. In experiment 3, GATT-Patch, Veriset™, TachoSil and GFC-Blank reached hemostasis after 10 seconds in 100%, 42.8%, 7.1% and 14.3% respectively, and at 3 minutes in 100%, 100%, 14.3% and 35.7% respectively, on all liver and spleen punctures and resections. CONCLUSIONS: NHS-POx-based patches, and particularly the GATT-Patch, are fast in achieving effective hemostatic sealing on standardized moderate and severe bleedings without apparent long term adverse events.