Validity of a novel ex vivo porcine liver perfusion model for studying haemostatic products.

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.

The Effect of Mycophenolate Mofetil on Early Wound Healing in a Rodent Model.

BACKGROUND: Immunosuppressant agents are inevitable for solid organ recipients, but may have a negative effect on wound healing that is difficult to measure because of clinical use of a polydrug regime. The evidence on mycophenolate mofetil (MMF) is scarce and contradictory. This study aims to investigate the effect of MMF administration on wound healing. METHODS: Ninety-six male Wistar rats divided into 4 groups underwent anastomotic construction in ileum and colon at day 0. Three groups received daily oral doses of 20 or 40 mg/kg MMF or saline (control group) from day 0 until the end of the experiment. Half of each group was analyzed after 3 days and half after 7 days. Another group started the medication 3 days after the laparotomy and was analyzed after 7 days, half of this group received 20 mg/kg and half 40 mg/kg MMF. Wound strength in anastomoses and in the abdominal wall was measured using bursting pressure, breaking strength, and histology. Trough levels were measured. RESULTS: Significant differences in wound strength were seen in ileum tissue after 3 days, which surprisingly showed a stronger anastomosis in the experimental groups. Bursting pressure as well as breaking strength was higher in the low-dose and high-dose MMF group compared with the control group. A negative effect was measured in abdominal wall tissue for the highest-dose group, which disappeared when the medication was delayed for 3 days. Histology showed poorer bridging of the submucosal layer and more polymorphonuclear cell infiltration in the ileum specimens of the control group compared with the treatment groups. CONCLUSIONS: As a single agent in a preclinical wound healing model in the rat, MMF has no negative effect on healing of bowel anastomoses but might have a negative effect on the healing of abdominal wall.