Abstract
For patients with non-cirrhotic liver-based metabolic disorders, hepatocyte transplantation can be an effective treatment. However, long-term function of transplanted hepatocytes following infusion has not been achieved due to insufficient numbers of hepatocytes reaching the liver cell plates caused by activation of the instant blood-mediated inflammatory reaction (IBMIR). Our aim was to determine if the natural immune modulator, alpha-1 antitrypsin (AAT), could improve engraftment of transplanted hepatocytes and investigate its mechanism of action. A tubing loop model was used to analyse activation of the IBMIR when human hepatocytes were in contact with ABO-matched blood and 4 mg/ml AAT. Platelet and white cell counts, complement and cytokine expression were analysed. To determine if AAT could improve short-term engraftment, female rats underwent tail vein injection of AAT (120 mg/kg) or water (control) prior to the intrasplenic transplantation of 2 × 107 male hepatocytes. At 48 h and 1 week, livers were collected for analysis. In our loop model, human hepatocytes elicited a significant drop in platelet count with thrombus formation compared to controls. Loops containing AAT and hepatocytes showed no platelet consumption and no thrombus formation. Further, AAT treatment resulted in reduced IL-1β, IL-6 and IFN-γ and increased IL-1RA compared to untreated loops. In vivo, AAT significantly improved engraftment of rat hepatocytes compared to untreated at 48 h. AAT infusion may inhibit the IBMIR, thus improving short-term engraftment of donor hepatocytes and potentially improve the outcomes for patients with liver-based metabolic disease.Key messages• Alpha-1 antitrypsin (AAT) acts as an immune modulator to improve the efficacy of hepatocyte transplantation.• Treatment with AAT decreased thrombus formation and pro-inflammatory cytokine expression in a tubing loop model.• AAT significantly improved engraftment of donor hepatocytes within the first 48 h post transplantation.
Highlights
Hepatocyte transplantation (HT) is a promising alternative to orthotopic liver transplantation (OLT) in paediatric patients with liver-based metabolic disorders [1,2,3]
Liver transplantation is curative for certain liver-based metabolic disorders such as Crigler–Najjar syndrome (CNS), ornithine transcarbamylase (OTC) deficiency and maple syrup urine disease (MSUD); organs of suitable size and quality are rarely available at the time when the infant has the greatest need
Images revealed numerous hepatocytes embedded within these thrombi which were identifiable by their large size and microvilli on the cell surface (Fig. 3a)
Summary
Hepatocyte transplantation (HT) is a promising alternative to orthotopic liver transplantation (OLT) in paediatric patients with liver-based metabolic disorders [1,2,3]. Liver transplantation is curative for certain liver-based metabolic disorders such as Crigler–Najjar syndrome (CNS), ornithine transcarbamylase (OTC) deficiency and maple syrup urine disease (MSUD); organs of suitable size and quality are rarely available at the time when the infant has the greatest need. These disorders, untreated, result in irreversible, neurological insult secondary to build. There are several clinical trials in progress testing the use of AAT in the context of islet transplantation [20]
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