Intrahepatic Administration of Human Liver Stem Cells in Infants with Inherited Neonatal-Onset Hyperammonemia: A Phase I Study

Previous studies have shown that human liver stem-like cells (HLSCs) may undergo differentiation in vitro into urea producing hepatocytes and in vivo may sustain liver function in models of experimentally induced acute liver injury. The aim of this study was to assess the safety of HLSCs intrahepatic administration in inherited neonatal-onset hyperammonemia. The study was approved by the Agenzia Italiana del Farmaco on favorable opinion of the Italian Institute of Health as an open-label, prospective, uncontrolled, monocentric Phase I study (HLSC 01-11, EudraCT-No. 2012-002120-33). Three patients affected by argininosuccinic aciduria (patient 1) and methylmalonic acidemia (patients 2 and 3) and included in the liver transplantation list were enrolled. In all patients, HLSCs were administered by percutaneous intrahepatic injections (once a week for two consecutive weeks) within the first months of life. The first patient received 125,000 HLSCs x gram of liver/dose while the other two patients received twice this dose. No immunosuppression was administered since HLSCs possess immunomodulatory activities. None of the patients experienced infections, hyperammonemia decompensation, or other adverse events during the whole observation period. No donor specific antibodies (DSA) against HLSCs were detected. Patients were metabolic stable despite an increase (~30%) in protein intake. Two patients underwent liver transplantation after 19 and 11 months respectively, and after explantation, the native livers showed no histological alterations. In conclusion, percutaneous intrahepatic administration of HLSCs was safe in newborn with inherited neonatal-onset hyperammonemia. These data pave the way for Phase II studies in selected inherited and acquired liver disorders.