Liver cell transplantation.

Liver cell transplantation is an emerging procedure, consisting of infusing mature adult hepatocytes in the portal system of the recipient. It aims to correct inborn errors of liver metabolism, bridge unstable patients to transplantation, or even allow bridge to recovery in fulminant liver failure. The technique addresses ideally patients with inborn errors of metabolism, unstable but not sick enough for orthotopic transplantation. Best results have so far been obtained in metabolic diseases, such as urea cycle disorders, glycogenosis type I, Crigler Najjar, Refsum disease and factor VII deficiency. Cryopreserved hepatocytes can be used, allowing delay between cell isolation and patient's transplantation. The percentage of engraftment obtained can reach up 10%, with de novo expression of deficient enzyme activity. Better results of engraftment have been obtained in animal studies by different chemical or physical techniques, but not yet applied in humans. Because supply of human cells can be limited, research also aims to obtain transplantable cells from other sources, such as embryonic or adult stem cells, or liver progenitor cells that could be expanded in vitro. Careful progression in this field, and collaboration between centers are mandatory to validate further the technique for wider clinical use.