Transplantation of genetically modified autologous hepatocytes into nonhuman primates: feasibility and short-term toxicity.

Ex vivo gene therapy directed to the liver is being developed for the treatment of inherited metabolic diseases. Transplantation of hepatocytes that have been transduced with a low-density lipoprotein (LDL) receptor gene is a potential form of therapy for familial hypercholesterolemia (FH). We have demonstrated efficacy of ex vivo gene therapy for familial hypercholesterolemia in a rabbit animal model of this disease. In preparation for human trials, we describe in this report experiments in baboons for documentation of the feasibility and safety of autologous hepatocyte transplantation. Three baboons underwent a partial hepatectomy and their hepatocytes were isolated, cultured, and transduced with a retrovirus containing the human LDL receptor gene. The hepatocytes were harvested and infused into an indwelling catheter that had been placed into the inferior mesenteric vein at the time of liver resection. The baboons tolerated the procedures well and are being maintained and clinically evaluated for an indefinite time period. Follow-up evaluations have ranged from 3 to 8 months. Clinical evaluations have been unremarkable and blood chemistry and hematology determinations have stayed within normal limits.