title: Cellular therapy and bioartificial approaches to liver replacement.
abstract: OBJECTIVE
  The success of liver transplantation has increased over the past 20 years due to improved immunosuppressive medications, surgical technique and donor-recipient selection. To date, the number of patients waiting for a liver transplant exceeds the number of transplants performed yearly by over a 2 : 1 ratio. Despite efforts to expand the donor pool, mortality of patients waiting for a liver remains high due to the shortage of donor organs. Herein, we discuss options for liver replacement that are currently under development.
  
  
  RESULTS
  Extracorporeal bioactive liver perfusion devices were investigated in the late 1990s and preliminarily demonstrated safety but failed to show clinical efficacy. Current research is ongoing, but the focus has shifted to xenotransplantation of whole organs, organ engineering and cell transplantation. These new modalities are limited to small and large animal studies and each present unique advantages and limitations.
  
  
  CONCLUSIONS
  Discovery of new sources of organs or cells to replace a damaged liver may be the only long-term solution to provide definitive therapy to all patients who require transplantation. The past 2 years have seen notable achievements in xenotransplantation, tissue engineering and cell transplantation. Though challenges remain, now identified, they may be readily solved.
authors.affiliation: Department of Surgery, Comprehensive Transplant Center, Northwestern University Feinberg School of Medicine, Chicago, Illinois, USA.
authors.forename: Jason A
authors.initials: JA
authors.lastname: Wertheim
authors.forename: Pedro M
authors.initials: PM
authors.lastname: Baptista
authors.forename: Alejandro
authors.initials: A
authors.lastname: Soto-Gutierrez
mesh_terms: D000818:Animals; D064987:Cell- and Tissue-Based Therapy; D022781:Hepatocytes / Q000637:transplantation; D006801:Humans; D017093:Liver Failure / Q000601:surgery / Q000628:therapy*; D016031:Liver Transplantation; D019164:Liver, Artificial; D023822:Tissue Engineering; D014183:Transplantation, Heterologous