The use of stem cells in liver disease.

PURPOSE OF REVIEW: Cell transplantation to restore liver function as an alternative to whole liver transplantation has thus far not been successful in humans. RECENT FINDINGS: Adult mature hepatocytes and various populations of liver progenitors and stem cells are being studied for their regenerative capabilities. Hepatocyte transplantation to treat metabolic deficiencies has shown promising early improvement in liver function; however, long-term success has not been achieved. Liver progenitor cells can now be identified and were shown to be capable to differentiate into a hepatocyte-like phenotype. Despite evidence of mesenchymal stem cell fusion in animal models of liver regeneration, encouraging results were seen in a small group of patients receiving autologous transplantation of CD133 mesenchymal stem cells to repopulate the liver after extensive hepatectomy for liver masses. Ethical issues, availability, potential rejection and limited understanding of the totipotent capabilities of embryonic stem cells are the limitations that prevent their use for restoration of liver function. The effectiveness of embryonic stem cells to support liver function has been proven with their application in the bioartificial liver model in rodents. SUMMARY: There is ongoing research to restore liver function in cell biology, animal models and clinical trials using mature hepatocytes, liver progenitor cells, mesenchymal stem cells and embryonic stem cells.