Hepatocyte transplantation: waiting for stem cells

Hepatocyte transplantation has been proposed as an attractive therapeutic approach to a variety of liver diseases. Progress, however, in several areas is needed, before this form of therapy is broadly accepted and applied to patients with liver disease. The purpose of the review is to provide the reader with the latest scientific developments relevant for future liver cell therapies.

Clinical application of hepatocyte transplantation is limited by good quality donor livers for the isolation of cells. Recent publications thus focus on stem cells as suitable sources for hepatocytes and liver repopulation strategies that could reduce the number of transplanted cells. How to overcome host immune responses against allogeneic cells can potentially be learned from a new tolerance protocol. Recently discovered technologies for reprogramming of postnatal cells into pluripotent stem cells may pave the way towards the generation of patient-specific autologous cells.

The current focus of research aims to reduce the shortage of transplantable cells by the application of stem cell sources or by the conditioning of recipient livers. Therapies for severe chronic liver diseases based on adult (stem) cells are already beginning to move into clinical trials. However, many questions about safety and efficacy need to be answered, before fetal liver progenitor cells, embryonic stem cells and induced pluripotent stem cells can be applied in humans.