The worldwide shortage of donor livers to transplant
end stage liver disease patients has prompted the search for alternative cell
therapies for intractable
liver disease. Embryonic stem cells can be readily differentiated into hepatocytes, and their
transplantation into animals has improved liver function in the absence of
teratoma formation: their use in
bioartificial liver support is an obvious application. In animal models of
liver disease, adopting strategies to provide a selective advantage for transplanted foetal or adult hepatocytes have proved highly effective in repopulating recipient livers, but the poor success of today's hepatocyte transplants can be attributed to the lack of a clinically applicable procedure to force a similar repopulation of the human liver. The activation of bipotential hepatic progenitor cells is clearly vital for survival in many cases of
acute liver failure, but surprisingly little progress has been made with these cells in terms of
transplantation. Finally there is the controversial subject of autologous bone marrow, and while the contribution of these indigenous cells to liver turnover seems at best, trivial, results from a small number of phase 1 studies of
transplantation of bone marrow to cirrhotic patients have been moderately encouraging.