Tiny livers grown from stem cells could repair damaged organs Experts have greeted the research as a "huge step" towards producing off the shelf livers that can be transplanted into patients. Around 700 liver transplants are carried out in the UK each year but around 100 patients die over the same period while on the waiting list due to a shortage of organ donors. "We proved that liver bud transplantation could offer therapeutic potential against liver failure," said Professor Takebe. This is a proof of principle approach. We're now planning to transplant the liver buds into the liver. To do that we have to reduce the size of the liver buds to a very small scale. That way they can be injected into the blood stream. I am optimistic that with a large infusion of several hundred of thousands of liver buds, around 30 per cent of the patient's original liver function could be restored and that should be enough to restore a viable liver system for that patient. Professor Takebe and his colleagues combined in the laboratory three types of human stem cells taken from bone marrow, blood vessels and reprogrammed skin cells known as induced pluripotent stem cells. In their study, which is published in the journal Nature, they claim the stem cells self-organised to form three-dimensional liver buds in around six days. When these were transplanted into mice, the liver buds became incorporated into the vascular system and began functioning as adult liver tissue. Previous attempts to grow livers from stem cells had failed to get them to grow the blood vessels needed to make them function properly. Professor Malcolm Alison, a stem cell biologist at Queen Mary University of London, said: This study has made a major step forward in improving the effectiveness of liver cell transplantation for treating acute liver failure. Human mature liver cells transplanted on their own can fail to thrive, but if immature liver cells are first combined with their normally nurturing supportive cells they can mature in the transplanted host and function efficiently. This science opens up the distinct possibility of being able to create mini-livers from the skin cells of a patient dying of liver failure, and when transplanted would not be subjected to immune rejection as happens with conventional liver transplants today. The human liver plays an important role in metabolising drugs and sugar in the blood. It also helps remove potentially harmful toxins from the blood stream. There is currently no way to compensate for the loss of liver function. While the liver has a great capacity to repair itself, diseases such as hepatitis or alcohol abuse can damage the liver. Professor Stuart Forbes, from the Centre for Regenerative Medicine at University of Edinburgh, said: "Although exciting there is still a lot more research needed before this approach could be applied to patients with liver disease. "The liver buds were small and scaling up to a "human relevant size" may be a challenge, as will creating a true liver structure."