There is a shortage of livers available for transplant, meaning thousands die every year (Reuters) Japanese scientists have grown a fully functional human liver from stem cells for the first time. The researchers from Yokohama City University created the organ by transplanting 'liver buds' from human stem cells to restore liver function in mice. Published in the journal Nature, Takanori Takebe and Hideki Taniguchi showed how they stopped mice with liver failure from dying by transplanting the stem cell-grown structures into them. At present, there is a huge demand for human livers for transplants. In the US last year, almost 3,000 people died waiting for a liver while 5,800 transplants took place. Embryonic stem cells were discovered in 1981 but scientists have hitherto been unable to generate a human organ because of the complex interactions between cells and tissues as they develop. However, the Yokohama City scientists challenged this belief by focusing on the earliest stage of organ creation# - the interactions during 'organ bud' development. There are two main types of stem cells: those that are harvested from embryos, and reprogrammed induced pluripotent stem cells (iPSCs) which are taken from skin and blood. The researchers used the latter type … Continue reading →

Scientists have created a tiny liver from stem cells that helped mice with chronic liver failure regain function. Researchers in Japan transplanted 4-millimeter-wide "liver buds" made from human stem cells into a mice. The transplanted liver buds, which were placed in the cranium or abdomen, were able to work in conjunction with the mice's own organs and secrete human liver-specific proteins. They also created human metabolites, tiny molecules that are produced when the body metabolizes a substance. Co-author Takanori Takebe, a stem-cell biologist at Yokohama City University in Japan, said to Nature this was the first time people have made a solid organ using pluripotent stem cells, which are mature skin cells that are re-programmed to become an embryonic cell that can express any genetic characteristics. Play Video Play Video In this case, the liver buds were made from pluripotent stem cells that were told to express liver genes. Endothelial cells (which line blood vessels) taken from umbilical chord blood and mesenchymal stem cells (which make bone, cartilage and fat) were put into the mix as well. "We just simply mixed three cell types and found that they unexpectedly self-organize to form a three-dimensional liver bud -- this is a … Continue reading →

Functional miniature human livers have been created from induced pluripotent stem cells, say Japanese researchers in a study published today in the journal Nature. (Click link to read study). Called "liver buds", these mini-livers metabolized drugs in a human fashion, and performed most other functions of a liver, the researchers said. Moreover, the implanted livers prolonged survival of mice with chemically induced liver failure, as compared to control mice given a sham operation. The researchers used a new method to create the liver buds, grown on glass slides. They surrounded the nascent liver tissue with two other cell types that supported formation of the buds, including human umbilical vein endothelial cells. These cells self-organized and created their own blood vessels. When implanted, the liver buds hooked up to the mouse circulatory system. "Notably, although cells were plated in two-dimensional conditions, human iPSC-HEs (liver cells grown from IPS cells) self-organized into macroscopically visible three-dimensional cell clusters by an intrinsic organizing capacity up to 48 (hours) after seeding," the paper stated. Takanori Takebe, of Yokohama City University Graduate School of Medicine, is the paper's first author. The senior author is Hideki Taniguchi, also of the university. Other organs such as kidneys can … Continue reading →