Scientists create human liver
from stem cells Release date: 7/10/2013
"The promise of an off-the-shelf liver seems much closer than one
could hope even a year ago," said Dusko Illic, a stem cell expert at
King's College London.
LONDON (Reuters) - Scientists have for the first time created a functional
human liver from stem cells derived from skin and blood and say their
success points to a future where much-needed livers and other transplant
organs could be made in a laboratory.
While it may take another 10 years before lab-grown livers could be used
to treat patients, the Japanese scientists say they now have important
proof of concept that paves the way for more ambitious organ-growing
experiments.
"The promise of an off-the-shelf liver seems much closer than one could
hope even a year ago," said Dusko Illic, a stem cell expert at King's
College London who was not directly involved in the research but praised
its success.
He said however that while the technique looks "very promising" and
represents a huge step forward, "there is much unknown and it will take
years before it could be applied in regenerative medicine."
Researchers around the world have been studying stem cells from various
sources for more than a decade, hoping to capitalize on their ability to
transform into a wide variety of other kinds of cell to treat a range of health
conditions.
Countries across the world have a critical shortage of donor organs for
treating patients with liver, kidney, heart and other organ failure. Scientists
are keenly aware of the need to find other ways of obtaining organs for
transplant.
The Japanese team, based at the Okohama City University Graduate
School of Medicine in Japan, used iPS cells to make three different cell
types that would normally combine in the natural formation of a human
liver in a developing embryo - hepatic endoderm cells, mesenchymal stem
cells and endothelial cells - and mixed them together to see if they would
grow.
They found the cells did grow and began to form three-dimensional
structures called "liver buds" - a collection of liver cells with the potential to
develop into a full organ.
When they transplanted them into mice, the researchers found the human
liver buds matured, the human blood vessels connected to the mouse
host's blood vessels and they began to perform many of the functions of
mature human liver cells.
"To our knowledge, this is the first report demonstrating the generation of a
functional human organ from pluripotent stem cells," the researchers wrote
in the journal Nature.
Malcolm Allison, a stem cell expert at Queen Mary University of London,
who was not involved in the research, said the study's results offered "the
distinct possibility of being able to create mini livers from the skin cells of a
patient dying of liver failure" and transplant them to boost the failing organ.
Takanori Takebe, who led the study, told a teleconference he was so
encouraged by the success of this work that he plans similar research on
other organs such as the pancreas and lungs.
A team of American researchers said in April they had created a rat kidney
in a lab that was able to function like a natural one, but their method used
a "scaffold" structure from a kidney to build a new organ.
And in May last year, British researchers said they had turned skin cells
into beating heart tissue that might one day be able to be used to treat
heart failure.
That livers and other organs may one day be made from iPS cells is an
"exciting" prospect, said Matthew Smalley of Cardiff University's European
Cancer Stem Cell Research Institute.
"(This) study holds out real promise for a viable alternative approach to
human organ transplants," he said.
Chris Mason, a regenerative medicine expert at University College London
said the greatest impact of iPS cell-liver buds might be in their use in
improving drug development.
"Presently to study the metabolism and toxicology of potential new drugs,
human cadaveric liver cells are used, " he said. "Unfortunately these are
only available in very limited quantities".
The suggestion from this new study is that mice transplanted with human
iPS cell-liver buds might be used to test new drugs to see how the human
liver would cope with them and whether they might have side-effects such
as liver toxicity.
(Reporting by Kate Kelland; Editing by Janet Lawrence)