By James Gallagher
Health and science reporter, BBC News
The rat kidney was grown in the laboratory
A kidney "grown" in the laboratory has been transplanted into animals where it started to produce urine, US scientists say.
Similar techniques to make simple body parts have already
been used in patients, but the kidney is one of the most complicated
organs made so far.
A study,
in the journal Nature Medicine, showed the engineered kidneys were less effective than natural ones.
But regenerative medicine researchers said the field had huge promise.
Kidneys filter the blood to remove waste and excess water.
They are also the most in-demand organ for transplant, with long waiting
lists.
The researchers' vision is to take an old kidney and strip it
of all its old cells to leave a honeycomb-like scaffold. The kidney
would then be rebuilt with cells taken from the patient.
This would have two major advantages over current organ transplants.
The tissue would match the patient, so they would not need a
lifetime of drugs to suppress the immune system to prevent rejection.
It would also vastly increase the number of organs available
for transplant. Most organs which are offered are rejected, but they
could be used as templates for new ones.
Scaffolding
Researchers at Massachusetts General Hospital have taken the first steps towards creating usable engineered kidneys.
They took a rat kidney and used a detergent to wash away the old cells.
The remaining web of proteins, or scaffold, looks just like a
kidney, including an intricate network of blood vessels and drainage
pipes.
This protein plumbing was used to pump the
right cells to the right part of the kidney, where they joined with the
scaffold to rebuild the organ.
It was kept in a special oven to mimic the conditions in a rat's body for the next 12 days.
When the kidneys were tested in the laboratory, urine production reached 23% of natural ones.
The team then tried transplanting an organ into a rat. Once inside the body, the kidney's effectiveness fell to 5%.
Yet the lead researcher, Dr Harald Ott, told the BBC that
restoring a small fraction of normal function could be enough: "If
you're on haemodialysis then kidney function of 10% to 15% would already
make you independent of haemodialysis. It's not that we have to go all
the way."
He said the potential was huge: "If you think about the
United States alone, there's 100,000 patients currently waiting for
kidney transplants and there's only around 18,000 transplants done a
year.
"I think the potential clinical impact of a successful treatment would be enormous."
" Really impressive'
There is a huge amount of further research that would be needed before this is even considered in people.
The technique needs to be more efficient so a greater level
of kidney function is restored. Researchers also need to prove that the
kidney will continue to function for a long time.
There will also be challenges with the sheer size of a human
kidney. It is harder to get the cells in the right place in a larger
organ.
Prof Martin Birchall, a surgeon at University College London, has been involved in windpipe transplants produced from scaffolds.
He said: "It's extremely interesting. It is really impressive.
"They've addressed some of the main technical barriers to
making it possible to use regenerative medicine to address a really
important medical need."
He said that being able to do this for people needing an
organ transplant could revolutionise medicine: "It's almost the nirvana
of regenerative medicine, certainly from a surgical point of view, that
you could meet the biggest need for transplant organs in the world - the
kidney."
From BBC.