A team of researchers led by Dr.Harald Ott of Massachusetts General Hospital in Boston have succesfully created a functioning rat's kidney using cells from newborn rats.

Ott and his team started with kidneys from 68 rats and used detergent to remove the actual cells. That left behind a "renal scaffold," a three-dimensional framework made of the fibrous protein collagen, complete with all of a kidney's functional plumbing, from filter to ureter.

The scientists then seeded that scaffold with renal cells from newborn rats and blood-vessel-lining cells from human donors. To make sure each kind of cell went to the right spot, they infused the vascular cells through the kidney's artery - part of the scaffold - and the renal cells through the ureter.

Three to five days later, the scientists had their "bioengineered" kidneys.

When the organs were placed in a dialysis-like device that passed blood through them, they filtered waste and produced urine.

But the true test came when the scientists transplanted the kidneys into rats from which one kidney had been removed. Although not as effective as real kidneys, the lab-made ones did pretty well, Ott and his colleagues reported.

In the United States, 100,000 people with end-stage renal disease are on waiting lists for a donor kidney, but 5,000 to 10,000 die each year before they reach the top of the transplant list.

If the technology is ever ready to make kidneys for people, the cells would come from the intended recipient, which would minimize the risk of organ rejection and reduce the need for lifelong immune suppression to prevent that.

Presented by Adam Justice