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April 16, 2013

Bioengineered Kidney a Possible Solution to Donor-Organ Crisis

by Jessica Berman

Scientists in Boston, Massachusetts, have for the first time bioengineered a functioning rat kidney, a development that could eventually change the lives of humans on lengthy organ-transplant waiting lists.  But some experts are concerned the technology could run up against a lengthy regulatory process.  

In the United States alone, an estimated 17,000 people a year with end-stage kidney disease are able to receive a life-saving donor organ.  But that’s only a fraction of the patients on waiting lists for transplantable kidneys.  About 90 percent of them are on dialysis; many die waiting.

That makes the achievement by researcher Harald Ott and colleagues at Boston's Massachusetts General Hospital especially exciting, says Stephen Badylak, a pioneer in the field of organ regeneration at the University of Pittsburgh in Pennsylvania.

“So, this has the potential to take care of that [donor shortage] problem and, even better, if it works, the patients who receive these types of engineered organs won’t have to receive an immunosuppressant," said Badylak. "I think everyone on renal dialysis now would applaud this work.”

Dr. Badylak's own work in regenerative medicine involves developing livers for transplant.

Dr. Ott’s team used a detergent to completely cleanse the rat kidney of living tissue, leaving a protein framework that retains the structure of the blood vessels and other parts of the organ.  The scientists then repopulated that framework with human cells for the blood vessel linings, and kidney cells from newborn rats.  The reassembled organ was then put in an incubating chamber for five days to let the tissues grow.  The result was a functioning rat kidney.  

Although the regenerated rat kidney in Ott's study produced urine, it did not function as well as a natural organ.

It’s possible, says Stephen Badylak, that patients needing transplants could have their own dysfunctional organs regenerated in the same way.  Badylak says they would not have to take immunosuppressant drugs, with all their unpleasant side effects, to keep their bodies from rejecting a donor organ.  

At the rate the field is progressing, Badylak predicts organ regeneration could become a real option for human transplant patients in five to seven years.  But he's concerned about major regulatory hurdles.

“We are going to be ready to help people with this before we are going to have regulatory agencies telling us 'wait until we figure out how to handle it.'  This should be a wake up call for them to say, ‘This is coming," he said. "How are we going to take care of this?'”

Curt Civin leads the Stem Cell Biology and Regenerative Medicine Center at the University of Maryland School of Medicine in Baltimore.  

He says hematopoietic stem cells, or master cells from bone marrow, have been studied longer than any other tissue.

Civin says the blood stem cells from marrow are at the heart of regenerative medicine because they animate the organ scaffold, making it function.   

But Civin believes the complexity of the field means it will be a while before entire customized organs, such as kidneys, are available for human transplant.

“So I think this problem will yield - in perhaps one decade, perhaps two decades - to where we have lots of rats and mice and other animals with transplanted kidneys made from stem cells, maybe by techniques very much like this, and then we’re at the setting to study in the [human] patients," said Civin.

The U.S. Food and Drug Administration, which has regulatory authority over any new drugs, medical devices and procedures, did not offer a comment.  The agency has strict guidelines requiring data from clinical trials before deciding whether to approve a procedure - a process that can take years.  

But the FDA also has a fast-track approval process to expedite the review of drugs or in this case, the regeneration of organs for transplantation, when there is a serious, unmet medical need.

An article on the creation of a functioning rat kidney by Harald Ott and colleagues is published in the journal Nature Medicine.