Rats implanted with human kidneys from aborted fetuses lived up to four months after transplant.

Credit: Eugene Gu et al

By Tanya Lewis, Staff Writer

Researchers say they have developed a new technique that will get more kidneys to people who need transplants, but the method is sure to be controversial: The research shows that it is feasible to remove a kidney from an aborted human fetus, and implant the organ into a rat, where the kidney can grow to a larger size.

It’s possible that further work could find a way to grow kidneys large enough that they could be transplanted into a person, the researchers said, although much more research is needed to determine whether this could be done.

“Our long-term goal is to grow human organs in animals, to end the human donor shortage,” said study co-author Eugene Gu, a medical student at Duke University and the founder and CEO of Ganogen, Inc., a biotech company in Redwood City, California. [The 9 Most Interesting Transplants]

Such organs could also be used to test drugs before human trials are started, which would help avoid the risks associated with using untested compounds in people, Gu added.

The new findings will be published tomorrow (Jan. 22) in the American Journal of Transplantation.

But the research raises a number of ethical questions, including whether it is acceptable to use human fetal organs in research, or to transplant human organs into animals. If the research moves forward, it must be determined that the organs were obtained with proper consent, and that the research was conducted with adequate oversight, experts said.

Human-rat transplants

More than 123,000 people in the United States currently need an organ transplant, and about 21 people die each day waiting for one, according to the U.S. Department of Health and Human Services.

Previously, other scientists had attempted to grow immature human kidneys in the abdomens of mice, but the new research “is definitely the first time an actual whole human organ has been grown in an animal, and has sustained the life of that animal,” Gu told Live Science.

In the new study, Gu and his colleagues obtained human fetal kidneys from Stem Express, a Placerville, California-based company that supplies researchers with tissue from deceased adults and fetuses. The people who donated the fetal tissues gave consent for the kidneys to be used in research, and the scientists were completely separated from the donation process, Gu said.

The researchers transplanted the fetal kidneys into adult rats that lacked an immune system (so as to avoid tissue rejection), and connected the animals’ blood vessels to the organs using a challenging procedure that involved tiny stitches, about three to four times smaller than the width of a human hair.

One of the main reasons that previous attempts to transplant fetal organs into animals have failed is due to a difference in the blood pressure between human fetuses and adult animals. In most adult animals, including rats, the average blood pressure is about three times higher than it is in human fetuses. If a fetal organ is transplanted without adjusting the pressure, “the organ basically hemorrhages everywhere,” Gu said.

To get around that problem, Gu’s team developed a device, called an arterial flow regulator, which they fitted around the rats’ blood vessels to decrease the pressure of the blood flowing into the fetal kidneys.

About a month after the researchers transplanted the fetal kidneys into the rats, the scientists surgically removed the animals’ own kidneys. The rats that received the transplanted kidneys survived an average of four months after transplant, and one even survived for 10 months, Gu said. By comparison, a control group of rats that did not receive a transplanted kidney lived for only three to four days after having their kidneys removed, the researchers said.

Kidney growth in a rat host

Kidney growth in a rat host

Credit: Eugene Gu et al

In addition to kidneys, the researchers have also transplanted human fetal hearts into rats, Gu said. The work is still in progress, but the researchers said it may also be possible to use the method with other organs. “This technology is applicable not just to the kidney, but to every kind of [blood-supplied] organ in the body,” Gu said.

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http://www.livescience.com/49503-human-kidneys-grown-in-rats.html?cmpid=558958

 

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