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Scientists Grow Replacement Urethra in Lab

Urinary function continues years after implant

U.S. doctors have announced the successful use of an artificial body part in reconstructive surgery. It's the latest example of what is known as tissue engineering.

Five boys in this new study, ages 10 to 14, all had damage to their urethra. That's the tube that carries urine out of the bladder.

The standard treatment is a graft - using a piece of the patient's own skin or other tissue to form a replacement urethra. But the procedure only works about half the time. In fact, that was the case with two of the boys in this study.

Dr. Anthony Atala of the Wake Forest Institute for Regenerative Medicine in North Carolina and his colleagues decided to try building a better urethra in the lab.

They started by taking a small biopsy from each boy's damaged urethra, which has different kinds of cells on the inside and on the outside. "And we then take that tissue and we tease the cells apart - muscle cells on the outside and urethral lining cells [on the inside]," Atala says. "And we're able to grow those outside the body in large quantities before we start creating the construct."

The construct starts with a tiny, tube-shaped framework that will support cells as they grow into a replacement urethra. The framework is made of the same sort of material used for surgical sutures that are absorbed by the body. The process takes months and then the artificial organ is surgically implanted into the patient.

In the cases reported in this study, published in The Lancet, an average of six years after surgery, there were no failures of the artificial urethras.

But it isn't just the doctors who pronounced the procedure a success. "The patients did end up filling out quality of life and satisfaction surveys," Atala reported, "and they recognized that organ as being their own. So they have no issues. They're emptying [their bladders] well and without any problems at this point."

If using tissue-engineered urethras becomes a standard treatment, Atala expects each procedure will be more costly than the current graft, because of the expense of growing the replacement in the laboratory. But it could save money if it avoids the need for repeat surgeries.

"So in the long run, this would be less expensive than the current technology."

Researchers at the Wake Forest Institute for Regenerative Medicine have been developing other tissue-engineered organs. Some of their successful recipients have been living with their artificial bladders, for example, for a decade. The institute is currently working on a wide variety of other tissues, but Anthony Atala cautions that growing complex solid organs with dense blood supplies is very challenging and is at least years away.