Muscle cells seeded on a urethra scaffold. (Wake Forest University School of Medicine)

By Mary Forgione, Tribune, March 8, 2011

Growing tissue outside the body — and then making it work inside the body — is an effort still in its infancy. But it has promise. Much promise. Now researchers have pushed the promise of regenerative medicine closer to reality, by creating urethras out of cells grown in a lab.

Researchers at Wake Forest University in North Carolina report that they have successfully taken tissue from five boys who had urethral defects, coaxed that tissue to grow on “tubularised polyglycolic acid:poly(lactide-co-glycolide acid) scaffolds” — i.e., they turned the tissue into tubes — and successfully inserted the tubes into the boys.

An account of their work was published Tuesday in the Lancet. The short version: The grafts appeared normal three months after they were implanted.

The researchers concluded, quite confidently: “Tubularised urethras can be engineered and remain functional in a clinical setting for up to 6 years. These engineered urethras can be used in patients who need complex urethral reconstruction.”

This diagram from Gray’s Anatomy shows what urethras actually do — helpful for anyone uncertain of the importance of the structures.

Obviously, such work bodes well for the future of regenerative medicine. Sure, it’s preliminary, but it seems to be a good start.

Anthony Atala MD: Surgeon

Anthony Atala asks, “Can we grow organs instead of transplanting them?” His lab at the Wake Forest Institute for Regenerative Medicine is doing just that — engineering over 30 tissues and whole organs.

Why you should listen to him:

Anthony Atala is the director of the Wake Forest Institute for Regenerative Medicine, where his work focuses on growing and regenerating tissues and organs. His team engineered the first lab-grown organ to be implanted into a human — a bladder — and is developing experimental fabrication technology that can “print” human tissue on demand.

In 2007, Atala and a team of Harvard University researchers showed that stem cells can be harvested from the amniotic fluid of pregnant women. This and other breakthroughs in the development of smart bio-materials and tissue fabrication technology promises to revolutionize the practice of medicine.

“Anthony Atala bakes things that will make you feel good inside, but we’re not talking cakes and muffins.”

Anthony Atala – Printing a Human Kidney 2011

Anthony Atala & Growing New Organs 2010

Urethras Created from Patients’ Own Cells

US doctors made urethras for five boys in Mexico after they were injured in accidents.
Photograph: Olivier Pirard/Rex Features

Construction of urethras for injured boys in US moves science a step closer to growing replacement body parts

LA, March 8, 2011  —  Doctors have created urethras using patients’ own cells for the first time, providing another example that scientists may be able to grow replacement body parts one day.

American doctors made the urethras for five boys in Mexico, aged 10 to 14, after they were injured in accidents several years ago.

The urethra is a thin tube that carries urine out of the body from the bladder; cells from both organs are very similar. Tissue grafts are normally used in such cases, but there’s a less than 50% success rate.

After removing a postage stamp-sized section of cells from the boys’ bladders, scientists put the cells into a special mixture in a laboratory to speed up their growth. They then constructed a tiny mesh tube out of the same material used for dissolvable stitches in surgeries to act as a scaffold. The tube was alternately coated with muscle cells on the outside and lining cells on the inside.

Dr Anthony Atala, a professor of surgical sciences at the Wake Forest University school of medicine in North Carolina, described the process as “very much like baking a layer cake”.

He said the new structure was put into an incubator for several weeks before being implanted in the patient. The scaffold eventually disintegrated, leaving the patient’s own cells as a new urethra.

Up to six years after having their new urethras implanted, Atala said the boys’ organs were fully functional and no major side effects were reported. “It’s like they now just have their own urethras.”

Atala said the techniques used might be applied to create more complicated tubular structures in the body, like blood vessels. She and her colleagues have previously made bladders using patients’ own cells.

The urethra research was paid for by the National Institute of Diabetes and Digestive and Kidney Diseases and the National Institutes of Health. It was published online in the medical journal Lancet.

In recent years, doctors have made new windpipes for patients partly from their own stem cells.

A tissue engineering expert at Bond University in Australia, Patrick Warnke, and his team have grown a replacement jaw and they are now working on an eye.

“It’s not so much science fiction anymore to think we can grow replacement organs,” Warnke said.

He also said he thought it was possible that children, who heal faster than adults, might be better candidates for such procedures in the future, though that could raise ethical dilemmas.

“Tissue regeneration is much faster in children, but my gut feeling tells me not to do it,” he said. “If you mess it up in a child, it will be horrific.”

Other experts said using science to reconstruct body parts was the ultimate medicine.

Chris Mason, the chair of regenerative medicine bioprocessing at University College London, said in a statement: “When an organ or tissue is irreparably damaged or traumatically destroyed, no amount of drugs or mechanical devices will restore the patient back to normal.

“If the goal is cure, then cell-based therapies are the answer.”

The Male Urethra

FIG. 1142– The male urethra laid open on its anterior (upper) surface.

(Urethra Virilis)

The male urethra (Fig. 1142) extends from the internal urethral orifice in the urinary bladder to the external urethral orifice at the end of the penis. It presents a double curve in the ordinary relaxed state of the penis (Fig. 1137). Its length varies from 17.5 to 20 cm.; and it is divided into three portions, the prostatic, membranous, and cavernous, the structure and relations of which are essentially different. Except during the passage of the urine or semen, the greater part of the urethral canal is a mere transverse cleft or slit, with its upper and under surfaces in contact; at the external orifice the slit is vertical, in the membranous portion irregular or stellate, and in the prostatic portion somewhat arched.

The prostatic portion (pars prostatica), the widest and most dilatable part of the canal, is about 3 cm. long, It runs almost vertically through the prostate from its base to its apex, lying nearer its anterior than its posterior surface; the form of the canal is spindle-shaped, being wider in the middle than at either extremity, and narrowest below, where it joins the membranous portion. A transverse section of the canal as it lies in the prostate is horse-shoe-shaped, with the convexity directed forward.

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