Reported March 14, 2011

Urethras Grown In The Lab And Implanted

(Ivanhoe Newswire) -- There's a new "first" in the world of tissue engineering. Researchers have used patients' own cells to build tailor-made urinary tubes and successfully replace damaged tissue.

The research team, from the Institute for Regenerative Medicine at Wake Forest University Baptist Medical Center, reported replacing damaged segments of urethras in five boys aged 10 to 14. Tests that measured urine flow and tube diameter revealed the engineered tissue remained functional throughout the six-year follow-up period.

"These findings suggest that engineered urethras can be used successfully in patients and may be an alternative to the current treatment, which has a high failure rate," Anthony Atala, M.D., senior author, director of the Wake Forest Institute for Regenerative Medicine and a pediatric urologic surgeon, was quoted as saying.

 "This is an example of how the strategies of tissue engineering can be applied to multiple tissues and organs."

Defective urethras can result from injury, disease or birth defects. While short defects in the tube are often easily repairable, larger defects may require a tissue graft, which is typically taken from skin or the lining of the cheek. These grafts have failure rates of more than 50 percent and often lead to infections, difficulty urinating, pain, or bleeding.

To engineer urethral segments, researchers first took a small bladder biopsy from each patient. They then isolated smooth muscle cells and endothelial cells (the cells that line blood vessels and other tubular structures). These cells were multiplied in the lab for weeks and were then placed on a 3-D scaffold that was shaped like a urethral tube. Smooth muscle cells were placed on the outside of the scaffold, while endothelial cells were placed on the inside. After cell placement, the scaffolds were incubated for seven days. By day six, all the surface areas were completely covered with cells.

After incubation, the tubes were surgically implanted by removing the defective segment of the urethra and scar tissue and sewing the replacement tubes in place. The cells continued to expand once they were placed in the body, and tissue formation began. Biopsies showed the engineered urethras had normal layers of epithelial and smooth muscle within three months of implantation.

SOURCE: The Lancet, March 7, 2011