9 March 2011
New urethras grown in lab
by George Atkinson 
Wake Forest University tissue engineering researchers have used patients' own cells to build brand new urinary tubes (urethras) for transplantation into the patients. Defective urethras can be the result of injury, disease or birth defects. While short defects in the tube are often easily repairable, larger defects can require tissue grafts which have a failure rate of over 50 percent. Documented in the The Lancet, the breakthrough alternative involved replacing damaged segments of urethras in five boys. Tests to measure urine flow and tube diameter showed that the engineered tissue remained functional throughout the six-year period of the study. The first step in engineering the replacement urethral segments involved taking a small bladder biopsy from each patient. From each sample, the scientists isolated smooth muscle cells and endothelial cells. The cells were multiplied in the lab for 3-6 weeks and were then placed on a three-dimensional scaffold shaped like a urethral tube. Smooth muscle cells were placed on the outside of the scaffold and endothelial cells on the inside. After cell placement, the scaffolds were incubated for seven days. The total time for construction ranged from four to seven weeks.
Once fully grown, the tubes were surgically implanted by removing the defective segment of the urethra and sewing the replacement tubes in place. Once in the body, the cells continued to expand and tissue formation began. Biopsies showed that the engineered urethras had normal layers of epithelial and smooth muscle within three months after implantation. "These findings suggest that engineered urethras can be used successfully in patients," said Anthony Atala, director of the Wake Forest Institute for Regenerative Medicine. "This is an example of how the strategies of tissue engineering can be applied to multiple tissues and organs." Related:
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