Scientists have used boys' own cells to tissue-engineer urethras that were viable and functional, just like regular urethras for over six years, according to an Article published in The Lancet. The researchers from Wake Forest Institute for Regenerative Medicine, Wake Forest University School of Medicine, USA explained that regular urethra characteristics appeared within three months.
Note: In medicine, autologous means that the donor and the recipient is the same person. As in this case, the boys received autologous tissue-engineered urethras; their own cells were used.
The patients, all boys, had complex urethral problems, which can be caused by injury, disease or congenital defects. They can considerably complicate the person's ability to urinate properly. If the urethra is too narrow (urethral strictures) the individual is much more susceptible to infections, may have blood in their urine, and experience straining and major discomfort.
Treatment options are often limitedOn-lay repairs are usually more effective than tubularized repairs for urethral reconstruction with tissue grafts, the authors explained. Sometimes, when the patient has complex or long urethral defects, tubularized tissue grafts may be required. However, a significant percentage of these procedures are not successful. No studies have looked at creating tubularized engineered urethras for patients, which might replace grafts.
Professor Anthony Atala and team carried out a study which included five boys with urethral defects. They took a sample of tissue (biopsy) from each child's bladder/urethral area. Muscle and epithelial cells were expanded and seeded onto tubularized scaffolds. The tissue-engineered tabularized urethras were used for urethral reconstruction. The boys were then followed-up with a number of tests, including urine flow and biopsies.
The boys, aged between ten and fourteen years underwent surgery between 2004 and 2007. Follow-ups, which took an average of 71 months, were completed in 2010.
In a communiqué, The Lancet wrote:
"Biopsies confirmed the presence of both epithelial and muscle cells in the reconstructed urethras. All five boys were continent at the end of follow up, with a median end maximum urinary flow rate was 27•1 mL/s. The reconstructed grafts had developed a normal appearing architecture by 3 months after implantation.
Entire segments of damaged urethra - between the penis and the prostate - were replaced using engineered tubes. Experts say these are the hardest areas to repair.
Whether this might be as effective with adult patients remains to be seen, the authors wrote. Further studies in this areas are needed, as well as trials to determine whether the technique might be effective for other parts of the urethra.
The scientists concluded:
"All five boys were continent at last follow-up..Tissue engineered urethras, created with patients' own cells, can be used to successfully treat complex urethral defects. The tubularised engineered urethras showed histological and functional characteristics similar to native urethras and maintained an adequate outflow for up to 6 years. Tissue engineered urethras could be a new alternative source for reconstruction."
In a Comment, Dr. Karl-Dietrich Sievert wrote that the cost-effectiveness of this method, in terms of actual tube length, needs to be demonstrated in a larger study including a wider group of patients. A multi-institutional trial is required, he added.
"Tissue-engineered autologous urethras for patients who need reconstruction: an observational study"
Atlantida Raya-Rivera MD, Diego R Esquiliano MD, James J Yoo MD, Prof Esther Lopez-Bayghen PhD, Shay Soker PhD, Prof Anthony Atala MD
The Lancet, Early Online Publication, 8 March 2011
doi:10.1016/S0140-6736(10)62354-9Cite or Link Using DOI
Source: The Lancet
Written by Christian Nordqvist