RECONSTRUCTIVE UROLOGY

Urethral stricture repair with an off-the-shelf collagen matrix
El-Kassaby AW, Retik AB, Yoo JJ, Atala A
From the Center for Genitourinary Tissue Reconstruction, Department of Urology, Harvard Medical School, Boston, Massachusetts, and Ain-Shams, University, Cairo, Egypt
J Urol. 2003; 169:170-3

• Purpose: In select patients with urethral strictures in whom genital skin is insufficient alternative tissues are needed for urethral reconstruction. We explored the feasibility of using a bladder submucosa collagen based inert matrix as a free graft substitute for urethral stricture repair.
• Materials and Methods: A total of 28 patients 22 to 61 years old with a diagnosis of urethral stricture underwent reconstructive surgery using a collagen based inert matrix for urethral repair. The inert collagen matrix was trimmed to size as needed for each patient and the neourethra was created by anastomosing the matrix in an onlay fashion to the urethral plate with continuous 6-zero absorbable sutures. The size of the created neourethra ranged from 1.5 to 16 cm. A voiding history, physical examination, retrograde urethrography, uroflowmetry and cystoscopic examinations were performed preoperatively and postoperatively. Random urethral biopsies were also performed.
• Results: After a 36 to 48-month followup (mean 37) 24 of the 28 patients had a successful outcome. The remaining 4 patients had a slight caliber decrease at the anastomotic sites on urethrography. A subcoronal fistula developed in 1 patient which closed spontaneously 1 year after repair. Mean maximum urine flow rate increased from the preoperative value of 9 +/- 1.29 to 19.7 +/- 3.07 ml. per second postoperatively. Cystoscopic studies revealed adequate caliber conduits and normal appearing urethral tissues. Histological examination of the biopsy specimens showed the typical urethral stratified epithelium.
• Conclusions: Use of an off-the-shelf collagen inert matrix appears to be beneficial for patients with urethral strictures and obviates the need for obtaining an autologous graft, thus eliminating donor site morbidity.
  
  
• Editorial Comment
  The authors are known for applying biomaterials for reconstructive purposes of the lower urinary tract. This paper deals with their first experience of acellular collagen matrix obtained from cadaveric human bladder tissue for the surgical treatment of urethral stricture disease. Half of the patients had some form of penile urethral strictures, which are usually the more difficult ones to treat. Still, a successful surgical outcome was claimed in 24 of 28 patients after a follow-up ranging from 36 to 48 months. It is remarkable that in 4 patients endoscopic biopsies revealed normal urethral tissue.
  Acellular cadaveric tissue can nowadays be produced in larger quantities and would thus be storable for regular use in urethral reconstructive surgery. It has the advantage of unlimited availability avoiding secondary harvesting at the time of urethral reconstruction.
  The potential and the advantages are obvious but one should still be cautious about immediate use of acellular collagen matrix. Possible remnant DNA, the issue of prions, and the still unproven fate of the cadaveric tissue must be explored in larger series of patients and under a long-term follow up. It will be especially interesting to see whether there are systemic immunologic changes or adaptations in these patients.
  Despite these cautious marks the future of reconstructive surgery of the lower urinary tract seems to be promising for absorbable biomaterials derived from human or animal sources.

Dr. Arnulf Stenzl
Professor and Chairman of Urology
Eberhard-Karls-University Tuebingen
Tuebingen, Germany