BASIC AND TRANSLATIONAL UROLOGY

Botulinum toxin-A to improve urethral wound healing: an experimental study in a rat model
Sahinkanat T, Ozkan KU, Ciralik H, Ozturk S, Resim S
Department of Urology, University of Kahramanmaras Sutcu Imam School of Medicine, Kahramanaras, Turkey
Urology. 2009; 73: 405-9

• Objectives: Tensile distracting forces caused by elements such as a muscle pull can cause widening of scars in the tissue during the wound healing process. The aim of the present study was to investigate whether induced immobilization of the urethral muscle using botulinum toxin-A (BTX-A) enhances wound healing and also reduces the amount of scar formation in an experimentally induced urethral injury in a male rat model.
• Methods: Prepubertal male albino rats were divided into 2 groups: 20 rats in the BTX-A group received BTX-A injection treatment during surgery and 10 rats in the control group received 0.9% saline solution injection. The penile skin was incised circumferentially and degloved. To make the urethral injury at a location approximately 15 mm proximal to the external meatus, the urethra was cut transversally with scissors, from the 2-o’clock to the 10-o’clock position and then sutured by a single suture at the 6-o’clock position. To evaluate chronic inflammation and fibrosis, the rats were killed, and the injured portions of the urethras were harvested for histopathologic examination after a follow-up period of 21 days.
• Results: On histopathologic evaluation, the control group rats had a more severe fibrotic change in the urethral tissue compared with the BTX-A injected rats, which showed a mild fibrotic change. The mean +/- SD and median fibrosis score was 2.4 +/- 0.5 and 2 in the control group and 1.5 +/- 0.5 and 1 in the BTX-A group, respectively (P < .01 and P < .01, respectively).
• Conclusions: The results of our study have shown that BTX-A prevented increases in collagen content during urethral wound healing.
  
• Editorial Comment
  This is a very interesting and inventive study that certainly will open new avenue for treatment of urethral stricture disease. In fact, using biochemical and stereological methods, we have recently found that, when compared to age-matched controls, there is no fibrosis and no collagen increase in the urethral edges of male patients submitted to end-to-end anastomosis for treating bulbar urethra stenosis (1). Therefore, in well conducted cases, with anastomosis of fibrosis-free urethral edges, the fibrosis that could compromise the results may be a consequence of tensile forces in the anastomic area and probably BTX-A would help in avoiding it.

Reference
1. Carvalho JP, Cavalcanti AG, Costa WS, Cardoso LE, Favorito LA, Sampaio FJ: Stereological and biochemical analysis of the urethral edges in patients submitted to end-to-end anastomosis for bulbar urethral stricture. J Urol. 2009 [submitted]

Dr. Francisco J. B. Sampaio
Full-Professor and Chair, Urogenital Research Unit
State University of Rio de Janeiro
Rio de Janeiro, RJ, Brazil
E-mail: sampaio@urogenitalresearch.org