Low Density Tubular Bovine Collagen Graft for Urethral Regeneration: Preliminary Canine Model
Patients with urethral stricture and hypospadias require urethral reconstructive surgery. The US Food and Drug Administration (FDA) requires the demonstration of safety and efficacy of medical device in at least 2 animal models before clinical translation.
This study is aimed to evaluate the efficacy of a tubular bovine collagen graft in urethral regeneration in a canine model.
A 4-cm long urethral graft was surgically implanted in an artificially created urethral defect proximal to the baculum in a pilot study involving 3 dogs. A transurethral urinary catheter was kept post-op.
Dog 1 had successful implant procedure but compromised by iatrogenic urinary catheter removal. The complications were urine leakage, scrotal excoriation and cystitis. Dog 1 was able to micturate normally following urinary catheter removal on post-op day 14. Post-op day 75, dog 1 was euthanized. Histological data showed narrowing of the urethra at the distal anastomotic site but patent urethra proximally. Both dogs 2 and 3 had catheters removed on post-op day 10. They were able to micturate normally. Ultrasound on post-op week 6 revealed no stenosis. Contrast study on dog C post-op 5 months revealed patent urethra at the grafted site and narrowing of the urethra at the distal anastomotic site. No clinical micturition difficulty observed. To date (February 2018), dogs 2 and 3 are still under observation for long-term graft complication.
This pilot study reveals the canine model is a promising model for urethral clinical translation studies and potential implant application in cases of canine urethral stenosis.