Liquid buccal mucosa graft endoscopic urethroplasty: a validation animal study

To validate a novel method of urethral stricture treatment using liquid buccal mucosal grafts (LBMG) to augment direct vision internal urethrotomy (DVIU) in an animal model.

A rabbit stricture model was used to test this method. Strictures were induced in 26 rabbits using electroresection of urethral epithelium. The animals were randomized into two groups: Group-1, treated with DVIU and LBMG in fibrin glue, and Group-2, DVIU with fibrin glue only. LBMG was prepared by suspension of mechanically minced buccal mucosa micrografts in fibrin glue. This LBMG-fibrin glue mixture was later injected into the urethrotomies of Group-1 animals. All animals were killed at 24 weeks after repeat retrograde urethrogram (RUG) and urethroscopy by surgeon blinded to the treatment arm. Radiographic images and histological specimens were reviewed by a radiologist and a pathologist, respectively, blinded to the treatment arm. Stricture treatment was considered a success if a diameter measured on RUG increased by ≥ 50% compared to pre-treatment RUG diameter. Histological specimens were assessed for the presence of BMG engraftment.

In Group-1, 8/12(67%) animals demonstrated engraftment of LBMG, compared to none in Group-2 (p = 0.0005). 7/12(58%) in Group-1 showed radiographic resolution/improvement of strictures compared to 5/13 Group-2 rabbits (38%, p = 0.145). The median percent change for the Group-1 was 59%, compared to 41.6% for Group-2 (p = 0.29).

This proof-of-concept study demonstrates feasibility of LBMG for endoscopic urethral stricture repairs. Further studies are needed to establish the role of this novel concept in treatment of urethral strictures.