Re-epithelialization of demucosalized stomach patch with tissue-engineered urothelial mucosa combined with Botox A in bladder augmentation.

UNLABELLED: Re-epithelialization demucosa stomach patch is important to prevent the patch being exposed to urine that might cause patch shrinkage and fibrosis formation due to urine-derived chemical irritation. Additionally, Botox A acts by blocking the transmission of nerve impulses to smooth muscles and so paralysing the muscles, which is commonly used to relax muscle for treatment of oesophageal achalasia due to overactive smooth muscle and sphincters of gastrointestinal tract. We fabricated in vitro tissue engineered urothelial mucosa with multi-layers of urothelium and smooth muscle layers seeded on SIS scaffold and then used this cell-scaffold construct to cover nuke gastro patch combining with Botox A for gastrocystoplasty in a canine model.

OBJECTIVE: To evaluate the demucosalized stomach patch covered with tissue-engineered urothelium for gastrocystoplasty and to determine whether or not injections of Botox A into the re-epithelialized stomach patch can protect the graft from contraction in a canine bladder reconstruction model.

MATERIALS AND METHODS: Gastrocystoplasty was performed in 10 adult beagles after hemi-cystectomy using five types of stomach patch (n = 2 per group): entire stomach patches (group I); demucosalized patches (group II); demucosalized patches covered with cell-free small intestinal submucosa (SIS) (group III); demucosalized patches with urothelial and smooth muscle cell-seeded SIS (group IV); and demucosalized patches with the cell-seeded SIS combined with injections of Botox A (group V). The bladder volume/pressure and the graft sizes were measured before surgery and again 10 weeks after bladder augmentation. The graft tissues were examined both histologically and using immunohistochemistry.

RESULTS: All dogs survived and their gastric grafts were all vital with a good blood supply. Gastric metaplasia of urothelium appeared on the top of stomach mucosa patches in two animals in group I. There was calcification formation at the centre of the graft in one animal in group II. As compared with urothelium that was partially covered over with stomach patches in groups II and III, stratified urothelium completely covered the demucosalized gastric patches in groups IV and V. There was less shrinkage of the stomach grafts in groups I and V, which shrank to half of their original size, than of the stomach grafts in groups II, III, and IV, which shrank significantly to one-quarter of their original sizes.

CONCLUSIONS: Botox A injections appear to protect the graft contraction in the re-epithelialized stomach flaps. The gastrocystoplasty using demucosalized patches covered with tissue-engineered urothelial mucosa combined with an injection of Botox A could have clinical potential for use in bladder reconstruction.