| Urethral scaffold reconstruction using freeze-dried acellular urinary bladder submucosaHypospadias is a common congenital abnormality of urogenital system in male. Distal urethral defect is the main manifestation. Urethral reconstruction requires adequate amounts of tissue. Many surgical techniques utilizing different types of biological tissues have been attempted: ①vascularized skin flaps from prepuce, penile shaft or scrotum.② full-thickness free skin grafts or scrotal skin graft ③ vesical or buccal mucosa grafts ④ ureter,artery,vein and appendix tissue. However, the use of these tissues may be associated with additional procedures for graft retrival, prolonged hospitalization, and donor-site morbidity. Besides, the source of autografts limits their clinical application. For these reasons,alternate materials have been sought for urethral repair.In our experiment, we developed an accellular collagen matrix of human urinary bladder submucosa, using freeze-thawed enzymatic treatment and freeze-drying technique.Complete cell extraction was confirmed by light and electron microscopy. No cellular elements were left in the matrix. The acellular urinary bladder submucosa appeared as an intact framework consisting of collagen fibers and elastin. The freeze-dried matrix had wonderful three-dimensional network structure.Subcultured human oral keratinocytes were inoculated in the freeze-dried acellullar urinary bladder submucosa. Continous oral epithelium layer was formed on the surface of matrix in 14 days.The freeze-dried matrix was implanted into the pocket created in the midabdominal muscle wall of S.D. mouse. The matrix induced cell infiltration .Completely replacement of the graft had been observed at 4 weeks after implantation. FITC labelled goat anti-rat IgG immunofluorescence revealed very little staining in the graft.In 14 male New Zealand rabbits,a piece of 1cm×0.5cm urethral tissue was resected, replaced with the freeze-dried matrix. 4 animals underwent sham operation.At varying intervals before sacrifice (from 1 to 24 weeks),the animals underwent retrograde urethrography.The grafted specimens were prepared for histological evaluation. Histological examination showed complete epithelization and progressive vessel infiltration.Myofibroblasts stained with... |
