Creation of Tissue-Engineered Urethras for Large Urethral Defect Repair in a Rabbit Experimental Model

Abstract

Introduction: Tissue engineering is a potential source of urethral substitutes to treat severe urethral defects. Our aim was to create tissue-engineered urethras by harvesting autologous cells obtained by bladder washes and then using these cells to create a neourethra in a chronic large urethral defect in a rabbit model.Methods: A large urethral defect was first created in male New Zealand rabbits by resecting an elliptic defect (70 mm2) in the ventral penile urethra and then letting it settle down as a chronic defect for 5–6 weeks. Urothelial cells were harvested noninvasively by washing the bladder with saline and isolating urothelial cells. Neourethras were created by seeding urothelial cells on a commercially available decellularized intestinal submucosa matrix (Biodesign® Cook-Biotech®). Twenty-two rabbits were divided into three groups. Group-A (n = 2) is a control group (urethral defect unrepaired). Group-B (n = 10) and group-C (n = 10) underwent on-lay urethroplasty, with unseeded matrix (group-B) and urothelial cell-seeded matrix (group-C). Macroscopic appearance, radiology, and histology were assessed.Results: The chronic large urethral defect model was successfully created. Stratified urothelial cultures attached to the matrix were obtained. All group-A rabbits kept the urethral defect size unchanged (70 ± 2.5 mm2). All group-B rabbits presented urethroplasty dehiscence, with a median defect of 61 mm2 (range 34–70). In group-C, five presented complete correction and five almost total correction with fistula, with a median defect of 0.3 mm2 (range 0–12.5), demonstrating a significant better result (p = 7.85 × 10−5). Urethrography showed more fistulas in group-B (10/10, versus 5/10 in group-C) (p = 0.04). No strictures were found in any of the groups. Group-B histology identified the absence of ventral urethra in unrepaired areas, with squamous cell metaplasia in the edges toward the defect. In group-C repaired areas, ventral multilayer urothelium was identified with cells staining for urothelial cell marker cytokeratin-7.Conclusions: The importance of this study is that we used a chronic large urethral defect animal model and clearly found that cell-seeded transplants were superior to nonseeded. In addition, bladder washing was a feasible method for harvesting viable autologous cells in a noninvasive way. There is a place for considering tissue-engineered transplants in the surgical armamentarium for treating complex urethral defects and hypospadias cases.

Ascorbic Acid 2-Phosphate-Releasing Supercritical Carbon Dioxide-Foamed Poly(L-Lactide-Co-epsilon-Caprolactone) Scaffolds Support Urothelial Cell Growth and Enhance Human Adipose-Derived Stromal Cell Proliferation and Collagen Production

“…Previous preclinical studies have demonstrated that cell seeding is benefcial in urethral tissue engineering [19,[26][27][28][29][30]. Most importantly, the use of adipose-derived stromal/stem cells (ASCs) or smooth muscle cells has been shown to enhance angiogenesis and the formation of the urethral stromal tissue during the tissue regeneration, inhibiting the formation of urethral fbrosis [26][27][28][29].…”

“…Previous preclinical studies have demonstrated that cell seeding is benefcial in urethral tissue engineering [19,[26][27][28][29][30]. Most importantly, the use of adipose-derived stromal/stem cells (ASCs) or smooth muscle cells has been shown to enhance angiogenesis and the formation of the urethral stromal tissue during the tissue regeneration, inhibiting the formation of urethral fbrosis [26][27][28][29]. Besides ASCs, several cell types have been utilized in urethral tissue engineering research, including fbroblasts [31,32], smooth muscle cells [27,33,34], stromal/stem cells [35][36][37][38] along with urothelial cells (UCs) [10,[39][40][41][42].…”

“…As a native cell type, UCs are frequently studied for urethral tissue regeneration. It is possible to obtain UCs by performing bladder washing without the need for an invasive biopsy [28,43,44]. Still, the regeneration of the urethral stroma is highly important for the tissue-engineered urethra.…”

Tissue Engineering and Regenerative Medicine in Pediatric Urology: Urethral and Urinary Bladder Reconstruction

“…Moreover, graft infection occurred in three patients. More recently, SIS was used for the repair of a large urethral defect in 22 male rabbits, both unseeded and seeded with UCs harvested noninvasively by washing the urinary bladder with saline solution [ 92 ]. The authors found that cell-seeded transplants were superior to unseeded ones in terms of the regeneration of a stratified epithelium similar to a native urethra.…”

Sources, Selection, and Microenvironmental Preconditioning of Cells for Urethral Tissue Engineering

“…Using UCs obtained by bladder irrigation, Fossum and coworkers successfully restored urethral function in patients with severe hypospadias [27]. Preclinical studies in rabbits have shown that these cells have the potential to form a stratified urothelium for the repair of long urethral defects [28]. Overall, these studies have demonstrated that bladder irrigation is a viable and reliable source of UCs and is more likely to be accepted by patients in the clinical setting than bladder biopsy.…”