AUTHOR=Amesty Maria Virginia , Chamorro Clara Ibel , López-Pereira Pedro , Martínez-Urrutia María José , Sanz Beatriz , Rivas Susana , Lobato Roberto , Fossum Magdalena 

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

JOURNAL=Frontiers in Pediatrics

VOLUME=9

YEAR=2021

URL=https://www.frontiersin.org/journals/pediatrics/articles/10.3389/fped.2021.691131

DOI=10.3389/fped.2021.691131

ISSN=2296-2360

ABSTRACT=<p><bold>Introduction:</bold> 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.</p><p><bold>Methods:</bold> A large urethral defect was first created in male New Zealand rabbits by resecting an elliptic defect (70 mm<sup>2</sup>) 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 (<italic>n</italic> = 2) is a control group (urethral defect unrepaired). Group-B (<italic>n</italic> = 10) and group-C (<italic>n</italic> = 10) underwent on-lay urethroplasty, with unseeded matrix (group-B) and urothelial cell-seeded matrix (group-C). Macroscopic appearance, radiology, and histology were assessed.</p><p><bold>Results:</bold> 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 mm<sup>2</sup>). All group-B rabbits presented urethroplasty dehiscence, with a median defect of 61 mm<sup>2</sup> (range 34–70). In group-C, five presented complete correction and five almost total correction with fistula, with a median defect of 0.3 mm<sup>2</sup> (range 0–12.5), demonstrating a significant better result (<italic>p</italic> = 7.85 × 10<sup>−5</sup>). Urethrography showed more fistulas in group-B (10/10, versus 5/10 in group-C) (<italic>p</italic> = 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.</p><p><bold>Conclusions:</bold> 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.</p>