Stretchable collagen-coated polyurethane-urea hydrogel seeded with bladder smooth muscle cells for urethral defect repair in a rabbit model.

The major challenge to treat the clinical adverse effects of long-segment urethra is in achieving viable tissue substitution. The substituted construct's properties-such as its resilience, contraction, and ability to minimize scar-stenosis formation should be considered. In the present work, a unique polyurethane-urea (PUU) fibrous membrane is fabricated by electrospinning. Then PUU was coated by collagen and formed the elasticity hydrogel after immersed in collagen solution. Meanwhile, the cPUU hydrogel exhibited a fibrous microstructure. This cPUU hydrogel had outstanding stretching property with 404 ± 40% elongation at break compared with traditional hydrogels, which satisfied the requirement of urethra. The cPUU hydrogel also supported the adhesion and growth of bladder smooth-muscle cells (BSMCs) in natural state cell morphology. Urethral defects in New Zealand male rabbits were repaired with cPUU seeded with BSMCs in vivo. After three months, more smooth-surface area of reconstructed urethral tissues was observed in the cPUU hydrogel-BMSCs groups compared with that of the control group. The luminal patency and the incidence of complications-including calculus formation, urinary fistula, and urethral-stricture occurrence were significantly lower in the cPUU group compared with that of the control group. Hence, cPUU fibrous hydrogels are promising scaffolds for application in urological tissue engineering.