Collagen-Coated Electrospun Polyurethane–Urea Scaffold For Urethral Defect Repair In A Rabbit Model

Objective: Through constructing rabbit urethral defect model,we studied the feasibility of collagen-coated polyurethane-urea electrospun fibrous scaffold(cc PUU)for repairing rabbit urethral defect and the growth of rabbit bladder smooth muscle cells(BSMCs)in vitro on polyurethane-urea electrospinning materials to evaluate the physical,chemical and biological characteristics.Methods:(1)The electrospinning technology was used to prepare polyurethane-urea fibrous scaffold with its chemical polymer.(2)The trypsin-collagenase enzymolysis approach was used to isolate and culture bladder smooth muscle cells from young New Zealand white rabbits(6 weeks old).Then seed BSMCs on the scaffold to observe the growth.(3)24 male New Zealand white rabbits were selected and the posterior urethral wall defect of 2.0 cm*0.8 cm was removed about 0.5 cm to the urethral orifice.Using randomized methods 24 male rabbits were divided into three groups: cc PUU group(n=8)using collagen-coated polyurethane-urea electrospun fibrous scaffold for repairing rabbit urethral defect;Control group ?(n=8)application of polyurethane-urea electrospun fibrous scaffold only for repairing rabbit urethral defect;Control group ?(n=8)suturing the segment of rabbit urethral defect directly.After the operation,at 6 weeks and 12 weeks,CT urethrography was used to observe the urine flow,and then collected the repairing section to study the appearance as well as difference of the rate between the urethral stricture,urinary fistula,urethral stone or other complications.Results:(1)The scaffold has good porosity and good elasticity.(2)The isolated and cultured rabbit bladder smooth muscle cells were elongated spindle cells,and the cell groups were mainly vortexed after colony formation.Through the test of CCK-8 experiment,Cytoskeleton staining and Live-Dead staining,it was proved the collagen-coated polyurethane-urea electrospun fibrous scaffold was nontoxic to the cells and the BSMCs grew well on the scaffold.(3)CT urethrography at 6 weeks and 12 weeks showed that the urethra of Experiment group was obviously unobstructed,and there was no obvious difference between the post-operation and before-operation.It was observed in Control group there were different degrees of urethral stricture and urinary fistula.Study on the repair effect of rabbit urethral defect repair region morphology,urethral wall of Experiment group was almost intact and smooth with fusion of the urethral defect area and normal tissue,but there were different degrees of urethral stricture and urinary fistula in the control groups.The rate of urethral stricture,fistula and stone of cc PUU group is 1/8,1/8 and 0/8,with the total rate 8.30%(2/24).And the rate of PUU group is 3/8,3/8 and 0/8,with the total rate 25.00%(6/24).The rate of Control group is 8/8,4/8 and 0/8,with the total rate 50.00%(12/24).Conclusion:(1)Collagen-coated polyurethane-urea electrospun fibrous scaffold is an ideal scaffold for tissue engineering with good physical,chemical characteristics and good histocompatibility.(2)Collagen-coated polyurethane-urea electrospun fibrous scaffold is able to be used for urethral reconstruction and shows good repair effect on a certain length of rabbit urethral defect.