ABSTRACT
Objective To explore the possibility of the inner vertical outer spiral complex tubular urethra scaffold vascularization in repairing long segment of urethral defect.Methods From August 2014 to October 2015,27 clean male New Zealand white rabbits were divided into 3 groups,S1 group was transfected recombinant vascular endothelial growth factor(VEGF) gene lentiviral vector group.S2 group was vascular pedicle transfer tube group.C group was simple stent group.A 3.0 cm inner vertical outer spiral complex scaffold was constructed by using the small intestine acellular matrix (SIS) and polylactic acid copolymer (PLGA) modified by type Ⅰ collagen surface,and adipose-derived mesenchymal stem cells (ADSC) and smooth muscle cells after transformation from New Zealand white rabbits.In S1 group,the seed cells were transfected by recombinant vascular endothelial growth factor (VEGF) gene lentivirus,which express VEGF protein.The complex scaffold was used to repair 3.0 cm rabbit urethral defect In S2 group,the untransfected cells were seeded into the scaffold and embedded in the skin near the groin artery 3 weeks for repairing urethral defect with vascular pedicle transfer tube.In group C,the unseeded scaffold was used to repair the urethral defect alone.Postoperative observation and urethrography were followed 4,8 and 24 weeks after implantation.The HE staining,fluorescence tracing,immunohistochemical and scanning electron microscopy were evaluated at the same phase.Results In S1 group,there were one urinary fistula and one urethral stricture-related death,respectively.The urethra was smooth and patent,histological examination showed active hyperplasia of urethral capillary.In S2 group,there were one urinary fistula and two urethral stricture-related deaths,respectively.The urethral was rough,local thinning or dilated.Fat accumulation and mucosal contraction were found in the urethral submucosal,respctively.In C group,there were one urinary fistula,three hypospadias,and three urethral stricture-related deaths.The thickness of the urethra was uneven and stricture bending.The urethral mucosa was poorly repaired and the scar was narrow.HE and CD31 staining showed that S1 and S2 groups were active in the proliferation of urethral capillaries,and the angiogenesis was abundant.VEGF staining showed that the cytoplasm of endothelial cell layer,smooth muscle layer of vascular wall and the urothelial epithelial cell layer were fully expressed at 24 weeks,especially in epithelial cell layer.CKpan staining showed that the epithelium of S1 and S2 group developed to stratified epithelium,and the morphology of urethra was similar to normal urethra at 24 weeks.The urethral epithelial in C group of grew poor as single-level,irregular arrangement,24 weeks is still a lack of effective stratified epithelium.HE and oα-SMA staining showed that the smooth muscle and actin gradually increased in group S1 and S2,α-SMA staining in group C was scarce and increased at 24 weeks.PLGA was encapsulated by the surrounding tissue and the structure of electrospinning was clear after 4 weeks,absorbed and degraded after 8 weeks and absorbed after 24 weeks.Conclusions The inner vertical outer spiral comnplex tubular urethra scaffold maybe a reasonable method in repairing long segment urethral defects,and the methods of tubular urethra scaffold vascularization by transfected VEGF gene recombinant lentiviral vector and vascular flap deserve more research.