[Study on small intestinal submucosa as repair materials in urethral reconstruction]

To explore the possibility of small intestinal submucosa (SIS) for reconstruction of urethral defect.

Twenty-four male rabbits were divided into 4 groups: group A (the tubular SIS graft for urethral repair), group B (control group, urethral tubular defect), group C (the SIS patch graft for urethral repairs), group D (control group, urethral part defect). Then the regenerative segment was studied with histological technique by hematoxylin-eosin straining and immunohistological straining for alpha-actin after 6 and 12 weeks postoperatively. The retrograde urethrography and urodynamics were used to evaluate the function of the regenerative urethra at 12 weeks after operation.

In groups A and C, at 6 weeks after operation, the luminal surface of matrix was completely covered by urothelium, minimal SIS graft was observed in the extracellular matrix, new smooth-muscle cells was confirmed; however, more inflammatory cells were observed in the host-matrix anastomosis in group A than in group C. At 12 weeks postoperatively, the regenerative tissue was equivalent to the normal urethral tissue and SIS disappeared in group C, but some minimal SIS grafts were observed in group A. In groups B and D, urethral strictures and fibrous connective tissue were observed except 3 cases. The urethrography showed wide smooth urethral in group A and C, meanwhile urodynamic evaluation didn't demonstrate significant difference (P > 0.05) in the bladder volume and the maximum urethral pressure between preoperation and postoperation in group A or group C.

SIS can be a useful material for urethral repair in rabbits, the SIS patch graft is superior to the tubular SIS graft in urethra reconstruction.