Rabbit Urethra Replacement With a Molecularly-Defined Tubular Type I Collagen Biomatrix

Purpose

The evaluation of a tubular molecularly-defined type I collagen biomatrix for replacement of the urethra in a rabbit model as a preclinical model.

Material and Methods

Highly purified type I collagen was obtained according to protocol. Tubular collagen biomatrices (Ø 3mm) were prepared by lyophilization and strengthened by chemical crosslinking. Sixteen rabbits underwent tubular urethral replacement (resection of 1.0cm segment of the urethra) which was replaced with the tubular biomatrix. The grafts of regenerated urethras were harvested at 2 weeks, 1, 3 and 6 months after surgery. Retrograde urethrography was performed in all rabbits before sacrifice. Then, the total penis of the rabbit was excised for histopathological examination.

Results

Biomatrices were biochemically analyzed and crosslinking was successful. No animals died before sacrifice. No strictures or urethrocutaneous fistula were observed on control urethrography. All animals showed no stenosis or loss of calibre at the biomatrix's position. There was relative anastomotic narrowing of the urethra in one rabbit at 2 weeks. Two rabbits had small diverticula at 3 months. Macroscopically, no infectious tissue was harvested. Currently, histological analysis is ongoing.

Conclusions

The tubular molecularly-defined biomatrices are successful in repairing urethral lesions. The results with our tubular biochemically defined biomatrix are promising, but remain to be confirmed by histological evaluation. Futurewise, the use of longer tubular segments and the addition of growth factors to biomatrices may be investigated.

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