Urethra

The urethra (from Greek οὐρήθρα – ourḗthrā; : urethras or urethrae) is a tube that connects the urinary bladder to the urinary meatus for the removal of urine from the body of both females and males. In human females and other primates, the urethra connects to the urinary meatus above the vagina, whereas in marsupials, the female's urethra empties into the urogenital sinus. Females use their urethra only for urinating, but males use their urethra for both urination and ejaculation. The external urethral sphincter is a striated muscle that allows voluntary control over urination. The internal sphincter, formed by the involuntary smooth muscles lining the bladder neck and urethra, receives its nerve supply by the sympathetic division of the autonomic nervous system. The internal sphincter is present both in males and females. Structure The urethra is a fibrous and muscular tube which connects the urinary bladder to the external urethral meatus. Its length differs between t

In-vivo performance of high-density collagen gel tubes for urethral regeneration in a rabbit model

Peter Frey, Jeffrey Alan Hubbell, Lionel Ambroise Micol

Congenital malformations or injuries of the urethra can be treated using existing autologous tissue, but these procedures are sometimes associated with severe complications. Therefore, tissue engineering may be advantageous for generating urethral grafts. We evaluated engineered high-density collagen gel tubes as urethral grafts in 16 male New Zealand white rabbits. The constructs were either acellular or seeded with autologous smooth muscle cells, isolated from an open bladder biopsy. After the formation of a urethral defect by excision, the tissue-engineered grafts were interposed between the remaining urethral ends. No catheter was placed postoperatively. The animals were evaluated at 1 or 3 months by contrast urethrography and histological examination. Comparing the graft caliber to the control urethra at 3 months, a larger caliber was found in the cell-seeded grafts (96.6% of the normal caliber) than in the acellular grafts (42.3%). Histology of acellular and cell-seeded grafts did not show any sign of inflammation, and spontaneous regrowth of urothelium could be demonstrated in all grafts. Urethral fistulae, sometimes associated with stenosis, were observed, which might be prevented by urethral catheter application. High-density collagen gel tubes may be clinically useful as an effective treatment of congenital and acquired urethral pathologies. (C) 2012 Elsevier Ltd. All rights reserved.

Elsevier2012

Engineered acellular collagen scaffold for endogenous cell guidance, a novel approach in urethral regeneration

Peter Frey, Jeffrey Alan Hubbell, Hans Mattias Larsson, Kalitha Pinnagoda, Elif Vardar, Ganesh Vythilingam

The treatment of congenital malformations or injuries of the urethra using existing autologous tissues can be associated with post-operative complications. Using rat-tail collagen, we have engineered an acellular high-density collagen tube. These tubes were made of 2 layers and they could sustain greater burst pressures than the monolayered tubes. Although it remains a weak material this 2 layered tube could be sutured to the native urethra. In 20 male New Zealand white rabbits, 2 cm long grafts were sutured in place after subtotal excision of the urethra. This long-term study was performed in Lausanne (Switzerland) and in Kuala Lumpur (Malaysia). No catheter was placed post-operatively. All rabbits survived the surgical implantation. The animals were evaluated at 1, 3, 6, and 9 months by contrast voiding cysto-urethrography, histological examination and immunohistochemistry. Spontaneous re population of urothelial and smooth muscle cells on all grafts was demonstrated. Cellular organization increased with time, however, 20% of both fistula and stenosis could be observed post-operatively. This off-the shelf scaffold with a promising urethral regeneration has a potential for clinical application. Statement of Significance In this study we have tissue engineered a novel cell free tubular collagen based scaffold and used it as a urethral graft in a rabbit model. The novelty of our technique is that the tube can be sutured. Testing showed better burst pressures and the grafts could then be successfully implanted after a urethral excision. This long term study demonstrated excellent biocompatibility of the 2 cm graft and gradual regeneration with time, challenging the current literature. Finally, the main impact is that we describe an off-the-shelf and cost-effective product with comparable surgical outcome to the cellular grafts. (C) 2016 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

Elsevier Sci Ltd2016

Engineered acellular collagen scaffold for endogenous cell guidance, a novel approach in urethral regeneration

Peter Frey, Jeffrey Alan Hubbell, Hans Mattias Larsson, Kalitha Pinnagoda, Elif Vardar, Ganesh Vythilingam

Elsevier Sci Ltd2016

In-vivo performance of high-density collagen gel tubes for urethral regeneration in a rabbit model

Engineered acellular collagen scaffold for endogenous cell guidance, a novel approach in urethral regeneration

Urethra reconstructions in rabbits using tubular collagen scaffolds seeded with labeled bladder smooth muscle cells

In-vivo performance of high-density collagen gel tubes for urethral regeneration in a rabbit model

Engineered acellular collagen scaffold for endogenous cell guidance, a novel approach in urethral regeneration

Urethra reconstructions in rabbits using tubular collagen scaffolds seeded with labeled bladder smooth muscle cells