Visceral Tissue Expansion In Urinary Tract

Tissue expansion techniques have also successfully been used in genitourinary tract tissues in the experimental setting (30-33). In 1996, Lailas and colleagues (31) initially reported chronic ureteral expansion for subsequent open ureterocystoplasty in a rabbit model. Ten rabbits underwent unilateral ligation at the ureterovesical junction and ipsilateral nephrectomy. A silicone catheter was placed into the proximal ureter and connected to a titanium injection port, which was placed subcutaneously at the level of costal margin. Two weeks later a saline antibiotic was injected in the port daily, limited by the pressure in the system. Within six weeks, the ureter was opened longitudinally on the anterior aspect, reconfigured into a U-shaped patch, anastomosed to the bladder and covered with an omental flap. A suprapubic tube was placed for 10 days after the procedure. After six months the animals were euthanized. The cystogram showed a mean increase of 260% in the bladder capacity. Urodynamic studies were compatible with a low-pressure, high-capacity bladder. In 1998, Ikeguchi and associates (32) performed chronic segmental ureteral expansion in eight pigs. A latex balloon was located in the distal ureter inserted through the renal parenchyma open surgically. A 10F Malecot nephrostomy was also placed. Daily ureteral dilation (150-1000 mL) was performed with 1-50 cm3 daily over a period of 2-4 weeks, with no anesthesia required. After this, an open ureterocystoplasty and reconstruction of the ipsilateral ureter were performed. A transurethral catheter was maintained for one week. Cystograms revealed an increased bladder capacity. The animals were sacrificed after four weeks, and the histological sections showed preservation of ureteral architecture with ephitelial regeneration. In 2003, we initially reported a completely minimally invasive approach for chronic ureteral balloon expansion followed by laparoscopic augmentation ureterocystoplasty in a survival porcine model (30).

The methodology of visceral tissue expansion in the genitourinary system has yet to be refined to a place where it can have a real practical use by urologists, to the extent that skin expansion has become an accepted part of plastic reconstructive surgery.

Although the potential for ureteral tissue expansion in the context of urinary tract reconstruction has been preliminarily explored, none of the investigators have taken the issue far enough to explore the cellular and molecular mechanism involved in visceral tissue expansion and remodeling.

Encouraged by the above principles and potential usefulness of expanded ureteral tissue, we have pursued development and proof of concept of a methodology that would enable us to obtain excess ureteral tissue with minimally invasive surgical techniques. The expanded ureteral tissue can be used in open or laparoscopic surgical techniques in a variety of reconstruction applications for the lower urinary tract. Further, our preliminary studies have provided stimulus for pursuit of biological markers possibly responsible for visceral tissue remodeling.

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