Laparoscopic replacement of urinary tract segments using biodegradable materials in a large-animal model.

OBJECTIVE: We elected to evaluate laparoscopic segmental bladder and ureteral replacement with free biodegradable graft materials in a large-animal model. MATERIALS AND METHODS: In 18 Yucatan minipigs, a 1.5- to 2.8-cm segment of the upper ureter was excised. In 15 study animals, the ureter was laparoscopically replaced: by a stinted (6F double-J stent) tube graft made of acellular matrix (AMX) prepared from minipig ureters (MUMX) in 6 animals, acellular matrix prepared from domestic pig ureters (DUMX) in 3, and small-intestinal submucosa (SIS) in 6. In 3 control animals, the ureteral gap was bridged only by an indwelling stent. The stent was removed at 6 weeks, and retrograde ureteropyelography was performed preoperatively and at 8 and 12 weeks postoperatively, when animals were sacrificed. In 18 Yucatan minipigs, 3 x 3-cm bladder dome segments were laparoscopically replaced: by acellular matrix prepared from minipig small bowel (MBMX) in 6 animals, and SIS in 6 animals. The bladder was closed primarily in 6 control animals. Bladder capacity was assessed preoperatively and at 6 and at 12 weeks, when the animals were sacrificed. RESULTS: The average operating time for ureteral replacement was 187 (range 105-360) minutes. At 12 weeks, all animals had complete obstruction at the level of the replacement, with fibrosis +/- bone formation at the level of the stricture. For the bladder replacement groups, the average operating time was 147 (range 85-200) minutes. At 12 weeks, the bladder capacity was 60% of the preoperative capacity in the control group, 118% in the MBMX group, and 142% in the SIS group. Histologic examination showed regeneration of urothelium and some muscle with both MBMX and SIS. CONCLUSIONS: We were able to develop a reliable laparoscopic technique for both segmental ureteral and partial bladder replacement in a porcine model. With AMX and SIS replacement, regeneration of urothelium occurred in both ureter and bladder. However, functional replacement was successful only in the bladder.     

Use of single layer small intestinal submucosa for long segment ureteral replacement: a pilot study

PURPOSE: Previous studies have demonstrated successful use of small intestinal submucosa (SIS) as a tube for replacing short segment (11 mm) proximal ureteral defects. However, such small segment ureteral defects could be managed by resection re-anastomosis. We evaluated the use of 1-layer SIS as a tube for the replacement of long segment ureteral defects. MATERIALS AND METHODS: The ureters of 5 female mongrel dogs were accessed through a median laparotomy incision. A 4 cm segment of mid ureter was resected on the right side. The right ureteral segments were replaced by tubularized SIS segments using 6-zero polydioxanone interrupted sutures. Internal pigtail stents were left for 6 weeks. All animals were sacrificed at 12 weeks. Ureteral patency was assessed by excretory urography and magnetic resonance urography 7 and 12 weeks after the initial procedures. Inflammation and regeneration were assessed histologically. RESULTS: At 12 weeks all ureters on the experimental side were completely occluded with significant hydroureteronephrosis and the subsequent deterioration of kidney function. At autopsy there was failure to calibrate any of the experimental ureters with a 3Fr catheter. Although histologically urothelium and muscular cells had proliferated over the graft, they were embedded in an intense fibrotic and inflammatory process. CONCLUSIONS: Technically 1-layer SIS was easily modeled, providing the conditions for watertight anastomosis. The regeneration of urothelium and muscle was induced and supported by the graft. However, functional replacement was not successful. One-layer SIS is not a suitable material for replacing long segment (4 cm) ureteral defects.     

The use of bowel interposed between proximal and distal ureter in urinary tract reconstruction

The replacement of lost ureter with bowel interposition is a feasible alternative in the reconstruction of the urinary tract. When adequate ureteral length is not present, interposition of a portion of small bowel between the proximal and distal ureteral segments is an option that minimizes the amount of bowel in the urinary tract. This, in turn, reduces mucus production and electrolyte absorption in the reconstructed urinary tract, and allows for more bowel to remain as part of the functioning gastrointestinal tract. This procedure allows use of the antirefluxing function of the normal ureterovesical junction when present. We have used successfully interposition of the small bowel between the proximal and distal ureteral segments for undiversion in 5 children. Generally, we strive to join urothelium to urothelium without the use of bowel in urinary tract reconstruction but when this is not feasible, bowel interposition has been a useful option.     

Intestinal interposition for complex ureteral reconstruction: A comprehensive review

Long ureteral defects have remained a challenge to urologists for a long time. Bowel interposition, including ileal ureter, appendiceal interposition and reconfigured colon substitution, has gained wide acceptance, even though it is a complicated procedure and associated with some potential complications. Mucus obstruction and metabolic disorders are common complications of intestinal substitution. To circumvent these troubles, modified techniques, such as tapering the bowel graft, intestinal onlay flap and the Yang–Monti procedure, are used. In particular, Yang–Monti ileal ureter replacement is a highly effective option for ureteral reconstruction, and the incidence of complications would be significantly reduced in select patients. After being combined with the Boari flap or psoas hitch technique, the length of intestinal segment used can also be significantly reduced. Most recent long-term results suggest that ileal ureter replacement with antireflux anastomosis seems to be remarkably free of complications, and we highly praise the distal nipple valve technique. Appendiceal interposition is available for patients with normal appendix, and usually this procedure is limited to reconstructing the right ureter. Appendiceal onlay ureteroplasty has emerged as a feasible and effective option to manage patients with complex proximal and mid-ureteral strictures of the right side. The colon is rarely used for ureteral reconstruction because of its large caliber and mucous surface area. However, a reconfigured colon segment is a good substitute to reconstruct long-segment ureteral defects, and long-term follow up confirmed minimal complications and improved renal function. This review provides a comprehensive perspective on complex ureteral reconstruction and replacement using intestinal segments, in particular, ileal ureter replacement.     

Ureteral segmental replacement using multilayer porcine small-intestinal submucosa

PURPOSE: To assess the outcome of segmental ureteral replacement using a new multilayer porcine small-intestinal submucosa (SIS), Surgisis ES (Cook Inc., Stouffville, ON, Canada) designed to provide enhanced strength. MATERIALS AND METHODS: The ureters of five female farm pigs were accessed through a median laparotomy incision. A segment of 2-cm midureter was resected bilaterally. The left ureteral segments were replaced by 10F tubularized SIS segments using 5-0 PDS interrupted sutures. The right ureters were primarily end-to-end anastomosed, serving as controls. Internal pigtail stents were left bilaterally for 6 weeks. One animal at 3 weeks, one animal at 6 weeks, and three animals at 12 weeks were sacrificed. The patency of the ureters was assessed by retrograde pyelography at 6 and 12 weeks, while inflammation and regeneration were assessed grossly and histologically. RESULTS: At 3 and 6 weeks, both experimental and control ureters were patent without extravasation on retrograde studies. Adhesions and signs of ureteral inflammation were found only on the SIS side. The graft was partially and completely epithelialized at 3 and 6 weeks, respectively. However, at 12 weeks, all the ureters on the experimental side were completely occluded, while on the control side, all were patent. Although histologically, urothelium and muscular cells had proliferated over the graft, they were embedded in an intense fibrotic and inflammatory process. At 12 weeks, all animals had developed hydroureteronephrosis above the grafts. CONCLUSIONS: Technically, Surgisis ES was easily modeled, providing conditions for a water-tight anastomosis. None of the animals developed urinary fistula. Regeneration of urothelium and muscle were induced and supported by the graft. However, functional replacement was not successful. A suitable material for this purpose has yet to be discovered.     

A surgical model of composite cystoplasty with cultured urothelial cells: a controlled study of gross outcome and urothelial phenotype

OBJECTIVES: To study the outcome of composite cystoplasty using cultured urothelial cells combined with de-epithelialized colon or uterus in a porcine surgical model, using appropriate controls, and to characterize the neo-epithelium created by composite cystoplasty. MATERIALS AND METHODS: Urothelial cells were isolated and propagated in vitro from open bladder biopsies taken from nine female minipigs. Cohesive sheets of confluent urothelial cells were transferred to polyglactin carrier meshes and sutured to de-epithelialized autologous colon in four animals and de-epithelialized autologous uterus in five. These composite segments were then used for augmentation cystoplasty. Conventional colocystoplasty, de-epithelialized colocystoplasty and sham operations were carried out in six control animals. After killing the animals at approximately 90 days the bladders were removed for examination and immunohistochemical analysis, using a panel of antibodies against cytokeratins and urothelial differentiation-associated antigens. RESULTS: Macroscopically, the bladders augmented with composite segments derived from uterine muscle had no evidence of shrinkage or contracture. Histological analysis showed that in four of five composite uterocystoplasties, the neo-urothelium was stratified and had a transitional morphology, although in some areas coverage was incomplete. Immunohistochemical analysis showed evidence of squamous differentiation in both native and augmented segments. All composite and de-epithelialized colonic segments showed significant contraction with poor urothelial coverage, reflecting the unsuitability of the thin-walled porcine colon for de-epithelialization. CONCLUSIONS: The functional and macroscopic outcome of bladder augmentation with a composite derived from cultured urothelium and de-epithelialized smooth muscle of uterine origin endorses the feasibility of composite cystoplasty.     

Laparoscopy-assisted reconstruction of a long-segment ureteral stricture using reconfigured ileal segment: application of the Yang Monti principle

We report the first laparoscopy-assisted replacement of the ureter with an ileal segment reconfigured by using the Yang Monti principle. We performed this surgery in a patient with a long segment right lower ureteral stricture from a nonspecific cause. The initial dissection of the colon and the ureter was done laparoscopically. The bowel was identified and delivered through a 3.5 cm midline infraumbilical incision. The bowel segment was isolated and reconfigured extracorporeally. The bowel was placed back in the peritoneal cavity, and the ureteroileal and the ileovesical anastomosis were performed using the laparoscopic intracorporeal suturing technique. The patient had an uneventful postoperative recovery. The ileal segment showed good patency on early follow-up.     

Multiple Oblique Illumination and High-Definition Microscopy for Breast Fine-Needle Aspirates

ABSTRACT We wished to determine whether small-intestinal submucosa (SIS) will epithelialize when used as a ureteral replacement material. An 11-mm segment of native ureter was excised from eight New Zealand White rabbits and replaced with an 11-mm porcine SIS graft, which was circumferentially wrapped around a ureteral stent. The SIS ureteral grafts were harvested at 11 days or 35 days postimplantation and examined grossly and by standard light microscopy techniques. Partial epithelialization with the ingrowth of urothelium, smooth muscle cells, and blood vessels was observed in the grafts harvested at 11 days postimplantation. The SIS ureteral grafts examined at 35 days postimplantation showed additional restructuring of the smooth muscle cell layer and more organized epithelialization in comparison to the SIS graft examined at 11 days. After 35 days of regenerative healing, elements of all three layers of the native ureter were observed within the collagen matrix of the SIS graft. No significant complications were observed, but all subjects (8/8) demonstrated mild intra-abdominal adhesions. Mild collecting system dilatations were observed in 4/4 (100%) of the animals harvested at 35 days and in 0/4 (0%) of the animals harvested at 11 days. We have this demonstrated in this preliminary study that SIS xenografts will epithelialize when used as a ureteral replacement material. The repair mechanism of these ureteral grafts occurred through a regenerative healing process rather than by scar formation. With further studies, this material may prove to be a useful treatment option in patients with ureteral injuries.     

Reconstruction of ureteral defects with microvascular vein grafts in a rat model

This study was undertaken to test the performance of an autologous vein graft as a ureteral replacement in the rat model. Twenty-six rats were divided into three groups. In Group 1 (n = 10), the animals had a 3-mm segment of the ipsilateral ureter excised and the ureteral defect repaired, using a superficial epigastric vein graft. In Group 2 (n = 10), the same ureteral defect was created and again repaired, using a superficial epigastric vein graft, with the addition of a Silastic stent. The control, Group 3 (n = 6), had the ureter transected and repaired solely by means of primary anastomosis. Animals from each group underwent urography and were sacrificed for histology at three different postoperative intervals: 1, 4, and 12 weeks. Postoperative urography results showed normal renal function in the animals with ureteral reconstruction using vein grafting aided by a stent, as well as in those with primary ureteral anastomosis. No renal function return was seen in the animals with ureteral reconstruction by vein grafting alone, without stent support. Histologically, a progressive loss of the vascular endothelium, and replacement with the urothelium typical of the ureter, was seen in the stented vein grafts. Severe ureteral obstruction at the proximal site of the graft and hydronephrosis were seen in the vein-graft group without stenting. This study demonstrates that autologous vein grafts can be used successfully to correct a ureteral deficit, contingent on accurate microsurgical technique and immediate stenting.     

Ureteral segment replacement using a circumferential small-intestinal submucosa xenogenic graft.

We wished to determine whether small-intestinal submucosa (SIS) will epithelialize when used as a ureteral replacement material. An 11-mm segment of native ureter was excised from eight New Zealand White rabbits and replaced with an 11-mm porcine SIS graft, which was circumferentially wrapped around a ureteral stent. The SIS ureteral grafts were harvested at 11 days or 35 days postimplantation and examined grossly and by standard light microscopy techniques. Partial epithelialization with the ingrowth of urothelium, smooth muscle cells, and blood vessels was observed in the grafts harvested at 11 days postimplantation. The SIS ureteral grafts examined at 35 days postimplantation showed additional restructuring of the smooth muscle cell layer and more organized epithelialization in comparison to the SIS graft examined at 11 days. After 35 days of regenerative healing, elements of all three layers of the native ureter were observed within the collagen matrix of the SIS graft. No significant complications were observed, but all subjects (8/8) demonstrated mild intra-abdominal adhesions. Mild collecting system dilatations were observed in 4/4 (100%) of the animals harvested at 35 days and in 0/4 (0%) of the animals harvested at 11 days. We have this demonstrated in this preliminary study that SIS xenografts will epithelialize when used as a ureteral replacement material. The repair mechanism of these ureteral grafts occurred through a regenerative healing process rather than by scar formation. With further studies, this material may prove to be a useful treatment option in patients with ureteral injuries.     

URETERAL TISSUE EXPANSION FOR BLADDER AUGMENTATION

Purpose

Ureteral augmentation is an effective method of bladder reconstruction using the native urothelium of a megaureter. Clinically this procedure is contingent on the presence of an enlarged ureter. We have iatrogenically produced a segmental megaureter, while preserving renal function in a pig model. The urothelium of the enlarged ureter was then used for augmentation cystoplasty.

Materials and Methods

A tissue expander suitable for insertion into the lumen of the ureter was constructed. The tissue expander was passed antegrade through a flank incision of 8 pigs, and a separate nephrostomy tube was left in place. During the ensuing 1 to 4 weeks the pigs underwent daily dilation of the tissue expander without anesthesia. After dilation the pigs underwent ureteral augmentation of the bladder. The segment of expanded ureter was isolated from the native ureter, opened and anastomosed to the bladder. The continuity of the left ureter was restored by primary ureteroureterostomy. The animals underwent cystograms at 1 and 4 weeks and were sacrificed 4 weeks after augmentation. Tissue was harvested for gross and microscopic histology.

Results

Of the 8 pigs starting the protocol 5 underwent successful ureteral tissue expansion followed by bladder augmentation. Tissue expansion was performed from 1 to 4 weeks, and volumes of 150 to 1,000 cc were obtained. Two to 3 weeks of dilation was optimal to achieve ease of dilation, and no animal showed evidence of discomfort or failure to thrive. All 5 animals underwent successful ureteral augmentation with primary ureteroureterostomy. Tissue expansion volumes of approximately 250 cc were optimal for tissue management and ease of augmentation. Cystograms of all augmented animals showed increased bladder capacity with filling of the ureteral segment. Histological examination of the ureteral augmentation revealed preservation and regeneration of the urothelial mucosa.

Conclusions

The use of a tissue expander in the lumen of the ureter is a novel method of generating urothelium for use in bladder augmentation. It may provide an alternative to bowel in patients who require bladder augmentation. Long-term studies are currently under way.     

Canine ureteral replacement with long acellular matrix tube: is it clinically applicable?

PURPOSE: We evaluated the effectiveness of acellular matrix used as a tube for replacement of a relatively long segment of the canine ureter. MATERIALS AND METHODS: Acellular matrix was obtained by excision of the whole ureter of donor dogs that were sacrificed and not included in the study group. Retrieved ureters were treated to have complete cell lysis, while maintaining the fiber framework. The study included 10 mongrel dogs in which a 3 cm segment was excised from 1 ureter and replaced by a tube of acellular matrix of the same length and width. The new tube was sutured proximal and distal by watertight interrupted sutures around a 5Fr Double-J stent (Medical Engineering Corp., New York, New York) that remained for 6 weeks. Excretory urography was done 1 and 2 weeks after stent removal and the dogs were then sacrificed. Before sacrifice the ureter was exposed and carefully examined, and the whole specimen was excised for histopathological examination. RESULTS: All dogs survived surgery except 1, which died 1 week postoperatively of a malpositioned stent and urinary ascites. There was no clinically apparent postoperative complications during the presence or after the removal of the ureteral stents. One week after stent removal excretory urography showed ipsilateral mild to moderate hydroureteronephrosis in 3 dogs and no dye excretion in 6 with a normal contralateral kidney. One week later no dye excretion was detected in all except 1 dog, which showed more radiological deterioration. At the time of sacrifice there was moderate to marked hydroureteronephrosis above the level of the new tube in all dogs. Although the graft was intact in all subjects, marked shrinkage was observed. On ureteral calibration there was significant narrowing of the lumen up to complete occlusion. At 8 weeks histopathological examination showed extensive fibrosis. CONCLUSIONS: An acellular matrix tube is not able to replace a 3 cm segment of the canine ureter.     

Distal ureteral replacement with tubularized porcine small intestine submucosa

Extensive ureteral injury can result from renal stone disease, iatrogenic injury, or penetrating trauma. A significant ureteral stricture can be repaired using various techniques, including the psoas hitch, Boari flap, transureteroureterostomy, ileal ureter, or renal autotransplantation. We describe a woman with a 5-cm, ischemic uretero-Indiana pouch stricture that developed after cystectomy and urinary diversion. Severe pelvic fibrosis prevented adequate mobilization of the ureter and Indiana pouch and would not permit any of the above-mentioned procedures. We report the first human use of tubularized small intestine submucosa to successfully replace a 5-cm strictured segment of distal ureter.     

Investigations of urothelial cells seeded on commercially available small intestine submucosa

OBJECTIVES: To examine adherence and viability of human urothelial cells seeded on commercially available small intestine submucosa (SIS) specimens under serum-free conditions. MATERIALS AND METHODS: Before seeding, SIS was either washed with incubation medium or coated with collagen A, fibronectin, or pronectin. A possible influence of SIS itself on the viability of urothelial cells was analysed with conditioned cell culture medium obtained by incubation of SIS for 24hours. In addition, untreated SIS and a setting without SIS were used as controls. Viability of urothelial cells was analysed with the WST-1 assay until day 9. Histology of seeded and unseeded SIS specimens was investigated after Papanicolaou staining. To demonstrate urothelial cell adherence on SIS, immunohistology was performed with a mixture of monoclonal AE1 and AE3 anticytokeratin antibodies. RESULTS: Urothelial cells seeded on SIS revealed no measurable cell viability. SIS-conditioned cell culture medium was cytotoxic for urothelial cells after 24 hours. Histology only demonstrated cell nuclei and no cytoplasm both in seeded and unseeded SIS specimens, thus indicating porcine DNA. Expression of the cell type-specific marker proteins AE1/AE3 could not be demonstrated. CONCLUSION: Since the commercially available SIS specimens used contained porcine DNA residues and demonstrated cytotoxic effects on urothelial cells, SIS is not suitable for in vitro construction of urothelial cell-matrix implants.     

Laparoscopy in ureteral engineering: a feasibility study

Objective

We recently bioengineered a ureter substitute from a seeded scaffold implanted by open surgery in the omentum. In view of the development of laparoscopy in the treatment of benign conditions of the ureter, obtaining a ureter substitute by minimally invasive techniques would be a desirable objective. However, conflicting results about the biological impact of carbon dioxide insufflation on the microcirculation of intra-abdominal organs prompted us to investigate first whether the results obtained by open surgery, in terms of vascular supply and maturation, could be reproduced laparoscopically.

Materials and methods

Bladder full-thickness tissue was harvested laparoscopically from three pigs for urothelial and smooth muscle cell primary cultures subsequently used to seed a small intestinal submucosa (SIS) matrix. After 2 wk, the in vitro seeded constructs were shaped around silicone drains and transferred laparoscopically into the abdomen for omental maturation. Three weeks later, the constructs were harvested for histological, immunohistochemical, and electron microscopic analysis.

Results

The laparoscopic procedures were performed successfully in all animals. After omental maturation, the constructs were vascularized and comprised of a well-differentiated multilayered urothelium with umbrella cells, over connective tissue and smooth muscle cells, with no evidence of fibrosis or inflammation. Electron microscopic analysis showed characteristics of a terminally differentiated urothelium.

Conclusion

As shown by conventional microscopy, immunochemistry, and electron microscopy, carbon dioxide insufflation does not impact cell growth and differentiation. These findings validate the laparoscopic approach for omental maturation of ureter substitutes.     

Cajal-like cells in the human upper urinary tract

PURPOSE: Interstitial cells of Cajal (ICCs) have an important role in the regulation of gut motility as they are responsible for the slow wave activity of smooth muscle. It is still unknown if ICCs also occur in the human upper urinary tract. Since these cells express and are marked by the c-kit receptor CD117, we investigated its occurrence and distribution along the human upper urinary tract. MATERIALS AND METHODS: Tissues from 56 human ureters, spanning proximal, middle and distal ureter segments, were analyzed by indirect immunohistochemistry using the alkaline phosphatase-anti-alkaline phosphatase method and double labeling immunofluorescence on consecutive tissue sections. Several monoclonal and polyclonal antibodies to c-kit receptor were used in combination with various cell markers for histiocytic, mast cell, endothelial, epithelial, neuronal, smooth muscle and stem cell differentiation. RESULTS: The c-kit receptor was found in 3 cell types of the ureter and in round or spindle-shaped cells. Due to their antigenic profile the first one was revealed as mast cells occurring in all layers of the ureteral wall except the urothelium. In contrast, the population of spindle-shaped cells was only marked by c-kit receptor, thus, resembling ICCs. These ICC-like cells were found among the inner and outer smooth muscle layers, and in the lamina propria. They showed a slight decrease from proximal to distal ureteral segments. However, unlike intestinal ICCs their cytomorphology differed and some cells, representing the third group of c-kit receptor positive cells, were found within the urothelium. CONCLUSIONS: Our data demonstrate the presence of ICC-like cells and their ubiquitous distribution in the human ureter. The physiological importance and pathological significance of these findings must be evaluated by functional studies and investigations of certain pathological with urinary outflow disturbance conditions.     

Scaffold seeded with cells is essential in urothelium regeneration and tissue remodeling in vivo after bladder augmentation using in vitro engineered graft

OBJECTIVE: Tissue-engineering methods using synthetic biodegradable scaffolds seeded with cells have potential to induce regeneration to a functional bladder wall. The aim of the study was to induce in vivo urothelial growth on implanted scaffolds previously seeded with stromal cells as compared with matrices implanted without cells for rat cystoplasty augmentation. MATERIALS AND METHODS: 3T3 mouse fibroblasts were multiplied up to total of 10(8) cells. Cells were grown on Dulbecco's modified essential medium supplemented with 10% of fetal bovine serum and antibiotics in CO(2) chambers. Cells were seeded on biodegradable polyglycolic acid (PGA) scaffolds in eight rats: four bladders were augmented with cell-seeded grafts and the other four with acellular scaffolds. Rats were sacrificed after 4 months in preparation for hematoxylin and eosin staining. RESULTS: One death in the acellular cystoplasty group was observed after 3 weeks. No epithelial layer was observed in the central part of the acellular graft. The cell-seeded grafts showed good visible multilayered epithelium with at least five layers of epithelial cells in the central part. The epithelium resembled rat native urothelium. The cell-seeded grafts showed a high degree of implanted 3T3 cells infiltration with good degradation of PGA fibers. CONCLUSIONS: Our data indicated that urothelial proliferation on PGA grafts was intensified using a "feeder layer" of fibroblasts.     

Distribution of neuropeptides, histamine content, and inflammatory cells in the ureter

OBJECTIVES: To determine the anatomic distribution of select neuropeptides (neurokinin A [NKA], substance P [SP], and bradykinin [BK]), of inflammatory cells (leukocytes and mast cells), and the histamine content in the normal swine ureter and compare the findings with regions of increased ureteral contractility. METHODS: Ureters from 10 pigs were obtained and cut into eight segments, proximally to distally. A portion of each ureteral segment was suspended in Krebs buffer (37 degrees C) and attached to force displacement transducers, and spontaneous contractility was measured for 30 minutes. A second portion was assayed for histamine, NKA, SP, and BK using enzyme-linked immunosorbent assay. A third portion was fixed in 10% buffered formalin, stained with hematoxylin-eosin, and evaluated histologically. RESULTS: Ureteral contractility was found to be highest in the most proximal and most distal regions of the ureter. Similarly, SP content was three times greater in the proximal ureter and two times greater in the distal ureter than in the midureter (P <0.05, n = 10). The total NKA and BK content were also higher in the proximal and distal ureter than in the midureter. Conversely, the histamine content was consistent throughout the ureter. Moreover, no significant difference in the distribution of inflammatory cells was identified throughout the ureter. CONCLUSIONS: The anatomic distribution of NKA, SP, and BK in the ureter corresponded to regions of increased spontaneous ureteral contractility, more specifically the proximal and distal ureter. Neuropeptides may play a significant role in ureteral contractility and may be a target for pharmacologic mediation during obstruction and stone passage.     

Laparoscopic ureteral reconstruction with small intestinal submucosa

PURPOSE: To evaluate the feasibility of laparoscopic ureteral reconstruction with small intestinal submucosa (SIS) in the pig ureter. MATERIALS AND METHODS: Eight female pigs weighing between 25 and 30 kg were enrolled. After anesthesia was administered, a double-pigtail stent was inserted, the animals were moved to a lateral decubitus position, pneumoperitoneum was established, and three 10-mm ports were positioned. The ureter was opened longitudinally for 7 cm, and two thirds of the periphery of the upper third of the left ureter was excised. The SIS was anastomosed to the upper and distal ureteral segments with chromic 4-0 sutures. The double-pigtail stent was removed 6 weeks after the initial procedure, and retrograde pyelography was performed a week later to confirm the viability of the pelvicaliceal system. RESULTS: The average duration of the procedures was 210 minutes (range 125-250 minutes). All animals survived the entire follow-up period of 7 weeks. Retrograde pyelography revealed a patent ureteral lumen, and no obstructive phenomena were observed. Histologically, the SIS-regenerated ureteral segments were remarkably similar to normal porcine ureters and were indistinguishable from neighboring tissue. CONCLUSION: Laparoscopic ureteral reconstruction with SIS proved to be effective and technically feasible. The SIS seems to be an effective biodegradable scaffold, facilitating regeneration of host tissue.     

Partial substitution of the ureter using a short segment of the ileum following the Monti procedure

The partial substitution of the ureter using a pediculated segment of the ileum is a technique used to re-establish ureteral transit and preserve the renal unit, following the resection of extensive ureteral lesions. Standard surgical procedure for an ileoureteroplasty consists of isolating an ileal duct of equal or greater length than the ureteral defect and interposing it in the urinary tract in an isoperistaltic direction. Monti described a surgical technique that allows for the creation of catheterizable stomas in continent urinary diversions, using the Mitrofanoff principle. These passageways were created from one or several 2.5 cm long ileal sections by means of their detubulization and transverse retubulization. The clinical case study presented here corresponds to a 57 year-old male with a history of ureteral lithiasis, with a 9 cm stenosis of the sacroiliac ureter. He was treated surgically by means of a resection of the stenotic ureter and the interposition of a duct made up of 2.5 ileal sections, treated in accordance with the Monti procedure. Since this operation, the patient's metabolic state has been completely normal. Morphological and functional results have also proved totally satisfactory, as the use of image techniques have shown.