Comprehensive evaluation of ureteral healing after electrosurgical endopyelotomy in a porcine model: original report and review of the literature

Heparin coating in biodegradable ureteral stents does not decrease bacterial colonization-assessment in ureteral stricture endourological treatment in animal model

Background

We assessed an antireflux biodegradable heparin-coated ureteral stent (BraidStent^®-H) in an animal model comparative study after endoscopic treatment of ureteral strictures.

Methods

A total of 24 female pigs underwent initial endoscopic, nephrosonographic, and contrast fluoroscopy assessment of the urinary tract. Afterward, unilateral laparoscopic ureteral stricture model was performed. Three weeks later, the animals underwent laser endoureterotomy and were randomly assigned to Group-I, in which a double-pigtail stent was placed for 6 weeks, or Group-II, in which a BraidStent®-H was placed. Follow-up was carried out by ultrasonography, contrast fluoroscopy, ureteroscopy, urinalysis and bacteriuria assessment at 3, 6, 12 and 5 months. Finally, a pathological study of the urinary system was performed.

Results

There were no animals in Group-II with vesicoureteral reflux, with significance at 6 weeks with Group-I. Distal ureteral peristalsis was maintained in 50–75% in Group-II at 1–6 weeks. The 91.7% of stents in Group-II were degraded between 3–6 weeks, without obstructive fragments. Bacteriuria in Group II was 33.3–50% at 3 and 6 weeks. The global success rate by groups was 91.6% and 87.5% in groups I and II, respectively, with no statistical significance.

Conclusions

BraidStent^®-H has been shown to be as efficacious as current ureteral stents in the treatment of benign ureteral strictures following laser endoureterotomy. In addition, it reduces the morbidity associated with current stents and has a homogeneous and predictable degradation rate of about 6 weeks, with no obstructive fragments. Future studies are required to improve the antibacterial coating to reduce BraidStent^®-H contamination in view of the results obtained with the heparin coating.

Macrophage-secreted TGF-β1 contributes to fibroblast activation and ureteral stricture after ablation injury

Iatrogenic injury to the healthy ureter during ureteroscope-guided ablation of malignant or nonmalignant disease can result in ureteral stricture. Transforming growth factor (TGF)-β1-mediated scar formation is considered to underlie ureteral stricture, but the cellular sources of this cytokine and the sequelae preceding iatrogenic stricture formation are unknown. Using a swine model of ureteral injury with irreversible electroporation (IRE), we evaluated the cellular sources of TGF-β1 and scar formation at the site of injury and examined in vitro whether the effects of TGF-β1 could be attenuated by pirfenidone. We observed that proliferation and α-smooth muscle actin expression by fibroblasts were restricted to injured tissue and coincided with proliferation of macrophages. Collagen deposition and scarring of the ureter were associated with increased TGF-β1 expression in both fibroblasts and macrophages. Using in vitro experiments, we demonstrated that macrophages stimulated by cells that were killed with IRE, but not LPS, secreted TGF-β1, consistent with a wound healing phenotype. Furthermore, using 3T3 fibroblasts, we demonstrated that stimulation with paracrine TGF-β1 is necessary and sufficient to promote differentiation of fibroblasts and increase collagen secretion. In vitro, we also showed that treatment with pirfenidone, which modulates TGF-β1 activity, limits proliferation and TGF-β1 secretion in macrophages and scar formation-related activity by fibroblasts. In conclusion, we identified wound healing-related macrophages to be an important source of TGF-β1 in the injured ureter, which may be a paracrine source of TGF-β1 driving scar formation by fibroblasts, resulting in stricture formation.

Gliding Basal Cell Migration of the Urothelium during Wound Healing

Collective cell migration during wound healing has been extensively studied in the epidermis. However, it remains unknown whether the urothelium repairs wounds in a manner similar to the epidermis. By in vivo two-photon excitation microscopy of transgenic mice that express fluorescent biosensors, we studied the collective cell migration of the urothelium in comparison with that of the epidermis. In vivo time-lapse imaging revealed that, even in the absence of a wound, urothelial cells continuously moved and sometimes glided as a sheet over the underlying lamina propria. On abrasion of the epithelium, the migration speed of each epidermal cell was inversely correlated with the distance to the wound edge. Repetitive activation waves of extracellular signal-regulated kinase (ERK) were generated at and propagated away from the wound edge. In contrast, urothelial cells glided as a sheet over the lamina propria without any ERK activation waves. Accordingly, the mitogen-activated protein kinase/ERK kinase inhibitor PD0325901 decreased the migration velocity of the epidermis but not the urothelium. Interestingly, the tyrosine kinase inhibitor dasatinib inhibited migration of the urothelium as well as the epidermis, suggesting that the gliding migration of the urothelium is an active, not a passive, migration. In conclusion, the urothelium glides over the lamina propria to fill wounds in an ERK-independent manner, whereas the epidermis crawls to cover wounds in an ERK-dependent manner.

Regulatory challenges for autologous tissue engineered products on their way from bench to bedside in Europe

Since the late eighties of last century the high potential of tissue engineered products (TEP)s has been shown for the treatment of various diseases and many scientific publications appeared in this field. However, only few products reached the market since. Development of TEPs is a promising but owing to its novelty a very challenging task that requires experts in this still developing field as well as ample financial resources. This paper summarises relevant regulatory challenges during quality, preclinical and clinical development of autologous TEPs in Europe. Selected strategies on how to manage major issues are presented, together with some examples from the development of an autologous TEP for urethroplasty. Considering these aspects may help other investigators with potential strategies during the development of novel TEPs.

Renal pelvis reduction during dismembered pyeloplasty: is it necessary?

OBJECTIVE

To compare treatment results in patients who underwent pyeloplasty with and without pelvic reduction for ureteropelvic junction obstruction (UPJO).

METHODS

This randomized prospective study involved 40 patients, all diagnosed with unilateral UPJO; 20 each were randomly selected to undergo open dismembered pyeloplasty with pelvic reduction (group A) or pelvis-sparing pyeloplasty (group B). Patients were evaluated with ultrasound and DPTA renography scans 6 months postoperatively. Mean follow-up was 9 months.

RESULTS

The mean age in group B was 5.71 ± 6.36 years; in group A it was 4.81 ± 6.78 years. There was a decrease in mean anteroposterior renal pelvic diameter (from 49.9 to 26.35 ± 0.949 mm in A and 50.9 to 30.8 ± 1.556 mm in B) with improvement of split renal function (from 39 ± 22.47% to 42.4 ± 22.13% in A and 34.92 ± 16.79% to 38.8 ± 19.66% in B), glomerular filtration rate (from 37.25 ± 15.33 to 41.7 ± 19.34 ml/min in A and 31.3 ± 18.50 to 38.1 ± 23.23 ml/min in B) and draining curves on the 6-month scans, but without any significant difference between groups (p > 0.05). Two cases in group A and three in group B needed redo pyeloplasty, but without any significant difference in failure rate.

CONCLUSION

Excision of the pelvis is not necessary in dismembered pyeloplasty procedures. We had similar surgical outcomes for patients with or without pelvis reduction.

Postureteroscopic lesion scale: a new management modified organ injury scale--evaluation in 435 ureteroscopic patients

BACKGROUND AND PURPOSE

Objective parameters for the classification of ureteral injuries and resulting indications for ureteral stent placement after ureteroscopy are lacking. We hereby present a new classification system including proof of interrater reliability and validation of recommendations for postoperative ureteral stent placement.

PATIENTS AND METHODS

The Postureteroscopic Lesion Scale (PULS) was applied in 435 patients undergoing ureteroscopy. Interrater reliability between three surgeons (junior resident, senior resident, and specialist) was evaluated in 112 patients. Postoperative ureteral stent placement was performed according to PULS. For follow-up with ultrasonography, we assumed hydronephrosis to be an indirect sign for significant postoperative ureteral obstruction.

RESULTS

No ureteral lesion was seen in 46.2% of patients (grade 0). A grade 1, 2, or 3 lesion was seen in 30.8%, 19.1%, and 3.9% of patients, respectively. No grade 4 or 5 lesions were observed in our series. Interrater reliability was high (Kendall W=0.91; mean Spearman Rho=0.86). This was particularly true between senior resident and specialist (Rho=0.95), compared with junior resident and senior resident or specialist (Rho=0.83, Rho=0.79, respectively). All patients with documented lesions had a Double-J stent placed. Indwelling time varied according to PULS. Results of a postoperative ultrasonographic follow-up could be obtained in 95.6% of cases. No patient showed clinical or sonographic signs of upper urinary tract obstruction.

CONCLUSIONS

According to these preliminary data for the clinical application of PULS, interrater reliability is high. Standardized empiric recommendations for the use and duration of postoperative stent placement after ureteroscopy might be useful in guiding urologists in this conversely discussed issue, ultimately preventing ureteral strictures as a late complication of ureteroscopy. These will have to be confirmed, however, by controlled trials in the future.

New combined approach in metallic ureteral stenting to avoid urothelial hyperplasia: study in swine model

PURPOSE

We assessed the therapeutic value of a new treatment option for ureteral strictures that may avoid urothelial hyperplasia, which is the main cause of metallic stent failure.

MATERIALS AND METHODS

We used 24 pigs in this study. An experimental model of ureteral stricture was induced in all animals. Obstruction was confirmed by ultrasound and retrograde ureteropyelogram 6 weeks after model creation. The pigs were then randomly allocated to 2 experimental groups. Therapy involved placement of a 6 × 30 mm metallic ureteral covered stent in the ureteral stricture in group 1 and subsequent endoureterotomy at the ureteral segments adjacent to the 2 ends of the stent in group 2. A double pigtail stent was then deployed for 3 weeks. Completion studies 6 months after therapy included retrograde ureteropyelogram, endoluminal ultrasound and ureteroscopy to assess urothelial hyperplasia formation.

RESULTS

At the end of the study evidence of urothelial hyperplasia was seen in 50% of the pigs in group 1 and in 29% in group 2. Four and 2 cases of cranial stent migration in groups 1 and 2, respectively, were seen at 6 months. Hyperplasia and renal involvement were statistically significantly different between the groups with more damage in group 1 than in group 2.

CONCLUSIONS

Hyperplasia was markedly reduced when ureteral peristalsis was inhibited by endoureterotomy at the area of interaction between the stent and the ureter.

Pelvic reduction during pyeloplasty for antenatal hydronephrosis: does it affect outcome in ultrasound and nuclear scan postoperatively?

OBJECTIVE

To compare ultrasound (US) scan and nuclear renography findings in patients who underwent pyeloplasty with and without pelvic reduction in a randomized prospective study.

METHODS

A total of 42 patients, all prenatally diagnosed with unilateral hydronephrosis, were included. Hydronephrosis was confirmed postnatally. Twenty patients were randomly selected to undergo pyeloplasty with pelvic reduction and 22 underwent pelvis-sparing pyeloplasty. Patients were evaluated with mercaptoacetyltriglycine-3 scans on the sixth month and US scans on the first, third, and sixth months, postoperatively. Mean follow-up was 37 +/- 5.6 weeks. Statistical analyses were performed using chi-square test and significance was set as P <.05. Power analyses were performed by the NCSS-PASS program. Power value of 0.84 was calculated for a sample size of 42.

RESULTS

The anteroposterior pelvic diameter decreased significantly in the pelvic reduction group compared with pelvis-sparing group in the first- and third-month US scans. However, the difference was not significant in the sixth month. The improvements in the US findings for the pelvis-sparing group match with those of the pelvic reduction group later in the postoperative period. Pelvic reduction significantly improved the renal washout time (T(1/2)) in mercaptoacetyltriglycine-3 renography when compared with pyeloplasty group without reduction at postoperative sixth month. Differential renal function was found to be unaffected from pelvic reduction.

CONCLUSIONS

Resolution of anteroposterior diameter in US scan is more prominent in the pelvic reduction group at earlier stages of the postoperative period. Although T(1/2) decreases more prominently in the pelvic reduction group, the utility of this procedure is still indecisive. This feature can reveal possible surgical failures earlier and strengthen the values of US and renography postoperatively.

Primary endoscopic management versus open revision of ureteroenteric anastomotic strictures after urinary diversion--single institution contemporary series

PURPOSE

To review our institutional experience in the management of ureteroenteric strictures by primary endoscopic intervention or primary open revision.

PATIENTS AND METHODS

Between January 2000 and December 2007, 28 patients with ureteroenteric strictures underwent endoscopic management (n = 21) or open revision (n = 7). Strictures were characterized with regard to length and side as well as time to failure between the two groups. Success was defined as symptomatic improvement and evidence of patency on follow-up radiologic imaging.

RESULTS

Of all study patients, 78.6% were symptomatic on presentation. Endoscopic intervention (balloon dilation, electroincision, or holmium endoureterotomy) was successful in six patients for an overall success rate of 27% with a median follow-up of 21 months. Open revision was successful in 87.5% (7 of 8) patients for whom initial endoscopic surgery had failed. The success rate of primary open revision was 71.4% (5 of 7 patients) with a mean follow-up of 18.1 months. For the entire series, left-sided strictures were more common than right sided strictures; however, side and stricture length were not found to be significant (P > 0.05) with regard to patency. Functional renal imaging studies were performed in 42.9% of all study patients postoperatively.

CONCLUSIONS

Endoscopic management continues to have success rates that remain lower than that of open revision. Left-sided strictures remain more common than right-sided strictures; however, side and stricture length were not found to be statistically significant in our series. The lack of consistent postoperative functional renal studies highlights the importance of diligent monitoring and warrants further study to develop a surveillance algorithm.

Cold cutting of ureteral stenosis with endoscopic scissors

OBJECTIVES

To study the procedure and results of cold cutting of ureteral stenosis with endoscopic scissors. Intrinsic or extrinsic ureteral stenosis can be congenital or acquired. Endoscopic dilation and incision is 1 potential option for ureteral intrinsic stenosis.

METHODS

During a 3-year period (2005-2007), a prospective study was performed of cold cutting of ureteral stenosis with endoscopic scissors in 17 consecutive patients (11 women and 6 men), aged 22-64 years. Of the 17 patients, 6 had been diagnosed with proximal ureteral stenosis, 3 with iliac ureteral stenosis, and 8 with pelvic ureteral stenosis. The procedure was performed with a semirigid 8.5Ch ureteroscope, catheterizing and dilation of the stenosis with a balloon catheter, cold cutting of the ureteral wall with scissors, including margins of healthy tissue at both ends of the stenosis, and a 6F double-J ureteral stent for 6 weeks.

RESULTS

The results were evaluated after 3 months with urography in 15 cases and diuretic renography in 2 cases. Analysis of the postoperative complications and urography was done at 12-24 months. Immediate success was obtained after the first endoscopic ureterotomy with scissors in 16 of 17 cases (94%). At 12-24 months, success was maintained in 88.5% of cases.

CONCLUSIONS

Cold cutting of ureteral stenosis with endoscopic scissors is a safe technique for the patient. This procedure could be a therapeutic option in cases of benign intrinsic ureteral stenosis of <15 mm.

Minimally invasive treatment of ureteropelvic junction obstruction: a critical analysis of results

OBJECTIVES

To analyse the indications and long-term results of endoscopic and minimal access approaches for the treatment of ureteropelvic junction (UPJ) obstruction and to compare them to open surgery.

METHODS

A review of the literature from 1950 to January 2007 was conducted using the Ovid Medline database.

RESULTS

A lack of standardisation of techniques used to diagnose UPJ obstruction and to follow up treated patients introduces a degree of inaccuracy in interpreting the success rates of the various modalities of treatment. However, there is no indication that any one of these techniques is affected by this to a greater or lesser extent than another. Open pyeloplasty achieves very good (90-100% success) results, endopyelotomy and balloon disruption of the UPJ fail to match these results by 15-20%, and minimal access pyeloplasty produces results that are at least as good as those of open surgery but with the advantages of a minimal access approach.

CONCLUSIONS

Minimal access pyeloplasty is likely to gradually replace endopyelotomy and balloon disruption of the UPJ for the treatment of UPJ obstruction. The much higher cost of robotic pyeloplasty and greater availability of laparoscopic expertise in teaching centres are likely to limit the dissemination of robotic pyeloplasty.

Evaluation of the duration of ureteral stenting following endopyelotomy: Animal study

BACKGROUND

The purpose of the present paper was to evaluate whether it is possible to reduce the duration of ureteral stenting following endopyelotomy, and thus reduce side-effects.

METHODS

Seventeen pigs were used. They were distributed at random into three groups. The study was divided as follows: phase I included baseline study of the urinary system and the creation of a ureteropelvic junction obstruction (UPJO) model. Phase II, 1 month later, consisted of diagnosing UPJO, Acucise endopyelotomy of the same, and the placement of a ureteral stent. Ureteral stents were left in situ for 1 week in group I, for 3 weeks in group II and 6 weeks in group III. Phase III, 3 months after treatment, consisted of follow up and post-mortem studies of the animals. The following procedures were carried out during each phase: ureteropelvic junction (UPJ) diameter measurement, ultrasound percutaneous and endoluminal studies, urine culture and determination of blood urea and creatinine levels.

RESULTS

On removal of the stent, the presence of urinoma was observed in two animals in group I. There were statistically significant differences between group I and III with regard to evolution of the internal diameter of the UPJ. However, the least severe histological lesion at the UPJ level was found in group II.

CONCLUSIONS

Ureteral stent placement for 1 week is insufficient in order to assure correct healing and evolution of the UPJ following endopyelotomy. Stenting for 3 weeks is effective, and it is not necessary to extend stenting time to 6 weeks. Endoluminal ultrasound is of great use in determining the effects of endourological techniques in the ureter and the retroperitoneal space. It is also useful for deciding which therapeutic technique to use, and for inserting the Acucise in order to prevent iatrogenic problems.

In vitro reconstruction of a tissue-engineered endothelialized bladder from a single porcine biopsy

OBJECTIVE

Augmentation of the urinary bladder using a tissue-engineered approach with autologous cells is a very promising technique. To prevent risks of necrosis after transplantation, the graft vascularization process could be markedly enhanced by incorporation of autologous endothelial cells in the tissue-engineered organ. The purpose of this study was to develop a separation technique to extract four bladder cell types from the same biopsy, and to prepare an endothelialized reconstructed bladder.

MATERIALS AND METHODS

Fibroblasts, smooth muscle cells (SMC), urothelial cells (UC) and endothelial cells (EC) were extracted from a small porcine bladder biopsy. The SMC, fibroblasts and EC were seeded on the top of the sponge and cultured for 10 days. Then, the UC were seeded on top of these cells for 15 additional days to produce a three-dimensional bladder wall.

RESULTS

The UC and EC extracts from a single porcine biopsy were 97.2+/-0.6% keratin 8/18-positive and 97.7+/-0.3% PECAM-1-positive pure cells, respectively, as assessed by flow cytometry. The SMC could not be dissociated from fibroblasts, and were present as 37+/-0.5% desmin-positive cells. UC differentiated into a urothelium characterized by umbrella cells and a laminin-positive basal membrane. The EC reorganized in the matrix to form PECAM-1-positive capillary-like tubes.

CONCLUSION

This new model of tissue-engineered bladder has the main advantages of being at least 2mm thick, autologous, and able to promote the formation of capillary-like tubes. It could be a promising alternative to the use of gastrointestinal segments to improve bladder capacity.

Comparative study of ureteral stents following endoureterotomy in the porcine model: 3 vs 6 weeks and 7F vs 14F

The aim of the study was to determine the optimal stent size and stenting duration following retrograde endoureterotomy of experimental ureteral strictures. Twenty healthy Large White female pigs were randomly divided into four groups, depending on stent size (7F vs 14F) and stenting duration (3 weeks vs 6 weeks). Three additional pigs were used as the control group. The internal ureteral diameter was measured 2 cm below the lower pole of the right kidney. Histopathological changes of the urinary tract, ultrasonographic and fluoroscopic studies, urine culture, and serum urea and creatine levels were analyzed during the different phases of the study. The study was divided into three phases. Phase I included premodel documentation of the normal urinary tract and laparoscopic ureteral stricture creation. During the second phase 1 month later, the diagnosis and endourologic treatment of strictures were performed. Phase III began 4 weeks after stent removal; follow-up imaging studies and postmortem evaluation of all animals were performed. Ureteral strictures developed in all animals 4 weeks after model creation. Results from ureteral diameter measurements and pathological studies revealed no statistically significant intergroup differences. However, prevalence of urinary infection proved to be directly related to stent size (14F) and permanence (6 weeks). The chi square results suggest a statistically significant relationship between the urinary tract infection and recurrent strictures (alpha = 0.046). We recommend the use of 7F stents for a period of 3 weeks or less, as these are more easily positioned and result in the reduction of secondary side effects (lower infection rate, less intramural ureteral lesions). A significant relationship between urinary tract infection and stricture recurrence was found in this experimental study.

Comparison of Running and Interrupted Vesicourethral Anastomoses in a Porcine Model

PURPOSE

To compare running and interrupted suturing techniques for porcine vesicourethral anastomosis with regard to procedure time, histopathologic effects, and leakage.

MATERIALS AND METHODS

Twelve domestic pigs were randomized to a running (N = 6) or an interrupted (N = 6) vesicourethral anastomosis with polyglycolic acid sutures. In each case, the bladder was drained for 7 days. A cystogram was performed immediately after completion of each anastomosis and on postoperative days 7 and 30. Animals were sacrificed on postoperative day 30, and the area of the anastomosis was excised en bloc for histopathologic evaluation.

RESULTS

All procedures were completed laparoscopically. The mean operative time for continuous and interrupted suturing were 27.5 and 36.8 minutes, respectively (P = 0.3324). A significant learning curve was noted for both anastomoses, with operative times decreasing with experience in both groups. There was no difference in anastomotic leakage. Histopathology examination revealed more muscle-layer fibrosis in the interrupted- suture group than in the continuous-suture group, with a mean score of 2.17 and 1.67, respectively (P = 0.0325).

CONCLUSIONS

Both continuous and interrupted vesicourethral anastomoses are feasible. In this in-vivo porcine comparison, there was no difference with respect to procedure time or anastomotic leakage. However, histopathologic grading demonstrated greater muscle fibrosis in the interrupted-suture group.

Evaluation of surgical models for renal collecting system closure during laparoscopic partial nephrectomy

OBJECTIVES

To evaluate the utility of the porcine and canine models for collecting system closure after partial nephrectomy involving violation of the renal collecting system. Advanced surgical technologies and novel techniques for performing laparoscopic partial nephrectomy are frequently evaluated in an animal model.

METHODS

After evaluation of the upper urinary tract with retrograde pyelography, laparoscopic partial nephrectomy, including violation of the renal collecting system, was performed in 8 domestic pigs (group 1) and 2 dogs (group 2) with documented normal upper urinary tract physiology. No collecting system closure was performed. Subsequently, in an attempt to generate an adequate model for renal collecting system closure, 6 pigs (group 3) underwent partial obstruction of the proximal ureter before laparoscopic partial nephrectomy without collecting system closure. After 3 weeks, the animals underwent evaluation, including retrograde pyelography, and were killed for histopathologic evaluation of the upper urinary tracts.

RESULTS

Despite documented transection of major calices in all animals, none with physiologically normal upper urinary tracts developed urinomas. After partial occlusion of the proximal ureter, all pigs had hydronephrosis, but only one of six developed a urinoma.

CONCLUSIONS

The porcine and canine models are inadequate for evaluating renal collecting system closure after partial nephrectomy. Our high-pressure partial occlusion model was similarly inadequate. The limitations of these animal models should be considered when reviewing published data regarding technologies for partial nephrectomy. Future data regarding novel technologies for partial nephrectomy should also be carefully considered before clinical application.

Smooth-muscle regeneration after electrosurgical endopyelotomy in a porcine model as confirmed by electron microscopy

BACKGROUND AND PURPOSE

Endopyelotomy is the preferred treatment for ureteropelvic junction (UPJ) obstruction because of its short operating time, limited morbidity, fast recovery, and reasonable efficacy. We used tissue and immunohistochemistry staining and electron microscopy to look at the muscle regeneration following an endopyelotomy incision in a porcine model.

MATERIALS AND METHODS

Bilateral electrosurgical endopyelotomy was performed in six domestic pigs with placement of 7F 20-cm Percuflex double-J stents for up to 4 weeks, and urinary tracts were harvested at 3 or 5 months. Specimen evaluation included tissue staining with hematoxylin-eosin, Masson's trichrome, and Verhoeff's iodine and Van Gieson solution; histochemical staining for smooth-muscle actin, desmin and myosin staining, and electron microscopy. Each specimen was assigned a "healing" score of 0 (normal) 1 (slight changes), 2 (mild changes), or 3 (severe changes). The fibrosis score was based on six factors: muscle layer fibrosis, lamina propria fibrosis, amount of granulation tissue present, new deposits of collagen, fibrosis in the periureteral fat, and presence of myofibroblasts. The muscles were characterized with immunohistochemistry and electron microscopy.

RESULTS

At both 3 and 5 months, the urothelium was healed, and the lamina propria was healed with focal loss. By 3 months, smooth-muscle bundles bridged the defect, and by 5 months, the whole defect was covered. Smooth muscle cells were evident by electron microscopy by 3 months, and actin and myosin could be detected by immunohistochemistry. Desmin-positive cells accounted for 50% of the population at 3 months and 40% at 5 months. The regenerated smooth-muscle bundles were oriented in different directions and intermingled with fibrous tissue. They could be distinguished easily from normal ureter under the microscope.

CONCLUSION

Verifiable, functional smooth-muscle bundles bridge the endopyelotomy defect by 3 months, as confirmed by immunohistochemistry staining and electron microscopy.

[Endourologic treatment of ureteral strictures. Experimental comparative study]

OBJECTIVES

To compare efficacy and efficiency of two different endourological therapies for ureteral stricture, and to evaluate pathological reactions of the ureters following both endourological techniques.

MATERIAL AND METHODS

Ten pigs underwent experimental induction of ureteral stricture. Four weeks later, ureteral strictures were demonstrated by imaging techniques. Animals were divided in two groups, according to the received therapy: -Group I. (5 pigs), endoballoon rupture endoureterotomy. -Group II (5 pigs), Acucise balloon endoureterotomy. Ureteral stents were placed for 3 weeks following endoureterotomy. Animals were followed up four weeks after ureteral stents retrieval.

RESULTS

In all cases, ureteral stricture was proved four weeks after model induction. In one case from each group, it was needed a second balloon dilatation to achieve complete endoureterotomy. Leading to ureteral restenosis, stent migration occurred in one animal from group I. Success was achieved in 80% of cases from group I, and 100% of cases from group II.

CONCLUSIONS

Our results suggest that both endourological therapies are effective. Nevertheless, a higher efficiency was proved with Acucise endoureterotomy. Our pathological evidences do not support Davis's studies on ureteral healing following endoureterotomy.