Single-stage dorsal inlay full-thickness genital skin grafts for hypospadias reoperations: extended follow up

Tissue Engineering and Regenerative Medicine in Pediatric Urology: Urethral and Urinary Bladder Reconstruction

In the case of pediatric urology there are several congenital conditions, such as hypospadias and neurogenic bladder, which affect, respectively, the urethra and the urinary bladder. In fact, the gold standard consists of a urethroplasty procedure in the case of urethral malformations and enterocystoplasty in the case of urinary bladder disorders. However, both surgical procedures are associated with severe complications, such as fistulas, urethral strictures, and dehiscence of the repair or recurrence of chordee in the case of urethroplasty, and metabolic disturbances, stone formation, urine leakage, and chronic infections in the case of enterocystoplasty. With the aim of overcoming the issue related to the lack of sufficient and appropriate autologous tissue, increasing attention has been focused on tissue engineering. In this review, both the urethral and the urinary bladder reconstruction strategies were summarized, focusing on pediatric applications and evaluating all the biomaterials tested in both animal models and patients. Particular attention was paid to the capability for tissue regeneration in dependence on the eventual presence of seeded cell and growth factor combinations in several types of scaffolds. Moreover, the main critical features needed for urinary tissue engineering have been highlighted and specifically focused on for pediatric application.

Cosmetic outcomes of grafted tubularized incised plate urethroplasty in primary distal penile hypospadias: prospective comparative study with the classic Snodgrass repair

Background

To compare the outcomes between classic tubularized incised plate (C-TIP), known as Snodgrass urethroplasty, and grafted TIP (G-TIP) in the repair of primary distal penile hypospadias.

Methods

Parents of all children presented to our tertiary care institution with primary distal penile hypospadias were asked to participate in this study. Patients were equally randomized using closed envelope method into two groups; Group A underwent repair using G-TIP and Group B underwent repair using the C-TIP. Circumcised cases and/or cases with penile chordee > 30 degrees were excluded from this study. Urethral catheter was kept for 7 to 10 days after surgery. The success rate and cosmetic outcomes assessed by HOSE score were evaluated at 6-month postoperatively.

Results

A total of 55 patients were recruited in each group. One hundred and seven patients of the 110 patients (54 and 53 in groups A and B, respectively) were evaluated at 6-month postoperatively using HOSE score. All preoperative data were comparable in both groups. Success was documented in 49/54 patients (90.7%) in group A. The five failures were secondary to two cases of glans dehiscence and three cases of residual postoperative chordee. Whereas, success was documented in 48/53 patients (90.5%) in group B. Complications were: a case of meatal stenosis, three cases of fistula, and a case of combined meatal stenosis and fistula. The HOSE score was comparable between the two groups (15.4 ± 1.09 vs. 15.6 ± 0.55; p = 0.29). However, the operative time was statistically longer in the G-TIP compared with the C-TIP (91.4 ± 6.2 min vs. 85.2 ± 6.3 min; p < 0.001), respectively.

Conclusion

The G-TIP urethroplasty provided comparable results with C-TIP in terms of cosmoses, success rate, and complications. However, G-TIP was accompanied with significantly longer operative time.

Augmentation of the insufficient tissue bed for surgical repair of hypospadias using acellular matrix grafts: A proof of concept study

Acellular matrices produced by tissue decellularisation are reported to have tissue integrative properties. We examined the potential for incorporating acellular matrix grafts during procedures where there is an inadequate natural tissue bed to support an enduring surgical repair. Hypospadias is a common congenital defect requiring surgery, but associated with long-term complications due to deficiencies in the quality and quantity of the host tissue bed at the repair site. Biomaterials were implanted as single on-lay grafts in a peri-urethral position in male pigs. Two acellular tissue matrices were compared: full-thickness porcine acellular bladder matrix (PABM) and commercially-sourced cross-linked acellular matrix from porcine dermis (Permacol™). Anatomical and immunohistological outcomes were assessed 3 months post-surgery. There were no complications and surgical sites underwent full cosmetic repair. PABM grafts were fully incorporated, whilst Permacol™ grafts remained palpable. Immunohistochemical analysis indicated a non-inflammatory, remodelling-type response to both biomaterials. PABM implants showed extensive stromal cell infiltration and neovascularisation, with a significantly higher density of cells (p < 0.001) than Permacol™, which showed poor cellularisation and partial encapsulation. This study supports the anti-inflammatory and tissue-integrative nature of non-crosslinked acellular matrices and provides proof-of-principle for incorporating acellular matrices during surgical procedures, such as in primary complex hypospadias repair.

Autologous granulation tissue tubes for replacement of urethral defects: An experimental study in male rabbits

INTRODUCTION

Tubularized urethroplasty is commonly performed in clinical practice using genital skin flaps, bladder mucosa, and buccal mucosa. However, the long-term effects are not satisfying, and donor site morbidities remain a problem. Besides, those grafts are unavailable with malignant conditions of the urinary tract, a history of lichen sclerosis, or oral disease.

OBJECTIVE

An autologous granulation tissue tube of any required length and diameter can be produced by implanting foreign objects subcutaneously (Summary Fig.). The current study aimed to investigate to what extent of length this fully autologous tissue could be used for tubularized urethroplasty, satisfying urethral patency and tissue regeneration, in male rabbits.

STUDY DESIGN

Twenty-seven New Zealand male rabbits were randomly divided into three groups. Silastic tubes were implanted subcutaneously in Group 1 and Group 2. By 2 weeks the granulation tissue encapsulating the tubes was harvested. In Group 1, pendulous urethral segments of 1 cm were excised, and urethroplasty was performed with the granulation tissue tube in an end-to-end fashion. In Group 2, a pendulous urethral segment of 1.5 cm was replaced with the tissue tube. In Group 3, a pendulous urethral defect of 1 cm was repaired by re-anastomosis as control. Serial urethrograms were performed at 1, 2 and 6 months postoperatively. Meanwhile, the neo-urethra were harvested and analyzed grossly and histologically.

RESULTS

The urethrograms showed that all animals in Group 1 maintained a wide urethral caliber. In contrast, animals in Group 2 and Group 3 developed progressive strictures. Histologically, an intact urothelium with one to two cell layers lined the graft by 1 month, which was surrounded by increasing organized smooth muscle in Group 1. By 6 months, the grafts were completely integrated into native urethra. Nevertheless, extensive fibrosis occurred in Group 2 and Group 3.

DISCUSSION

The tissue successfully maintained patency and guided urethral regeneration across a distance of 1 cm. As an epithelium-free graft, the tissue showed better results than acellular matrix for tubularized urethroplasty compared with previous studies. Nevertheless, several limitations existed: (1) the urethral defect was created in healthy urethra, which could not fully simulate the clinical situation; (2) as a small animal model, rabbit was less informative for clinical problems; (3) the tissue was inadequate for long segmental urethral replacement. Further study is needed before the procedure is used clinically.

CONCLUSION

An autologous granulation tissue tube grown subcutaneously could be successfully used to repair urethral defects of 1 cm in male rabbits.

Current Status of Tissue Engineering in the Management of Severe Hypospadias

Hypospadias, characterized by misplacement of the urinary meatus in the lower side of the penis, is a frequent birth defect in male children. Because of the huge variation in the anatomic presentation of hypospadias, no single urethroplasty procedure is suitable for all situations. Hence, many surgical techniques have emerged to address the shortage of tissues required to bridge the gap in the urethra particularly in the severe forms of hypospadias. However, the rate of postoperative complications of currently available surgical procedures reaches up to one-fourth of the patients having severe hypospadias. Moreover, these urethroplasty techniques are technically demanding and require considerable surgical experience. These limitations have fueled the development of novel tissue engineering techniques that aim to simplify the surgical procedures and to reduce the rate of complications. Several types of biomaterials have been considered for urethral repair, including synthetic and natural polymers, which in some cases have been seeded with cells prior to implantation. These methods have been tested in preclinical and clinical studies, with variable degrees of success. This review describes the different urethral tissue engineering methodologies, with focus on the approaches used for the treatment of hypospadias. At present, despite many significant advances, the search for a suitable tissue engineering approach for use in routine clinical applications continues.

Urethral Reconstruction Using Mesothelial Cell-Seeded Autogenous Granulation Tissue Tube: An Experimental Study in Male Rabbits

Objective. This study was to evaluate the utility of the compound graft for tubularized urethroplasty by seeding mesothelial cells onto autogenous granulation tissue. Methods. Silastic tubes were implanted subcutaneously in 18 male rabbits, of which nine underwent omentum biopsies simultaneously for in vitro expansion of mesothelial cells. The granulation tissue covering the tubes was harvested 2 weeks after operation. Mesothelial cells were seeded onto and cocultured with the tissue for 7 days. A pendulous urethral segment of 1.5 cm was totally excised. Urethroplasty was performed with mesothelial cell-seeded tissue tubes in an end-to-end fashion in nine rabbits and with unseeded grafts in others as controls. Serial urethrograms were performed at 1, 2, and 6 months postoperatively. Meanwhile, the neourethra was harvested and analyzed grossly and histologically. Results. Urethrograms showed cell-seeded grafts maintained wide at each time point, while strictures formation was found in unseeded grafts. Histologically, layers of urothelium surrounded by increasingly organized smooth muscles were observed in seeded grafts. In contrast, myofibroblasts accumulation and extensive scarring occurred in unseeded grafts. Conclusions. Mesothelial cell-seeded granulation tissue tube can be successfully used for tubularized urethroplasty in male rabbits.

Grafted tubularised incised-plate urethroplasty: An objective assessment of outcome with lessons learnt from surgical experience with 263 cases

Objective

Snodgrass urethroplasty remains the preferred technique in primary distal hypospadias but development of meatal stenosis often limits distal extension of the midline incision of the urethral plate (MIUP), which remains a limiting factor in reconstructing an apical neomeatus (NM). We here-in assess the cosmetic and functional outcome with distal extension of the MIUP in grafted tubularised incised-plate urethroplasty (G-TIP) repair.

Patients and methods

This prospective study included the surgical experience of 263 cases of primary hypospadias operated upon between 2012 and 2015. The G-TIP technique included standard steps of Snodgrass urethroplasty, including degloving and harvesting of glans wings, followed by MIUP that was extended distally beyond the margins of the urethral plate (UP) into the glans. The incised bed was grafted with a free preputial skin graft and fixed to the bed with polydioxanone 7-0 suture. The UP was tubularised and the suture line reinforced with a Dartos flap. The urethral catheter was removed at 7–10 days after the repair and the outcome was assessed at follow-up using the Hypospadias Objective Scoring Evaluation (HOSE) system.

Results

An apical NM was achieved in 96% of the patients with a 3.7% incidence of urethrocutaneous fistula. The presence of suture tracks and graft at the margins of the NM were seen in the initial 4% and 5% of cases, respectively. Acceptable cosmetic results, with objective HOSE scores of >14, were achieved in 96% of cases.

Conclusion

The G-TIP repair is a straightforward and feasible technique facilitating reconstruction of an apical NM, with an optimum outcome based on HOSE scoring. However, multicentre data are needed for undertaking comparative analysis and to assess the universal applicability of this technique in primary hypospadias.

Urethral plate grafting improves the results of tubularized incised plate urethroplasty in primary hypospadias

OBJECTIVE

We conducted a competitive efficacy trial in order to examine whether grafting the raw area of the urethral plate (UP) with inner preputial skin in children with primary hypospadias (PH) during tubularized incised plate urethroplasty (TIP) improves the results of the operation.

MATERIAL AND METHODS

Fifty consecutive patients with pathology ranging from glanular to proximal penile PH were randomized into two groups, comparable for age and pathology, to be operated on either with TIP or a grafted TIP (G-TIP) procedure. Three patients failed the re-examination protocol, so the TIP group comprised 23 children aged 9.0 months-9.6 years (mean age 3.4 years) and the G-TIP group comprised 24 children, aged 10.0 months-9.4 years (mean 3.5 years). The patients were followed up for a period of 2-5 years (mean 3.2 years).

RESULTS

Within the TIP group, we observed the development of fistula with concomitant neourethral stenosis in two cases (8.7%), stenosis without fistula in four (17.4%), and glans dehiscence in one case (4.35%). Within the G-TIP group there was one case of fistula without stenosis (4.16%), no case of neourethral stenosis, and one case of glans dehiscence (4.16%). Two cases of non-slit-like meatus were observed in the TIP group. The results show that the complications of neourethral stenosis are significantly reduced (p < 0.05) in the G-TIP group, as is the total number of complications and unsatisfactory results. The duration of the TIP operation was 72-110 (mean 92) min, and for the G-TIP 100-136 (mean 115) min. No postoperative symptoms were observed that could be attributed to prolonged anesthesia time.

CONCLUSION

UP grafting with inner preputial skin, when added to the TIP procedure in the treatment of PH, results in a significantly smaller number of unsatisfactory results, and particularly fewer cases of neourethral stenosis. G-TIP can be used as the procedure of choice in PH patients.

Long-term outcome of male genital reconstruction in childhood

Hypospadias, epispadias with or without exstrophy, and disorders of sex development are among the most common anomalies of genitalia that occur during childhood. Considering the tremendous effect of genitourinary reconstruction on adult life, the evaluation of the long-term results of different techniques of genitoplasty in pediatrics is of the utmost importance. After reviewing the literature, the authors summarize the available long-term outcomes of genitoplasty in childhood, specifically focusing on the cosmetic, psychosocial, psychosexual and functional results, and emphasize that, contrary to the widely available data on early outcomes of genital reconstruction in the pediatric population, very few well described controlled studies have evaluated the long-term effect of genitoplasty in puberty and adulthood, in the sense that the surgeon should describe the peroperative findings in more detail and also be more structured in evaluating the postoperative result at follow-up visits. Finally, the authors conclude that more attention should be paid to the impact of these techniques on cosmetic aspects and psychosexual development in these patients after puberty, as they play a crucial role in their adult quality of life.

Urethral stricture: etiology, investigation and treatments

BACKGROUND

Urethral stricture is a narrowing of the urethra due to scar tissue, which leads to obstructive voiding dysfunction with potentially serious consequences for the entire urinary tract. Its prevalence among men in industrial countries is estimated at 0.9%. It produces obstructive and irritative urinary symptoms and can ultimately impair renal function. Urethral strictures can be caused by diagnostic or therapeutic urological procedures. These procedures are being performed ever more commonly, because the population is aging; thus, urethral strictures will probably become more common as well.

METHODS

We selectively reviewed pertinent original articles and meta-analyses (1995-2012) on the causes, diagnostic evaluation, and treatment of urethral strictures, which were retrieved by a search in the PubMed database.

RESULTS

Most of the relevant publications are reports of retrospective studies from single centers. Only a few prospective randomized trials and structured reviews are available. The overall level of the scientific evidence is low. 45% of urethral strictures are iatrogenic, 30% idiopathic, and 20% due to bacterial urethritis. Strictures are diagnosed with a flow test and a retrograde urethrogram. Short bulbar strictures can be treated endoscopically. For recurrent and complex strictures, only open urethral surgery can reliably and permanently remove the infravesical obstruction.

CONCLUSION

Urethral strictures must be recognized and treated so that their most serious long-term complication, impaired renal function, can be prevented. The clinical utility of urethrotomy is limited by a high recurrence rate.

Penile urethra replacement with autologous cell-seeded tubularized collagen matrices

Acellular collagen matrices have been used as an onlay material for urethral reconstruction. However, cell-seeded matrices have been recommended for tubularized urethral repairs. In this study we investigated whether long segmental penile urethral replacement using autologous cell-seeded tubularized collagen-based matrix is feasible. Autologous bladder epithelial and smooth muscle cells from nine male rabbits were grown and seeded onto preconfigured tubular matrices constructed from decellularized bladder matrices obtained from lamina propria. The entire anterior penile urethra was resected in 15 rabbits. Urethroplasties were performed with tubularized matrices seeded with cells in nine animals, and with matrices without cells in six. Serial urethrograms were performed at 1, 3 and 6 months. Retrieved urethral tissues were analysed using histo- and immunohistochemistry, western blot analyses and organ bath studies. The urethrograms showed that animals implanted with cell-seeded matrices maintained a wide urethral calibre without strictures. In contrast, the urethras with unseeded scaffolds collapsed and developed strictures. Histologically, a transitional cell layer surrounded by muscle was observed in the cell-seeded constructs. The epithelial and smooth muscle phenotypes were confirmed with AE1/AE3 and α-actin antibodies. Organ bath studies of the neourethras confirmed both physiological contractility and the presence of neurotransmitters. Tubularized collagen matrices seeded with autologous cells can be used successfully for long segmental penile urethra replacement, while implantation of tubularized collagen matrices without cells leads to poor tissue development and stricture formation. The cell-seeded collagen matrices are able to form new tissue, which is histologically similar to native urethra.