Analysis of Primary Urethral Wound Healing in the Rat

Four-dimensional hydrogel dressing adaptable to the urethral microenvironment for scarless urethral reconstruction

The harsh urethral microenvironment (UME) after trauma severely hinders the current hydrogel-based urethral repair. In fact, four-dimensional (4D) consideration to mimic time-dependent physiological processes is essential for scarless urethral reconstruction, which requires balancing extracellular matrix (ECM) deposition and remodeling at different healing stages. In this study, we develop a UME-adaptable 4D hydrogel dressing to sequentially provide an early-vascularized microenvironment and later-antifibrogenic microenvironment for scarless urethral reconstruction. With the combination of dynamic boronic ester crosslinking and covalent photopolymerization, the resultant gelatin methacryloyl phenylboronic acid/cis-diol-crosslinked (GMPD) hydrogels exhibit mussel-mimetic viscoelasticity, satisfactory adhesion, and acid-reinforced stability, which can adapt to harsh UME. In addition, a temporally on-demand regulatory (TOR) technical platform is introduced into GMPD hydrogels to create a time-dependent 4D microenvironment. As a result, physiological urethral recovery is successfully mimicked by means of an early-vascularized microenvironment to promote wound healing by activating the vascular endothelial growth factor (VEGF) signaling pathway, as well as a later-antifibrogenic microenvironment to prevent hypertrophic scar formation by timing transforming growth factor-β (TGFβ) signaling pathway inhibition. Both in vitro molecular mechanisms of the physiological healing process and in vivo scarless urethral reconstruction in a rabbit model are effectively verified, providing a promising alternative for urethral injury treatment.

Development of a Wound-Healing Protocol for In Vitro Evaluation of Urothelial Cell Growth

Urethral healing is plagued by strictures, impacting quality of life and medical costs. Various growth factors (GFs) have shown promise as therapeutic approaches to improve healing, but there is no protocol for in vitro comparison between GFs. This study focuses the development of a biomimetic in vitro urothelial healing assay designed to mimic early in vivo healing, followed by an evaluation of urothelial cell growth in response to GFs.

METHODS

Wound-healing assays were developed with human urothelial cells and used to compared six GFs (EGF, FGF-2, IGF-1, PDGF, TGF-β1, and VEGF) at three concentrations (1 ng/mL, 10 ng/mL, and 100 ng/mL) over a 48 h period. A commercial GF-containing medium (EGF, TGF-α, KGF, and Extract P) and a GF-free medium were used as controls.

RESULTS

There was a statistically significant increase in cell growth for IGF-1 at 10 and 100 ng/mL compared to both controls (p < 0.05). There was a statistically significant increase in cell growth for EGF at all concentrations compared to the GF-free medium control (p < 0.05).

CONCLUSION

This study shows the development of a clinically relevant wound-healing assay to evaluate urothelial cell growth. It is the first to compare GFs for future use in reconstructive techniques to improve urethral healing.

Wound healing responses of urinary extravasation after urethral injury

The post-surgical fluid leakage from the tubular tissues is a critical symptom after gastrointestinal or urinary tract surgeries. Elucidating the mechanism for such abnormalities is vital in surgical and medical science. The exposure of the fluid such as peritonitis due to urinary or gastrointestinal perforation has been reported to induce severe inflammation to the surrounding tissue. However, there have been no reports for the tissue responses by fluid extravasation and assessment of post-surgical and injury complication processes is therefore vital. The current model mouse study aims to investigate the effect of the urinary extravasation of the urethral injuries. Analyses on the urinary extravasation affecting both urethral mesenchyme and epithelium and the resultant spongio-fibrosis/urethral stricture were performed. The urine was injected from the lumen of urethra exposing the surrounding mesenchyme after the injury. The wound healing responses with urinary extravasation were shown as severe edematous mesenchymal lesions with the narrow urethral lumen. The epithelial cell proliferation was significantly increased in the wide layers. The mesenchymal spongio-fibrosis was induced by urethral injury with subsequent extravasation. The current report thus offers a novel research tool for surgical sciences on the urinary tract.

Complications after Prostate Cancer Treatment: Pathophysiology and Repair of Post-Radiation Urethral Stricture Disease

Radiation therapy (RT) in the management of pelvic cancers remains a clinical challenge to urologists given the sequelae of urethral stricture disease secondary to fibrosis and vascular insults. The objective of this review is to understand the physiology of radiation-induced stricture disease and to educate urologists in clinical practice regarding future prospective options clinicians have to deal with this condition. The management of post-radiation urethral stricture consists of conservative, endoscopic, and primary reconstructive options. Endoscopic approaches remain an option, but with limited long-term success. Despite concerns with graft take, reconstructive options such as urethroplasties in this population with buccal grafts have shown long-term success rates ranging from 70 to 100%. Robotic reconstruction is augmenting previous options with faster recovery times. Radiation-induced stricture disease is challenging with multiple interventions available, but with successful outcomes demonstrated in various cohorts including urethroplasties with buccal grafts and robotic reconstruction.

Exploring Relevant mRNAs and miRNAs in Injured Urethral Tissues of Rats with High-Throughput Sequencing

Acute urethral injuries caused by urethral endoscopy and other mechanical injuries are the main reasons for secondary infection and late urethral stricture. However, there are no studies to explore the transcriptomic changes in urethral injury and the molecular mechanism of urethral injury, which is important for the treatment and cure of urethral injury. Therefore, we used RNA-seq and sRNA-seq profiles from normal and injured urethral tissues to identify and characterize differentially expressed mRNAs and miRNAs. In total, we found 166 differentially expressed mRNAs, of which 69 were upregulated, and 97 were downregulated in injured urethral tissues. The differentially expressed mRNAs were mainly involved in the positive regulation of epithelial cell differentiation, focal adhesion, cell adhesion molecules, protein activation cascade, complement activation, complement and coagulation cascades, and chemokine-mediated signaling pathway. Additionally, we found six upregulated and four downregulated miRNAs, respectively, in the injured urethral tissues. Notably, their target genes were involved in the vascular endothelial growth factor receptor 2 binding, PI3k-Akt signaling pathway, and Notch signaling pathway. In summary, our results suggest that the cell damage response induced by mechanical injury activates the pathological immune response in a variety of ways in injured urethral tissues.

Long-term effects of muscle-derived stem cell therapy on the regeneration of the urethra of female rats

INTRODUCTION AND HYPOTHESIS

The aim was to analyze the long-term effects of muscle-derived stem cells (MDSCs) therapy in traumatized urethras of female rats regarding messenger ribonucleic acid (mRNA) expression of collagens 1 and 3, Ngf and Ki67; and the mRNA and protein expression of Myh11 and Myh2.

METHODS

Muscle-derived stem cells were injected into the tail vein of rats 3 days after trauma by vaginal distention. Urethras were analyzed from 30 animals divided into three groups: control without injury or treatment, trauma (30 days post-injury), and MDSC (30 days post-injury who received MDSC therapy). Real-time quantitative polymerase chain reaction (RT-qPCR) and immunohistochemistry were performed. The Kruskal-Wallis and ANOVA tests were used with p < 0.05 indicating significance.

RESULTS

We detected increased Myh11 and Myh2 mRNA expression in the trauma group compared with the control group (p = 0.03 and p = 0.04 respectively). Ki67 and Col1a1 genes were overexpressed in the MDSC group compared with both the trauma (p = 0.02 and p = 0.008 respectively) and the control group (p = 0.01 and p = 0.03 respectively). Col3a1 gene was upregulated in the MDSC compared with the control group (p = 0.03). Ngf mRNA level was lower in the MDSC group than in the trauma group (p = 0.002). Myh11, Myh2, and Desmin proteins were overexpressed in the MDSC compared with the trauma group (1.5-fold, p = 0.01; 1.5-fold, p = 0.04; 1.3-fold, p = 0.01 respectively).

CONCLUSIONS

Muscle-derived stem cell therapy may have had long-term structural and molecular effects on the injured urethra of female rats, particularly on markers of cell proliferation, neural growth factor, extracellular matrix, and muscle content. This study suggests that MDSC therapy acted mainly to produce urethral sphincter regeneration marked by increased immunohistochemical expression of the proteins desmin, smooth muscle Myh11, and skeletal muscle Myh2.

Mesenchymal Stem Cell-Derived Exosomes Induced by IL-1β Attenuate Urethral Stricture Through Let-7c/PAK1/NF-κB-Regulated Macrophage M2 Polarization

Background

Urethral stricture is a clinical challenge for both patients and clinicians. Post-traumatic urethral stricture is associated with formation of scar tissue caused by excessive inflammation. The aim of this study is exploring potential therapeutic strategies for this condition.

Methods

In vivo experiments on New Zealand rabbits and in vitro experiments on THP-1 monocytes and urethral fibroblasts were performed to investigate the effects on post-traumatic urethral stricture of exosomes isolated from IL-1β-treated mesenchymal stem cells (Exo-MSCs^IL-1β) and the role of macrophage M2 polarization in this process. Additionally, related signaling and mechanism behind were explored.

Results

In a New Zealand rabbit model of post-traumatic urethral stricture, injection of Exo-MSCs^IL-1β significantly reduced urethral stricture and collagen fiber accumulation compared with Exo-MSCs. Addition of Exo-MSCs^IL-1β to THP-1 monocytes in vitro induced M2 macrophage polarization, which, in turn, inhibited activation of urethral fibroblasts and synthesis of collagen. Mechanistically, Exo-MSCs^IL-1β were found to contain high levels of the microRNA let-7c, and luciferase reporter assays showed that let-7c interacted with the 3'UTR of PAK1 mRNA. Transfection of THP-1 cells with a let-7c mimic downregulated PAK1 expression and inhibited activation of the NF-κB signaling pathway.

Conclusion

These results support a role for let-7c-containing Exo-MSCs^IL-1β in reducing urethral stricture via inhibition of PAK1-NF-κB signaling, M2 macrophage polarization, and differentiation of urethral myofibroblasts.

Does intraurethral erythropoietin administration effect wound healing after hypospadias correction? an experimental rat study

OBJECTIVES

To analyze effects of intraurethral EPO application on urethral wound healing by defining hystopathologic changes in a rat model of hypospadias.

METHODS

A hypospadias model was created in 30 rats and randomized into 3 groups of 10. For 14 days, the first group was administered 25 iu EPO instillation intraurethrally once a day, while group 2 was administered with 50 iu EPO in the same manner. The third group was assigned as control group. On the day 15, rats were sacrificed and penectomies were performed. One independent pathologist who is blinded to groups and treatments evaluated the penis samples.

RESULTS

Histopathologic examinations yielded the mean fibrosis scores (± SD) as 1.9 ± 0.568, 1.1 ± 0.786 and 2.5 ± 0.535 in groups I, II and III, respectively. There was significant difference between the EPO groups and the control group (p = 0.04-I, p = 0.003-II). The mean inflammation scar scores (± SD) were determined as 1 ± 1.054, 2 ± 1.247, 2.63 ± 0.744 in groups I, II and III, respectively. There was a significant difference in terms of inflammation between control group and group I (p = 0.005). Mean congestion scores (± SD) were found 1.2 ± 0.789 in groups I-II and 0.75 ± 0.463 in group III (p = 0.310). Hyperemia was seen in 60% 70% and 37.5% in groups I, II and III, respectively (p = 0.387).

CONCLUSION

Intraurethral EPO therapy effected urethral wound healing in a good way. Thus it could be feasible to treat the patients with after hypospadias surgeries and to improve success rates.

Histamine H3 Receptor Signaling Regulates the NLRP3 Inflammasome Activation in C2C12 Myocyte During Myogenic Differentiation

NLRP3 inflammasome has been implicated in impaired post-injury muscle healing and in muscle atrophy. Histamine receptors play an important role in inflammation, but the role of histamine H₃ receptor (H₃R) in myocyte regeneration and in the regulation of NLRP3 inflammasome is not known. We studied the effects of H₃R signaling on C2C12 myocyte viability, apoptosis, and tumor necrosis factor alpha (TNFα)-induced NLRP3 inflammasome activation during striated myogenic differentiation at three time points (days 0, 3, and 6). Expression of Nlrp3, interleukin-1β (IL-1β), and myogenesis markers were determined. TNFα reduced overall viability of C2C12 cells, and exposure to TNFα induced apoptosis of cells at D6. Activation of H₃R had no effect on viability or apoptosis, whereas inhibition of H₃R increased TNFα-induced apoptosis. Stimulation of C2C12 cells with TNFα increased Nlrp3 mRNA expression at D3 and D6. Moreover, TNFα reduced the expression of myogenesis markers MyoD1, Myogenin, and Myosin-2 at D3 and D6. H₃R attenuated TNFα-induced expression of Nlrp3 and further inhibited the myogenesis marker expression; while H₃R -blockage enhanced the proinflammatory effects of TNFα and increased the myogenesis marker expression. TNFα-induced secretion of mature IL-1β was dependent on the activation of the NLRP3 inflammasome, as shown by the reduced secretion of mature IL-1β upon treatment of the cells with the small molecule inhibitor of the NLRP3 inflammasome (MCC950). The activation of H₃R reduced TNFα-induced IL-1β secretion, while the H₃R blockage had an opposite effect. In conclusion, the modulation of H₃R activity regulates the effects of TNFα on C2C12 myocyte differentiation and TNFα-induced activation of NLRP3 inflammasome. Thus, H₃R signaling may represent a novel target for limiting postinjury muscle inflammation and muscle atrophy.

Incised urethral diversion reduces the rate of fistula after one-stage hypospadias repair: a single-center retrospective controlled study

OBJECTIVE

Urethrocutaneous fistula is the most prevalent complication after hypospadias repair. The aim of this study was to evaluate whether incised urethral diversion was superior to traditional transurethral diversion in minimizing complications.

PATIENTS AND METHODS

We retrospectively collected and analyzed 113 cases with proximal penile or penoscrotal hypospadias that were repaired by one-stage transverse preputial island flap urethroplasty between January 2016 and January 2020. Of those cases, 60 used incised urethral diversion (group A), whereas the remaining 53 were managed by transurethral diversion (group B) for urinary drainage after surgery. Postoperative complications in both groups were assessed for fistula, urethral diverticulum, meatal stenosis, wound infection, and distal urethral breakdown.

RESULTS

Fistula was reported in 2 patients (3.3%) in group A, while it was observed in 15 patients (28.3%) in group B (p < 0.001). Wound infection occurred in one patient (1.7%) in group A, compared with six patients (11.3%) in group B (p < 0.05). The incidence rates of distal urethral breakdown were 1.7% (1/60) and 11.3% (6/53) for group A and group B, respectively (p < 0.05). One patient (1.7%) in group A and three patients (5.7%) in group B had a meatal stenosis (p > 0.05). There were two patients who developed urethral diverticulum in either group (p > 0.05).

CONCLUSIONS

The use of incised urethral diversion for urinary drainage had an advantage over transurethral diversion in one-stage hypospadias repair with respect to the post-operational fistula occurrence, wound infection, and distal urethral breakdown.

Electrotherapy for urethral modulation: Are extracellular matrix molecules and growth factors potential targets?

AIMS

To evaluate the expression of genes and proteins involved in the urethral components: vessels, nerves, and extracellular matrix, in female rats after trauma by vaginal distension (VD) and after electrical stimulation therapy (electrotherapy).

METHODS

We analyzed the urethras of three groups of 18 female rats 30 days posttrauma by VD: control (no interventions); trauma (animals that had VD); and electrotherapy group (those that had VD and were treated with electrical stimulation). We compared the expression of vascular endothelial growth factor (VEGF), nerve growth factor (NGF), collagen types I and III (COL1a1 and COL3a1), and lysyl-oxidase like 1 (LOXL1) among the groups. Real-time reverse transcription-polymerase chain reaction, Western blot, and immunohistochemistry were used for molecule quantification. We used the Kruskal-Wallis test and analysis of variance for statistical analyses with p < 0.05 for significance.

RESULTS

The COL1a1 gene expression was higher in the electrotherapy group than the trauma group (p = 0.036). COL3a1, VEGF, NGF, LOXL1 messenger RNA (mRNA) expression did not differ among the groups (p ≥ 0.05). COL1a1, COL3a1, VEGF, NGF, LOXL1 protein levels did not significantly differ among the groups (p ≥ 0.05) in Western blot analysis or immunohistochemistry assays.

CONCLUSIONS

Electrotherapy caused a long-term increase in the COL1a1 mRNA level but did not change COL1a1 protein expression or VEGF, NGF, COL3a1, and LOXL1 genes and proteins in the urethras of rats after trauma by VD.

Effects of Anti-Inflammatory Nanofibers on Urethral Healing

Protracted postsurgical inflammation leading to postoperative complications remains a persistent problem in urethral reconstruction. Nanofibers in the form of peptide amphiphiles expressing anti-inflammatory peptides (AIF-PA) have positively modulated local inflammatory responses. Urethroplasty is performed to repair 5 mm ventral urethral defects with: uncoated small intestinal submucosa (SIS); SIS dip-coated with AIF-PA1 (anti-inflammatory treatment), or SIS dip-coated with AIF-PA6 (control) on 12-week-old male Sprague Dawley rats (n = 6/group/timepoint). Animals are euthanized at 14 and 28 d postsurgery. Hematoxylin-eosin, Masson's Trichrome, and immunohistochemistry with primary antibodies against myeloperoxidase (MPO; neutrophils), CD68, CD86, CD206 (macrophages), and proinflammatory cytokines TNFα and IL-1β are performed. Complete urethral healing occurs in 3/6 uncoated SIS (50%), 2/6 SIS+AIF-PA6 (33.3%), and 5/6 SIS+AIF-PA1 (83.3%) animals at 14 d and all at 28 d. Application of AIF-PA1 to SIS substitution urethroplasty decreases MPO⁺ neutrophils, CD86⁺ M1 proinflammatory macrophages, TNFα, and IL-1β levels while concurrently increasing levels of CD206⁺ M2 proregenerative/anti-inflammatory macrophages at the anastomoses and the regenerated tissue at the wound bed (REGEN). AIF-PA1 treatment enhances the healing process, contributing to earlier, complete urethral healing, and increased angiogenesis. Further studies are needed to elucidate the specific mechanism of inflammatory response modulation on angiogenesis and overall urethral healing.

The effect of zinc sulfate on penile corpus spongiosum after hypospadias repair in rats: A stereological study

Hypospadias repair involves correcting urethra defects and improving the wound healing process. Zinc has been well accepted as an effective agent in wound healing. This study aimed to investigate the effect of zinc on corpus spongiosum after experimental hypospadias in rats. The animals were divided into three groups. The control group rats underwent general anesthesia, but did not receive any surgeries and treatments. The second and third groups underwent surgeries and respectively received Distilled Water (DW, 2 ml) and zinc sulfate solution (2 ml, containing 4 mg zinc sulfate) by gavages twice a day for 14 days. Stereological methods were used to quantify the corpus spongiosum tissue. The volumes of corpus spongiosum, spongy tissue, urethral lumens, urethral epithelium, and collagen bundles and the number of fibroblasts were respectively amplified by 28%, 40%, 36%, 48%, 40%, and 29% in the surgery + zinc sulfate group in comparison to the surgery + DW group (p < 0.02). It can be concluded that consumption of 4 mg/day zinc sulfate for 14 days could improve the healing of hypospadias through increasing the population of fibroblasts, producing collagen bundles, and building a wider lumen and more epithelized urethra.

The histopathological effect of tissue adhesive on urethra wound healing process: An experimental animal study

INTRODUCTION AND OBJECTIVE

The present study aimed to determine the histopathological effect of Tisseel tissue adhesive on the urethral wound healing process after urethroplasty in a rat model.

STUDY DESIGN

A total of 24 animals were randomly allocated into three groups: Group 1; control group (n = 6); Group 2; suture-closure group (n = 9); and Group 3; suture + adhesive group (n = 9). In group 2, an incision 4 mm long was made on the ventral skin of the penis along the midline from the glans penis, to open the dartos muscle, corpus spongiosum, and urethra. Next, initially, the urethra alone, and then the layers up to the skin were covered in layers with 8/0 vicryl interrupted sutures. Group 3 underwent the same procedures as group 2, but after the urethra was repaired 0.1 cc of Tisseel tissue adhesive was applied over the urethra. Penile tissue samples were obtained 21 days later, and tissue samples were sent for histopathological analysis.

RESULTS

Urethral epithelial thickness and connective tissue thickness in group 3 were higher than in group 1 and group 2. Fibrosis in group 3 was higher than in group 2. The difference in inflammation between group 3 and group 2 was not significant. There was no significant difference in microvessel density between group 2 and group 3.

DISCUSSION

Both increased fibrosis and connective tissue thickness were noted in group 3 compared to group 2 and group 1. These increases may have been caused by the hemostatic effect of the Tisseel adhesive and its triggering of fibroblast growth factors. The epithelial thickness increased significantly in group 3 and group 2 compared to group 1. This increase in tissue thickness without an increased number of epithelial cells can be explained by the development of oedema.

CONCLUSION

The present study suggests that while Tisseel tissue adhesive increases connective tissue thickness and fibrosis, it does not demonstrate a prolonged inflammation or increased neovascularization in the urethral wound at 3 weeks after surgery. The data obtained in our study does not support the use of Tisseel in urethroplasty surgery. The results obtained in this study demonstrate a significantly higher formation of fibrosis (scar tissue), which underlines the importance of new studies to identify new treatments for urethral wound healing after urethra trauma or surgery.

Biodegradable drug-eluting urethral stent in limiting urethral stricture formation after urethral injury: An experimental study in rabbit

In this study, a reproducible urethral injury animal model was developed and the role of the biodegradable drug-eluting urethral stent in limiting urethral stricture formation after urethral injury was evaluated. A total of 22 rabbits were used, and 20 rabbits were randomly chosen to develop urethral injury animal model. Bulbar urethral injury was made by a self-designed explosion device in the 20 rabbits. The urethral injury animal model was then randomly assigned to 2 groups of 10 each, which received a treatment of biodegradable paclitaxel-eluting urethral stent or only end-to-end anastomosis. Other two rabbits served as normal control group. Stents were surgically implanted into the injured urethras of rabbits under direct vision. Reparative effects, including stent degradation, were evaluated by urethroscopy, retrograde urethrography, and histology at different intervals at weeks 4, 8, and 12. In stent-free group, 8 of 10 rabbits developed obvious urethral stricture which was demonstrated by urethroscopy and retrograde urethrography, while in biodegradable paclitaxel-eluting stent group, urethral stricture was absent in all animals (p < 0.05). Histological follow-up indicated that the drug-eluting stents can also minimize the inflammatory reactions and fibrosis formation compared with the stent-free groups. Scanning electron microscope demonstrated that the biodegradable drug-eluting stent can gradually degrade in 12 weeks. The biodegradable paclitaxel-eluting urethral stent is effective in limiting urethral stricture formation after urethral injury.

Penile nerve block predicts higher revision surgery rate following distal hypospadias repair when compared with caudal epidural block: A consecutive cohort study

INTRODUCTION

Recent literature has suggested caudal epidural blocks (CEB) may increase revision surgery rates following hypospadias repair. We sought to investigate this using a large, multi-surgeon series.

OBJECTIVE

The primary objective of this study was to identify the impact of CEB or penile nerve blocks (PNB) on revision surgery rates following distal hypospadias repair at our centre.

STUDY DESIGN

A prospectively maintained database of consecutive patients undergoing primary hypospadias repairs under the supervision of 8 different paediatric surgeons at our centre between January 2015 and December 2018 was queried for the following potential risk factors: Age at surgery, American Society of Anaesthesiologist's (ASA) grade, hypospadias type, type of surgery, CEB or PNB, and training level of primary surgeon. Revision surgery was defined as reoperation for fistulas, dehiscence, strictures or meatal stenosis. Univariate and Multivariate analysis was performed using logistic regression.

RESULTS

188 patients underwent primary distal hypospadias repair over the study time period. Patients were aged between 7 months and 15 years of age. Median age at surgery was 14 months. Revision surgery was performed for 31 patients (16.5%). Indications were urethrocutaneous fistula (n = 17, 9.0%), meatal stenosis or stricture (n = 9, 4.8%) and glans dehiscence (n = 5, 2.7%). 114 (60.6%) received a penile block and 74 (39.4%) a caudal block. On univariate analysis, PNB (HR 2.55 95% CI 1.04-6.27, p = 0.04) was statistically significant for revision surgery. This association remained significant on multivariate analysis (HR 2.74 95% CI 1.09-6.92, p = 0.03). All other prognostic factors examined were not statistically significant for revision surgery.

DISCUSSION

Our findings suggest PNB are associated with higher revision surgery rates following distal hypospadias repair. This contrasts with the findings of other authors.

CONCLUSION

Our study is the first to demonstrate an association between PNB and higher revision surgery rates following distal hypospadias repair.

Histopathologic Evaluation of the Effects of Intraurethral Platelet Rich Plasma in Urethral Trauma Experimentally Induced in Rat Model

OBJECTIVE

To determine the efficacy of platelet rich plasma applied early initialization after urethral trauma for preventing inflammation and spongiofibrosis.

MATERIALS AND METHODS

Twenty-three rats were randomized and divided into 3 groups, with 10 rats in 2 groups. Only sham group had 3 rats. The urethras of all rats were traumatized with a pediatric urethrotome knife at 6- and 12-o'clock. For 15 days, group I was given platelet rich plasma (PRP) once a day without urethral injury (sham group), group II (n = 10) was not given any medical treatment only urethral injury group (UI-PRP), group III (n = 10) was given PRP once a day intraurethrally as instillation using a 22 ga catheter sheath with urethral injury (UI+PRP). On day 15, the penises of the rats were degloved to perform penectomy.

RESULTS

A significant difference was detected in all parameters when the sham, UI-PRP, UI+PRP groups were compared (respectively, P = .001, / <.001, / .008 / .007) and a significant difference was observed among mucosal inflammation, fibrosis, and edema parameters when UI-PRP and UI+PRP groups were compared. (Respectively; P <.001, / <.001 / .006).

CONCLUSION

In this study, it was shown that intraurethral PRP applied after urethral trauma significantly decreased mucosal inflammation, spongiofibrosis, and edema. Depending on the results we acquired in this study, we think that PRP may be a promising option in urethral stricture treatment.

Molecular and histological studies of bladder wound healing in a rodent model

The field of regenerative medicine encounters different challenges. The success of tissue-engineered implants is dependent on proper wound healing. Today, the process of normal urinary bladder wound healing is poorly characterized. We aspired to explore and elucidate the natural response to injury in an in vivo model in order to further optimize tissue regeneration in future studies. In this study, we aimed to characterize histological and molecular changes during normal healing in a rat model by performing a standardized incisional wound followed by surgical closure. We used a rodent model (n = 40) to follow the healing process in the urinary bladder for 28 days. Surgical exposure of the bladder without incision (n = 40) was performed in controls. Histological characterization and western blot analyses of proteins was carried out using specific staining and markers for inflammation, proliferation, angiogenesis, and tissue maturation. For the molecular characterization of gene expression total RNA was collected for RT² -PCR in wound healing pathway arrays. Analysis of histology revealed distinct, but overlapping, phases of healing with a local inflammatory response (days 1-8) simultaneous with a rapid formation of granulation tissue and proliferation (days 2-8). We also identified significant changes in gene expression related to inflammation, proliferation, and extracellular matrix formation. Healing of an incisional wound in a rodent urinary bladder demonstrated that all the classical phases of wound healing: hemostasis, inflammation, proliferation followed by tissue maturation were present. Our data suggest that the bladder and the skin share similar molecular signaling during wound healing, although we noted differences in the duration of each phase compared to previous studies in rat skin. Further studies will address whether our findings can be extrapolated to the human bladder.

Bone Marrow Stem/Progenitor Cells Attenuate the Inflammatory Milieu Following Substitution Urethroplasty

Substitution urethroplasty for the treatment of male stricture disease is often accompanied by subsequent tissue fibrosis and secondary stricture formation. Patients with pre-existing morbidities are often at increased risk of urethral stricture recurrence brought upon in-part by delayed vascularization accompanied by overactive inflammatory responses following surgery. Within the context of this study, we demonstrate the functional utility of a cell/scaffold composite graft comprised of human bone marrow-derived mesenchymal stem cells (MSC) combined with CD34+ hematopoietic stem/progenitor cells (HSPC) to modulate inflammation and wound healing in a rodent model of substitution urethroplasty. Composite grafts demonstrated potent anti-inflammatory effects with regards to tissue macrophage and neutrophil density following urethral tissue analyses. This was accompanied by a significant reduction in pro-inflammatory cytokines TNFα and IL-1β and further resulted in an earlier transition to tissue remodeling and maturation with a shift in collagen type III to I. Grafted animals demonstrated a progressive maturation and increase in vessel size compared to control animals. Overall, MSC/CD34+ HSPC composite grafts reduce inflammation, enhance an earlier transition to wound remodeling and maturation concurrently increasing neovascularization in the periurethral tissue. We demonstrate the feasibility and efficacy of a stem cell-seeded synthetic graft in a rodent substitution urethroplasty model.

Three-week or one-week bladder catheterization for hypospadias repair? A retrospective-prospective observational study of 189 patients

PURPOSE

While there is little scientific evidence over the optimal duration for transurethral bladder catheterization after hypospadias repair, most surgeons leave the catheter for 7-10 days. We herein describe our experience with bladder catheterization for three weeks after hypospadias repair, an approach not previously described in the literature.

PATIENTS AND METHODS

We reviewed the charts of 189 patients who underwent hypospadias repair by a single pediatric urologist. The study population was divided as follows: group 1 consisted of children operated between March 2007 and September 2010 and whose catheters were left for one week (n=95); group 2 consisted of those operated between September 2010 and July 2013 and whose catheters were left for three weeks (n=94). The primary objective of the study was to compare complication rates between the two groups. Secondary outcomes were evaluation of the effect of age, surgical technique, curvature, and hypospadias degree as potential factors for postoperative complications.

RESULTS

Median age at hypospadias repair was 18 months (range, 3-100 months) in group 1, and 16 months (range, 2-96 months) in group 2, P=.209. The complication rate was 22.1% (n=21) for group 1 and 7.4% (n=7) for group 2, P=.005. Complications observed in group 1 and 2 were meatal stenosis (n=4 and 2, respectively) and urethro-cutaneous fistulas (n=17 and 5, respectively). Coronal fistulas manifested more frequently in patients in group 1 compared to those in group 2 (13.7% vs. 3.2%, P=.01). Complications were observed in 20 patients out of 139 (11.5%) after Duplay, and in 8 patients out of 15 (53.3%) after Duckett (P<.001). In Duplay cases, complications were significantly associated with one-week bladder catheterization (OR: 5.00; 95% CI: 1.53-16.32; P=.008) and higher age group at operation (OR: 1.88; 95% CI 1.07-3.28; P=.026). In Duckett cases, number of surgeries, age, severity, curvature and catheter duration were not found to be associated with complications.

CONCLUSION

In cases of Duplay, a three-week instead of one-week catheterization and age below 6 months at hypospadias repair are associated with a better outcome and fewer complications.

Expression of VEGF in neonatal urinary obstruction: does expression of VEGF predict hydronephrosis?

BACKGROUND

In animal studies, the inhibition of VEGF activity results in high mortality and impaired renal and glomerular development. Mechanical stimuli, like mechanical stretch in respiratory and circulatory systems, results in an elevated expression of VEGF. In animal models, the experimental urinary obstruction is associated with stretching of tubular cells and activations of the renin-angiotensin system. This results in the upregulation of vascular endothelial growth factor (VEGF) and TNF-alfa.

MATERIAL/METHODS

Tissue samples from urinary tract obstruction were collected and immunohistochemistry was performed in 14 patients (average age: 7.1±4.1 years). The control histology group consisted of ureteropelvic junction tissue from 10 fetuses after midtrimester artificial abortion. The fetuses did not have any failure at ultrasound screening and pathological examination. The mean gestational age was 20.6 weeks of gestation (±2.2SD). Expression of VEGF was detected with immunohistochemistry method.

RESULTS

Expression of VEGF was found in varying intensity in the submucosa and subserosa layers, but only in the test tissue (placental tissue). The tissue of the patients with urinary obstruction and the tissue of the fetal ureteropelvic junction without urinary obstruction were negative for expression of VEGF. The repeated examination showed negative cells and no color staining.

CONCLUSIONS

The pressure due to congenital urogenital obstruction resulting in mechanical stress in cells did not increase the expression of VEGF in young children in our study. To find a correlation between urogenital tract obstruction and increased expression of VEGF, we need to perform more examinations because the connection may be of therapeutic significance.

Morphological effects of mitomycin C on urothelial responses to experimentally-induced urethral stricture in rats

OBJECTIVES

To analyze the urothelial responses to mitomycin C treatment after urethral injury in rats, as the urothelium might play a role in the pathogenesis of urethral stricture.

METHODS

Male Sprague-Dawley rats were divided into four groups (n = 5/group): negative control, positive control without further treatment, experimental control treated with sodium hyaluronate and sodium carboxymethylcellulose, and experimental treated with mitomycin C after internal urethrotomy.

RESULTS

Compared with negative controls, positive controls showed a significant increase in cell proliferation and DNA damage accompanied by a considerable decrease in DNA repair in the urothelium, which resulted in urethral stricture. Experimental controls showed a significant increase in cell proliferation, DNA damage and DNA repair compared with negative controls. The mitomycin C-treated group showed a significant decrease in cell proliferation and DNA damage, but a considerable increase in DNA repair compared with the positive and experimental control groups. DNA damage was immediately increased after urethral injury, but DNA repair and cell proliferation showed belated and upregulated expression after mitomycin C treatment.

CONCLUSIONS

Mitomycin C could induce healthy re-epithelialization without severe damage in the urothelium. This finding might support the possibility of using mitomycin C as an adjuvant therapy for urethral strictures, and it might also suggest a urothelial role in the process of urethral stricture after urethral injury.

Wound healing in urology

Wound healing is a dynamic and complex phenomenon of replacing devitalized tissues in the body. Urethral healing takes place in four phases namely inflammation, proliferation, maturation and remodelling, similar to dermal healing. However, the duration of each phase of wound healing in urology is extended for a longer period when compared to that of dermatology. An ideal wound dressing material removes exudate, creates a moist environment, offers protection from foreign substances and promotes tissue regeneration. A single wound dressing material shall not be sufficient to treat all kinds of wounds as each wound is distinct. This review includes the recent attempts to explore the hidden potential of growth factors, stem cells, siRNA, miRNA and drugs for promoting wound healing in urology. The review also discusses the different technologies used in hospitals to treat wounds in urology, which make use of innovative biomaterials synthesised in regenerative medicines like hydrogels, hydrocolloids, foams, films etc., incorporated with growth factors, drug molecules or nanoparticles. These include surgical zippers, laser tissue welding, negative pressure wound therapy, and hyperbaric oxygen treatment.