One-stage dorsal inlay oral mucosa graft urethroplasty for anterior urethral stricture

Encapsulated three-dimensional bioprinted structure seeded with urothelial cells: a new construction technique for tissue-engineered urinary tract patch

BACKGROUND

Traditional tissue engineering methods to fabricate urinary tract patch have some drawbacks such as compromised cell viability and uneven cell distribution within scaffold. In this study, we combined three-dimensional (3D) bioprinting and tissue engineering method to form a tissue-engineered urinary tract patch, which could be employed for the application on Beagles urinary tract defect mode to verify its effectiveness on urinary tract reconstruction.

METHODS

Human adipose-derived stem cells (hADSCs) were dropped into smooth muscle differentiation medium to generate induced microtissues (ID-MTs), flow cytometry was utilized to detect the positive percentage for CD44, CD105, CD45, and CD34 of hADSCs. Expression of vascular endothelial growth factor A (VEGFA) and tumor necrosis factor-stimulated gene-6 (TSG-6) in hADSCs and MTs were identified by Western blotting. Then the ID-MTs were employed for 3D bioprinting. The bioprinted structure was encapsulated by transplantation into the subcutaneous tissue of nude mice for 1 week. After retrieval of the encapsulated structure, hematoxylin and eosin and Masson's trichrome staining were performed to demonstrate the morphology and reveal collagen and smooth muscle fibers, integral optical density (IOD) and area of interest were calculated for further semi-quantitative analysis. Immunofluorescent double staining of CD31 and α-smooth muscle actin (α-SMA) were used to reveal vascularization of the encapsulated structure. Immunohistochemistry was performed to evaluate the expression of interleukin-2 (IL-2), α-SMA, and smoothelin of the MTs in the implanted structure. Afterward, the encapsulated structure was seeded with human urothelial cells. Immunofluorescent staining of cytokeratins AE1/AE3 was applied to inspect the morphology of seeded encapsulated structure.

RESULTS

The semi-quantitative assay showed that the relative protein expression of VEGFA was 0.355 ± 0.038 in the hADSCs vs. 0.649 ± 0.150 in the MTs (t = 3.291, P = 0.030), while TSG-6 expression was 0.492 ± 0.092 in the hADSCs vs. 1.256 ± 0.401 in the MTs (t = 3.216, P = 0.032). The semi-quantitative analysis showed that the mean IOD of IL-2 in the MT group was 7.67 ± 1.26, while 12.6 ± 4.79 in the hADSCs group, but semi-quantitative analysis showed that there was no statistical significance in the difference between the two groups (t = 1.724, P = 0.16). The semi-quantitative analysis showed that IOD was 71.7 ± 14.2 in non-induced MTs (NI-MTs) vs. 35.7 ± 11.4 in ID-MTs for collagen fibers (t = 3.428, P = 0.027) and 12.8 ± 1.9 in NI-MTs vs. 30.6 ± 8.9 in ID-MTs for smooth muscle fibers (t = 3.369, P = 0.028); furthermore, the mean IOD was 0.0613 ± 0.0172 in ID-MTs vs. 0.0017 ± 0.0009 in NI-MTs for α-SMA (t = 5.994, P = 0.027), while 0.0355 ± 0.0128 in ID-MTs vs. 0.0035 ± 0.0022 in NI-MTs for smoothelin (t = 4.268, P = 0.013), which indicate that 3D bioprinted structure containing ID-MTs could mimic the smooth muscle layer of native urinary tract. After encapsulation of the urinary tract patch for additional cell adhesion, urothelial cells were seeded onto the encapsulated structures, and a monolayer urothelial cell was observed.

CONCLUSION

Through 3D bioprinting and tissue engineering methods, we provided a promising way to fabricate tissue-engineered urinary tract patch for further investigation.

A critical outcome analysis of Asopa single-stage dorsal inlay substitution urethroplasty for penile urethral stricture

PURPOSE

To critically report outcomes from a contemporary series of patients undergoing single-stage Asopa dorsal inlay urethroplasty for penile stricture.

METHODS

First, we retrospectively evaluated patients who underwent Asopa urethroplasty for penile stricture between 2009 and 2016 at our department. Clinical and surgical characteristics were compared across treatment groups (proximal penile, mid-penile, distal penile). Recurrence-free survival was plotted using Kaplan-Meier curves. Treatment satisfaction was assessed using a validated outcome measurement tool. Second, a literature review was performed through Medline to summarize the available evidence on Asopa urethroplasty and put our own results into context.

RESULTS

Of 125 patients, 38 (30%), 74 (59%), and 13 (10%) had distal penile, mid-penile, and proximal penile stricture, respectively. Patients with distal strictures were younger and graft length was shorter compared to other groups (P ≤ 0.009). The majority of strictures were iatrogenic (38%), followed by hypospadias related (24%), congenital (17%), traumatic (10%), inflammatory (9%), and post-infectious strictures (2.4%). At a median follow-up of 36 months, overall success rate was 70%. In sensitivity analyses, success rates were only marginally improved to 71% after exclusion of hypospadias- and lichen sclerosus-associated strictures. Patients with mid-penile strictures were significantly more satisfied compared to other groups. Overall, 272 patients from 9 studies in the literature review underwent Asopa urethroplasty and success rates ranged from 73 to 100%.

CONCLUSIONS

Success rates of Asopa urethroplasty in penile strictures are lower than previously reported. This is most likely due to both complex stricture etiology and surgical history and last resort single-stage surgery in many cases. Pre-operative counseling must consider high recurrence risk and staged urethroplasty should be discussed in selective cases to optimize patient satisfaction.

Evaluation of the results of dorsolateral buccal mucosal augmentation urethroplasty

OBJECTIVE

Evaluation of the results of dorsolateral buccal mucosal augmentation urethroplasty in patients with a long- segment urethral strictures.

MATERIAL AND METHODS

Twenty male patients who underwent urethroplasty in our clinic between November 2015 and January 2017 were evaluated. The outcomes of single-stage dorsolateral buccal mucosal augmentation urethroplasty were retrospectively evaluated. Patients were followed-up at 2^nd-3^rd weeks, 3^rd and 6^th months after the operation.

RESULTS

Mean age of the patients was 59.45±13.6 years. Mean length of the strictures was 4.59±1.99 cm (3-11 cm) and mean length of buccal mucosal graft was 6.8±1.98 cm (5-13 cm). Mean duration of operation was 149.25±47.39 minutes (95-270 min) and mean blood loss was calculated as 165.5±63.05 mL (75-280 mL). The success rate of dorsolateral buccal mucosal augmentation urethroplasty was calculated as 85% after a mean follow-up of 7.38±2.6 months. There were no perioperative or postoperative complications in the urethroplasty region or the mouth except one patient. Three patients who were found to have a decline in the maximum voiding rate in the postoperative 3^rd month were included in the dilation program.

CONCLUSION

Single-stage dorsolateral buccal mucosal augmentation urethroplasty is a surgical option to be used in the treatment of long segment urethral strictures with high success and low complication rates in experienced hands.

Involvement of neural crest and paraxial mesoderm in oral mucosal development and healing

Tissue engineering therapies using adult stem cells derived from neural crest have sought accessible tissue sources of these cells because of their potential pluripotency. In this study, the gingiva and oral mucosa and their associated stem cells were investigated. Biopsies of these tissues produce neither scarring nor functional problems and are relatively painless, and fresh tissue can be obtained readily during different chairside dental procedures. However, the embryonic origin of these cells needs to be clarified, as does their evolution from the perinatal period to adulthood. In this study, the embryonic origin of gingival fibroblasts were determined, including gingival stem cells. To do this, transgenic mouse models were used to track neural crest derivatives as well as cells derived from paraxial mesoderm, spanning from embryogenesis to adulthood. These cells were compared with ones derived from abdominal dermis and facial dermis. Our results showed that gingival fibroblasts are derived from neural crest, and that paraxial mesoderm is involved in the vasculogenesis of oral tissues during development. Our in vitro studies revealed that the neuroectodermal origin of gingival fibroblasts (or gingival stem cells) endows them with multipotential properties as well as a specific migratory and contractile phenotype which may participate to the scar-free properties of the oral mucosa. Together, these results illustrate the high regenerative potential of neural crest-derived stem cells of the oral mucosa, including the gingiva, and strongly support their use in cell therapy to regenerate tissues with impaired healing.

The Impact of Age on Urethroplasty Success

OBJECTIVE

To determine if age is an independent predictor of surgical success in patients undergoing urethroplasty. Urethroplasty performed by excision and primary anastomosis depends on vascular collateralization. Successful augmented urethroplasty depends on graft neovascularization. Older patients have more comorbid conditions including peripheral vascular disease associated with reduced penile blood flow.

METHODS

This is a retrospective review of urethroplasties from 11 institutions. Primary outcome was functional success at 1 year from surgery, defined as freedom from post-urethroplasty procedures. Secondary outcome was freedom from cystoscopic evidence of stricture recurrence at 3 months. Study outcomes were compared between 2 age cohorts (<60 years old and ≥60 years old). Multivariable logistic regression analysis evaluated the influence of patient factors on our primary and secondary outcomes, using age as a continuous variable.

RESULTS

Of 322 urethroplasties, 258 were performed in patients <60 years and 64 in patients ≥60 years. Median follow-up was 1.8 years. The following were not significantly different between groups: stricture length or location, smoking status, number of previous urethrotomies or dilations, and urethroplasty type. The following were more common in patients ≥60 years: diabetes, hypertension, hyperlipidemia, coronary artery and peripheral vascular disease, chronic obstructive pulmonary disease, and cancer. There was no difference in need for repeat procedures or anatomic recurrence between age groups or with increasing age. Stricture length was the only statistically significant clinical factor.

CONCLUSION

Urethroplasty success may be affected by comorbidities but not age. Age alone should not be used as an absolute exclusion criterion for men needing urethral reconstruction.

Tissue transfer techniques in reconstructive urology

Tissue transfer techniques are an essential part of the reconstructive urologist's armamentarium. Flaps and graft techniques are widely used in genital and urethral reconstruction. A graft is tissue that is moved from a donor site to a recipient site without its native blood supply. The main types of grafts used in urology are full thickness grafts, split thickness skin grafts and buccal mucosa grafts. Flaps are transferred from the donor site to the recipient site on a pedicle containing its native blood supply. Flaps can be classified based on blood supply, elevation methods or the method of transfer. The most used flaps in urology include penile, preputial, and scrotal skin. We review the various techniques used in reconstructive urology and the outcomes of these techniques.

Acellular matrix in urethral reconstruction

The treatment of severe urethral stenosis has always been a challenge even for skilled urologists. Classic urethroplasty, skin flaps and buccal mucosa grafting may not be used for long and complex strictures. In the quest for an ideal urethral substitute, acellular scaffolds have demonstrated the ability to induce tissue regeneration layer by layer. After several experimental studies, the use of acellular matrices for urethral reconstruction has become a clinical reality over the last decade. In this review we analyze advantages and limitations of both biological and polymeric scaffolds that have been reported in experimental and human studies. Important aspects such as graft extension, surgical technique and cell-seeding versus cell-free grafts will be discussed.