Buccal epithelium Expanded and Encapsulated in Scaffold-Hybrid Approach to Urethral Stricture (BEES-HAUS) procedure: A novel cell therapy-based pilot study

Comparative analysis of holmium: YAG laser internal urethrotomy versus Cold-Knife optical internal urethrotomy in the management of urethral stricture - a systematic review and meta-analysis

OBJECTIVE

Urethral stricture management has posed enduring challenges in urology, demanding innovative and effective treatment modalities. This study addresses the persistent issues associated with urethral strictures, focusing on the comparative evaluation of two contemporary treatment modalities: Ho: YAG Laser Internal Urethrotomy (HIU) and Cold Knife Optical Internal Urethrotomy (CIU).

METHODS

A comprehensive search of PubMed, Embase, Web of Science, Cochrane Library, and ResearchGate was conducted to identify relevant studies up to November 2023. Inclusion criteria encompassed comparative studies evaluating HIU and CIU in patients with urethral stricture. Data extraction, quality assessment, and subgroup analyses were performed using standardized methods. Outcome measures included preoperative and postoperative mean the maximum urine flow rate (Qmax), mean surgical time, recurrence rates, and perioperative complications.

RESULTS

Nine articles met the inclusion criteria, and their data were analyzed using RevMan 5.4.1. Forest plots were generated for preoperative and postoperative mean Qmax, mean surgical time, recurrence rates, and perioperative complications. While postoperative mean Qmax (MD -0.06; 95% CI: -0.28-0.16; P =0.60, I2 =75%) and mean surgical time (MD 2.16; 95% CI: -1.66-5.99; P =0.27, I2 =98%) showed no significant differences between HIU and CIU, a trend towards lower recurrence rates (RR 0.71; 95% CI: 0.48-1.06; P =0.09, I2 =46%) was observed with HIU but without statistical significance. Perioperative complications, particularly bleeding (RR 0.21; 95% CI: 0.08-0.53; P =0.001, I2 =0%), favored HIU over CIU. The subanalysis indicates that for the treatment of complex urethral strictures, the two surgical methods differ in terms of mean Qmax at 6 months postoperatively (MD -2.51; 95% CI: -4.10--0.91; P =0.002, I2 =59%) and 12 months postoperatively (MD 2.62; 95% CI: 0.93-4.30; P =0.002, I2 =0%). The HIU group shows a significant decrease in recurrence rate at 12 months postoperatively (RR 0.44; 95% CI: 0.21-0.92; P =0.03, I2 =0%). For short-segment urethral strictures with a length ≤1.5 cm, CIU had a shorter operative time compared to the HIU (MD 4.49; 95% CI: 3.87-5.10; P <0.00001, I2 =44%).

CONCLUSION

Overall, both interventions demonstrated similar efficacy in improving postoperative mean Qmax, mean surgical time, and recurrence rates. However, subanalysis indicates that in the short-term, CIU is more effective than HIU in improving Qmax after complex urethral stricture surgery. In long-term Qmax follow-up after surgery, HIU is significantly higher than CIU, and HIU has a low recurrence rate. In addition, for short-segment urethral stricture (≤1.5 cm), CIU requires less time. In terms of complications, HIU has a lower risk of bleeding.

Cell-Based Therapy for Urethral Regeneration: A Narrative Review and Future Perspectives

Urethral stricture is a common urological disease that seriously affects quality of life. Urethroplasty with grafts is the primary treatment, but the autografts used in clinical practice have unavoidable disadvantages, which have contributed to the development of urethral tissue engineering. Using various types of seed cells in combination with biomaterials to construct a tissue-engineered urethra provides a new treatment method to repair long-segment urethral strictures. To date, various cell types have been explored and applied in the field of urethral regeneration. However, no optimal strategy for the source, selection, and application conditions of the cells is available. This review systematically summarizes the use of various cell types in urethral regeneration and their characteristics in recent years and discusses possible future directions of cell-based therapies.

Prospects and Challenges of Electrospun Cell and Drug Delivery Vehicles to Correct Urethral Stricture

Current therapeutic modalities to treat urethral strictures are associated with several challenges and shortcomings. Therefore, significant strides have been made to develop strategies with minimal side effects and the highest therapeutic potential. In this framework, electrospun scaffolds incorporated with various cells or bioactive agents have provided promising vistas to repair urethral defects. Due to the biomimetic nature of these constructs, they can efficiently mimic the native cells’ niches and provide essential microenvironmental cues for the safe transplantation of multiple cell types. Furthermore, these scaffolds are versatile platforms for delivering various drug molecules, growth factors, and nucleic acids. This review discusses the recent progress, applications, and challenges of electrospun scaffolds to deliver cells or bioactive agents during the urethral defect repair process. First, the current status of electrospinning in urethral tissue engineering is presented. Then, the principles of electrospinning in drug and cell delivery applications are reviewed. Finally, the recent preclinical studies are summarized and the current challenges are discussed.

Emerging Bioactive Agent Delivery-Based Regenerative Therapies for Lower Genitourinary Tissues

Injury to lower genitourinary (GU) tissues, which may result in either infertility and/or organ dysfunctions, threatens the overall health of humans. Bioactive agent-based regenerative therapy is a promising therapeutic method. However, strategies for spatiotemporal delivery of bioactive agents with optimal stability, activity, and tunable delivery for effective sustained disease management are still in need and present challenges. In this review, we present the advancements of the pivotal components in delivery systems, including biomedical innovations, system fabrication methods, and loading strategies, which may improve the performance of delivery systems for better regenerative effects. We also review the most recent developments in the application of these technologies, and the potential for delivery-based regenerative therapies to treat lower GU injuries. Recent progress suggests that the use of advanced strategies have not only made it possible to develop better and more diverse functionalities, but also more precise, and smarter bioactive agent delivery systems for regenerative therapy. Their application in lower GU injury treatment has achieved certain effects in both patients with lower genitourinary injuries and/or in model animals. The continuous evolution of biomaterials and therapeutic agents, advances in three-dimensional printing, as well as emerging techniques all show a promising future for the treatment of lower GU-related disorders and dysfunctions.

Single-Port, Robot-Assisted Transanal Harvest of Rectal Mucosa Grafts for Substitution Urethroplasty

OBJECTIVE

To describe a novel single-port, endorobotic technique for harvesting rectal mucosa grafts (RMGs) for urethral reconstruction.

METHODS

A 57-year-old man with prior transurethral procedures developed recurrent obstructive voiding symptoms. Urethrography revealed a panurethral stricture, meatus to the bulbomembranous junction. It was decided to proceed with surgical repair. Owing to the stricture's length, available oral mucosa would require additional material, and repair with a single rectal mucosa graft was offered instead. Single-port (SP) endorobotic approach offered ideal access for transanal harvest. With the patient placed in a modified lithotomy position, a GELPOINT™ Path transanal access platform was inserted through the anal canal. Pneumorectum was established at 12 mmHg with an AirSeal® CO₂ insufflator. A Da Vinci SP® surgical system was docked, equipped with Maryland bipolar forceps and a monopolar spatula. After injection of ORISE™ gel, endorobotic submucosal dissection began posteriorly proximal to the dentate line.

RESULTS

Proceeding cranially through the rectal submucosa, a 21 ✕ 3 cm strip of mucosa was obtained with appropriate hemostasis. The resulting graft was thoroughly thinned. The robot was undocked, and the patient repositioned to high lithotomy. The patient underwent a penis-inverting, dorsolateral approach augmentation urethroplasty. With an indwelling catheter placed, the patient was discharged on postoperative day 2 with no postoperative complications.

CONCLUSIONS

Transanal rectal mucosal dissection with a single-port endorobotic approach can be an enticing and minimally invasive harvesting technique to provide substitution grafts for long-segment urethral reconstruction.

Ability of photocurable gelatin to prevent stricture recurrence after urethral dilation in rabbits

OBJECTIVES

To evaluate the ability of photocurable gelatin to prevent stricture recurrence after urethral dilation in a rabbit urethral stricture model.

METHODS

We created urethral strictures in the bulbar urethras of 10 male Japanese white rabbits using electrocoagulation. After 1 month, the rabbits were randomly divided into Group A (n = 5; urethral stricture dilation and the local application of photocurable gelatin using a ruthenium photoinitiator and irradiation with a light-emitting diode light [λ = 455 nm, 50 mW/cm2 ] for 1 min) and Group B (n = 5; dilation only). Urethral stricture status was evaluated 1-2 months later by retrograde urethrography and urethroscopy. The lumen ratio (urethral width at the stricture site to the normal urethral width on retrograde urethrography) was calculated. Urethral patency was considered to be improved when the urethral lumen could accommodate a 10-Fr urethroscope without resistance. Urethral specimens were harvested for histopathological examination.

RESULTS

The mean lumen ratio did not differ significantly between Groups A and B before dilation (25.8% vs 23.4%; P = 0.40), but differed significantly after dilation (65.5% vs 27.3%, respectively; P = 0.03). Urethral patency improved in all rabbits in Group A (100%) versus one rabbit in Group B (20%; P = 0.02). The mean circumference of the regenerated urethral epithelium at the stricture site was larger in Group A than in Group B (14 mm vs 6.6 mm; P = 0.06).

CONCLUSIONS

Photocurable gelatin can reduce urethral stricture recurrence after dilation in a rabbit model.

An efficient polymer cocktail-based transportation method for cartilage tissue, yielding chondrocytes with enhanced hyaline cartilage expression during in vitro culturing

BACKGROUND

Chondrocytes are used in cell-based therapies such as autologous chondrocyte implantation (ACI) and matrix-associated cartilage implantation (MACI). To transport the cartilage tissue to the laboratory for in vitro culturing, phosphate-buffered saline (PBS), Euro-Collins solution (ECS) and Dulbecco's Modified Eagle's Medium (DMEM) are commonly employed at 4-8 °C.

METHODS

In this study, eight samples of human cartilage biopsy tissues from elderly patients with severe osteoarthritis undergoing arthroscopy, which would otherwise have been discarded, were used. The cartilage tissue samples were compared to assess the cell yield between two transportation groups: i) a thermo-reversible gelation polymer (TGP) based method without cool preservation (∼25 °C) and ii) ECS transport at 4 °C. These samples were subjected to in vitro culture in a two-dimensional (2D) monolayer for two weeks and subsequently in a three-dimensional (3D) TGP scaffold for six weeks.

RESULTS

The cell count obtained from the tissues transported in TGP was higher (0.2 million cells) than those transported in ECS (0.08 million cells) both after initial processing and after in vitro culturing for 2 weeks in 2D (18 million cells compared with 10 million cells). In addition, mRNA quantification demonstrated significantly higher expression of Col2a1 and SOX-9 in 3D-TGP cultured cells and lower expression of COL1a1 in RT-PCR, characteristic of the hyaline cartilage phenotype, than in 2D culture.

CONCLUSION

This study confirms that the TGP cocktail is suitable for both the transport of human cartilage tissue and for in vitro culturing to yield better-quality cells for use in regenerative therapies.

In Vitro Culture Expansion and Characterization of Buccal Mucosal Epithelial Cells for Tissue Engineering Applications in Urethral Stricture After Transportation Using a Thermoreversible Gelation Polymer

Introduction: The transportation of tissues from hospitals to clinical laboratories for cell therapy is an essential component of regenerative medicine. Previously, we used laboratory-cultured mucosal cells from buccal epithelium expanded and encapsulated using a scaffold-hybrid approach to the urethral stricture (BEES-HAUS) procedure. In this study, to improve the outcomes, we compared the thermoreversible gelation polymer (TGP) transportation procedure with conventional culture methods, and reported its advantages. Methods: Human buccal mucosal tissues in Phase I of the study were transported in Euro-Collins solution (ECS) and the cells obtained were cultured in two-dimensional (2D) Dulbecco's modified Eagle's medium (DMEM), CnT-Prime epithelial 2D differentiation medium (CnT-PR), and a three-dimensional (3D)-TGP scaffold. In Phase II, tissues were transported in a TGP cocktail and the ECS. The cells were cultured in 2D-DMEM and 3D-TGP, quantified, and characterized by immunohistochemistry. Results: The cells in 3D-TGP culture maintained epithelial morphology in a better manner compared with 2D-DMEM, in which they developed fibroblast-like morphology. The TGP-transported cells grew rapidly. Immunohistochemical analysis results for AE1/AE3, EGFR, integrin-β1, p63, and p75 were intensely positive in 3D-TGP. Conclusion: The TGP-based cocktail used in human buccal tissue transportation yielded cells with better morphology maintenance. The TGP scaffold provides an optimal in vitro environment wherein epithelial cells better maintain their native phenotype compared to those cultured through conventional methods. These results suggest using TGP for the transportation and culture of human buccal tissues for clinical applications. In addition, the use of a TGP-based cocktail for the transport of other tissues for regenerative medicine applications is worth further analysis.

Advancements in transurethral management of urethral stricture disease

PURPOSE OF REVIEW

To explore and report the recent evolution of transurethral management of urethral stricture disease.

RECENT FINDINGS

In recent years, new promising techniques in the transurethral management of urethral stricture disease have emerged including adjuvant therapies to direct vision internal urethrotomy, regenerative therapy with buccal mucosa cells and minimally invasive transurethral urethroplasty procedures that avoid skin incisions.

SUMMARY

Although further work is needed, the expanding field of transurethral therapies for urethral stricture disease demonstrates early promising results through a variety of modalities.

Reversal of senescence-associated beta-galactosidase expression during in vitro three-dimensional tissue-engineering of human chondrocytes in a polymer scaffold

Regenerative medicine applications require cells that are not inflicted with senescence after in vitro culture for an optimal in vivo outcome. Methods to overcome replicative senescence include genomic modifications which have their own disadvantages. We have evaluated a three-dimensional (3D) thermo-reversible gelation polymer (TGP) matrix environment for its capabilities to reverse cellular senescence. The expression of senescence-associated beta-galactosidase (SA-βgal) by human chondrocytes from osteoarthritis-affected cartilage tissue, grown in a conventional two-dimensional (2D) monolayer culture versus in 3D-TGP were compared. In 2D, the cells de-differentiated into fibroblasts, expressed higher SA-βgal and started degenerating at 25 days. SA-βgal levels decreased when the chondrocytes were transferred from the 2D to the 3D-TGP culture, with cells exhibiting a tissue-like growth until 42-45 days. Other senescence associated markers such as p16INK4a and p21 were also expressed only in 2D cultured cells but not in 3D-TGP tissue engineered cartilage. This is a first-of-its-kind report of a chemically synthesized and reproducible in vitro environment yielding an advantageous reversal of aging of human chondrocytes without any genomic modifications. The method is worth consideration as an optimal method for growing cells for regenerative medicine applications.

Successful engraftment of epithelial cells derived from autologous rabbit buccal mucosal tissue, encapsulated in a polymer scaffold in a rabbit model of a urethral stricture, transplanted using the transurethral approach

Background

A pilot study reported an autologous buccal mucosal cell transplant in humans through the trans-urethral route using the buccal epithelium expanded and encapsulated in scaffold-hybrid approach to urethral stricture (BEES-HAUS), a minimally invasive approach to treat urethral stricture. Although successful outcomes were achieved in that study, for further validation, it is essential to prove that the transplanted buccal epithelium was engrafted over the urothelium through histological examination of the urethra, harvested post-transplant, which is infeasible in humans. Herein, we report the successful creation of an animal model of urethral stricture and the engraftment of epithelial cells derived from autologous buccal mucosal tissue, encapsulated in a thermo-reversible gelation polymer (TGP) scaffold, transplanted by trans-urethral route.

Methods

An animal model of urethral stricture was created in Japanese white male rabbits using electro-coagulation. Buccal tissue was harvested from the rabbits and subjected to enzyme digestion, followed by 5-7 days of in vitro culture in conventional two-dimensional (2D) culture and in a 3D platform of thermo-reversible gelation polymer (3D-TGP) culture. The cells harvested from the groups were mixed and encapsulated and transplanted with TGP, by transurethral catheterization. Fourteen days later, the urethra was harvested and subjected to histological examination. The buccal biopsy tissue, cells after digestion and cells post-culture were also subjected to histological examination. Urethrogram and endoscopy images were recorded at different time points.

Results

The stricture was successfully created, with the coagulated area markedly stenosed. Histological staining of the cells after in vitro processing showed that the cells grew with native epithelial and rounded cell morphology in 3D-TGP while they differentiated into fibroblast like-cells in 2D culture. Histological staining of the urethral tissue after transplantation revealed the engraftment of the transplanted buccal mucosal cells, with stratified squamous epithelium over the specialized stratified urothelium in the urethrotomy site.

Conclusion

We used histology to prove the successful engraftment of TGP-encapsulated buccal mucosal epithelial cells in an animal model of urethral injury with healing of the injured tissue. The model of urethral stricture and cell therapy, using a transurethral approach, recapitulates the previously reported BEES-HAUS approach and lays the foundation for larger multi-centric translational clinical studies.

Recurrent Anterior Urethral Stricture: Challenges and Solutions

Recurrent male anterior urethral stricture disease is a complex surgical challenge that should be managed by reconstructive urologists with experience in stricture management. Diagnosis of recurrence requires both anatomic narrowing and patient symptoms identified on validated questionnaires, with limited role for intervention in asymptomatic treatment “failures”. Endoscopic management has a very specific role in recurrence, and the choice of technique for urethroplasty depends on pre-operative urethrography and cystoscopy. Surgical success depends on addressing patient concerns, complete stricture excision, tissue quality optimization, and the use of multi-stage repair when indicated. Augmentation with genital skin flaps and/or grafts is often required, with buccal mucosa as the ideal graft source if local tissue is compromised. Salvage options including urinary diversion and perineal urethrostomy must also be considered in debilitated patients with severe disease or repeated treatment failures. Unique patient populations including patients with hypospadias and lichen sclerosis are among the highest risk for repeated recurrence and require special care in surgical technique, graft selection, and post-operative management.

Enhanced expression of hyaluronic acid in osteoarthritis-affected knee-cartilage chondrocytes during three-dimensional in vitro culture in a hyaluronic-acid-retaining polymer scaffold

BACKGROUND

Chondrocyte transplantation to address cartilage damage is an established solution. Because hyaluronic acid (HA) is an essential component for homeostasis of the cartilage, in order to arrive at methodologies to utilize its advantages in cell-based therapies, we compared the HA retention capability of a thermoreversible gelation polymer scaffold-based environment (3D-TGP) with conventional in vitro cell culture methodologies.

METHODS

Chondrocytes derived from osteoarthritis-affected knee joint cartilage of elderly patients were used and accomplished in three phases. In Phase I, the levels of HA secreted by chondrocytes were measured in culture supernatant. In Phase II, retention capacity of externally added HA was quantified indirectly by measuring the HA released in culture supernatant, and in Phase III, the expression of CD44 on cells was analysed by immunohistochemistry.

RESULTS

In Phase I, the average HA in the 3D supernatant was 3% that of 2D. In phase II, 80% of externally added HA was detected in the 2D on day 7, while in 3D-TGP, only 0.1% was released until day 21. In Phase III, 2D yielded individual cells that started degenerating from the third week; in 3D-TGP cells grew for a longer duration, formed a tissue-like architecture with extracellular matrix with significantly intense staining of CD44 than 2D.

CONCLUSION

The capability of the 3D-TGP culture environment to retain HA and support chondrocytes to grow with a tissue-like architecture expressing higher HA content is considered advantageous as it serves as an in vitro culture platform that enables tissue engineering of cartilage tissue with native hyaline phenotype and higher HA expression. The in vitro environment being conducive, based on this data, we also recommend that the TGP be tried as an encapsulation material in clinical studies of chondrocyte implantation for optimal clinical outcome.

Recent Advances in treatment of urethral stricture disease in men

Urethral stricturing is a narrowing of the urethral lumen as a result of ischaemic spongiofibrosis. The main challenge of currently available treatment options is recurrence of the stricture. Recent advancements in the treatment of urethral strictures mainly came from the fields of regenerative medicine and tissue engineering. Research efforts have primarily focused on decreasing the recurrence of stricture after internal urethrotomy and constructing tissue-engineered urethral substitutes to improve clinical outcomes of urethroplasty surgeries. The aim of this article is to review the most recent advancements in the management of urethral stricture disease in men.

Current state of urethral tissue engineering

PURPOSE OF REVIEW

Urethrotomy remains the first-line therapy in the treatment of a urethral stricture despite data showing no real chance of a cure after repeated urethroplasties. An anastomotic or an augmentation urethroplasty with oral mucosa should be offered to patients with a failed urethrotomy. The availability of grafts can be a concern for both patients and surgeons. The potential for a tissue-engineered solution has been explored in recent years and is explored in this article.

RECENT FINDINGS

More than 80 preclinical studies have investigated a tissue-engineered approach for urethral reconstruction mostly using decellularized natural scaffolds with or without cell seeding. The animal models used in preclinical testing are not representative of disease processes seen with strictures in man. The available clinical studies were of small sample size and lacked control groups. The choice of biomaterial were mostly acellular matrices derived from natural extracellular matrix. The reported success rates in the pilot clinical studies were highly variable.

SUMMARY

The research with tissue engineering of the urethra has not yet been translated into a clinically available material. This is an area where much more research is needed and we would conclude that it is an area of unmet clinical need where users of tissue-engineered urethra in the future need to carry out a rigorous basic science programme and need to be cautious in drawing conclusions based on initial experience and report on long-term clinical results.