Comparative Assessment of Cultures from Oral and Urethral Stem Cells for Urethral Regeneration

Cell therapy in the cornea: The emerging role of microenvironment

The cornea is an ideal testing field for cell therapies. Its highly ordered structure, where specific cell populations are sequestered in different layers, together with its accessibility, has allowed the development of the first stem cell-based therapy approved by the European Medicine Agency. Today, different techniques have been proposed for autologous and allogeneic limbal and non-limbal cell transplantation. Cell replacement has also been attempted in cases of endothelial cell decompensation as it occurs in Fuchs dystrophy: injection of cultivated allogeneic endothelial cells is now in advanced phases of clinical development. Recently, stromal substitutes have been developed with excellent integration capability and transparency. Finally, cell-derived products, such as exosomes obtained from different sources, have been investigated for the treatment of severe corneal diseases with encouraging results. Optimization of the success rate of cell therapies obviously requires high-quality cultured cells/products, but the role of the surrounding microenvironment is equally important to allow engraftment of transplanted cells, to preserve their functions and, ultimately, lead to restoration of tissue integrity and transparency of the cornea.

Tissue Engineering for Penile Reconstruction

The penis is a complex organ with a development cycle from the fetal stage to puberty. In addition, it may suffer from either congenital or acquired anomalies. Penile surgical reconstruction has been the center of interest for many researchers but is still challenging due to the complexity of its anatomy and functionality. In this review, penile anatomy, pathologies, and current treatments are described, including surgical techniques and tissue engineering approaches. The self-assembly technique currently applied is emphasized since it is considered promising for an adequate tissue-engineered penile reconstructed substitute.

Validation of airway porcine epithelial cells as an alternative to human in vitro preclinical studies

Animal models are currently used in several fields of biomedical research as useful alternatives to human-based studies. However, the obtained results do not always effectively translate into clinical applications, due to interspecies anatomical and physiological differences. Detailed comparability studies are therefore required to verify whether the selected animal species could be a representative model for the disease or for cellular process under investigation. This has proven to be fundamental to obtaining reliable data from preclinical studies. Among the different species, swine is deemed an excellent animal model in many fields of biological research, and has been largely used in respiratory medicine, considering the high homology between human and swine airways. In the context of in vitro studies, the validation of porcine airway epithelial cells as an alternative to human epithelial cells is crucial. In this paper, porcine and human tracheal and bronchial epithelial cells are compared in terms of in vivo tissue architecture and in vitro cell behaviour under standard and airlifted conditions, analyzing the regenerative, proliferative and differentiative potentials of these cells. We report multiple analogies between the two species, validating the employment of porcine airway epithelial cells for most in vitro preclinical studies, although with some limitations due to species-related divergences.

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.

The Growing Medical Need for Tracheal Replacement: Reconstructive Strategies Should Overcome Their Limits

Breathing, being predominantly an automatic action, is often taken for granted. However, respiratory diseases affect millions of people globally, emerging as one of the major causes of disability and death overall. Among the respiratory dysfunctions, tracheal alterations have always represented a primary challenge for clinicians, biologists, and engineers. Indeed, in the case of wide structural alterations involving more than 50% of the tracheal length in adults or 30% in children, the available medical treatments are ineffective or inapplicable. So far, a plethora of reconstructive approaches have been proposed and clinically applied to face this growing, unmet medical need. Unfortunately, none of them has become a well-established and routinely applied clinical procedure to date. This review summarizes the main clinical reconstructive attempts and classifies them as non-tissue engineering and tissue engineering strategies. The analysis of the achievements and the main difficulties that still hinder this field, together with the evaluation of the forefront preclinical experiences in tracheal repair/replacement, is functional to promote a safer and more effective clinical translation in the near future.

Regenerative Medicine of Epithelia: Lessons From the Past and Future Goals

This article explores examples of successful and unsuccessful regenerative medicine on human epithelia. To evaluate the applications of the first regenerated tissues, the analysis of the past successes and failures addresses some pending issues and lay the groundwork for developing new therapies. Research should still be encouraged to fill the gap between pathologies, clinical applications and what regenerative medicine can attain with current knowledge.

Regenerative and engineered options for urethroplasty

Surgical correction of urethral strictures by substitution urethroplasty - the use of grafts or flaps to correct the urethral narrowing - remains one of the most challenging procedures in urology and is frequently associated with complications, restenosis and poor quality of life for the affected individual. Tissue engineering using different cell types and tissue scaffolds offers a promising alternative for tissue repair and replacement. The past 30 years of tissue engineering has resulted in the development of several therapies that are now in use in the clinic, especially in treating cutaneous, bone and cartilage defects. Advances in tissue engineering for urethral replacement have resulted in several clinical applications that have shown promise but have not yet become the standard of care.

Preclinical study for treatment of hypospadias by advanced therapy medicinal products

PURPOSE

This paper explores the feasibility of a new therapy for the treatment of hypospadias patients. Hypospadias is a very common congenital malformation of male genitals, with very high rate of recurrences after surgery. The field of regenerative medicine, which offers innovative solutions for many pathologies, still does not offer reliable solution for this pathology. Here, we propose quality, safety, and clinical feasibility assessment for an oral mucosa advanced therapy medicinal product (ATMP) grown on a biocompatible scaffold for a clinical study on urethral reconstruction of hypospadias patients.

METHODS

Urethral and oral mucosal epithelia from donor biopsies were cultivated between two fibrin layers, under clinical-grade conditions for cell and tissue characterization and comparison, aimed at tissue engineering. In addition, single-clone analyses were performed to analyze gene expression profiles of the two epithelia by microarray technology.

RESULTS

Oral mucosa appeared suitable for urethral reconstruction. The resulting ATMP was proven to maintain stem cells and regenerative potency. The preclinical safety studies were performed on human tissues to assess abnormalities and tumorigenicity, and confirmed the safety of the ATMP. Finally, the patient selection and the clinical protocol for the upcoming clinical trial were defined.

CONCLUSIONS

Against this backdrop, in this paper, we are proposing a new reproducible and reliable ATMP for the treatment of hypospadias.

Urothelial or oral mucosa cells for tissue-engineered urethroplasty: A critical revision of the clinical outcome

Objective

To report the clinical outcome of urethral reconstruction by cultured urothelial or oral mucosa cells for tissue-engineered urethroplasty.

Methods

We systematically searched for studies reporting the use of tissue-engineered techniques for hypospadias and urethral stricture repair in humans in PubMed and Embase (OvidSP) through January, 1990 to June, 2018. We excluded studies based on titles that clearly were not related to the subject, studies in which tissue-engineered biomaterial were used only in laboratory or experimental animals, and in the absence of autologous cultured epithelial cells. Studies were also excluded if they were not published in English, had no disease background and adequate follow-up. Finally, we search all relevant abstract presented at two of the main urological meetings in the last 10 years: European Association of Urology (EAU) and American Urological Association (AUA).

Results

A total of six articles, reporting the clinical use of tissue-engineered techniques in humans, were fully reviewed in our review. The epithelial cells were harvested from the urethra (10 patients), the bladder (11 patients) and the mouth (104 patients). The tissue-engineered grafts were used in children for primary hypospadias repair in 16 cases, and in adults for posterior and anterior urethral strictures repair in 109 cases. Tissue-engineered grafts were showed working better in children for primary hypospadias repair than in adults for urethral strictures repair.

Conclusion

One hundred and twenty-five patients received tissue-engineered urethroplasty using cultured epithelial cells for primary hypospadias or urethral strictures repair. The studies demonstrate a high degree of heterogeneity respect to epithelial cells (from urethra, bladder, and mouth), type of scaffold, etiology, site of urethral stricture, number of patients, follow-up and outcomes.

Anterior Urethroplasty Using a New Tissue Engineered Oral Mucosa Graft: Surgical Techniques and Outcomes

PURPOSE

We investigated whether tissue engineered material may be adopted using standard techniques for anterior urethroplasty.

MATERIALS AND METHODS

We performed a retrospective multicenter study in patients with recurrent strictures, excluding those with failed hypospadias, lichen sclerosus, traumatic and posterior strictures. A 0.5 cm² oral mucosa biopsy was taken from the patient cheek and sent to the laboratory to manufacture the graft. After 3 weeks the tissue engineered oral mucosal MukoCell® graft was sent to the hospital for urethroplasty. Four techniques were used, including ventral onlay, dorsal onlay, dorsal inlay and a combined technique. Cystourethrography was performed 1 month postoperatively. Patients underwent clinical evaluation, uroflowmetry and post-void residual urine measurement every 6 months. When the patient showed obstructive symptoms, defined as maximum urine flow less than 12 ml per second, the urethrography was repeated. Patients who underwent further treatment for recurrent stricture were classified as having treatment failure.

RESULTS

Of the 38 patients with a median age of 57 years who were included in study the strictures were penile in 3 (7.9%), bulbar in 29 (76.3%) and penobulbar in 6 (15.8%). Median stricture length was 5 cm and median followup was 55 months. Treatment succeeded in 32 of the 38 patients (84.2%) and failed in 15.8%. Success was achieved in 85.7% of ventral onlay, 83.3% of dorsal onlay, 80% of dorsal inlay and 100% of combined technique cases. No local or systemic adverse reactions due to the engineered material were noted.

CONCLUSIONS

Our findings show that a tissue engineered oral mucosa graft can be implanted using the same techniques suggested for anterior urethroplasty and native oral mucosa, and guaranteeing a similar success rate.

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.

One-stage Penile Urethroplasty Using Oral Mucosal Graft and Glue

BACKGROUND

Repair of penile urethral strictures is a challenging problem for which different techniques have been suggested.

OBJECTIVE

To describe a new surgical technique for one-stage penile urethroplasty using an oral graft and glue, and to assess its safety and efficacy.

DESIGN, SETTING, AND PARTICIPANTS

A retrospective review of medical records for patients who underwent one-stage penile urethroplasty using oral mucosa and glue from February 2013 to October 2014 was performed.

SURGICAL PROCEDURE

The penile urethra was opened and the urethral plate was incised to create a wide window within which the oral graft was pasted with glue. The urethra was sutured over the catheter.

OUTCOME MEASUREMENTS AND STATISTICAL ANALYSIS

Clinical data were collected in a database. Intraoperative and postoperative complications and outcomes were assessed. A descriptive statistical analysis was performed.

RESULTS AND LIMITATIONS

Fourteen patients were included in the study. Median operative time was 60min. The median postoperative stay was 3 d. Three intraoperative and one postoperative complication occurred. In all patients, voiding cystourethrography 2 wk after surgery failed to show urethral fistula or sacculation. No patients complained of penile chordee or sexual dysfunction after surgery. Median follow-up was 16 mo. Among the 14 patients, 12 (85.7%) procedures were successful and two (14.3%) were failures. Study limitations include the small sample size and short follow-up.

CONCLUSIONS

An in vitro study and a one-stage reconstruction of penile urethral strictures with an oral mucosa graft and glue showed that the procedure is safe and efficient, but further studies including larger series of patients and longer follow-up are required.

PATIENT SUMMARY

We report on the repair of penile urethral stricture using one-stage urethroplasty with oral mucosa and glue. This new technique was safe and effective, with limited complications and satisfactory outcomes. We plan to increase the use of this technique in the future.