Stem cells for regeneration of urological structures

Effect of muscle-derived stem cells on the restoration of corpora cavernosa smooth muscle and erectile function in the aged rat

OBJECTIVE

To determine whether skeletal muscle-derived stem cells (MDSCs) convert into smooth muscle cells (SMCs) both in vitro and in vivo, and in so doing ameliorate the erectile dysfunction (ED) of aged rats, and whether endogenous stem cells are present in the rat corpora cavernosa.

MATERIALS AND METHODS

MDSCs were obtained from mouse muscle, and shown by immunocytochemistry for alpha-smooth muscle actin (alpha SMA) to originate in vitro in myofibroblasts and SMCs, discriminating SMCs by calponin 1 expression. In vivo these MDSCs, labelled with 4',6-diamidino-2-phenylindole, were implanted into the corpora cavernosa of young adult (5-month old) and aged (20-month old) rats for 2 and 4 weeks. Histological changes were assessed by immunohistochemistry and quantitative Western blot. Functional changes were determined by electrical field stimulation (EFS) of the cavernosal nerve.

RESULTS

The exogenous cells replicated and converted into SMCs, as shown in corporal tissue sections by confocal immunofluorescence microscopy for proliferating cell nuclear antigen (PCNA), alpha SMA, and smoothelin, and also by Western blot for alpha SMA and PCNA. MDSC differentiation was confirmed by the activation of the alpha SMA promoter-linked beta-galactosidase in transfected cells, both in vitro and after implantation in the corpora. Putative endogenous stem cells were shown in corporal tissue sections and Western blots by detecting CD34 and a possible Sca1 variant. EFS showed that implanted MDSCs raised in aged rats the maximal intracavernosal pressure/mean arterial pressure levels above (2 weeks) or up to (4 weeks) those of young adult rats.

CONCLUSIONS

MDSCs implanted into the corpora cavernosa of aged rats converted into SMCs and corrected ED, and endogenous cells expressing stem cell markers were also found in untreated tissue. This suggests that exogenous stem cell implantation and/or endogenous stem cell modulation might be viable therapeutic approaches for ageing-related ED.

Tissue Engineering for the Lower Urinary Tract: A Review of a State of the Art Approach

OBJECTIVES

Tissue engineering (TE) has become synonymous with physiological and functional reconstructive approaches in medicine. Although the goals of TE are ambitious and have not yet been attained, significant milestones have been achieved and future possibilities are great. To examine these possibilities with a special emphasis on the lower urinary tract, we provide a review of the development of TE techniques and a high-level overview of related regulatory and legal issues.

METHODS

Current trends in the field of TE, including the use of stem cells, scaffold optimization, and acellular tissue and growth factors, were reviewed and critically assessed through a comprehensive literature review using the PubMed database. Because of the rapid development of new TE approaches, recent abstracts from international urology conventions were included. A review of 2007 European Medicines Agency and Commission for Advanced Therapies legal regulations was also performed.

RESULTS

Although several clinical TE approaches have been developed, most lack objective validation. A variety of TE techniques are currently under development or investigation, but thus far, no one approach is clearly superior on the basis of significant long-term studies. A medical product based on TE and stem cells can be successfully developed only with careful consideration of legal and ethical regulations.

CONCLUSIONS

TE holds the promise for a tremendous impact on reconstructive urology. However, research must be focused and intensified for the full potential clinical benefits to be made widely available. Because the product development is affected by legal regulations, consensus must be achieved.

Terminal Urothelium Differentiation of Engineered Neoureter After In Vivo Maturation in the “Omental Bioreactor”

OBJECTIVE

Long ureteric defects may theoretically be repaired with the use of tissue-engineered neoureter. However, attempts to construct such a neoureter in animal models have failed because of major inflammatory response. Avoidance of such inflammation requires a well-differentiated urothelium. We investigated whether omental maturation of a seeded construct in a pig model could achieve terminal differentiation of the urothelium to allow construction of a stricture-free neoureter.

MATERIAL AND METHOD

Bladder biopsies were taken to allow urothelial and smooth muscle cell cultures. These cultured cells were used to seed small intestinal submucosa (SIS) matrix. After 2 wk of cell growth, the in vitro SIS-seeded construct was shaped around a silicone drain and wrapped by the omentum to obtain neoureters. These neoureters were left in the omentum without any contact with urine, and then harvested 3 wk later for histologic and immunohistochemical studies.

RESULTS

Before implantation, the in vitro constructs were composed of a mono- or bilayer of undifferentiated urothelium overlying a monolayer of smooth muscle cells. After 3 wk of omental maturation, these constructs were vascularized and comprised a terminally differentiated multilayered urothelium with umbrella cells over connective tissue and smooth muscle cells, with no evidence of fibrosis or inflammation.

CONCLUSION

We obtained, for the first time, with this model of in vivo maturation in the omentum, a mature neoureter composed of a well-differentiated multilayered urothelium.

Adult stem cell therapy of female stress urinary incontinence

OBJECTIVES

To investigate the efficacy of transurethral ultrasound (TUUS)-guided injections of autologous myoblasts and fibroblasts in women with incontinence.

METHODS

Between January and June 2005, 20 female patients suffering from stress urinary incontinence (SUI) were included. Skeletal muscle biopsies were taken from the left arm to obtain cultures from autologous fibroblasts and myoblasts. By TUUS guidance the fibroblasts were injected into the urethral submucosa and the myoblasts were injected into the rhabdosphincter. A defined incontinence score, quality-of-life score and urodynamic, electromyographic, and laboratory parameters, as well as morphology and function of urethra and rhabdosphincter were evaluated before and up to 2 yr after therapy.

RESULTS

Eighteen of 20 patients were cured 1 yr after injection of autologous stem cells and in 2 patients SUI was improved. Two years after therapy 16 of the 18 patients presented as cured, 2 others were improved, and 2 were lost to follow-up. Incontinence and quality-of-life scores were significantly improved postoperatively. The thickness of urethra and rhabdosphincter as well as activity and contractility of the rhabdosphincter were also statistically significantly increased after therapy.

CONCLUSIONS

Clinical results demonstrate that SUI can be treated effectively with autologous stem cells. The present data support the conclusion that this therapeutic concept represents an elegant and minimally invasive treatment modality to treat SUI.