Stem Cells: A Review and Implications for Urology

The histocompatibility research of hair follicle stem cells with bladder acellular matrix

BACKGROUND

Hair follicle stem cells (HFSCs) were reported to have multidirectional differentiation ability and could be differentiated into melanocytes, keratin cells, smooth muscle cells, and neurons. However, the functionality of HFSCs in bladder tissue regeneration is unknown.

METHODS

This study was conducted to build HFSCs vs bladder acellular matrix (BAM) complexes (HFSCs-BAM complexes) in vitro and evaluated whether HFSCs have well biocompatibility with BAM. HFSCs were separated from SD rats. BAM scaffold was prepared from the submucosa of rabbit bladder tissue. Afterwards, HFSCs were inoculated on BAM.

RESULTS

HFSCs-BAM complexes grew rapidly through inverted microscope observation. Cell growth curve showed the proliferation was in stagnate phase at 7th and 8th day. Cytotoxicity assay showed the toxicity grading of BAM was 0 or 1. Scanning electron microscopy, HE staining, and masson staining showed that cells have germinated on the surface of scaffold.

CONCLUSION

The results provide evidence that HFSCs-BAM complexes have well biocompatibility and accumulate important experimental basis for clinical applying of tissue engineering bladder.

New advances in the pathophysiologic and radiologic basis of the exstrophy spectrum

The exstrophy-epispadias complex is a rare spectrum of anomalies affecting the genitourinary system, anterior abdominal wall, and pelvis. Recent advances in the repair of classic bladder exstrophy (CBE) and cloacal exstrophy (CE) have resulted in significant changes in outcomes of surgical management (including higher continence rate, fewer surgical complications, and better cosmesis) and health-related quality of life in these patients. These noteworthy changes resulted from advances in the pathophysiological and genetic backgrounds of this disease and better radiologic assessment of the three-dimensional anatomy of the bony pelvis and its musculature. A PubMed search was performed with the keyword exstrophy. The resulting literature pertaining to genetics, stem cells, imaging, tissue engineering, epidemiology, and endocrinology was reviewed. The following represents an overview of the advances in basic science understanding and imaging of the exstrophy-epispadias spectrum and discusses their possible and future effects on the management of CBE and CE.

Pathologic bladder microenvironment attenuates smooth muscle differentiation of skin derived precursor cells: implications for tissue regeneration

Smooth muscle cell containing organs (bladder, heart, blood vessels) are damaged by a variety of pathological conditions necessitating surgery or organ replacement. Currently, regeneration of contractile tissues is hampered by lack of functional smooth muscle cells. Multipotent skin derived progenitor cells (SKPs) can easily be isolated from adult skin and can be differentiated in vitro into contractile smooth muscle cells by exposure to FBS. Here we demonstrate an inhibitory effect of a pathologic contractile organ microenvironment on smooth muscle cell differentiation of SKPs. In vivo, urinary bladder strain induces microenvironmental changes leading to de-differentiation of fully differentiated bladder smooth muscle cells. Co-culture of SKPs with organoids isolated from ex vivo stretched bladders or exposure of SKPs to diffusible factors released by stretched bladders (e.g. bFGF) suppresses expression of smooth muscle markers (alpha SMactin, calponin, myocardin, myosin heavy chain) as demonstrated by qPCR and immunofluorescent staining. Rapamycin, an inhibitor of mTOR signalling, previously observed to prevent bladder strain induced de-differentiation of fully differentiated smooth muscle cells in vitro, inhibits FBS-induced smooth muscle cell differentiation of undifferentiated SKPs. These results suggest that intended precursor cell differentiation may be paradoxically suppressed by the disease context for which regeneration may be required. Organ-specific microenvironment contexts, particularly prevailing disease, may play a significant role in modulating or attenuating an intended stem cell phenotypic fate, possibly explaining the variable and inefficient differentiation of stem cell constructs in in vivo settings. These observations must be considered in drafting any regeneration strategies.

Differentiation of adipose-derived stem cells promotes regeneration of smooth muscle for ureteral tissue engineering

BACKGROUND

The purpose of the present study was to assess the differentiation potential of adipose-derived stem cells (ASCs) into smooth muscle cells (SMCs) and their potential for promoting regeneration of smooth muscle for ureteral tissue engineering.

METHODS

ASCs were isolated, proliferated, and identified in vitro. SMC differentiation was induced using SMC induction medium. Gene expression was evaluated by quantitative polymerase chain reaction, immunofluorescence, and Western blotting. Vessel extracellular matrix was obtained by a decellularization process. The induced cells were seeded onto vessel extracellular matrix for ureter reconstitution. Grafts were obtained for evolutionary histologic studies. Renal function and ureteral patency was evaluated by intravenous urography at 16 wk.

RESULTS

Flow cytometry demonstrated that the ASCs expressed CD90, but did not express CD45 or CD34. After 6 wk of induction, upregulation of α-smooth muscle actin expression was determined by quantitative polymerase chain reaction, and smooth muscle myosin heavy chain expression was confirmed by immunofluorescence and Western blotting in the induced cells. Vessel extracellular matrix exhibited a nontoxic and bioactive effect on the induced cells. Histologically, stratified urothelium and organized muscle bundles were observed in the grafts at 16 wk. Intravenous urography demonstrated no ureteral stricture or hydroureteronephrosis.

CONCLUSIONS

These results have demonstrated that ASCs can be differentiated into SMCs and this potential promoted smooth muscle regeneration for ureteral tissue engineering.

Tissue engineering and stem cell application of urethroplasty: from bench to bedside

OBJECTIVE

To review the advances in the basic research and clinical application of tissue engineering and stem cell technology in urethral reconstruction. Urethral defects resulting from congenital malformations, trauma, inflammation, or cancer are a common urologic issue. Traditional urethral reconstruction is associated with various complications. Tissue engineering and stem cell technology hold novel therapeutic promise for urethral reconstruction.

METHODS

One of us searched the PubMed database (January 1999 to January 2011) using the English search terms "tissue engineering," "stem cells," "urethral reconstruction," and "urethra." A total of 86 reports were retrieved. After the repetitive and irrelevant reports were excluded, 40 were included in the final analysis. The review outlined and evaluated the advances in basic research and clinical application and the current status and prospects of tissue engineering and stem cell technology in urinary reconstruction.

RESULTS

Two therapeutic strategies are available for urethral reconstruction using tissue engineering: the acellular matrix bioscaffold model and the cell-seeded bioscaffold model. The acellular matrix bioscaffold model has been successfully used in the clinic and the cell-seeded bioscaffold model is making its transition from bench to bedside.

CONCLUSION

Stem cells can provide the seed cells for urologic tissue engineering, but much basic research is still needed before their clinical use is possible.

The clinical relevance of cell-based therapy for the treatment of stress urinary incontinence

Stress urinary incontinence is a common disorder affecting the quality of life for millions of women worldwide. Effective surgical procedures involving synthetic permanent meshes exist, but significant short- and long-term complications occur. Cell-based therapy using autologous stem cells or progenitor cells presents an alternative approach, which aims at repairing the anatomical components of the urethral continence mechanism. In vitro expanded progenitor cells isolated from muscle biopsies have been most intensely investigated, and both preclinical trials and a few clinical trials have provided proof of concept for the idea. An initial enthusiasm caused by positive results from early clinical trials has been dampened by the recognition of scientific irregularities. At the same time, the safety issue for cell-based therapy has been highlighted by the appearance of new and comprehensive regulatory demands. The influence on the cost effectiveness, the clinical relevance and the future perspectives of the present clinical approach are discussed.

Bone marrow-derived mesenchymal stem cells: current and future applications in the urinary bladder

Mesenchymal stem cells can be isolated from almost any adult tissue. In this paper we focus on bone marrow-derived mesenchymal stem cells which have captured the interest of researchers since their introduction because of the promising potential of tissue regeneration and repair. They are known for their ability to self-renew and differentiate into diverse lineages while maintaining low immunogenicity. The exact mechanisms behind how these cells work still remain unclear, and there is a continuing shift in the paradigms that support them. There has been extensive research in multiple organ systems; however, the genitorurinary system has been vastly underrepresented. This article discusses the background behind bone marrow-derived mesenchymal stem cells and they are currently being applied to the urinary bladder in the realm of tissue engineering. We also postulate on their future applications based on the current literature in other organ systems.

Tissue engineering and stem cells: basic principles and applications in urology

To overcome problems of damaged urinary tract tissues and complications of current procedures, tissue engineering (TE) techniques and stem cell (SC) research have achieved great progress. Although diversity of techniques is used, urologists should know the basics. We carried out a literature review regarding the basic principles and applications of TE and SC technologies in the genitourinary tract. We carried out MEDLINE/PubMed searches for English articles until March 2010 using a combination of the following keywords: bladder, erectile dysfunction, kidney, prostate, Peyronie's disease, stem cells, stress urinary incontinence, testis, tissue engineering, ureter, urethra and urinary tract. Retrieved abstracts were checked, and full versions of relevant articles were obtained. Scientists have achieved great advances in basic science research. This is obvious by the tremendous increase in the number of publications. We divided this review in two topics; the first discusses basic science principles of TE and SC, whereas the second part delineates current clinical applications and advances in urological literature. TE and SC applications represent an alternative resource for treating complicated urological diseases. Despite the paucity of clinical trials, the promising results of animal models and continuous work represents the hope of treating various urological disorders with this technology.