Prospects for engineering the urinary tract

Effect of adipose tissue-derived stem cell injection in a rat model of urethral fibrosis

INTRODUCTION

We sought to evaluate the therapeutic effect of adi-pose tissue-derived stem cells (ADSCs) in a rat model of urethral fibrosis.

METHODS

Eighteen (18) male Sprague-Dawley rats (300‒350 g) were divided into three groups: (1) sham (saline injection); (2) urethral fibrosis group (10 μg transforming growth factor beta 1 (TGF-β1) injection); and (3) ADSCs group (10 μg TGF-β1 injection plus 2 × 10⁵ ADSCs). Rat ADSCs were harvested from rat inguinal fat pads. All study animals were euthanized at two weeks after urethral injection. Following euthanasia, rat urethral tissue was harvested for histologic evaluation. Type I and III collagen levels were quantitated by Western blot analysis.

RESULTS

TGF-β1 injection induced significant urethral fibrosis and increased collagen type I and III expression (p<0.05). Significant decrease in submucosal fibrosis and collagen type I and III expression were noted in the ADSCs group compared with the urethral fibrosis group (p<0.05). TGF-β1 induced fibrotic changes were ameliorated by injection of ADSCs.

CONCLUSIONS

Local injection of ADSCs in a rat model of urethral fibrosis significantly decreased collagen type I and III. These findings suggest that ADSC injection may prevent scar formation and potentially serve as an adjunct treatment to increase the success rate of primary treatment for urethral stricture disease. Further animal and clinical studies are needed to confirm these results.

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.

[In vitro three-dimensional reconstruction of human bladder mucosa]

OBJECTIVE

The purpose of this study is to apply the in vitro keratinocyte culture techniques and the tissue engineering principles to human urothelium, to reconstruct an in vitro three-dimensional human bladder mucosa, suitable for grafting.

MATERIAL AND METHODS

Biopsy specimens of human bladder mucosa were obtained from patients undergoing suprapubic prostatectomy, in vitro cultured and finally, an immunohistochemical study was made.

RESULTS

A three-dimensional in vitro tissue was obtained, composed of a bio-artificial submucosa (fibrin gel and fibroblast) where the uroepithelial cells were seeding. We used a biodegradable polyglycolic acid mesh to facilitate the tissue manipulation and implantation. An immature epithelium was obtained with a weak immunostaining to cytokeratins. The immunohistochemical study could not demonstrate the development of basement membrane.

CONCLUSIONS

In vitro keratinocyte culture techniques could be applied to other epithelial tissues like the urothelium. We obtained a three-dimensional in vitro tissue suitable for grafting in a relatively short time, which needs the matrix interactions in order to mature.