Urethral Tissue Engineering Using Urine-Derived Stem Cells

As a tubularized organ in the distal portion of urinary tract system, urethras may have strictures often due to injury, infections, and congenital defects. Two types of tissue engineering technologies have been used to build urethral tissue, namely cell-seeded and non-seeded. Cell-seeded technology uses scaffolds that are seeded in vitro with primary cultured cells obtained from a bladder or oral mucosa biopsy. This composite graft is then implanted back in the host to continue the regenerative process. The non-seeded technology uses cell-free biodegradable scaffolds to allow the natural process of regeneration to occur in vivo and was successfully applied experimentally in partial (patch tissue replacement) urethral reconstruction models. Increasing evidence has demonstrated that use of autologous cells seeded on biodegradable scaffolds achieved better outcomes in urethral tissue regeneration, particularly in long segment of urethral replacement. Stem cells obtained from patients’ own tissues provide an alternative for cell therapy and tissue engineering in urology. Our recent study displayed that a subpopulation of cells isolated from naturally voided urine possesses the features of progenitor/stem cells and has potential as an alternative cell source for tissue engineering and cell therapy in urology. These cells adhere to plastic, are clonogenic, express mesenchymal stem cells/pericyte cell surface markers, and display high telomerase activity. In addition, they possess high expansion capability and multipotential differentiation capacity. Importantly, these cells can give rise to urothelium, smooth muscle to form urethral tissue in vivo in a highly efficient manner when seeded on porous natural collagen-based scaffolds. In this chapter, we discuss the recent progress made in urethral tissue engineering with urine-derived stem cells and acellular matrix for potential use in clinical applications.