Contemporary approaches to tissue engineering and cell therapy for urinary tract reconstruction require invasive tissue biopsies to obtain autologous cells. However, these procedures are associated with potential complications. We determined whether the cells present in urine have characteristics of normal bladder cells and investigated their potential uses for urological reconstructive procedures. A total of 55 urine samples were collected from 15 healthy individuals and 8 patients with vesicoureteral reflux. Urine derived cells were isolated, expanded and tested for progenitor and differentiated cell specific markers using flow cytometry, immunofluorescence and Western immunoblotting. The chromosomal stability of cultured urine derived cells was determined by karyotype analysis. Clones were successfully established from primary cultures of urine derived cells. Isolated cells showed 3 phenotypes, including fully differentiated, differentiating and progenitor-like cells. Some urine derived cells stained positive for the surface markers c-Kit, SSEA4, CD105, CD73, CD91, CD133 and CD44. Two to 7 cells per 100 ml urine were multipoint progenitors that could expand extensively in culture. Single progenitor cells had the ability to differentiate into the cell lineages expressing urothelial, smooth muscle, endothelial and interstitial cell markers. The expression of lineage markers was characterized by Western blot and immunofluorescence analysis. Urine derived cells also maintained a normal karyotype after serial culture. A subpopulation of cells isolated from urine had progenitor cell features and the potential to differentiate into several bladder cell lineages. Urine derived cells could serve as an alternative cell source for urinary tract tissue engineering and reconstruction.

Background: The goals of this study were to characterize urine-derived stem cells obtained from the upper urinary tract (uUSC), induce these cells to differentiate into urothelial and smooth muscle cells, and determine whether they could serve as a potential stem cell source for bladder tissue engineering. Materials and Methods: Urine samples were collected from five patients with normal upper urinary tracts during renal pyeloplasty. Cells were isolated from this urine and extensively expanded in vitro. Results: The mean population doubling of uUSC was 46.5±7.7. The uUSC expressed surface markers associated with mesenchymal stem cells and pericytes. These cells could differentiate into smooth muscle-like cells that expressed smooth muscle-specific gene transcripts and proteins, including α-smooth muscle actin, desmin, and myosin, when exposed to TGF-β1 and PDGF-BB. In a collagen lattice assay, these myogenic-differentiated uUSC displayed contractile function that was similar to that seen in native smooth muscle cells. Urothelial-differentiated uUSC expressed urothelial-specific genes and proteins such as uroplakin-Ia and -III, cytokeratin (CK)-7, and CK-13. Conclusions: uUSC possess expansion and differentiation (urothelial and myogenic) capabilities, and can potentially be used as an alternative cell source in bladder tissue engineering for patients needing cystoplasty.

Bone marrow mesenchymal stem cells (BMSCs) are capable of differentiating into multiple cell types, providing an alternative cell source for cell-based therapy and tissue engineering. Simultaneous differentiation of human BMSCs into smooth muscle cells (SMCs) and urothelium would be beneficial for clinical applications in bladder regeneration for patients with bladder exstrophy or cancer who need cystoplasty. We investigated the ability of human BMSCs to differentiate toward both SMCs and urothelium with cocultured or conditioned media and analyzed growth factors from a coculture system. After being cocultured with urothelium or cultured using urothelium-derived conditioned medium, human BMSCs expressed urothelium-specific genes and proteins: uroplakin-Ia, cytokeratin-7, and cytokeratin-13. When cocultured with SMCs or cultured in SMC-conditioned medium, human BMSCs expressed SMC-specific genes and proteins: desmin and myosin. Several growth factors (hepatocyte growth factor, platelet-derived growth factor-homodimer polypeptide of B chain (BB), transforming growth factor-β1, and vascular endothelial growth factor) were detected in the SMC cocultured media and in the urothelium cocultured media (epidermal growth factor, platelet-derived growth factor-BB, transforming growth factor-β1, and vascular endothelial growth factor). BMSC–scaffold constructs significantly improved cell contractility after myogenic differentiation. In vivo-grafted cells displayed significant matrix infiltration and expressed SMC-specific markers in the nanofibrous poly-l-lactic acid scaffolds. In conclusion, smooth muscle- and urothelium-like cells derived from human BMSCs provide an alternative cell source for potential use in bladder tissue engineering.