Urine-Derived Stem Cells: Differentiation Potential into Smooth-Muscle Cells and Urothelial Cell

Background: Tissue engineering of low urinary tract organs requires biopsy of urinary bladder material. The current study describes non-invasive approach of obtaining autologous stem cells from urine of healthy adults. These cells were studied for potential to differentiate into epithelial cells and smooth muscle cells of the urinary bladder. Aims: To describe properties of urine-derived stem cells (USCs) and investigate their differentiation potential for tissue engineering of low urinary tract organs. Materials and Methods: USCs were isolated from urine of healthy volunteers with centrifugation and seeded in media to 24-well plates. Expression of stem cells markers (CD73, CD90, CD105, CD34, CD45, CD29, CD44, CD54, SSEA4) by USCs was assessed with flow cytometry. Expression of specific markers of smooth muscle cells and urothelial cells was assessed with fluorescence microscopy with following computational image analysis. Results: Median number of USCs per 100 ml urine was 6. Doubling time for USC was 1.440.528 days (n=4) and there were 26.34.79 population doublings for USC cultures (n=4). Median expression of markers of postnatal stem cells was CD73 ― 79.8%, CD90 ― 56.6%, CD105 ― 40.7%, CD34 1.0%, CD45 2.0%, CD29 99.0%, CD44 99.0%, CD54 ― 97.7% and SSEA4 99.0%. Treatment of cells with high concentration of EGF in media with low concentration of FBS for 10 days increased cytokeratin (CK) expression to 24.9% for CK AE1/AE3 and to 7.6% for CK 7. Treatment of USCs with media inducing smooth muscle differentiation for 10 days increased expression of -smooth muscle actin to 79.6% and expression of calponin to 97.6%. Conclusions: USCs are cells that can be found in urine in small quantities. They have high proliferative potential and express markers of postnatal stem cells. Under effect of PDGF-BB and TGF- 1 they differentiate into smooth muscle cells.