Identification and characterization of two morphologically distinct stem cell subpopulations from human urine samples

Urine-derived stem cells (USCs) have shown potentials for the treatment of skeletal and urological disorders. Based on published literature and our own data, USCs consist of heterogeneous populations of cells. In this paper, we identify and characterize two morphologically distinct subpopulations of USCs from human urine samples, named as spindle-shaped USCs (SS-USCs) and rice-shaped USCs (RS-USCs) respectively. The two subpopulations showed similar clone-forming efficiency, while SS-USCs featured faster proliferation, higher motility, and greater potential for osteogenic and adipogenic differentiation, RS-USCs showed greater potential for chondrogenic differentiation. POU5F1 was strongly expressed in both subpopulations, but MYC was weakly expressed. Both subpopulations showed similar patterns of CD24, CD29, CD34, CD44, CD73, CD90 and CD105 expression, while a higher percentage of RS-USCs were positive for CD133. SS-USCs were positive for VIM, weakly positive for SLC12A1 and UMOD, and negative for KRT18, NPHS1, AQP1 and AQP2, indicating a renal mesenchyme origin; while RS-USCs are positive for VIM, partially positive for KRT18, NPHS1, AQP1, SLC12A1 and UMOD, and negative for AQP2, indicating a nephron tubule origin. The above results can facilitate understanding of the biological characteristics of subpopulations of USCs, and provide a basis for further research and applications of such cells.