Influence of cell type of origin to the differentiation potential of induced pluripotent stem cells derived from human urinary tract cells

Abstract

Background: Direct reprogramming of human somatic cells to pluripotent embryonic stem (ES) cell -like cells, termed induced pluripotent stem (iPS) cells, can be achieved by expression of defined transcription factors. The potential use of iPS cells derived from the urinary tract provides a substantial opportunity in developing new disease models, drug screening and tissue engineering. We aimed to generate, for the first time, human induced pluripotent stem cells derived from the urinary tract (UT-iPS) cells and to assess capacity for directed differentiation into bladder lineages. Methods: Human primary culture cells derived from benign bladder and ureters were transduced with OCT4, SOX2, KLF4 and C-MYC genes to generate human UT-iPS cells. Generated cells were characterised using RT-PCR and immunofluorescence. Differentiation capacity was evaluated by embryoid body formation in vitro and teratoma assay in vivo. Established co-culture based directed differentiation into bladder cells was assessed in comparison with classical skin-derived iPS cells. Results: We demonstrated successful re-programming of adult urinary tract cells from both bladder and ureter into human UT-iPS cells. Most of the clones showed efficient transgene silencing and maintained a normal diploid karyotype. Specifically, we showed expression of ES cell markers and functional pluripotency by the generation of endodermal, ectodermal and mesodermal lineages. Differentiation into bladder lineages was demonstrated by expression of urothelial-specific markers, uroplakins (UPIb, UPII, UPIIIa, and UPIIIb), claudins (CLD1 and CLD5) and cytokeratin (CK7); and stromal smooth muscle markers a-SMA, calponin, and desmin. Human UT-iPS cells were shown to be more efficient than skin-derived iPS cells in undergoing bladder differentiation, underlining the importance of the origin of the parent cell for re-programming. Conclusions: We demonstrated that the induction of human urinary tract cells into iPS cells is possible, offering a new exciting opportunity for tissue engineering and for the study of bladder disease.