ABSTRACT: Human urine is now recognized as a non-invasive source of stem cells with regeneration potential. These cells are mesenchymal stem cells but their detailed molecular and cellular identities are poorly defined. Furthermore, unlike the mouse, the gene regulatory network driving stemness and differentiation into functional renal cells in vitro remain unresolved. In this study, we isolated urine mesenchymal stem cells from 10 individuals of both genders and distinct ages, these cells express pluripotency- associated proteins- TRA-1-160, TRA-1-181, SSEA4, C-KIT and CD133. Expression of pluripotency-associated proteins enabled rapid reprogramming into iPSCs using episomal-based plasmids without pathway purtabations. Transcriptome analysis revealed expression of a plethora of nephrogenesis-related genes such as SIX2, OSR1, CITED1, NPHS2, NPHS1, PAX2, SALL1, AQP2, EYA1, SLC12A1 and UMOD. As expected the cells transport Albumin by endocytosis. Based on this we refer to these cells as urine derived renal progenitor cells- UdRPCs. Associated GO-term analysis of UdRPCs and UdRPC-iPSCs underlined their renal identity and functionality. Upon differentiation by WNT activation using the GSK3β inhibitor (CHIR99021), transcriptome and KEGG pathway analysis revealed upregulation of WNT-associated genes-AXIN2, JUN and NKD1. Protein interaction network identified JUN,- a downstream target of the WNT pathway in association with STAT3, ATF2 and MAPK1 as a putative key regulator of self-renewal and differentiation in UdRPCs. Furthermore, like pluripotent stem cells, self-renewal is maintained by FGF2-driven TGFβ-SMAD2/3 pathway. Ultimately, our in vitro model and the data presented in this study should lay the foundation for studying nephrogenesis in man.
