A Synthetic Niche for Nephron Progenitor Cells

• NPCs are enzymatically liberated from embryonic kidneys
• NPCs are purified from other cells in the niche by magnetic depletion
• NPC expansion medium provides niche signals for undifferentiated proliferation
• NPCs expanded in NPEM form nephron tubules when cultured in organotypic conditions

SummaryFGF, BMP, and WNT balance embryonic nephron progenitor cell (NPC) renewal and differentiation. By modulating these pathways, we have created an in vitro niche in which NPCs from embryonic kidneys or derived from human embryonic stem cells can be propagated. NPC cultures expanded up to one billion-fold in this environment can be induced to form tubules expressing nephron differentiation markers. Single-cell culture reveals phenotypic variability within the early CITED1-expressing NPC compartment, indicating that it is a mixture of cells with varying progenitor potential. Furthermore, we find that the developmental age of NPCs does not correlate with propagation capacity, indicating that cessation of nephrogenesis is related to factors other than an intrinsic clock. This in vitro nephron progenitor niche will have important applications for expansion of cells for engraftment and will facilitate investigation of mechanisms that determine the balance between renewal and differentiation in these cells.

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