A Synthetic Niche for Nephron Progenitor Cells

Abstract

Summary FGF, 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 (hESCs) can be propagated. NPC cultures expanded up to a 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.

Repair after nephron ablation reveals limitations of neonatal neonephrogenesis

“…In the mouse, it is generally accepted that the induction of new nephrons, or active nephrogenesis, continues to occur during the first 3 days after birth while the nephron progenitors are still present (12,13,16,22). The timeline of our experiments, as indicated in Figure 1E, was designed to evaluate whether there was potential for "de novo" induction of new nephrons in response to injury during this period.…”

“…pathway inhibition with LDN-193189, which blocks SMAD1/5, results in an extension of the time after birth that CITED1 + /SIX2 + nephron progenitors are present and an increase in nephron number (16). It is unclear whether this increase occurs with additional ureteric bud branching or a further increase in the number of nephrons per ureteric bud tip.…”

“…New nephrons are continuously being generated during kidney development, with the induction of nephron progenitor cells in the cap mesenchyme through interactions with the ureteric bud and the surrounding cortical interstitium. Recent work suggests this niche depends on growth factor signaling pathways (16). This raised the possibility that we might be able to prolong nephrogenesis after parturition by invoking an intrinsic repair response to acute reduction of nephron endowment and learn how we might do so in humans from this response.…”

“…It has been proposed that organ formation and growth are regulated according to the size and functional demand of the newborn (19). Recent work suggests that nephron progenitors can be provided with signals that extend their self-renewal, raising the possibility of extending the neonephrogenesis in vivo (16). We hypothesized that reducing nephron mass during active nephrogenesis would alter this putative regulation, resulting in compensatory new nephron formation, a response that would be only possible during the early neonatal period when nephron progenitors were present.…”

Studying Kidney Disease Using Tissue and Genome Engineering in Human Pluripotent Stem Cells

“…Recently, different laboratories have succeeded in extending the lifespan of primary nephron progenitor cells (NPCs) in culture. By recapitulating the signalling the environment of NPCs, Brown et al [24] developed specific culture conditions that enabled the in vitro expansion of murine NPCs up to 10 passages [24]. In another study, Tanigawa et al [25] could propagate mouse or rat NPCs for 5 passages using a different protocol.…”