Article

Identification of adult nephron progenitors capable of kidney regeneration in zebrafish

Center for Regenerative Medicine, Massachusetts General Hospital, Boston, Massachusetts 02114, USA.
Nature (Impact Factor: 42.35). 02/2011; 470(7332):95-100. DOI: 10.1038/nature09669
Source: PubMed

ABSTRACT Loss of kidney function underlies many renal diseases. Mammals can partly repair their nephrons (the functional units of the kidney), but cannot form new ones. By contrast, fish add nephrons throughout their lifespan and regenerate nephrons de novo after injury, providing a model for understanding how mammalian renal regeneration may be therapeutically activated. Here we trace the source of new nephrons in the adult zebrafish to small cellular aggregates containing nephron progenitors. Transplantation of single aggregates comprising 10-30 cells is sufficient to engraft adults and generate multiple nephrons. Serial transplantation experiments to test self-renewal revealed that nephron progenitors are long-lived and possess significant replicative potential, consistent with stem-cell activity. Transplantation of mixed nephron progenitors tagged with either green or red fluorescent proteins yielded some mosaic nephrons, indicating that multiple nephron progenitors contribute to a single nephron. Consistent with this, live imaging of nephron formation in transparent larvae showed that nephrogenic aggregates form by the coalescence of multiple cells and then differentiate into nephrons. Taken together, these data demonstrate that the zebrafish kidney probably contains self-renewing nephron stem/progenitor cells. The identification of these cells paves the way to isolating or engineering the equivalent cells in mammals and developing novel renal regenerative therapies.

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Available from: Richard W Naylor, Aug 23, 2015
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    • "Both the zebrafish embryonic and adult kidney are useful models for research about renal injury and regeneration (Diep et al., 2011; Gerlach et al., 2011; Hellman et al., 2010; Hentschel et al., 2005; Huang et al., 2013; Johnson et al., 2011; McCampbell et al., 2014; Zhou and Hildebrandt, 2012; Zhou et al., 2010). In particular, adult zebrafish possess a high capacity for renal regeneration after AKI in the nephron tubule (Diep et al., 2011; McCampbell and Wingert, 2014; Zhou et al., 2010). Within just two weeks following widespread proximal tubule damage due to the nephrotoxin gentamicin, the adult kidney regenerates injured tubular epithelia and undergoes the formation of new nephrons (termed neonephrogenesis) from renal progenitors located throughout the kidney. "
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    ABSTRACT: The kidney is comprised of nephrons—epithelial tubes with specialized segments that reabsorb and secrete solutes, perform osmoregulation, and produce urine. Different nephron segments exhibit unique combinations of ion channels, transporter proteins, and cell junction proteins that govern permeability between neighboring cells. The zebrafish pronephros is a valuable model to study the mechanisms of vertebrate nephrogenesis, but many basic features of segment gene expression in renal progenitors and mature nephrons have not been characterized. Here, we analyzed the temporal and spatial expression pattern of tight junction components during zebrafish kidney ontogeny. During nephrogenesis, renal progenitors show discrete expression domains of claudin (cldn) 15a, cldn8, occludin (ocln) a, oclnb, tight junction protein (tjp) 2a, tjp2b, and tjp3. Interestingly, transcripts encoding these genes exhibit dynamic spatiotemporal domains during the time when pronephros segment domains are established. These data provide a useful gene expression map of cell junction components during zebrafish nephrogenesis. As such, this information complements the existing molecular map of nephron segment characteristics, and can be used to characterize kidney development mutants as well as various disease models, in addition to aiding in the elucidation of mechanisms governing epithelial regeneration after acute nephron injury.
    Gene Expression Patterns 11/2014; 16(2):104-113. DOI:10.1016/j.gep.2014.11.001 · 1.36 Impact Factor
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    • "The mesonephros assembles gradually, as clusters of renal progenitors located near the pronephros undergo proliferation and morphogenesis to make more nephrons (Diep et al., 2011; Zhou et al., 2010). During the early stages of mesonephros development, the new nephrons emerge in close proximity to the pronephros and form connections to one of these original nephrons (Diep et al., 2011; Zhou et al., 2010). Over time, the nephron networks become increasingly elaborate as more units are added. "
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    ABSTRACT: During development, vertebrates form a progression of up to three different kidneys that are comprised of functional units termed nephrons. Nephron composition is highly conserved across species, and an increasing appreciation of the similarities between zebrafish and mammalian nephron cell types has positioned the zebrafish as a relevant genetic system for nephrogenesis studies. A key component of the nephron blood filter is a specialized epithelial cell known as the podocyte. Podocyte research is of the utmost importance as a vast majority of renal diseases initiate with the dysfunction or loss of podocytes, resulting in a condition known as proteinuria that causes nephron degeneration and eventually leads to kidney failure. Understanding how podocytes develop during organogenesis may elucidate new ways to promote nephron health by stimulating podocyte replacement in kidney disease patients. In this review, we discuss how the zebrafish model can be used to study kidney development, and how zebrafish research has provided new insights into podocyte lineage specification and differentiation. Further, we discuss the recent discovery of podocyte regeneration in adult zebrafish, and explore how continued basic research using zebrafish can provide important knowledge about podocyte genesis in embryonic and adult environments. © 2014 Wiley Periodicals, Inc.
    genesis 09/2014; 52(9):771-792. DOI:10.1002/dvg.22798 · 2.04 Impact Factor
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    • "This is in contrast to invertebrates (Singh et al., 2007) (fly) and lower vertebrates (Diep et al., 2011) (fish), where multipotent renal stem/progenitors are thought to exist in adulthood. In the developing mouse embryo, lineagetracing studies demonstrate that undifferentiated CM gives rise to all epithelial cell types of the adult nephron (Herzlinger et al., 1992; Kobayashi et al., 2008; Boyle et al., 2008) and that this population self-renews, fulfilling the requirements for stem cells similar to the reports from the adult fly and fish (Singh et al., 2007; Diep et al., 2011). Although the regenerative capacity of the adult mammalian kidney remains largely unexplored at the single cell level, the appearance of epithelial cells in the urine due to normal shedding (68,000–72,000 cells/hr; Prescott, 1966) and the documented renal repair that follows damage suggest that the mammalian kidney undergoes constant cellular renewal (Little, 2006). "
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    ABSTRACT: The mechanism and magnitude by which the mammalian kidney generates and maintains its proximal tubules, distal tubules, and collecting ducts remain controversial. Here, we use long-term in vivo genetic lineage tracing and clonal analysis of individual cells from kidneys undergoing development, maintenance, and regeneration. We show that the adult mammalian kidney undergoes continuous tubulogenesis via expansions of fate-restricted clones. Kidneys recovering from damage undergo tubulogenesis through expansions of clones with segment-specific borders, and renal spheres developing in vitro from individual cells maintain distinct, segment-specific fates. Analysis of mice derived by transfer of color-marked embryonic stem cells (ESCs) into uncolored blastocysts demonstrates that nephrons are polyclonal, developing from expansions of singly fated clones. Finally, we show that adult renal clones are derived from Wnt-responsive precursors, and their tracing in vivo generates tubules that are segment specific. Collectively, these analyses demonstrate that fate-restricted precursors functioning as unipotent progenitors continuously maintain and self-preserve the mouse kidney throughout life.
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