Isolation of clonogenic, long-term self renewing embryonic renal stem cells

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Volume 5, Issue 1, Pages 1-90
$ o% a1 z2 m" v; O. y; ^/ l       Isolation of clonogenic, long-term self renewing embryonic renal stem cells
# J0 I- ~9 ~- Y0 E$ C$ T       M. Lusis a,c, J. Li a,c, J. Ineson a,c, M.E. Christensen b, A. Rice b,M.H. Little a,c,⁎' |% c" B; \5 u2 J# g
       Abstract A tissue stem cell should exhibit long-term self-renewal, clonogenicity and a capacity to differentiate into the
# u4 N; r( d: e# ~tissue of origin. Such a postnatal renal stem cell has not been formally identified. The metanephric mesenchyme (MM) of the
7 E) Z8 Y6 y! d- h2 {developing kidney gives rise to both the renal interstitium and the nephrons and is regarded as the progenitor population of the4 y- I0 `- g2 ^: o( I5 K
developing kidney. However, isolated MM does not self renew and requires immortalization for survival in culture. Here we
( M# r9 @) N$ p! ?% S2 h4 \' n/ qreport the isolation and sustained culture of long-term repopulating, clonal progenitors from the embryonic kidney as free
! c% l- ^1 ]- \3 `- c2 {& Gfloating nephrospheres. Such cells displayed clonal self renewal for in excess of twenty passages when cultured with bFGF and2 X8 T& g" L9 W: F/ Z) r- N
thrombin, showed broad mesodermal multipotentiality, but retained expression of key renal transcription factors (Wt1, Sall1,
3 u* u! M7 L$ ~; i% I2 }Eya1, Six1, Six2, Osr1 and Hoxa11). While these cells did display limited capacity to contribute to developing embryonic
9 Q: {% ]9 p7 `8 z* r5 ~6 u5 h6 t% h: Nkidney explants, nephrospheres did not display in vitro renal epithelial capacity. Nephrospheres could be cultured from
/ m' @& D9 a1 |& W5 l4 K7 oboth Sall1+ and Sall1- fractions of embryonic kidney, suggesting that they were derived from the MM as a whole and not
2 x" g* V2 a+ r6 yspecifically the MM-derived cap mesenchyme committed to nephron formation. This embryonic renal stem cell population was7 g3 ?) f& I: f0 Z; l$ [6 Y8 c
not able to be isolated from postnatal kidney confirming that while the embryonic MM represents a mulitpotent stem cell, C2 E, I3 }* R* b3 `
population, this does not persist after birth.