Regeneration of the Kidney - Viewed from ES Cell

Embryonic stem (ES) cells are derived from inner cell mass of blastocyst stage of fertilized eggs and remain undifferentiated in the presence of leukemia inhibitory factor (LIF) (Evans M.J & Kaufman M.H. (1981), Martin G.R. (1981).). Depletion of LIF leads to ES cell to form embryoid body (EB) that can differentiate into several different lineage cells such as endodermal, mesodermal and ectodermal lineage cells. Until now, ES cells have been induced to differentiate in vitro into several cell types such as hematopoietic cell (Nakano T.,et al. (1994), Nishikawa S.I.,et al. (1998), Palacios R.,et al. (1995).), pancreatic cell (Soria B.,et al. (2000).), neuronal cell (Brustle O.,et al. (1999), Scholer H.R.,et al. (1991).) and cardiomyocyte (Boheler K.R.,et al. (2002), Doetschman T.C.,et al. (1985), Klug M.G.,et al. (1996).). To be sure that ES cells are pluripotent, but mere transplantation of non-differentiated ES cells leads to teratomas as Yamamoto reported the teratoma formation after the transplantation of undifferentiated ES cells into retroperitoneum of nude mice (Yamamoto M.,et al. (2006).). This is one of the main obstacles that limit the clinical application of ES cell transplantation therapy. Therefore, it is essential to differentiate ES cells to some degree before transplantation. But the information as to the directed differentiation of ES cells to kidney lineages are limited although spontaneous differentiation of ES cells to various cells is observed. We have gathered pieces of information of the developmental biology and the differentiation conditions of several stem/progenitor cells to matured kidney. In this review, we focus on a dream of the generation of kidney from ES cells or stem/progenitor cells.