Potential renal stem/progenitor cells identified by in vivo lineage tracing

Mammalian kidneys consist of more than 30 different types of cells. A challenging task is to identify and characterize the stem/progenitor subpopulations that establish the lineage relationships among these cellular elements during nephrogenesis in the embryonic and neonate kidneys and during tissue homeostasis and/or injury repair in the mature kidney. Moreover, the potential clinical utility of stem/progenitor cells holds promise for the development of new regenerative medicine approaches for the treatment of renal diseases. Stem cells are defined by unlimited self-renewal capacity and pluripotentiality. Progenitor cells have pluripotentiality but no or limited self-renewal potential. Cre-LoxP-based in vivo genetic lineage tracing is a powerful tool to identify stem/progenitor cells in their native environment. Hypothetically, this technique enables investigators to accurately track the progeny of a single cell or a group of cells. The Cre/LoxP system has been widely used to uncover the function of genes in various mammalian tissues and to identify stem/progenitor cells through in vivo lineage tracing analyses. In this review, we summarize the recent advances in the development and characterization of various Cre drivers and their use in identifying potential renal stem/progenitor cells in both developing and mature mouse kidneys.