Persistent and inducible neogenesis repopulates progenitor renin lineage cells in the kidney.

Renin lineage cells (RLCs) serve as a progenitor cell reservoir during nephrogenesis and after renal injury. The maintenance mechanisms of the RLC pool are still poorly understood. Since RLCs were also identified as a progenitor cell population in bone marrow we first considered that these may be their source in the kidney. However, transplantation experiments in adult mice demonstrated that bone marrow-derived cells do not give rise to RLCs in the kidney indicating their non-hematopoietic origin. Therefore we tested whether RLCs develop in the kidney through neogenesis (de novo differentiation) from cells that have never expressed renin before. We used a murine model to track neogenesis of RLCs by flow cytometry, histochemistry, and intravital kidney imaging. During nephrogenesis RLCs first appear at e14, form a distinct population at e16, and expand to reach a steady state level of 8-10% of all kidney cells in adulthood. De novo differentiated RLCs persist as a clearly detectable population through embryogenesis until at least eight months after birth. Pharmacologic stimulation of renin production with enalapril or glomerular injury induced the rate of RLC neogenesis in the adult mouse kidney by 14% or more than three-fold, respectively. Thus, the renal RLC niche is constantly filled by local de novo differentiation. This process could be stimulated consequently representing a new potential target to beneficially influence repair and regeneration after kidney injury.