The renal papilla is a niche for adult kidney stem cells

Abstract

Many adult organs contain stem cells, which are pluripotent and are involved in organ maintenance and repair after injury. In situ, these cells often have a low cycling rate and locate in specialized regions (niches). To detect such cells in the kidney, we administered a pulse of the nucleotide bromodeoxyuridine (BrdU) to rat and mouse pups and, after a long (more than 2-month) chase, examined whether the kidney contained a population of low-cycling cells. We found that in the adult kidney, BrdU-retaining cells were very sparse except in the renal papilla, where they were numerous. During the repair phase of transient renal ischemia, these cells entered the cell cycle and the BrdU signal quickly disappeared from the papilla, despite the absence of apoptosis in this part of the kidney. In vitro isolation of renal papillary cells showed them to have a plastic phenotype that could be modulated by oxygen tension and that when injected into the renal cortex, they incorporated into the renal parenchyma. In addition, like other stem cells, papillary cells spontaneously formed spheres. Single-cell clones of these cells coexpressed mesenchymal and epithelial proteins and gave rise to myofibroblasts, cells expressing neuronal markers, and cells of uncharacterized phenotype. These data indicate that the renal papilla is a niche for adult kidney stem cells.

Adult stem-like cells in kidney

“…LRC cells was very sparse in the kidney, but they found numerous LRC cells in renal papilla [33] . In 3 dimensional culture, LRC cells in renal papilla spontaneously formed spheroids, and clones from single cell of LRC cells expressed both mesencymal and epithelial markers.…”

“…To identify the stem-like cells in kidney, Oliver et al [33,34] performed pulse label of rat and mouse pups by BrdU, and confirmed the existence of LRC cells in the kidney. LRC cells was very sparse in the kidney, but they found numerous LRC cells in renal papilla [33] .…”

Contribution of Stem Cells to Kidney Repair

“…However, the location and the characteristics of renal SC are controversial. Based on the retention of bromodeoxyuridine, Oliver et al [59] identified slow cycling SC in the renal papilla of adult rat kidney suggesting the presence of an SC population capable of epithelial differentiation after ischemic injury. Based on these observations, the authors proposed that the renal papilla is a niche for the adult kidney SC in rats.…”

Do Stem Cells Exist in the Adult Kidney?

“…Oliver et al [36] have isolated cells from the kidney papilla of young mice and rats that are slow-cycling cells and have characteristics of kidney stem cells. When grown in culture, these papillary cells express epithelial and mesenchymal markers, form cellular spheres, and display some evidence of plasticity with differentiation into neurons under appropriate culture conditions.…”