Developmental origins and functions of stromal cells in the normal and diseased mammalian kidney.

The kidney is a model developmental paradigm of vertebrate organogenesis. As in many other organs, kidney development involves reciprocal inductive tissue interactions between multiple cell lineages. The most well defined of these interactions occurs between the ureteric bud and the nephrogenic mesenchyme. A population of mesenchymal cells distinct from nephrogenic precursors and termed stromal cells, have been relatively understudied. Yet existing knowledge indicates that stromal cells are critical regulators in the normal and diseased kidney. This commentary reviews current knowledge regarding the origin and functional roles of the stromal cell population during kidney development. Gaps in our current understanding of renal stromal cells and future directions needed to advance this expanding field of study are highlighted.