Pericytes in the renal vasculature: roles in health and disease.

In the dense circulatory system of the kidney, as in all vascularized tissues, pericytes enwrap capillaries and microvessels to regulate angiogenesis, stabilize microvascular networks and control blood flow by vasoconstriction. Specialized renal pericytes known as mesangial cells provide physical support to glomerular capillaries, whereas a subset of juxtaglomerular arteriolar pericytes control the local blood pressure in the glomerulus via contraction and influence systemic blood pressure by secreting renin. Similar to pericytes from many other organs, cultured human renal pericytes give rise to mesenchymal stem/stromal cells, suggesting a role of perivascular cells in renal homeostasis and regeneration. On the other hand, pericytes directly contribute to renal fibrosis, and mesangial cells may have an essential role in the development of glomerulosclerosis and other nephropathies. From their early emergence in the renal embryonic rudiment to their distribution in diverse perivascular niches in the adult organ, we review the anatomy and function of pericytes in the healthy and diseased kidney. Many aspects of the ontogeny, specification and functional specialization of renal pericytes remain elusive. The development of powerful models in the easily accessible and genetically tractable zebrafish will help to uncover the multiple facets of these cells.