title: Pericytes in kidney fibrosis.
abstract: OBJECTIVE
  Pericytes and perivascular fibroblasts have emerged as poorly appreciated yet extensive populations of mesenchymal cells in the kidney that play important roles in homeostasis and responses to injury. This review will update readers on the evolving understanding of the biology of these cells.
  
  
  RESULTS
  Fate mapping has identified pericytes and perivascular fibroblasts as the major source of pathological fibrillar matrix-forming cells in interstitial kidney disease. In other organs similar cells have been described and independent fate mapping indicates that pericytes or perivascular cells are myofibroblast progenitors in multiple organs. Over the last year, new insights into the function of pericytes in kidney homeostasis has been uncovered and new molecular pathways that regulate detachment and their transdifferentiation into pathological myofibroblasts, including Wingless/Int, ephrin, transforming growth factor β, platelet derived growth factor, and Hedgehog signaling pathways, have been reported. In addition provocative studies indicate that microRNAs, which regulate posttranscriptional gene expression, may also play important roles in their transdifferentiation.
  
  
  CONCLUSIONS
  Pericytes and perivascular fibroblasts are the major source of pathological collagen fiber-forming cells in interstitial kidney diseases. New avenues of research into their activation and differentiation has identified new drug candidates for the treatment of interstitial kidney disease.
authors.affiliation: Division of Nephrology, Institute of Stem Cell and Regenerative Medicine, Center for Lung Biology, Kidney Research Institute, University of Washington, Seattle, Washington 98109, USA.
authors.forename: Shuyu
authors.initials: S
authors.lastname: Ren
authors.forename: Jeremy S
authors.initials: JS
authors.lastname: Duffield
mesh_terms: D000818:Animals; D054338:Cell Transdifferentiation; D024022:Fibrillar Collagens / Q000378:metabolism*; D005347:Fibroblasts / Q000378:metabolism* / Q000473:pathology; D005355:Fibrosis; D006801:Humans; D007668:Kidney / Q000378:metabolism* / Q000473:pathology; D007674:Kidney Diseases / Q000235:genetics / Q000378:metabolism* / Q000473:pathology / Q000628:therapy; D020782:Matrix Metalloproteinases / Q000378:metabolism; D035683:MicroRNAs / Q000378:metabolism; D058628:Myofibroblasts / Q000378:metabolism / Q000473:pathology; D020286:Pericytes / Q000378:metabolism* / Q000473:pathology; D015398:Signal Transduction
chemical_list: D024022:Fibrillar Collagens; D035683:MicroRNAs; D020782:Matrix Metalloproteinases