Figure 5.

Kidney pericytes are essential to the integrity of peritubular capillaries. (A) In peritubular capillaries of the normal kidney, kidney pericytes (green) are attached to capillary endothelial cells (red) to stabilize capillary tube formation. Pericytes share the capillary basement membrane with endothelial cells. (B) In response to injury, kidney pericytes promptly migrate away from the capillary basement membrane, resulting in activation of endothelial cells. (C) Following further injury, kidney pericytes differentiate into scar-forming myofibroblasts or activated fibroblasts. These populations synthesize extracellular matrices such as collagens, promoting tissue fibrosis. Capillary endothelial cells are not able to maintain the capillary basement membrane without pericytes. Finally, peritubular capillaries start to disappear due to apoptosis, as myofibroblasts can no longer stabilize capillary tube formation.