Fig. 2.

Characterization of pericytes in normal human kidney biopsy sample and in Coll-GFP^Tg mouse kidney cortex. (A) Normal adult human kidney cortex, immunostained for CollagenIα(1) protein. Note that CollagenIα(1) protein is strongly expressed in glomerular podocytes (arrowheads), and in perivascular cells from capillaries (arrows). (B) Normal adult Coll-GFP^Tg kidney cortex, immunostained for GFP. Coll-GFP^Tg mice express GFP under regulation by the Coll1α1 promoter, so GFP protein expression indicates Coll1α1 transcription. Note that GFP-expressing cells (glomerular podocytes (arrowheads), perivascular cells (arrows)) in Coll-GFP^Tg mice are the same as Coll1α1-expressing cells in human kidney cortex. Therefore, Coll-GFP^Tg mice are faithful reporters of all cells that produce CollagenIα(1) protein in human kidney. (C) Four color-confocal image of the cortex of the Coll-GFP^Tg mouse kidney stained for the capillary basement membrane-specific protein Lamininα4 (red) and the endothelial marker CD31 (white). Note numerous GFP+ cells that lack endothelial, epithelial or leukocyte markers (not shown) that form extensive processes along capillaries. Note direct interactions with endothelial cell bodies (arrows) and note Coll-GFP+ processes passing through splits in capillary basement membrane (arrowheads).