Fig. 3.

Histopathological findings in mouse kidneys lacking endothelial Pfn1. A) Upper panels are representative images of H&E staining (×100) sections of the kidneys of a littermate control Pfn1^WT (left) vs Pfn1^EC-KO mouse (right). The glomeruli of Pfn1^EC-KO mice were smaller than those of the littermate controls (arrows), and the tubules showed apoptotic epithelial cells, intraluminal edema, and erythrocytes (arrowheads). Lower panels are higher magnification images (×500) showing proliferation of mesangial cells (arrowheads), an abundance of eosinophilic deposits compatible with mesangial matrix, and dead EC (arrows) in Pfn1^EC-KO mice. B) Masson trichrome staining of kidney sections shows the absence of fibrosis (upper panels ×100, lower panels ×500). C) CD31 staining of kidney sections shows normal vascularization of glomeruli (arrows) and surrounding the tubules (arrowheads) in littermate control Pfn1^WT mouse (upper left panel). The upper right panel shows a lack of mature capillaries in the glomeruli (arrows) and between tubules (arrowheads) in sections of kidneys from Pfn1^EC-KO mice. Lower panels are high magnifications of glomeruli showing the presence of mature blood vessels in the glomerulus of a Pfn1^WT mouse (left) contrasting scarce endothelial cells with immature characteristics in the glomerulus of a Pfn1^EC-KO mouse (right). Upper panels ×100, lower panels ×500. D) Upper left: cartoon of a normal glomerulus (generated using the BioRender illustration software). The upper right panels are TEM images (×5,000) of a glomerulus from a Pfn1^WT mouse showing normal endothelial cells (E), podocytes (P), and mesangial cells (Mc). Lower panels are images of a glomerulus from a Pfn1^EC-KO mouse showing a high number of mesangial cells (arrows) and deposits of the mesangial matrix (Mm) surrounding a collapsed capillary (dotted area). The lower right shows a capillary lined by apoptotic endothelial cells, thickening of the basal membrane (asterisk), and apoptotic podocytes.