Viable podocytes detach in experimental diabetic nephropathy: potential mechanism underlying glomerulosclerosis.
BACKGROUND
A decrease in podocyte number contributes to the development of glomerulosclerosis in diabetic nephropathy. Although podocytes have been detected in the urine in certain glomerular diseases, their viability is poorly understood.


METHODS
Diabetes was induced in rats with streptozotocin. Urine was collected from control rats (given citrate), and rats with diabetic nephropathy, and cells obtained by centrifugation were resuspended in tissue culture media, and seeded onto collagen-coated tissue culture plates. Cells were grown under standard cell culture conditions ex vivo. Cell number was measured, the cell type in the urine was identified by immunostaining with specific antibodies, and morphology was assessed by light and electron microscopy.


RESULTS
Within 24 h, cells obtained from the urine of diabetic rats attached to tissue culture plates ex vivo. Cells were not detected in the urine from control rats. All cells from diabetic rats stained positive for the podocyte-specific proteins synaptopodin, nephrin, podocin and Glepp-1 and negative for mesangial (OX-7), tubular (Tamm-Horsfall protein) and endothelial (RECA) cell antigens. The cell number increased daily, which is consistent with cell growth ex vivo.


CONCLUSIONS
Rats with diabetic nephropathy shed podocytes into the urine that attach and grow ex vivo. These results are consistent with the detachment of viable podocytes in diabetes and add new perspectives into our understanding of development of glomerulosclerosis in diabetes mellitus.
Petermann
Arndt T
AT
Department of Medicine, Division of Nephrology, University of Washington School of Medicine, Seattle, Wash 98195, USA.
Pippin
Jeffrey
J
Krofft
Ron
R
Blonski
Mary
M
Griffin
Sian
S
Durvasula
Raghu
R
Shankland
Stuart J
SJ
D000818:Animals; D017209:Apoptosis; D002448:Cell Adhesion; D002470:Cell Survival; D002478:Cells, Cultured; D003921:Diabetes Mellitus, Experimental / Q000209:etiology / Q000473:pathology; D003928:Diabetic Nephropathies / Q000209:etiology* / Q000473:pathology; D008297:Male; D050199:Podocytes / Q000166:cytology* / Q000473:pathology / Q000648:ultrastructure; D051381:Rats; D017207:Rats, Sprague-Dawley; D014556:Urine / Q000166:cytology