Podocytes that detach in experimental membranous nephropathy are viable.
BACKGROUND
Podocyte loss contributes to the development of glomerulosclerosis. Although podocytes have been detected in the urine in certain glomerular diseases, the viability of detached cells is not known.


METHODS
Urine was collected from rats with experimental membranous nephropathy [passive Heymann nephritis (PHN) model], centrifuged, and following resuspension in tissue culture media, cells were seeded onto collagen-coated tissue culture plates. Cells were grown under typical cell culture conditions. Cell number was measured, the cell type was identified by immunostaining with specific antibodies, and cell morphology was assessed by light and electron microscopy.


RESULTS
Cells obtained in the urine from PHN rats were positive for synaptopodin, nephrin, podocin, WT-1, and GLEPP1 (podocyte-specific antigens). When grown ex vivo under cell culture conditions, cells obtained in the urine from PHN rats adhered to tissue culture plates, and expressed podocyte-specific proteins at the mRNA [reverse transcription-polymerase chain reaction (RT-PCR)] and protein (immunostaining) level. Cells did not stain with antibodies to mesangial (OX-7), tubular (Tamm-Horsfall protein) and endothelial (RECA) cells. Electron microscopy showed the presence of foot processes, and podocytes from PHN rats stained positive for C5b-9. Although podocyte number increased transiently during the first 5 days ex vivo, apoptosis increased significantly thereafter, reducing overall cell number.


CONCLUSIONS
Rats with experimental membranous nephropathy shed podocytes into the urine that attach to tissue culture plates ex-vivo, and proliferate. These results suggest that detached podocytes are viable. These results add new perspectives into our understanding of podocyte loss in the development of glomerulosclerosis.
Petermann
Arndt T
AT
Department of Medicine, University of Washington School of Medicine, Seattle, Washington 98195, USA.
Krofft
Ron
R
Blonski
Mary
M
Hiromura
Keiju
K
Vaughn
Michael
M
Pichler
Raimund
R
Griffin
Sian
S
Wada
Takehiko
T
Pippin
Jeffrey
J
Durvasula
Raghu
R
Shankland
Stuart J
SJ
D000818:Animals; D002448:Cell Adhesion; D002452:Cell Count; D002455:Cell Division; D002470:Cell Survival; D002478:Cells, Cultured; D015938:Complement Membrane Attack Complex / Q000378:metabolism; D005455:Fluorescent Antibody Technique; D015433:Glomerulonephritis, Membranous / Q000473:pathology* / Q000503:physiopathology* / Q000652:urine; D007668:Kidney / Q000378:metabolism / Q000473:pathology* / Q000503:physiopathology* / Q000648:ultrastructure; D008297:Male; D008854:Microscopy, Electron; D051381:Rats; D017207:Rats, Sprague-Dawley; D013194:Staining and Labeling; D014556:Urine / Q000166:cytology
D015938:Complement Membrane Attack Complex