Structured illumination microscopy and automatized image processing as a rapid diagnostic tool for podocyte effacement

• Published in: Scientific reports Vol. 7; no. 1; pp. 11473 - 11
• Main Authors: Siegerist, Florian, Ribback, Silvia, Dombrowski, Frank, Amann, Kerstin, Zimmermann, Uwe, Endlich, Karlhans, Endlich, Nicole
• Format: Journal Article
• Language: English
• Published: London Nature Publishing Group UK 13.09.2017; Nature Publishing Group
• Subjects: 14/1; 14/34; 14/56; 14/63; 692/4022/1585/2759; 692/4022/1585/2759/2758; 692/699/1585/2759; Automation; Biomarkers; Biopsy; Diaphragm; Disease; Electron microscopy; Feet; Histopathology; Humanities and Social Sciences; Humans; Illumination; Image processing; Image Processing, Computer-Assisted - methods; Imaging, Three-Dimensional; Kidney Diseases - metabolism; Kidney Diseases - pathology; Kidneys; Microscopy; Microscopy - methods; Microscopy, Electron; Molecular Imaging - methods; Morphology; multidisciplinary; Pathology; Podocytes - metabolism; Podocytes - pathology; Podocytes - ultrastructure; Renal function; Science; Science (multidisciplinary)
• ISSN: 2045-2322; 2045-2322
• DOI: 10.1038/s41598-017-11553-x

The morphology of podocyte foot processes is obligatory for renal function. Here we describe a method for the superresolution-visualization of podocyte foot processes using structured illumination microscopy of the slit diaphragm, which before has only been achieved by electron microscopy. As a proof of principle, we measured a mean foot process width of 0.249 ± 0.068 µm in healthy kidneys and a significant higher mean foot process width of 0.675 ± 0.256 µm in minimal change disease patients indicating effacement of foot processes. We then hypothesized that the slit length per glomerular capillary surface area (slit diaphragm density) could be used as an equivalent for the diagnosis of effacement. Using custom-made software we measured a mean value of 3.10 ± 0.27 µm −1 in healthy subjects and 1.83 ± 0.49 µm −1 in the minimal change disease patients. As foot process width was highly correlated with slit diaphragm density (R 2  = 0.91), we concluded that our approach is a valid method for the diagnosis of foot process effacement. In summary, we present a new technique to quantify podocyte damage, which combines superresolution microscopy with automatized image processing. Due to its diverse advantages, we propose this technique to be included into routine diagnostics of glomerular histopathology.