Confocal super-resolution imaging of the glomerular filtration barrier enabled by tissue expansion

Kidney Int. 2018 Apr;93(4):1008-1013. doi: 10.1016/j.kint.2017.09.019. Epub 2017 Dec 11.


The glomerular filtration barrier, has historically only been spatially resolved using electron microscopy due to the nanometer-scale dimensions of these structures. Recently, it was shown that the nanoscale distribution of proteins in the slit diaphragm can be resolved by fluorescence based stimulated emission depletion microscopy, in combination with optical clearing. Fluorescence microscopy has advantages over electron microscopy in terms of multiplex imaging of different epitopes, and also the amount of volumetric data that can be extracted from thicker samples. However, stimulated emission depletion microscopy is still a costly technique commonly not available to most life science researchers. An imaging technique with which the glomerular filtration barrier can be visualized using more standard fluorescence imaging techniques is thus desirable. Recent studies have shown that biological tissue samples can be isotropically expanded, revealing nanoscale localizations of multiple epitopes using confocal microscopy. Here we show that kidney samples can be expanded sufficiently to study the finest elements of the filtration barrier using confocal microscopy. Thus, our result opens up the possibility to study protein distributions and foot process morphology on the effective nanometer-scale.

Keywords: glomerulus; imaging; podocyte; renal pathology.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Autoantibodies
  • Biomarkers / metabolism
  • Collagen Type IV / immunology
  • Collagen Type IV / metabolism
  • Disease Models, Animal
  • Fluorescent Antibody Technique, Indirect
  • Glomerular Filtration Barrier / immunology
  • Glomerular Filtration Barrier / metabolism
  • Glomerular Filtration Barrier / pathology*
  • Glomerulonephritis / immunology
  • Glomerulonephritis / metabolism
  • Glomerulonephritis / pathology*
  • Intracellular Signaling Peptides and Proteins / immunology
  • Intracellular Signaling Peptides and Proteins / metabolism
  • Membrane Proteins / immunology
  • Membrane Proteins / metabolism
  • Mice, Transgenic
  • Microscopy, Confocal*
  • Microscopy, Fluorescence*
  • Rats
  • Tissue Expansion / methods*


  • Autoantibodies
  • Biomarkers
  • Collagen Type IV
  • Intracellular Signaling Peptides and Proteins
  • Membrane Proteins
  • NPHS2 protein
  • antiglomerular basement membrane antibody
  • nephrin