title: Super-resolution stimulated emission depletion imaging of slit diaphragm proteins in optically cleared kidney tissue.
abstract: The glomerular filtration barrier, consisting of podocyte foot processes with bridging slit diaphragm, glomerular basement membrane, and endothelium, is a key component for renal function. Previously, the subtlest elements of the filtration barrier have only been visualized using electron microscopy. However, electron microscopy is mostly restricted to ultrathin two-dimensional samples, and the possibility to simultaneously visualize multiple different proteins is limited. Therefore, we sought to implement a super-resolution immunofluorescence microscopy protocol for the study of the filtration barrier in the kidney. Recently, several optical clearing methods have been developed making it possible to image through large volumes of tissue and even whole organs using light microscopy. Here we found that hydrogel-based optical clearing is a beneficial tool to study intact renal tissue at the nanometer scale. When imaging samples using super-resolution STED microscopy, the staining quality was critical in order to assess correct nanoscale information. The signal-to-noise ratio and immunosignal homogeneity were both improved in optically cleared tissue. Thus, STED of slit diaphragms in fluorescently labeled, optically cleared, intact kidney samples is a new tool for studying the glomerular filtration barrier in health and disease.
authors.affiliation: Science for Life Laboratory, Department of Applied Physics, Royal Institute of Technology, Solna, Sweden.
authors.forename: David
authors.initials: D
authors.lastname: Unnersjö-Jess
authors.affiliation: Science for Life Laboratory, Department of Women's and Children's Health, Karolinska Institutet, Solna, Sweden.
authors.forename: Lena
authors.initials: L
authors.lastname: Scott
authors.affiliation: Science for Life Laboratory, Department of Applied Physics, Royal Institute of Technology, Solna, Sweden.
authors.forename: Hans
authors.initials: H
authors.lastname: Blom
authors.affiliation: Science for Life Laboratory, Department of Applied Physics, Royal Institute of Technology, Solna, Sweden; Science for Life Laboratory, Department of Women's and Children's Health, Karolinska Institutet, Solna, Sweden. Electronic address: brismar@kth.se.
authors.forename: Hjalmar
authors.initials: H
authors.lastname: Brismar
mesh_terms: D000818:Animals; D005456:Fluorescent Dyes; D060730:Glomerular Filtration Barrier / Q000737:chemistry*; D020100:Hydrogels; D047908:Intracellular Signaling Peptides and Proteins / Q000032:analysis; D008565:Membrane Proteins / Q000032:analysis; D018613:Microscopy, Confocal; D008856:Microscopy, Fluorescence; D057054:Molecular Imaging / Q000379:methods*; D009393:Nephritis / Q000378:metabolism; D051381:Rats; D059629:Signal-To-Noise Ratio; D013194:Staining and Labeling
chemical_list: D005456:Fluorescent Dyes; D020100:Hydrogels; D047908:Intracellular Signaling Peptides and Proteins; D008565:Membrane Proteins; C407223:NPHS2 protein
keywords: STED; glomerulus; optical clearing; podocyte; super-resolution