Imaging the Kidney with an Unconventional Scanning Electron Microscopy Technique: Analysis of the Subpodocyte Space in Diabetic Mice

• Published in: International journal of molecular sciences Vol. 23; no. 3; p. 1699
• Main Authors: Conti, Sara, Remuzzi, Giuseppe, Benigni, Ariela, Tomasoni, Susanna
• Format: Journal Article
• Language: English
• Published: Switzerland MDPI AG 01-02-2022; MDPI
• Subjects: Animal models; Animals; Biopsy; Carbon; Diabetes; Diabetes mellitus (non-insulin dependent); Diabetes Mellitus, Experimental - pathology; Diabetes Mellitus, Type 2 - pathology; Diabetic nephropathy; Digital imaging; Glomerular Filtration Barrier - ultrastructure; Kidneys; Light microscopy; Membranes; Mice; Microscopy, Electron, Scanning; Optical microscopy; Podocytes - ultrastructure; Resolution; Scanning electron microscopy; Signal to noise ratio; subpodocyte space; Transmission electron microscopy; scanning electron microscopy; subpodocyte space; diabetic nephropathy
• DOI: 10.3390/ijms23031699
• EISSN: 1422-0067
• ISSN: 1422-0067; 1661-6596

Transmission electron microscopy (TEM) remains the gold standard for renal histopathological diagnoses, given its higher resolving power, compared with light microscopy. However, it imposes several limitations on pathologists, including longer sample preparation time and a small observation area. To overcome these, we introduced a scanning electron microscopy (SEM) technique for imaging resin-embedded semi-thin sections of renal tissue. We developed a rapid tissue preparation protocol for experimental models and human biopsies which, alongside SEM digital imaging acquisition of secondary electrons (SE-SEM), enables fast electron microscopy examination, with a resolution similar to that achieved by TEM. We used this unconventional SEM imaging approach to investigate the subpodocyte space (SPS) in BTBR
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mice with type 2 diabetes. Analysis of semi-thin sections with secondary electrons revealed that the SPS had expanded in volume and covered large areas of the glomerular basement membrane, forming wide spaces between the podocyte body and the underlying filtering membrane. Our results show that SE-SEM is a valuable tool for imaging the kidney at the ultrastructural level, filling the magnification gap between light microscopy and TEM, and reveal that in diabetic mice, the SPS is larger than in normal controls, which is associated with podocyte damage and impaired kidney function.