Quantitative super-resolution microscopy reveals promoting mitochondrial interconnectivity protects against AKI

December 07, 2021

Kensei Taguchi (1), Bertha C. Elias (1), Evan Krystofiak (2), Subo Qian (1), Snehal Sant (1), Haichun Yang (3), Agnes B. Fogo (3), Craig R. Brooks (1,4)
Kidney360, 2, December 2021: 1892–1907. DOI: 10.34067/KID.0001602021


Background The root of many kidney diseases in humans can be traced to alterations or damage to subcellular organelles. Mitochondrial fragmentation, endoplasmic reticulum (ER) stress, and lysosomal inhibition, among others, ultimately contribute to kidney injury and are the target of therapeutics in development. Although recent technological advancements allow for the understanding of disease states at the cellular level, investigating changes in subcellular organelles from kidney tissue remains challenging. Methods Using structured illumination microscopy, we imaged mitochondria and other organelles from paraffin sections of mouse tissue and human kidney biopsy specimens. The resulting images were 3D rendered to quantify mitochondrial size, content, and morphology. Results were compared with those from transmission electron microscopy and segmentation. Results Super-resolution imaging reveals kidney tubular epithelial cell mitochondria in rodent and human kidney tissue form large, interconnected networks under basal conditions, which are fragmented with injury. This approach can be expanded to other organelles and cellular structures including autophagosomes, ER, brush border, and cell morphology. We find that, during unilateral ischemia, mitochondrial fragmentation occurs in most tubule cells and they remain fragmented for .96 hours. Promoting mitochondrial fusion with the fusion promotor M1 preserves mitochondrial morphology and interconnectivity and protects against cisplatin-induced kidney injury. Conclusions We provide, for the first time, a nonbiased, semiautomated approach for quantification of the 3D morphology of mitochondria in kidney tissue. Maintaining mitochondrial interconnectivity and morphology protects against kidney injury. Super-resolution imaging has the potential to both drive discovery of novel pathobiologic mechanisms in kidney tissue and broaden the diagnoses that can be made on human biopsy specimens.

How Our Software Was Used

Dragonfly was used to perform image segmentation and 3D rendering.

Author Affiliation

(1) Division of Nephrology and Hypertension, Department of Medicine, Vanderbilt University Medical Center, Nashville, Tennessee.
(2) Cell Imaging Shared Resource, Vanderbilt University, Nashville, Tennessee.
(3) Department of Pathology, Microbiology and immunology, Vanderbilt University School of Medicine, Nashville, Tennessee.
(4) Department of Cell and Developmental Biology, Vanderbilt University, Nashville, Tennessee.