Poster abstracts

Poster number 76 submitted by Kevin Walsh

Magnetic Force Microscopy in Histology

Kevin J. Walsh, Gunjan Agarwal (Biophysics Graduate Program), Angela R. Blissett, Josh Sifford (Department of Biomedical Engineering), Binbin Deng, David W. McComb (Center for Electron Microscopy and Analysis), Ping Wei, Andrew D. Sauerbeck Dana M. McTigue (The Center for Brain and Spinal Cord Repair and the Department of Neuroscience)

Abstract:
Ferritin is the major iron storage protein in the mammalian body consisting of ~ 8 nm iron core in the form of ferrihydrite. The size, distribution and oxidation state of ferritin(iron) is important for several physiological and pathological processes. Histochemical staining, the routinely used approach to characterize iron distribution, offers limited insight. In this study, we demonstrate how Magnetic Force Microscopy (MFM) can be utilized for histological analysis of iron at the ultrastructural level. Spleen and spinal cord tissues extracted from a naïve versus spinal cord-injury rat model were analyzed for ferritin(iron). Perl’s histochemical staining was used to map ferric iron and adjacent, unstained sections were analyzed via MFM. No significant difference in the magnitude of MFM signal was observed across tissues, however the roughness of MFM signal was notably higher for injured animals. Causes for the increased roughness of MFM signal were examined via Transmission Electron Microscopy and Electron Energy Loss Spectroscopy. Electron microscopy analysis indicated that the density and not the oxidation state of lysosomal ferritin(iron), was the major factor accounting for MFM roughness. Overall, our results indicate how rich and physiologically relevant information can be obtained through magnetic mapping and ultrastructural analysis of histological iron.

References:
Blissett, A. R., B. Deng, P. Wei, K. J. Walsh, B. Ollander, J. Sifford, A. D. Sauerbeck, D. W. McComb, D. M. McTigue, and G. Agarwal. “Sub-Cellular In-Situ Characterization of Ferritin(Iron) in a Rodent Model of Spinal Cord Injury.” Scientific Reports 8, no. 1 (February 23, 2018): 3567. https://doi.org/10.1038/s41598-018-21744-9.

Keywords: Atomic Force Microscopy, Cellular Imaging