Citation

Cooper JG, Sicard D, Sharma S, Van Gulden S, McGuire TL, Cajiao MP, Tschumperlin DJ, Kessler J. J. Neurotrauma 2019; ePub(ePub): ePub.

Affiliation

Northwestern University Feinberg School of Medicine, 12244, Department of Neurology, Chicago, Illinois, United States; jakessler@northwestern.edu.

Copyright

(Copyright © 2019, Mary Ann Liebert Publishers)

DOI

10.1089/neu.2019.6540

PMID

31516087

Abstract

Gliosis and fibrosis after spinal cord injury (SCI) lead to formation of a scar that is thought to present both molecular and mechanical barriers to neuronal regeneration. The scar consists of a meshwork of reactive glia and deposited, cross-linked, extracellular matrix that has long been assumed to present a mechanically "stiff" blockade. However, remarkably little quantitative information is available about the rheological properties of chronically injured spinal tissue. In this study we utilize atomic force microscopy microindentation to provide quantitative evidence of chronic mechanical stiffening after spinal cord injury, confirming a decades-old assumption. Using the results of this tissue characterization, we assessed the sensitivity of both mouse and human astrocytes in vitro and determined that they are exquisitely mechanosensitive within the relevant range of substrate stiffness observed in the injured/uninjured spinal cord. We then utilized a novel immune modifying nanoparticle (IMP) treatment as a tool to reveal fibrotic scarring as one of the key drivers of mechanical stiffening after SCI in vivo. We also demonstrate that glial scar-forming astrocytes form a highly aligned, anisotropic, network of glial fibers after SCI, and that IMP nanoparticle treatment mitigates this pathological alignment. Taken together, our results identify chronic mechanical stiffening as a critically important aspect of the complex lesion milieu after SCI that must be considered when assessing and developing potential clinical interventions for SCI.

Language: en

Keywords

EXTRACELLULAR MATRIX; GLIA CELL RESPONSE TO INJURY; INFLAMMATION; THERAPEUTIC APPROACHES FOR THE TREATMENT OF CNS INJURY; spinal cord injury