Open AccessAtomic force microscopy imaging for nanoscale and microscale assessments of extracellular matrix in intervertebral disc and degeneration
Author(s) -
Cauble Meagan A.,
Mancini Nickolas S.,
Kalinowski Judith,
Lykotrafitis George,
Moss Isaac L.
Publication year - 2020
Publication title -
jor spine
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.125
0ISSN - 2572-1143
DOI - 10.1002/jsp2.1125
Subject(s) - extracellular matrix , microscale chemistry , intervertebral disc , fibril , degeneration (medical) , nanoscopic scale , materials science , matrix (chemical analysis) , degenerative disc disease , annulus (botany) , biomedical engineering , biophysics , anatomy , chemistry , nanotechnology , pathology , medicine , composite material , biology , mathematics education , mathematics , lumbar , biochemistry
Degeneration of the intervertebral disc (IVD) is a condition that is often associated with debilitating back pain. There are no disease‐modifying treatments available to halt the progression of this ubiquitous disorder. This is partly due to a lack of understanding of extracellular matrix (ECM) changes that occur at the micro‐ and nanometer size scales as the disease progresses. Over the past decade, atomic force microscopy (AFM) has been utilized as a tool to investigate the impact of disease on nanoscale structure of ECM in bone, skin, tendon, and dentin. We have expanded this methodology to include the IVD and report the first quantitative analysis of ECM structure at submicron size scales in a murine model for progressive IVD degeneration. Collagen D‐spacing, a metric of nanoscale structure at the fibril level, was observed as a distribution of values with an overall average value of 62.5 ± 2.5 nm. In degenerative discs, the fibril D‐spacing distribution shifted towards higher values in both the annulus fibrosus and nucleus pulposus (NP) ( P < .05). A novel microstructural feature, collagen toroids , defined by a topographical pit enclosed by fibril‐forming matrix was observed in the NP. With degeneration, these microstructures became more numerous and the morphology was altered from circular (aspect ratio 1.0 ± 0.1) to oval (aspect ratio 1.5 ± 0.4), P < .005. These analyses provide ECM structural details of the IVD at size scales that have historically been missing in studies of disc degeneration. Knowledge gained from these insights may aid the development of novel disease‐modifying therapeutics.