Multiscale and multimodal structure-function analysis of intervertebral disc degeneration in a rabbit model

B G Ashinsky; S E Gullbrand; E D Bonnevie; S A Mandalapu; C Wang; D M Elliott; L Han; R L Mauck; H E Smith

doi:10.1016/j.joca.2019.07.016

Multiscale and multimodal structure-function analysis of intervertebral disc degeneration in a rabbit model

Osteoarthritis Cartilage. 2019 Dec;27(12):1860-1869. doi: 10.1016/j.joca.2019.07.016. Epub 2019 Aug 13.

Authors

B G Ashinsky¹, S E Gullbrand², E D Bonnevie³, S A Mandalapu⁴, C Wang⁵, D M Elliott⁶, L Han⁷, R L Mauck⁸, H E Smith⁹

Affiliations

¹ Department of Orthopaedic Surgery, McKay Orthopaedic Research Laboratory, University of Pennsylvania, Philadelphia, PA, USA; School of Biomedical Engineering, Science and Health Systems, Drexel University, Philadelphia, PA, USA; Translational Musculoskeletal Research Center, Corporal Michael J. Crescenz VA Medical Center, Philadelphia, PA, USA. Electronic address: beth.ashinsky@gmail.com.
² Department of Orthopaedic Surgery, McKay Orthopaedic Research Laboratory, University of Pennsylvania, Philadelphia, PA, USA; Translational Musculoskeletal Research Center, Corporal Michael J. Crescenz VA Medical Center, Philadelphia, PA, USA. Electronic address: sgullb@pennmedicine.upenn.edu.
³ Department of Orthopaedic Surgery, McKay Orthopaedic Research Laboratory, University of Pennsylvania, Philadelphia, PA, USA; Translational Musculoskeletal Research Center, Corporal Michael J. Crescenz VA Medical Center, Philadelphia, PA, USA. Electronic address: edbon@pennmedicine.upenn.edu.
⁴ Department of Orthopaedic Surgery, McKay Orthopaedic Research Laboratory, University of Pennsylvania, Philadelphia, PA, USA; Translational Musculoskeletal Research Center, Corporal Michael J. Crescenz VA Medical Center, Philadelphia, PA, USA. Electronic address: sai.mandalapu@pennmedicine.upenn.edu.
⁵ School of Biomedical Engineering, Science and Health Systems, Drexel University, Philadelphia, PA, USA. Electronic address: cw583@drexel.edu.
⁶ Department of Biomedical Engineering, University of Delaware, Newark, DE, USA. Electronic address: delliott@udel.edu.
⁷ School of Biomedical Engineering, Science and Health Systems, Drexel University, Philadelphia, PA, USA. Electronic address: lh535@drexel.edu.
⁸ Department of Orthopaedic Surgery, McKay Orthopaedic Research Laboratory, University of Pennsylvania, Philadelphia, PA, USA; Translational Musculoskeletal Research Center, Corporal Michael J. Crescenz VA Medical Center, Philadelphia, PA, USA. Electronic address: lemauck@pennmedicine.upenn.edu.
⁹ Department of Orthopaedic Surgery, McKay Orthopaedic Research Laboratory, University of Pennsylvania, Philadelphia, PA, USA; Translational Musculoskeletal Research Center, Corporal Michael J. Crescenz VA Medical Center, Philadelphia, PA, USA. Electronic address: harvey.smith@uphs.upenn.edu.

Abstract

Objectives: The objective of this study was to perform a quantitative analysis of the structural and functional alterations in the intervertebral disc during in vivo degeneration, using emerging tools that enable rigorous assessment from the microscale to the macroscale, as well as to correlate these outcomes with noninvasive, clinically relevant imaging parameters.

Design: Degeneration was induced in a rabbit model by puncturing the annulus fibrosus (AF) with a 16-gauge needle. 2, 4, 8, and 12 weeks following puncture, degenerative changes in the discs were evaluated via magnetic resonance imaging (MRI), whole motion segment biomechanics, atomic force microscopy, histology and polarized light microscopy, immunohistochemistry, biochemical content, and second harmonic generation imaging.

Results: Following puncture, degeneration was evident through marked changes in whole disc structure and mechanics. Puncture acutely compromised disc macro and microscale mechanics, followed by progressive stiffening and remodeling. Histological analysis showed substantial anterior fibrotic remodeling and osteophyte formation, as well as an overall reduction in disc height, and disorganization and infolding of the AF lamellae into the NP space. Increases in NP collagen content and aggrecan breakdown products were also noted within 4 weeks. On MRI, NP T2 was reduced at all post-puncture time points and correlated significantly with microscale indentation modulus.

Conclusion: This study defined the time dependent changes in disc structure-function relationships during IVD degeneration in a rabbit annular injury model and correlated degeneration severity with clinical imaging parameters. Our findings identified AF infolding and occupancy of the space as a principle mechanism of disc degeneration in response to needle puncture, and provide new insights to direct the development of novel therapeutics.

Keywords: Animal model; Atomic force microscopy; Intervertebral disc degeneration; Magnetic resonance imaging.

Publication types

Research Support, N.I.H., Extramural
Research Support, U.S. Gov't, Non-P.H.S.

MeSH terms

Aggrecans / metabolism
Animals
Annulus Fibrosus / diagnostic imaging*
Annulus Fibrosus / metabolism
Annulus Fibrosus / pathology
Annulus Fibrosus / physiopathology
Biomechanical Phenomena
Collagen / metabolism
Disease Models, Animal
Disease Progression
Immunohistochemistry
Intervertebral Disc / diagnostic imaging
Intervertebral Disc / metabolism
Intervertebral Disc / pathology
Intervertebral Disc / physiopathology
Intervertebral Disc Degeneration / diagnostic imaging*
Intervertebral Disc Degeneration / metabolism
Intervertebral Disc Degeneration / pathology
Intervertebral Disc Degeneration / physiopathology
Magnetic Resonance Imaging
Microscopy, Atomic Force
Microscopy, Polarization
Nucleus Pulposus / diagnostic imaging*
Nucleus Pulposus / metabolism
Nucleus Pulposus / pathology
Nucleus Pulposus / physiopathology
Punctures
Rabbits
Second Harmonic Generation Microscopy

Substances

Aggrecans
Collagen

Abstract

Publication types

MeSH terms

Substances

Grants and funding