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

Area of Science:

• Biomaterials Science
• Orthopedics
• Regenerative Medicine

Background:

• Intervertebral disc degeneration (IVDD) is a complex process affecting spinal health.
• Understanding the microscale and macroscale changes during IVDD is crucial for developing effective treatments.

Purpose of the Study:

• To quantitatively analyze structural and functional alterations in the intervertebral disc during in vivo degeneration.
• To correlate microscale and macroscale disc changes with noninvasive, clinically relevant imaging parameters.

Main Methods:

• Degeneration was induced in a rabbit model via annulus fibrosus (AF) puncture.
• Evaluated changes using MRI, biomechanics, atomic force microscopy, histology, immunohistochemistry, biochemical analysis, and second harmonic generation imaging at multiple time points.

Main Results:

• Annulus fibrosus (AF) puncture led to acute mechanical compromise, followed by progressive stiffening and remodeling.
• Histology revealed fibrotic remodeling, osteophyte formation, reduced disc height, and AF lamellae infolding into the nucleus pulposus (NP).
• MRI T2 values in the NP decreased and correlated significantly with microscale mechanical properties.

Conclusions:

• Defined time-dependent changes in disc structure-function relationships during IVDD in a rabbit annular injury model.
• Identified AF infolding as a primary mechanism of disc degeneration following needle puncture.
• Provided new insights for the development of novel therapeutics for IVDD.