Multiphoton imaging and Raman spectroscopy of the bovine vertebral endplate

Area of Science:

• Biomedical Engineering
• Biochemistry
• Spinal Anatomy

Background:

• The intervertebral disc-vertebral body interface is crucial for spinal biomechanics and is implicated in disc pathology.
• Understanding the structure and biochemistry of the vertebral endplate is key to understanding disc health.

Purpose of the Study:

• To biochemically and structurally characterize the bony endplate, cartilage endplate, and intervertebral disc in healthy bovine tails.
• To investigate the interface between the intervertebral disc and vertebral body.

Main Methods:

• Multiphoton imaging techniques, including second-harmonic generation (SHG) and two-photon fluorescence (TPF), were used for structural analysis.
• Spontaneous Raman spectroscopy was employed for biochemical analysis, quantifying mineral and matrix components with high spatial resolution.

Main Results:

• The cartilage endplate was identified as a structurally distinct region, functioning as a transition zone between the hard bone and soft disc tissues.
• Collagen fibers were observed to be continuous across the tidemark, indicating a structural link between mineralized and non-mineralized endplate regions.
• Raman spectroscopy revealed gradients in phosphate and carbonate content within the endplate and differential composition beneath the nucleus and annulus, suggesting varied remodeling rates.

Conclusions:

• The cartilage endplate's distinct structure supports its role as a critical transition zone in spinal biomechanics.
• Biochemical gradients in the endplate, particularly differences under the nucleus and annulus, highlight regional variations in tissue remodeling and disc-vertebral interactions.