Diffusion of charged and uncharged contrast agents in equine mandibular condylar cartilage is not affected by an increased level of sugar-induced collagen crosslinking.

This research explored the diffusion properties in horse jaw joint cartilage under aging-like conditions. The study found that even with the structural alterations brought about by age, the diffusion of solutes, which is essential for nourishing cartilage, remained unaffected.

Objective of Research

The researchers sought to understand how aging-induced collagen crosslinking in fibrocartilage of the mandibular condyle (jaw joint) affects the diffusion process. By simulating aging conditions, they aimed to highlight any potential changes in the diffusive transport of solutes, a process that plays a key role in the nutrition of articular cartilage since it lacks blood vessels.

Methodology

• The researchers performed their study on osteochondral plugs sourced from young equine mandibular condyles.
• To induce an aging-like effect, they treated these plugs with 500 mM ribose for a week, a process known to result in collagen accumulation.
• Different types of contrast agents — charged (Hexabrix) and uncharged (Visipaque) — were used to investigate the potential effects of steric hindrance and electrostatic forces on diffusion.
• Dynamic indentation was employed to measure the impact of crosslinking on mechanical properties.
• The tissue specimens were subsequently exposed to the contrast agents and imaged with contrast-enhanced computed tomography (CECT) at 18 different points over 48 hours to assess diffusion.
• They then determined the normalized concentration of these contrast agents in the tissue, the contrast agent diffusion flux, and the content of pentosidine, water, collagen, and glycosaminoglycan (GAG).

Findings

• The ribose treatment considerably raised pentosidine level from 0.01 to 7.6 mmol/mol collagen, contributing to tissue stiffness increase of about 1.5 times.
• The diffusion properties, such as normalized concentration and diffusion flux, showed no change for both Hexabrix and Visipaque even with higher levels of pentosidine present.

In conclusion, the study provides valuable insights, showing that sugar-induced collagen crosslinking in the mentioned cartilage does not manipulate its diffusion properties. This finding has potential implications for understanding how cartilage manages to stay nourished as it undergoes aging-related changes.