Interspecies Comparison of Multilayer Mechanical Properties of Synovium Using Atomic Force Microscopy

Area of Science:

• Biomedical Engineering
• Tissue Mechanics
• Drug Delivery

Background:

• The synovium, a joint tissue, influences intra-articular drug clearance.
• Understanding synovium's mechanical properties is crucial for optimizing drug delivery.
• Previous studies focused on larger joints; data for smaller joints is limited.

Purpose of the Study:

• To measure the Young's moduli of synovium from small joints (rat knee) and compare with pig and human synovium.
• To investigate the mechanical properties of the intima and subintima layers of the synovium.
• To assess the contribution of non-collagenous components to synovium's mechanical properties.

Main Methods:

• Atomic Force Microscopy (AFM) was used to measure Young's moduli of synovium from rat, pig, and human joints.
• Intima and subintima layers were analyzed separately.
• Enzymatic digestion (chondroitinase ABC, collagenase) was performed on pig synovium.

Main Results:

• Young's moduli of subintimal regions were consistent across rat, pig, and human species (1-1.5 kPa).
• Little difference in Young's moduli was observed between intima and subintima layers within each species.
• Enzymatic digestion with chondroitinase ABC reduced moduli, suggesting non-collagenous contributions.

Conclusions:

• AFM is suitable for measuring mechanical properties in small joint synovium.
• Synovium exhibits consistent mechanical properties across species and layers, relevant for intra-articular drug clearance models.
• Non-collagenous components significantly influence synovium's mechanical characteristics.