In vitro non-enzymatic ribation reduces post-yield strain accommodation in cortical bone

Area of Science:

• Biomaterials Science
• Bone Biology
• Materials Science

Background:

• Non-enzymatic glycation (NEG) and advanced glycation endproducts (AGEs) are implicated in bone fragility by altering collagen structure and mechanical properties.
• Previous studies suggest NEG-induced collagen modification, particularly increased crosslinking, leads to reduced bone ductility.

Purpose of the Study:

• To investigate how collagen modification via in vitro non-enzymatic ribation affects cortical bone toughness.
• To elucidate the relationship between NEG, collagen crosslinking, and mechanical properties in cortical bone.

Main Methods:

• Bovine metatarsal bone beams were subjected to in vitro non-enzymatic ribation.
• Mechanical properties were assessed using three-point bending tests.
• Collagen crosslinking (pentosidine, pyridinoline) and molecular stability were analyzed using HPLC, differential scanning calorimetry, and hydrothermal isometric tension testing.

Main Results:

• Ribation increased non-enzymatic collagen modification and pentosidine content, leading to reduced post-yield strain and flexural toughness.
• Fracture surfaces showed smoother textures with less collagen fibril deformation in ribated specimens.
• Positive correlations were observed between pentosidine content and measures of strain accommodation/energy absorption in the ribated group.

Conclusions:

• Non-enzymatic ribation reduces cortical bone pseudo-plasticity by impairing post-yield strain accommodation.
• Increased collagen crosslinking may not entirely explain the embrittlement of cortical bone caused by NEG.
• The findings highlight the complex role of NEG in bone mechanical integrity.