Cartilage surface charge. A possible determinant in aging and osteoarthritic processes

Area of Science:

• Biochemistry
• Orthopedics
• Biomaterials science

Background:

• The mandibular condyle's articular surface plays a crucial role in temporomandibular joint function.
• Understanding the surface charge and composition of cartilage is vital for elucidating age-related changes and diseases like osteoarthritis.

Purpose of the Study:

• To investigate the surface negative charges of mandibular condyles in ICR mice.
• To examine the impact of enzymatic treatments on the surface charge density.
• To explore the potential link between age-related charge reduction and osteoarthritis.

Main Methods:

• Utilized polycationic labels (cationized ferritin, colloidal iron) to assess surface negative charges.
• Applied enzymes (neuraminidase, hyaluronidase, pronase, collagenase) to probe the composition of the articular surface.
• Microscopic analysis to observe label binding and distribution.

Main Results:

• The cartilaginous condyle surface exhibits significant negative charges.
• Enzymatic treatments altered the binding of cationic labels, indicating specific charged components.
• A notable decrease in surface negative charge density, particularly sialic acid residues, was observed with increasing age.
• The condylar surface composition is primarily collagenous material within a proteinaceous matrix.

Conclusions:

• The mandibular condyle's articular surface is negatively charged, composed mainly of collagen and proteins.
• Age-related decline in negative charge density, especially sialic acids, is evident.
• Reduced cartilage surface charge may be a contributing factor to the development of osteoarthritis in aging individuals and animals.