X-ray diffraction studies on human tendon show age-related changes in collagen packing

Area of Science:

• Biophysics
• Connective Tissue Biology
• Gerontology

Background:

• Human aging involves progressive changes in connective tissues.
• Collagen is a primary structural protein in tendons, crucial for mechanical function.
• Non-enzymatic glycosylation is a proposed mechanism contributing to age-related tissue stiffening.

Purpose of the Study:

• To establish X-ray diffraction as a quantitative monitor of human aging in tendons.
• To investigate the relationship between collagen structure and chronological age.
• To explore the role of non-enzymatic glycosylation in age-related tendon alterations.

Main Methods:

• X-ray diffraction analysis of native hydrated human toe extensor tendons.
• Recording diffraction patterns from individuals aged 1.6 to 87 years.
• Analyzing meridional reflections (67 nm axial repeat) and equatorial maximum spacing.

Main Results:

• A linear increase in the ratio of 16:17 order intensities with age was observed.
• Increased equatorial maximum spacing, indicating altered lateral collagen packing, was found in older tendons.
• X-ray parameter trends mimicked those of in vitro non-enzymatic glycosylation, correlating with Maillard products and pentosidine levels.

Conclusions:

• X-ray diffraction parameters of collagen fibrils serve as reliable indicators of human aging.
• Cumulative non-enzymatic glycosylation drives structural changes in connective tissues throughout the lifespan.
• While aging effects are evident, other factors introduce variability, particularly in individuals over 60.