Cyclic loading of tendon fascicles using a novel fatigue loading system increases interleukin-6 expression by...

Area of Science:

• Biomechanics
• Molecular Biology
• Tendon Research

Background:

• Repetitive strain (overuse) is a primary cause of tendinopathy.
• Understanding the mechanical and molecular responses of tendons to loading is crucial for injury prevention and treatment.

Purpose of the Study:

• To develop a novel cyclic loading system for tendon fascicles.
• To investigate the impact of defined cyclic loading conditions on tendon mechanical properties and gene expression.

Main Methods:

• Isolated bovine tendon fascicles were subjected to cyclic tensile strain (1 Hz) at 30% or 60% of failure strain for varying durations.
• Mechanical properties were assessed via quasi-static tensile testing to failure.
• Gene expression analysis (Collagen-1-alpha-chain-1, IL-6) was performed using quantitative real-time PCR.

Main Results:

• Loading at 60% of failure strain significantly reduced failure stress within 15 minutes.
• Loading at 30% of failure strain for 5 hours significantly decreased failure stress.
• 1 hour of loading at 30% failure strain increased Collagen-1-alpha-chain-1 and IL-6 gene expression without significant structural damage.

Conclusions:

• The novel cyclic loading system effectively simulates mechanical stress on tendon fascicles.
• Tendon mechanical properties degrade rapidly under high strain, while moderate strain may initiate adaptive responses.
• Interleukin-6 (IL-6) may play a role in tendon adaptation to exercise-induced loading.