Tendon overload results in alterations in cell shape and increased markers of inflammation and matrix degradation.

This research studied how cells in horse tendons respond to heavy loads, observing indications of inflammation and breakdown in the tendon structure. The study suggests that these responses could be key in understanding the onset of a tendon disease known as tendinopathy.

Objective and Methodology

• The research aimed at understanding how the cells within a tendon react to extreme cyclic overloads that often mimic high-intensity exercise. This understanding is critical in discovering the root causes of tendinopathy, a tendon disease.
• The researchers conducted this study by subjecting bundles of fascicle, which are from the equine superficial digital flexor tendon, to cyclic loadings in a carefully controlled laboratory environment.

Findings and Analysis

• The study discovered that extreme loading resulted in damage to the matrix that makes up the tendon. This matrix damage subsequently leads to changes in cell shapes, making them rounder than usual.
• Damage to the tendon also triggered an increase in markers indicating inflammation and matrix degradation. Cyclooxygenase-2 and interleukin-6, which are markers for inflammation, were detected in higher levels in loaded samples.
• Similarly, an increase was also observed in the matrix metalloproteinase-13, a marker that relates to tissue remodelling and collagen degradation marker C1,2C, which indicates the collagen breakdown in the tendon.

Implications and Conclusions

• The study therefore suggests that heavy loading initiates upregulation of inflammatory and degradative pathways within the tendon. Furthermore, this may be triggered by changes in cell strain resulting from localized tendon damage.
• This provides vital insights into the commencement of tendinopathy, emphasizing that inflammation might play a significant role in the early cellular response to tendon damage. The research concludes that full comprehension of the initial response of tendon cells to matrix damage is key in formulating effective treatments for tendinopathy.