Insulin-like growth factor-I improves cellular and molecular aspects of healing in a collagenase-induced model of flexor tendinitis.

This research explored the effects of insulin-like growth factor-I (IGF-I) injections on the healing process of flexor tendinitis in horses. It found that this method could reduce swelling, decrease lesion size, amplify cell proliferation, increase collagen content, and potentially strengthen tendons.

Research Background

• Flexor tendinitis is a common condition that affects both elite and recreational athletes, resulting in significant discomfort and disability. This research aimed to discover a more effective treatment method.
• The research hypothesized that administering insulin-like growth factor-I (IGF-I) injections to tendons could stimulate mitogenesis (cell division), enhance tendon matrix manufacturing, and accelerate the healing process.

Experiment Methodology

• In this study, an equine model was used to experiment with this new treatment method. Collagenase-induced lesions were artificially created in the flexor digitorum superficialis tendons of eight horses.
• IGF-I was then injected into the lesion every other day for 10 injections. The control group received normal saline (0.9% NaCl) injections.
• Throughout the 8-week trial period, tendon fiber deposition and organization were continually monitored and evaluated using ultrasonography.
• After euthanasia, the tendons were harvested and their DNA, hydroxyproline, and glycosaminoglycan content were examined. The tendons’ strength, stiffness, and the arrangement of collagen types I and III were also assessed.

Research Findings

• IGF-I treated limbs displayed reduced local soft tissue swelling compared to control group limbs. Also, lesion size in IGF-I treated tendons was smaller three and four weeks after treatment began.
• Cell proliferation and collagen content were found to be higher in IGF-I treated tendons compared to the control group’s tendons. IGF-I treated tendons also showed a trend toward increased stiffness.
• The reduced soft tissue swelling, decline in lesion size, increase in cell proliferation, collagen content, and improved sonographic healing pointed towards a potential use of intralesional IGF-I injections for treating debilitating tendon injuries.