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

Abstract

Flexor tendinitis is a common and debilitating injury of elite and recreational athletes. Healing may be improved through intratendinous injection of insulin-like growth factor-I (IGF-I), which has been shown in vitro to stimulate mitogenesis and enhance tendon matrix production. This study investigated the effects of intratendinous injection of IGF-I on tendon healing in an equine model of flexor tendinitis. Collagenase-induced lesions were created in the tensile region of theflexor digitorum superficialis tendon of both forelimbs of eight horses. Treated tendons were injected with 2 microg rhlGF-I intralesionally every other day for 10 injections, while controls received 0.9% NaCl. Tendon fiber deposition and organization were evaluated serially using ultrasonography throughout the 8 week trial period. Following euthanasia, the tendons were harvested and DNA, hydroxyproline, and glycosaminoglycan content determined, mechanical strength and stiffness evaluated, gene expression and spatial arrangement of collagen types I and III assessed by northern blot and in situ hybridization, and tendon fiber architecture assessed by polarized light microscopy. Local soft tissue swelling was reduced in the IGF-I treated limbs. Similarly, lesion size in IGF-I treated tendons was smaller 3 and 4 weeks after initiation of treatment. Cell proliferation and collagen content of the IGF-I treated tendons were increased compared to controls. Mechanically, IGF-I treated tendons showed a trend toward increased stiffness compared to saline treated controls. Considered together with the decreased soft tissue swelling and improved sonographic healing, these data support the potential use of intralesional IGF-I for treatment of debilitating tendon injuries.

• Authors: Linda A Dahlgren, Marjolein C H van der Meulen, John E A Bertram, Greg S Starrak, Alan J Nixon
• Journal: Journal of orthopaedic research : official publication of the Orthopaedic Research Society (J Orthop Res) Vol. 20 Issue 5 Pg. 910-9 (Sep 2002) ISSN: 0736-0266 [Print] United States
• PMID: 12382953 (Publication Type: Journal Article, Research Support, Non-U.S. Gov't)

Chemical References

• RNA, Messenger
• Insulin-Like Growth Factor I
• Collagen
• Collagenases

Topics

• Animals
• Blotting, Northern (veterinary)
• Collagen (genetics, metabolism)
• Collagenases (adverse effects)
• Disease Models, Animal
• Female
• Horse Diseases (chemically induced, drug therapy, pathology)
• Horses
• In Situ Hybridization (veterinary)
• Injections, Intralesional
• Insulin-Like Growth Factor I (administration & dosage)
• Male
• RNA, Messenger (metabolism)
• Stress, Mechanical
• Tendinopathy (chemically induced, drug therapy, pathology, veterinary)
• Tendon Injuries (chemically induced, drug therapy, pathology, veterinary)
• Tendons (diagnostic imaging, drug effects, pathology, physiopathology)
• Ultrasonography
• Wound Healing (drug effects, physiology)