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Local administration of insulin-like growth factor-I (IGF-I) stimulates tendon collagen synthesis in humans

Authors

  • M. Hansen,

    Corresponding author
    1. Department of Endocrinology and Internal Medicine, Aarhus University Hospital and The Medical Research Laboratories, Institute of Clinical Medicine, Faculty of Health Sciences, Aarhus University, Aarhus, Denmark
    • Institute of Sports Medicine, Department of Orthopedic Surgery M81, Bispebjerg Hospital and Center for Healthy Aging, Faculty of Health Sciences, University of Copenhagen, Copenhagen, Denmark
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  • A. Boesen,

    1. Institute of Sports Medicine, Department of Orthopedic Surgery M81, Bispebjerg Hospital and Center for Healthy Aging, Faculty of Health Sciences, University of Copenhagen, Copenhagen, Denmark
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  • L. Holm,

    1. Institute of Sports Medicine, Department of Orthopedic Surgery M81, Bispebjerg Hospital and Center for Healthy Aging, Faculty of Health Sciences, University of Copenhagen, Copenhagen, Denmark
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  • A. Flyvbjerg,

    1. Department of Endocrinology and Internal Medicine, Aarhus University Hospital and The Medical Research Laboratories, Institute of Clinical Medicine, Faculty of Health Sciences, Aarhus University, Aarhus, Denmark
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  • H. Langberg,

    1. Institute of Sports Medicine, Department of Orthopedic Surgery M81, Bispebjerg Hospital and Center for Healthy Aging, Faculty of Health Sciences, University of Copenhagen, Copenhagen, Denmark
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  • M. Kjaer

    1. Institute of Sports Medicine, Department of Orthopedic Surgery M81, Bispebjerg Hospital and Center for Healthy Aging, Faculty of Health Sciences, University of Copenhagen, Copenhagen, Denmark
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Corresponding author: Mette Hansen, Institute of Sports Medicine, Copenhagen, Build. 8, Bispebjerg Hospital, Bispebjerg Bakke 23, DK-2400 Copenhagen NV, Denmark. Tel: +45 35 31 60 89, Fax: +45 35 31 27 33, E-mail: kontakt@mettehansen.nu

Abstract

Collagen is the predominant structural protein in tendons and ligaments, and can be controlled by hormonal changes. In animals, injections of insulin-like growth factor I (IGF-I) has been shown to increase collagen synthesis in tendons and ligaments and to improve structural tissue healing, but the effect of local IGF-I administration on tendon collagen synthesis in human has not been studied. The purpose of this study was to study whether local injections of IGF-I would have a stimulating effect on tendon collagen synthesis. Twelve healthy nonsmoking men [age 62 ± 1 years (mean ± SEM), BMI 27 ± 1] participated. Two injections of either human recombinant IGF-I (0.1 mL Increlex©) or saline (control) into each patellar tendon were performed 24-h apart, respectively. Tendon collagen fractional synthesis rate (FSR) was measured by stable isotope technique in the hours after the second injection. Simultaneously, interstitial peritendinous (IGF-I) and [procollagen type I N-terminal propeptide (PINP)], as a marker for type I collagen synthesis, were determined by microdialysis technique. Tendon collagen FSR and PINP were significantly higher in the IGF-I leg compared with the control leg (P < 0.05). In conclusion, local IGF-I administration can directly enhance tendon collagen synthesis both within and around the human tendon tissue.

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