Biochemical and site-specific effects of insulin-like growth factor I on intrinsic tenocyte activity in equine flexor tendons.
Abstract: To examine the site-specific and dose-dependent effects of insulin-like growth factor I (IGF-I) on normal equine tendon in vitro. Methods: Superficial digital flexor tendon explants derived from a euthanatized 3-year-old horse. Methods: Explants in culture were treated with 0, 100, 250, or 500 ng of IGF-I/ml for 14 days with an end-stage radiolabel of 20 microCi of [3H]proline/ml or 5 microCi of [3H]thymidine/ml. The tendon tissues were then analyzed biochemically for hydroxyproline content by reverse-phase high-performance liquid chromatography, DNA content by fluorometry, and glycosaminoglycan content by the dimethylmethylene blue dye-binding assay. In addition, morphologic analysis of the explants comprised histologic examination, autoradiography, and immunohistochemistry. Results: Hydroxyproline content was significantly increased in explants treated with 100 and 250 ng of IGF-I/ml. Additionally, the collagen synthetic rate, measured by incorporation of [3H]proline into hydroxyproline, was significantly increased for all treatment groups. On the basis of autoradiograms, fibroblast proliferation and collagen synthesis were predominantly confined to the endcap and adjacent endotenon of the explants. Enhanced immunoreactivity for type-I collagen, compared with type-III collagen, was evident in the treated explants, an observation supported by positive staining for type-I collagen with picrosirius red. Histologically, treated explants contained greater numbers of larger and more metabolically active fibroblasts, compared with untreated controls. Conclusions: IGF-I enhances collagen synthesis in normal equine flexor tendon in a dose-dependent manner. IGF-I also exerts its primary effect on cell proliferation and collagen synthesis in the epitenon and adjacent endotenon and accompanying perivascular connective tissues, consistent with enhancement of intrinsic tendon metabolism. Conclusions: IGF-I may have a potential role in the treatment of tendinitis in horses.
Publication Date: 1997-01-01 PubMed ID: 8989505
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- Journal Article
- Research Support
- Non-U.S. Gov't
Summary
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This study investigates the specific and varying effects of insulin-like growth factor I (IGF-I) on healthy horse tendons in a controlled environment. The main finding is that IGF-I can enhance the production of collagen in these tendons, suggesting potential usefulness in the treatment of equine tendonitis.
Methodology
- The researchers derived explants from the superficial digital flexor tendon of a 3-year-old horse that had been euthanatized.
- These explants were cultured and treated with varying dosages of IGF-I for a period of 14 days.
- Subsequent analysis of the tendon tissues allowed the researchers to assess the hydroxyproline content, DNA content, and glycosaminoglycan content by utilising various assays and chromatography techniques. Additionally, the researchers used morphologic analysis techniques including histologic examination, autoradiography, and immunohistochemistry.
Results
- The hydroxyproline content, which is a major component of the protein collagen, was found to be significantly increased in explants treated with 100 and 250 ng of IGF-I per milliliter.
- The collagen synthetic rate was also significantly escalated in all treatment groups, which was measured by the incorporation of proline into hydroxyproline
- Based on autoradiograms, the scientists noticed that fibroblast proliferation and collagen synthesis was mainly confined to the endcap and adjacent endotenon of the explants.
- Increased immunoreactivity for type-I collagen was noted in treated explants, along with an increase in the number of active fibroblasts.
Conclusions
- The study concluded that IGF-I enhances collagen synthesis in healthy horse tendons in a dose-dependent manner.
- The primary effect of IGF-I is found to be on cell proliferation and collagen synthesis in the epitenon and tandem endotenon along with perivascular connective tissues.
- The study hints at a potential role of IGF-I in the treatment of tendinitis in horses, but more research in this direction is necessary.
Cite This Article
APA
Murphy DJ, Nixon AJ.
(1997).
Biochemical and site-specific effects of insulin-like growth factor I on intrinsic tenocyte activity in equine flexor tendons.
Am J Vet Res, 58(1), 103-109.
Publication
Researcher Affiliations
- Comparative Orthopaedics Laboratory, College of Veterinary Medicine, Cornell University, Ithaca, NY 14853, USA.
MeSH Terms
- Animals
- Autoradiography / methods
- Autoradiography / veterinary
- Cell Division / drug effects
- Cell Division / physiology
- Chromatography, High Pressure Liquid / methods
- Chromatography, High Pressure Liquid / veterinary
- Collagen / metabolism
- DNA / analysis
- DNA / metabolism
- Dose-Response Relationship, Drug
- Glycosaminoglycans / analysis
- Glycosaminoglycans / metabolism
- Horses / metabolism
- Horses / physiology
- Hydroxyproline / analysis
- Hydroxyproline / metabolism
- Immunohistochemistry
- Insulin-Like Growth Factor I / pharmacology
- Organ Culture Techniques
- Proline / analysis
- Proline / metabolism
- Tendons / cytology
- Tendons / drug effects
- Tendons / metabolism
- Thymidine / analysis
- Thymidine / metabolism
- Tritium
Citations
This article has been cited 9 times.- Miescher I, Rieber J, Calcagni M, Buschmann J. In Vitro and In Vivo Effects of IGF-1 Delivery Strategies on Tendon Healing: A Review. Int J Mol Sci 2023 Jan 25;24(3).
- Roberts JH, Halper J. Growth Factor Roles in Soft Tissue Physiology and Pathophysiology. Adv Exp Med Biol 2021;1348:139-159.
- Siadat SM, Zamboulis DE, Thorpe CT, Ruberti JW, Connizzo BK. Tendon Extracellular Matrix Assembly, Maintenance and Dysregulation Throughout Life. Adv Exp Med Biol 2021;1348:45-103.
- Citeroni MR, Ciardulli MC, Russo V, Della Porta G, Mauro A, El Khatib M, Di Mattia M, Galesso D, Barbera C, Forsyth NR, Maffulli N, Barboni B. In Vitro Innovation of Tendon Tissue Engineering Strategies. Int J Mol Sci 2020 Sep 14;21(18).
- Barbon S, Stocco E, Macchi V, Contran M, Grandi F, Borean A, Parnigotto PP, Porzionato A, De Caro R. Platelet-Rich Fibrin Scaffolds for Cartilage and Tendon Regenerative Medicine: From Bench to Bedside. Int J Mol Sci 2019 Apr 5;20(7).
- Ramos JE, Al-Nakkash L, Peterson A, Gump BS, Janjulia T, Moore MS, Broderick TL, Carroll CC. The soy isoflavone genistein inhibits the reduction in Achilles tendon collagen content induced by ovariectomy in rats. Scand J Med Sci Sports 2012 Oct;22(5):e108-14.
- Onambele-Pearson GL, Pearson SJ. The magnitude and character of resistance-training-induced increase in tendon stiffness at old age is gender specific. Age (Dordr) 2012 Apr;34(2):427-38.
- Scott A, Sampaio A, Abraham T, Duronio C, Underhill TM. Scleraxis expression is coordinately regulated in a murine model of patellar tendon injury. J Orthop Res 2011 Feb;29(2):289-96.
- Doessing S, Heinemeier KM, Holm L, Mackey AL, Schjerling P, Rennie M, Smith K, Reitelseder S, Kappelgaard AM, Rasmussen MH, Flyvbjerg A, Kjaer M. Growth hormone stimulates the collagen synthesis in human tendon and skeletal muscle without affecting myofibrillar protein synthesis. J Physiol 2010 Jan 15;588(Pt 2):341-51.
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