title: Ageing does not result in a decline in cell synthetic activity in an injury prone tendon.
abstract: Advancing age is a well-known risk factor for tendon disease. Energy-storing tendons [e.g., human Achilles, equine superficial digital flexor tendon (SDFT)] are particularly vulnerable and it is thought that injury occurs following an accumulation of micro-damage in the extracellular matrix (ECM). Several authors suggest that age-related micro-damage accumulates due to a failure of the aging cell population to maintain the ECM or an imbalance between anabolic and catabolic pathways. We hypothesized that ageing results in a decreased ability of tendon cells to synthesize matrix components and matrix-degrading enzymes, resulting in a reduced turnover of the ECM and a decreased ability to repair micro-damage. The SDFT was collected from horses aged 3-30 years with no signs of tendon injury. Cell synthetic and degradative ability was assessed at the mRNA and protein levels. Telomere length was measured as an additional marker of cell ageing. There was no decrease in cellularity or relative telomere length with increasing age, and no decline in mRNA or protein levels for matrix proteins or degradative enzymes. The results suggest that the mechanism for age-related tendon deterioration is not due to reduced cellularity or a loss of synthetic functionality and that alternative mechanisms should be considered.
authors.affiliation: Institute of Orthopaedics and Musculoskeletal Science, Royal National Orthopaedic Hospital, University College London, Stanmore, UK.
authors.forename: C T
authors.initials: CT
authors.lastname: Thorpe
authors.affiliation: Department of Musculoskeletal Biology, University of Liverpool, Cheshire, UK.
authors.forename: B T
authors.initials: BT
authors.lastname: McDermott
authors.affiliation: Institute of Orthopaedics and Musculoskeletal Science, Royal National Orthopaedic Hospital, University College London, Stanmore, UK.
authors.forename: A E
authors.initials: AE
authors.lastname: Goodship
authors.affiliation: Department of Musculoskeletal Biology, University of Liverpool, Cheshire, UK.
authors.forename: P D
authors.initials: PD
authors.lastname: Clegg
authors.affiliation: Institute of Orthopaedics and Musculoskeletal Science, Royal National Orthopaedic Hospital, University College London, Stanmore, UK.
authors.forename: H L
authors.initials: HL
authors.lastname: Birch
mesh_terms: D000072199:ADAM12 Protein / Q000235:genetics; D000072198:ADAM17 Protein / Q000235:genetics; D000071096:ADAMTS Proteins / Q000235:genetics; D000375:Aging / Q000378:metabolism* / Q000473:pathology; D000818:Animals; D004247:DNA / Q000378:metabolism; D005109:Extracellular Matrix / Q000502:physiology*; D006736:Horses; D020782:Matrix Metalloproteinases / Q000235:genetics / Q000378:metabolism*; D010446:Peptide Fragments / Q000096:biosynthesis*; D011347:Procollagen / Q000096:biosynthesis*; D012333:RNA, Messenger / Q000378:metabolism; D059506:Telomere Shortening; D013710:Tendons / Q000166:cytology* / Q000201:enzymology / Q000378:metabolism*; D019717:Tissue Inhibitor of Metalloproteinase-3 / Q000235:genetics; D019714:Tissue Inhibitor of Metalloproteinases / Q000235:genetics; D000097792:Tissue Inhibitor of Metalloproteinase-4
chemical_list: D000072199:ADAM12 Protein; D000072198:ADAM17 Protein; D000071096:ADAMTS Proteins; D004247:DNA; D020782:Matrix Metalloproteinases; D010446:Peptide Fragments; D011347:Procollagen; D012333:RNA, Messenger; D019717:Tissue Inhibitor of Metalloproteinase-3; D019714:Tissue Inhibitor of Metalloproteinases; D000097792:Tissue Inhibitor of Metalloproteinase-4; C047202:procollagen Type I N-terminal peptide
keywords: Tendon; ageing; degeneration; metabolism; telomere; tenocyte