title: Local trauma in human patellar tendon leads to widespread changes in the tendon gene expression.
abstract: Low cellular activity and slow tissue turnover in human tendon may prolong resolution of tendinopathy. This may be stimulated by moderate localized traumas such as needle penetrations, but whether this results in a widespread cellular response in tendons is unknown. In an initial hypothesis-generating study, a trauma-induced tendon cell activity (increased total RNA and collagen I mRNA) was observed after repeated patellar tendon biopsies in young men. In a subsequent controlled study, 25 young men were treated with two 0.8-mm-diameter needle penetrations [n = 13, needle-group (NG)] or one 2.1-mm-diameter needle biopsy [n = 12, biopsy-group (BG)] in one patellar tendon. Four weeks later biopsies were taken from treated (5 mm lateral from trauma site) and contralateral tendons for analyses of RNA content (ribogreen assay), DNA content (PCR based), and gene expression for relevant target genes (Real-time RT-PCR) (NG, n = 11 and BG, n = 8). Intervention increased RNA content, and mRNA expression of collagen I and III and TGF-β1 (P < 0.05), with biopsy treatment having greatest effect (tendency for RNA and collagen I). Results for DNA content were inconclusive, and no changes were detected in expression of insulin-like growth factor-I, connective tissue growth factor, scleraxis, decorin, fibromodulin, tenascin-C, tenomodulin, VEGFa, CD68, IL-6, MMP12, and MMP13. In conclusion, a moderate trauma to a healthy human tendon (e.g., biopsy sampling) results in a widespread upregulation of tendon cell activity and their matrix protein expression. The findings have implications for design of studies on human tendon and may provide perspectives in future treatment strategies in tendinopathy.
authors.affiliation: Department of Biomedical Sciences, Center for Healthy Aging, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark; Institute of Sports Medicine, Department of Orthopaedic Surgery M, Bispebjerg Hospital, Center for Healthy Aging, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark; kh@sund.ku.dk.
authors.forename: Katja M
authors.identifier: 0000-0003-4888-5808
authors.initials: KM
authors.lastname: Heinemeier
authors.affiliation: Institute of Sports Medicine, Department of Orthopaedic Surgery M, Bispebjerg Hospital, Center for Healthy Aging, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark;
authors.forename: Marc P
authors.initials: MP
authors.lastname: Lorentzen
authors.affiliation: Institute of Sports Medicine, Department of Orthopaedic Surgery M, Bispebjerg Hospital, Center for Healthy Aging, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark;
authors.forename: Jacob K
authors.initials: JK
authors.lastname: Jensen
authors.affiliation: Institute of Sports Medicine, Department of Orthopaedic Surgery M, Bispebjerg Hospital, Center for Healthy Aging, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark;
authors.forename: Peter
authors.identifier: 0000-0001-7138-3211
authors.initials: P
authors.lastname: Schjerling
authors.affiliation: Department of Physical Performance, Norwegian School of Sport Sciences, Oslo, Norway; and.
authors.forename: Olivier R
authors.initials: OR
authors.lastname: Seynnes
authors.affiliation: Institute for Biomedical Research into Human Movement and Health, Manchester Metropolitan University, Manchester, United Kingdom.
authors.forename: Marco V
authors.initials: MV
authors.lastname: Narici
authors.affiliation: Institute of Sports Medicine, Department of Orthopaedic Surgery M, Bispebjerg Hospital, Center for Healthy Aging, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark;
authors.forename: Michael
authors.initials: M
authors.lastname: Kjaer
mesh_terms: D004247:DNA / Q000378:metabolism; D015870:Gene Expression / Q000502:physiology*; D006801:Humans; D008297:Male; D017847:Patellar Ligament / Q000378:metabolism / Q000502:physiology*; D011506:Proteins / Q000378:metabolism; D012333:RNA, Messenger / Q000378:metabolism; D052256:Tendinopathy / Q000378:metabolism; D013710:Tendons / Q000378:metabolism / Q000502:physiology*; D014947:Wounds and Injuries / Q000378:metabolism
chemical_list: D011506:Proteins; D012333:RNA, Messenger; D004247:DNA
keywords: injury; tendon fat; total RNA; trauma