TY - JOUR

T1 - Local trauma in human patellar tendon leads to widespread changes in the tendon gene expression

AU - Heinemeier, Katja Maria

AU - Lorentzen, Marc P

AU - Kildevang Jensen, Jacob

AU - Schjerling, Peter

AU - Sennes, Olivier

AU - Narici, Marco

AU - Kjær, Michael

PY - 2016/5/1

Y1 - 2016/5/1

N2 - 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-ß1 (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 up-regulation 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.

AB - 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-ß1 (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 up-regulation 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.

U2 - 10.1152/japplphysiol.00870.2015

DO - 10.1152/japplphysiol.00870.2015

M3 - Journal article

C2 - 26769953

VL - 120

SP - 1000

EP - 1010

JO - Journal of Applied Physiology

JF - Journal of Applied Physiology

SN - 8750-7587

IS - 9

ER -