Project description:Adhesion formation after flexor tendon repair remains a clinical problem. Early postoperative motion after tendon repair has been demonstrated to reduce adhesion formation while increasing tendon strength. It is hypothesized that during mobilization, tendon cells experience mechanical shear forces that alter their biology in a fashion that reduces scar formation but also activates key genes involved in tendon healing. To test this hypothesis, primary intrinsic tenocyte cultures were established from flexor tendons of 20 Sprague-Dawley rats and sheared at 50 rpm (0.41 Pa) using a cone viscometer for 6 and 12 hours. Total RNA was harvested and compared with time-matched unsheared controls using cDNA microarrays and Northern blot analysis. Microarray analysis demonstrated that mechanical shear stress induced an overall "antifibrotic" expression pattern with decreased transcription of collagen type I and collagen type III. Shear stress down-regulated profibrotic molecules in the platelet-derived growth factor, insulin-like growth factor, and fibroblast growth factor signaling pathways. In addition, shear stress induced an overall decrease in transforming growth factor (TGF)-beta signaling pathway molecules with down-regulation of TGF-beta2, TGF-beta3, TGF-RI, and TGF-RII expression. Moreover, sheared tendon cells increased expression of matrix metalloproteinases and decreased expression of tissue inhibitors of metalloproteinase, an expression pattern consistent with an antifibrotic increase in extracellular matrix degradation. However, up-regulation of genes implicated in tendon healing, specifically, vascular endothelial growth factor-A and several bone morphogenetic proteins. Interestingly, the known mechanoresponsive gene, TGF-beta1, also implicated in tendon healing, was differentially up-regulated by shear stress. Northern blot validation of our results for TGF-beta1, TGF-beta2, TGF-beta3, and collagen type I demonstrated direct correlation with microarray data.

Project description:Adhesion formation after flexor tendon repair remains a clinical problem. Early postoperative motion after tendon repair has been demonstrated to reduce adhesion formation while increasing tendon strength. It is hypothesized that during mobilization, tendon cells experience mechanical shear forces that alter their biology in a fashion that reduces scar formation but also activates key genes involved in tendon healing. To test this hypothesis, primary intrinsic tenocyte cultures were established from flexor tendons of 20 Sprague-Dawley rats and sheared at 50 rpm (0.41 Pa) using a cone viscometer for 6 and 12 hours. Total RNA was harvested and compared with time-matched unsheared controls using cDNA microarrays and Northern blot analysis. Microarray analysis demonstrated that mechanical shear stress induced an overall "antifibrotic" expression pattern with decreased transcription of collagen type I and collagen type III. Shear stress down-regulated profibrotic molecules in the platelet-derived growth factor, insulin-like growth factor, and fibroblast growth factor signaling pathways. In addition, shear stress induced an overall decrease in transforming growth factor (TGF)-beta signaling pathway molecules with down-regulation of TGF-beta2, TGF-beta3, TGF-RI, and TGF-RII expression. Moreover, sheared tendon cells increased expression of matrix metalloproteinases and decreased expression of tissue inhibitors of metalloproteinase, an expression pattern consistent with an antifibrotic increase in extracellular matrix degradation. However, up-regulation of genes implicated in tendon healing, specifically, vascular endothelial growth factor-A and several bone morphogenetic proteins. Interestingly, the known mechanoresponsive gene, TGF-beta1, also implicated in tendon healing, was differentially up-regulated by shear stress. Northern blot validation of our results for TGF-beta1, TGF-beta2, TGF-beta3, and collagen type I demonstrated direct correlation with microarray data. Groups of assays that are related as part of a time series. Computed

Project description:Healing process after connective tissues (CT) injury is complex but important as CT are critical for human moving, and patient outcome of CT injured patients is protracted with high individual variation. Specific markers which could be used for healing prognosis will be great help to monitor patient outcome, and furtherly improve target treatment and patient recovery. Although several common factors like age, gender and body mass index (BMI) were reported to predict ATR healing outcome [references], more specific markers which can be used as predictors of patient outcome after ATR are still lacking. Several biomarkers have been reported to associate with tendon healing, and indicated their relationship with patient outcome(1-4). These results highlight the potential of protein expression detection and analysis for tendon study in general and healing outcome prognosis in particular. Collagen type I (Col1a1) is the main component of Achilles tendon and plays vital role in tendon healing via involving in collagen fibrils production among tendon fibroblasts(5). Higher production of Col1a1 is associated with faster tendon repair(6), previous study on animal model reported the increased Col1a1 synthesis can exert a positive effect on tendon healing[?]. Thus, functional proteins with high impact on Col1a1 can be used not only to improve tendon healing, also can be as targets for healing improvement and outcome prediction. The proteome file of Achilles tendon which is important to increase understanding of tendon healing and help to identify accurate outcome-related biomarkers is however lagged behind. The identification of proteomic profile of Achilles tendon is very much limited in number of proteins and sample size(7-9), and is even few on human. Recent improvement in proteomic assay based on mass spectrometry (MS) made it possible to assemble the proteomic landscape of human tissues(10, 11) with high quality and sensitivity. To characterize the proteomic components in human Achilles tendon, we utilized biopsies from ATR patients with both good and poor 1-year healing outcome. A validated platform including quantitative MS and clinical database was used to identify proteomic landscape and potential bio-predictors of clinical outcome. Our study may provide a more comprehensive landscape of proteins for human Achilles tendon, as well as specific biomarkers which can be used for long term outcome prognosis after ATR.

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Mechanical shear effects on flexor tendon cells

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