ABSTRACT: Tendons are prominent members of the family of fibrous connective tissues (FCTs), which collectively are the most abundant tissues in vertebrates and have crucial roles in transmitting mechanical force and linking organs. Tendon diseases are among the most common arthropathy disorders; thus knowledge of tendon gene regulation is essential for a complete understanding of FCT biology. Here we show autonomous circadian rhythms in mouse tendon and primary human tenocytes, controlled by an intrinsic molecular circadian clock. Time-series microarrays identified the first circadian transcriptome of murine tendon, revealing that 4.6% of the transcripts (745 genes) are expressed in a circadian manner.
Project description:Tendons are prominent members of the family of fibrous connective tissues (FCTs), which collectively are the most abundant tissues in vertebrates and have crucial roles in transmitting mechanical force and linking organs. Tendon diseases are among the most common arthropathy disorders; thus knowledge of tendon gene regulation is essential for a complete understanding of FCT biology. Here we show autonomous circadian rhythms in mouse tendon and primary human tenocytes, controlled by an intrinsic molecular circadian clock. Time-series microarrays identified the first circadian transcriptome of murine tendon, revealing that 4.6% of the transcripts (745 genes) are expressed in a circadian manner. One of these genes was Grem2, which oscillated in antiphase to BMP signaling. Moreover, recombinant human Gremlin-2 blocked BMP2-induced phosphorylation of Smad1/5 and osteogenic differentiation of human tenocytes in vitro. We observed dampened Grem2 expression, deregulated BMP signaling, and spontaneously calcifying tendons in young CLOCK?19 arrhythmic mice and aged wild-type mice. Thus, disruption of circadian control, through mutations or aging, of Grem2/BMP signaling becomes a new focus for the study of calcific tendinopathy, which affects 1-in-5 people over the age of 50 years.
Project description:Tendons play a critical role in the transmission of forces between muscles and bones, and chronic tendon injuries and diseases are among the leading causes of musculoskeletal disability. For many types of tendinopathies, women have worse clinical outcomes than men. It is possible that sex-based differences in tendon morphology, composition and mechanical properties may explain the greater susceptibility of women to develop tendinopathies. Our objective was to evaluate the mechanical properties, biochemical composition, transcriptome, and cellular activity of plantarflexor tendons from four month old male and female C57Bl/6 mice using in vitro biomechanics, mass spectrometry-based proteomics, genome-wide expression profiling, and cell culture techniques. Differences between groups were tested using t-tests (α=0.05). While the Achilles tendons of male mice were approximately 6% larger than female mice (P<0.05), the cell density of female mice was around 19% larger than males (P<0.05). No significant differences in the length (P=0.34), peak force (P=0.86), peak stress (P=0.52) or energy loss during stretch (P=0.94) of plantaris tendons were observed. Mass spectrometry proteomics analysis revealed no significant difference between sexes in the abundance of major extracellular matrix (ECM) proteins like collagen types I (P=0.30) and III (P=0.68), but female mice had approximately two-fold elevations (P<0.05) in different minor ECM proteins such as fibronectin, periostin, and tenascin. Using microarray analysis, there was no significant differences (P>0.05) in the expression of most major and minor ECM genes, and in the expression of genes involved in tendon fibroblast specification or proliferation. Whole tendon qPCR analysis showed significant expression differences in elastin, scleraxis, and tenomodulin. Cell culture techniques to test the effects of sex-specific extracellular environment on cellular activity show significant differences in gene expression of type I and III collagen, Ki67, scleraxis, and tenomodulin. Histologic analysis demonstrated that males have larger tendon cross-sectional area and lower cell density when compared to females. However, there were no differences between the sexes in the mechanical properties of tendons or in the majority of primary structural extracellular matrix proteins, although elevations were observed in some minor ECM proteins. Microarray analysis also showed no significant sex-based differences in the expression of major genes associated with collagen composition, extracellular components and turnover, and fibroblast proliferation. Cell culture tests of non-autonomous cellular activity show no major signals for ECM synthesis nor fibroblast proliferation. Our results indicate that while male mice expectedly had larger tendons, male and female mice have very similar mechanical properties and biochemical composition, with small increases in minor ECM proteins and proteoglycans in female tendons. The role that these minor ECM proteins and proteoglycans play in tendon repair should be evaluated in future studies. No treatment administered, study done to evaluate normal expression profiles of male and female tenocytes. This analysis is based on a Mouse Gene ST 2.1 strip that was processed in the microarray facility in May 2015 using the wt-pico kit.
Project description:This microarray study compared the gene expression profile of rat tail tendon tissue in three different developmental stages: embryonic day 21, postnatal 3 weeks and postnatal 6 weeks.<br><br><br><br>Key words: rat tail tendon, tissue development, embryonic and postnatal
Project description:Despite the importance of tendons and ligaments for transmitting movement and providing stability to the musculoskeletal system, their development is considerably less well understood than that of the tissues they serve to connect. Zebrafish have been widely used to address questions in muscle and skeletal development, yet few studies describe their tendon and ligament tissues. We have analyzed in zebrafish the expression of several genes known to be enriched in mammalian tendons and ligaments, including scleraxis (scx), collagen 1a2 (col1a2) and tenomodulin (tnmd), or in the tendon-like myosepta of the zebrafish (xirp2a). Co-expression studies with muscle and cartilage markers demonstrate the presence of scxa, col1a2 and tnmd at sites between the developing muscle and cartilage, and xirp2a at the myotendinous junctions. We determined that the zebrafish craniofacial tendon and ligament progenitors are neural crest derived, as in mammals. Cranial and fin tendon progenitors can be induced in the absence of differentiated muscle or cartilage, although neighboring muscle and cartilage are required for tendon cell maintenance and organization, respectively. By contrast, myoseptal scxa expression requires muscle for its initiation. Together, these data suggest a conserved role for muscle in tendon development. Based on the similarities in gene expression, morphology, collagen ultrastructural arrangement and developmental regulation with that of mammalian tendons, we conclude that the zebrafish tendon populations are homologous to their force-transmitting counterparts in higher vertebrates. Within this context, the zebrafish model can be used to provide new avenues for studying tendon biology in a vertebrate genetic system.
Project description:Tendons play a fundamental role in the musculoskeletal system and locomotion by transferring forces generated from muscles to the skeleton. Tendon injuries can occur due to sports related incidents, as a result of trauma to overuse or during disease or ageing. Using proteomic techniques tendon protein profiles could be defined under different conditions. The aim of this study was to optimise tendon sample preparation for mass spectrometry analysis, which will be valuable for future tendon studies.
Project description:Tendons play fundamental role in the musculoskeletal system and locomotion by transferring forces generated by muscles to the skeleton. Chronic tendon injuries and diseases are among the leading causes of musculoskeletal disability. For many types of tendinopathies, women have worse clinical outcomes than men. It is possible that tendon sex-based differences in protein composition are related to an altered injury response. The aim of this study was to compare the proteome of male and female tendon using label-free protein quantification. These data could provide new insight into pathways which may beinvolved in tendinopathies, and potentially in the differential injury response of female tendon.
Project description:PURPOSE:To investigate the difference between sonographic findings in extensor pollicis longus tendons rupture and other finger tendons rupture in patients sustaining hand and wrist trauma. METHODS:Twenty-four patients who presented with signs and symptoms clinically suspicious for tendon injury and surgically confirmed tendon rupture were included in this study. We analyzed 6 sonographic features: discontinuity of the tendon, pseudomass formation, decreased echogenicity of the tendon, retraction of the ruptured tendon, fluid collection within the tendon sheath, and the motion of the tendon. We compared the sonographic features of ruptured extensor pollicis longus tendons with the other ruptured finger tendons. RESULTS:Discontinuity of the tendon was the most common sonographic findings and retraction of the ruptured tendon was the second most common findings. Fourteen of 16 cases with a dynamic study on sonography showed loss of normal motion of the tendon. Pseudomass formation was the second most common feature in ruptured extensor pollicis longus tendons, in contrast to the other ruptured finger tendons (p < 0.05). CONCLUSION:Using ultrasonography, detection of discontinuity of the tendon, retraction of the ruptured tendon, and limitation of tendon motion could be very helpful for diagnosing a tendon rupture in hand and wrist trauma. Pseudomass formation could be more specific for diagnosing extensor pollicis longus tendon ruptures compared with other finger tendons.
Project description:We have compared the gene expression profile of post-natal 1 day and 7 day rat Achilles tendons. Post-natal 1 day and 7 day rat Achilles tendons were collected. Each sample contains at least two individuals. Total RNA was extracted and fragmented biotin-tagged cRNA was hybridized to Rat Genome 230 2.0 Array.
Project description:The long tendons of the limb extend from muscles that reside in the zeugopod (arm/leg) to their skeletal insertions in the autopod (paw). How these connections are established along the length of the limb remains unknown. Here, we show that mouse limb tendons are formed in modular units that combine to form a functional contiguous structure; in muscle-less limbs, tendons develop in the autopod but do not extend into the zeugopod, and in the absence of limb cartilage the zeugopod segments of tendons develop despite the absence of tendons in the autopod. Analyses of cell lineage and proliferation indicate that distinct mechanisms govern the growth of autopod and zeugopod tendon segments. To elucidate the integration of these autopod and zeugopod developmental programs, we re-examined early tendon development. At E12.5, muscles extend across the full length of a very short zeugopod and connect through short anlagen of tendon progenitors at the presumptive wrist to their respective autopod tendon segment, thereby initiating musculoskeletal integration. Zeugopod tendon segments are subsequently generated by proximal elongation of the wrist tendon anlagen, in parallel with skeletal growth, underscoring the dependence of zeugopod tendon development on muscles for tendon anchoring. Moreover, a subset of extensor tendons initially form as fused structures due to initial attachment of their respective wrist tendon anlage to multiple muscles. Subsequent individuation of these tendons depends on muscle activity. These results establish an integrated model for limb tendon development that provides a framework for future analyses of tendon and musculoskeletal phenotypes.
Project description:Autogenous hamstring harvesting for knee ligament reconstruction is a well-established standard. Minimally invasive posterior hamstring harvest is a simple, efficient, reproducible technique for harvest of the semitendinosus or gracilis tendon or both medial hamstring tendons. A 2- to 3-cm longitudinal incision from the popliteal crease proximally, in line with the semitendinosus tendon, is sufficient. The deep fascia is bluntly penetrated, and the tendon or tendons are identified. Adhesions are dissected. Then, an open tendon stripper is used to release the tendon or tendons proximally; a closed, sharp tendon stripper is used to release the tendon or tendons from the pes. Layered, absorbable skin closure is performed, and the skin is covered with a skin sealant, bolster dressing, and plastic adhesive bandage for 2 weeks.