Tendon Samples Research Articles

Interleukin-17 Cytokines and Receptors: Potential Amplifiers of Tendon Inflammation.

Interleukin (IL)-17A, a pro-inflammatory cytokine that is linked to the pathology of several inflammatory diseases, has been shown to be upregulated in early human tendinopathy and to mediate inflammatory and tissue remodelling events. However, it remains unclear which cells in tendons can respond to IL-17A, and how IL-17A, and its family members IL-17F and IL-17AF, can affect intracellular signalling activation and mRNA expression in healthy and diseased tendon-derived fibroblasts. Using well-phenotyped human tendon samples, we show that IL-17A and its receptors IL-17RA and IL-17RC are present in healthy hamstring, and tendinopathic and torn supraspinatus tendon tissue. Next, we investigated the effects of IL-17A, IL-17F, or IL-17AF on cultured patient-derived healthy and diseased tendon-derived fibroblasts. In these experiments, IL-17A treatment significantly upregulated IL6, MMP3, and PDPN mRNA expression in diseased tendon-derived fibroblasts. IL-17AF treatment induced moderate increases in these target genes, while little change was observed with IL-17F. These trends were reflected in the activation of intracellular signalling proteins p38 and NF-B p65, which were significantly increased by IL-17A, modestly increased by IL-17AF, and not increased by IL-17F. In combination with TNF-α, all three IL-17 cytokines induced IL6 and MMP3 mRNA expression to similar levels. Therefore, this study confirms that healthy and diseased tendon-derived fibroblasts are responsive to IL-17 cytokines and that IL-17A induces the most profound intracellular signalling activation and mRNA expression of inflammatory genes, followed by IL-17AF, and finally IL-17F. The ability of IL-17 cytokines to induce a direct response and activate diverse pro-inflammatory signalling pathways through synergy with other inflammatory mediators suggests a role for IL-17 family members as amplifiers of tendon inflammation and as potential therapeutic targets in tendinopathy.

The Development of a Gracilis and Quadriceps Tendons Calibration Device for Uniaxial Tensile Tests

To determine the biomechanical properties of the distal tendon of the gracilis muscle and the upper third of the quadriceps femoris muscle used for reconstruction of the medial patellofemoral ligament (MPFL), it is necessary to develop a calibration device for specimen preparation for uniaxial tensile tests. The need to develop this device also stems from the fact that there is currently no suitable regulatory or accurate protocol by which soft tissues such as tendons should be tested. In recent studies, various methods have been used to prepare test specimens, such as the use of different ratios of gauge lengths, different gripping techniques, etc., with the aim of obtaining measurable and comparable biomechanical tissue properties. Since tendons, as anisotropic materials, have viscoelastic properties, the guideline for manufacturing calibrator devices was the ISO 527-1:1993 standard, used for testing polymers, since they also have viscoelastic behaviour. The functionality of a calibrator device was investigated by preparing gracilis and quadriceps tendon samples. Fused deposition modeling (FDM) technology was used for the manufacturing of parts with complex geometry. The proposed calibrator could operate in two positions, horizontal and vertical. The maximum gauge length to be achieved was 60 mm, with the maximum tendon length of 120 mm. The average preparation time was 3 min per tendon. It was experimentally proven that it is possible to use a calibrator to prepare tendons for tensile tests. This research can help in the further development of soft tissue testing devices and also in the establishment of standards and exact protocols for their testing.

Effects of aging on the histology and biochemistry of rat tendon healing

IntroductionTendon diseases and injuries are a serious problem for the aged population, often leading to pain, disability and a significant decline in quality of life. The purpose of this study was to determine the influence of aging on biochemistry and histology during tendon healing and to provide a new strategy for improving tendon healing.MethodA total of 24 Sprague-Dawley rats were equally divided into a young and an aged group. A rat patellar tendon defect model was used in this study. Tendon samples were collected at weeks 2 and 4, and hematoxylin-eosin, alcian blue and immunofluorescence staining were performed for histological analysis. Meanwhile, reverse transcription-polymerase chain reaction (RT-PCR) and western blot were performed to evaluate the biochemical changes.ResultsThe histological scores in aged rats were significantly lower than those in young rats. At the protein level, collagen synthesis-related markers Col-3, Matrix metalloproteinase-1 and Metallopeptidase Inhibitor 1(TIMP-1) were decreased at week 4 in aged rats compared with those of young rats. Though there was a decrease in the expression of the chondrogenic marker aggrecan at the protein level in aged tendon, the Micro-CT results from weeks 4 samples showed no significant difference(p>0.05) on the ectopic ossification between groups. Moreover, we found more adipocytes accumulated in the aged tendon defect with the Oil Red O staining and at the gene and protein levels the markers related to adipogenic differentiation.ConclusionsOur findings indicate that tendon healing is impaired in aged rats and is characterized by a significantly lower histological score, decreased collagen synthesis and more adipocyte accumulation in patellar tendon after repair.

Softening Effects in Biological Tissues and NiTi Knitwear during Cyclic Loading.

Samples of skin, tendons, muscles, and knitwear composed of NiTi wire are studied by uniaxial cyclic tension and stretching to rupture. The metal knitted mesh behaves similar to a superelastic material when stretched, similar to soft biological tissues. The superelasticity effect was found in NiTi wire, but not in the mesh composed of it. A softening effect similar to biological tissues is observed during the cyclic stretching of the mesh. The mechanical behavior of the NiTi mesh is similar to the biomechanical behavior of biological tissues. The discovered superelastic effects allow developing criteria for the selection and evaluation of mesh materials composed of titanium nickelide for soft tissue reconstructive surgery.

Evaluation of cytokines in protective effect of docosahexaenoic acid in experimental achilles tendinopathy rat model induced with type-1 collagenase

ABSTRACT Background We aimed to investigate the effectiveness of docosahexaenoic acid (DHA) as a treatment for Achilles tendinopathy (AT) induced with type-I collagenase in rats and compare it with collagen. Methods The AT model was induced with type I collagenase, and animals were randomly assigned to groups. Group 1:AT, Group 2: Collagen (7.2 mg/kg/day), Group 3:DHA (300 mg/kg/day), and Group 4:DHA (100 mg/kg/day). Right tendons of Group1 were used as a healthy control (HC). Oral treatments were applied for eight weeks. Serum tumor necrosis factor-alpha(TNF-α), matrix metalloproteinase-13 (MMP-13), and interleukin-1 beta(IL-1β) concentrations were determined by ELISA. Tendon samples were taken for histopathological evaluation and examined immunohistochemically with antibodies specific for Col1A1, TNF-α, MMP-13, IL-1β, and nitric oxide synthase-2(NOS-2). The ultimate tensile force (UTF) yield force(YF) and stiffness were measured by biomechanical assessments. Results UTF,YF and stiffness values were increased in all treatment groups compared to the AT control, a significant increase was found in Group 2 (p < 0.05). There was severe degeneration of tendon cells in the AT control. The tendon cells in samples from Groups 2-3 were less degraded, and this was statistically significant (p < 0.05). TNF-α, MMP-13, IL-1β, and NOS-2 expressions were significantly higher in the AT control compared to the HC. In all treatment groups, their concentrations were lower than in the AT control. Serum TNF-α, MMP-13, and IL-1β levels were lower in all treatment groups (Especially in Group3 (p < 0.001)) compared to Group1. Conclusion The efficacy of high-dose DHA as a treatment for AT was investigated from biochemical, histopathological, and biomechanical perspectives. The results showed that DHA could be an alternative treatment compound to collagen.

BRD4 promotes heterotopic ossification through upregulation of LncRNA MANCR.

AimsAcquired heterotopic ossification (HO) is a debilitating disease characterized by abnormal extraskeletal bone formation within soft-tissues after injury. The exact pathogenesis of HO remains unknown. It was reported that BRD4 may contribute to osteoblastic differentiation. The current study aims to determine the role of BRD4 in the pathogenesis of HO and whether it could be a potential target for HO therapy.MethodsAchilles tendon puncture (ATP) mouse model was performed on ten-week-old male C57BL/6J mice. One week after ATP procedure, the mice were given different treatments (e.g. JQ1, shMancr). Achilles tendon samples were collected five weeks after treatment for RNA-seq and real-time quantitative polymerase chain reaction (RT-qPCR) analysis; the legs were removed for micro-CT imaging and subsequent histology. Human bone marrow mesenchymal stem cells (hBMSCs) were isolated and purified bone marrow collected during surgeries by using density gradient centrifugation. After a series of interventions such as knockdown or overexpressing BRD4, Alizarin red staining, RT-qPCR, and Western Blot (Runx2, alkaline phosphatase (ALP), Osx) were performed on hBMSCs.ResultsOverexpression of BRD4 enhanced while inhibition of Brd4 suppressed the osteogenic differentiation of hBMSCs in vitro. Overexpression of Brd4 increased the expression of mitotically associated long non-coding RNA (Mancr). Downregulation of Mancr suppressed the osteoinductive effect of BRD4. In vivo, inhibition of BRD4 by JQ1 significantly attenuated pathological bone formation in the ATP model (p = 0.001).Conclusion BRD4 was found to be upregulated in HO and Brd4-Mancr-Runx2 signalling was involved in the modulation of new bone formation in HO.Cite this article: Bone Joint Res 2021;10(10):668–676.

Tendon-Derived Progenitor Cells With Multilineage Potential Are Present Within Human Patellar Tendon.

Background:Progenitor cells serve as a promising source of regenerative potential in a variety of tissue types yet remain underutilized in tendinopathy. Tendon-derived progenitor cells (TDPCs) have previously been isolated from hamstring tendon but only as part of a concomitant medical procedure. Determining the presence of TDPCs in patellar tendon may facilitate clinical utilization of these cells because of the relative accessibility of this location for tissue harvest.Purpose:To characterize TDPCs in human patellar tendon samples.Study Design:Descriptive laboratory study.Methods:Human patellar tendon samples were obtained during elective knee surgery. TDPCs were isolated and seeded at an optimal low cell density and subcultured to confluence for up to 2 passages. Flow cytometry was used to analyze for the expression of CD90+, CD105+, CD44+, and CD31–, CD34–, and CD45– markers. The multilineage differentiation potential of TDPCs was tested in vitro via adipogenic, osteogenic, and chondrogenic culture with subsequent cytochemical staining for Oil Red O, Alizarin Red, and Alcian Blue, respectively. Enzyme-linked immunosorbent assay was used to quantify the amount of adiponectin, alkaline phosphatase, and SRY-box transcription factor 9 secreted into cell culture supernatant for further confirmation of lineage differentiation. Results were analyzed statistically using the 2-tailed Student t test.Results:TDPCs demonstrated near-uniform expression of CD90, CD105, and CD44 with minimal expression of CD34, CD31, and CD45. Adipogenic, osteogenic, and chondrogenic differentiation of TDPCs was confirmed using qualitative analysis. The expression of adiponectin, alkaline phosphatase, and SRY-box transcription factor 9 were significantly increased in differentiated cells versus undifferentiated TDPCs (P < .05).Conclusion:TDPCs can be successfully isolated from human patellar tendon samples, and they exhibit characteristics of multipotent progenitor cells.Clinical Relevance:These data demonstrate the promise of patellar tendon tissue as a source of progenitor cells for use in biologic therapies for the treatment of tendinopathy.

RNA sequencing and immunofluorescence of the myotendinous junction of mature horses and humans.

The myotendinous junction (MTJ) is a specialized interface for transmitting high forces between the muscle and tendon and yet the MTJ is a common site of strain injury with a high recurrence rate. The aim of this study was to identify previously unknown MTJ components in mature animals and humans. Samples were obtained from the superficial digital flexor (SDF) muscle-tendon interface of 20 horses, and the tissue was separated through a sequential cryosectioning approach into muscle, MTJ (muscle tissue enriched in myofiber tips attached to the tendon), and tendon fractions. RT-PCR was performed for genes known to be expressed in the three tissue fractions and t-distributed stochastic neighbor embedding (t-SNE) plots were used to select the muscle, MTJ, and tendon samples from five horses for RNA sequencing. The expression of previously known and unknown genes identified through RNA sequencing was studied by immunofluorescence on human hamstring MTJ tissue. The main finding was that RNA sequencing identified the expression of a panel of 61 genes enriched at the MTJ. Of these, 48 genes were novel for the MTJ and 13 genes had been reported to be associated with the MTJ in earlier studies. The expression of known [COL22A1 (collagen XXII), NCAM (neural cell adhesion molecule), POSTN (periostin), NES (nestin), OSTN (musclin/osteocrin)] and previously undescribed [MNS1 (meiosis-specific nuclear structural protein 1), and LCT (lactase)] MTJ genes was confirmed at the protein level by immunofluorescence on tissue sections of human MTJ. In conclusion, in muscle-tendon interface tissue enriched with myofiber tips, we identified the expression of previously unknown MTJ genes representing diverse biological processes, which may be important in the maintenance of the specialized MTJ.

Computational multi-directional optical coherence tomography for visualizing the microstructural directionality of the tissue.

We demonstrate computational multi-directional optical coherence tomography (OCT) to assess the directional property of tissue microstructure. This method is the combination of phase-sensitive volumetric OCT imaging and post-signal processing. The latter comprises of two steps. The first step is an intensity-directional analysis, which determines the dominant en face fiber orientations. The second step is the phase-directional imaging, which reveals the sub-resolution depth-orientation of the microstructure. The feasibility of the method was tested by assessing muscle and tendon samples. Stripe patterns with several sizes were visualized in the phase-directional images. In order to interpret these images, the muscle and tendon structures were numerically modeled, and the phase-directional images were generated from the numerical model. The similarity of the experimental and numerical results suggested that the stripe patterns correspond to the muscle fiber bundle and its crimping.

Collagenase Induced Tendinitis in Forelimb Superficial Digital Flexor Tendon in Donkey (Equus asinus): Long Term Ultrasonographic and Biomechanical Assessments

Injuries to tendons are among the most common injuries in competition horses and represent a significant cause of morbidity and mortality. The present study aimed at an eight -week period ultrasonographic and biomechanical assessments of collagenase induced tendinitis in forelimb superficial digital flexor tendon (SDFT) in donkeys. Four healthy male donkeys were used. 1000 U collagenase type I from Clostridium histolyticum was injected in the center of the SDFT guided by ultrasonography. Ultrasonographical images of the SDFT were recorded prior to injury and 8 weeks after confirmation of tendinitis on a weekly basis. Images were digitized and lesion area to cross-sectional tendon area ratio (LA/TA ratios) was measured. At the end of the study period, the animals underwent tenectomy and tendon samples were evaluated biomechanically. Collagenase induced tendinitis was confirmed ultrasonographically 10 days post-injection. The animals showed swelling and response to palpation, however, no lameness was found in animals within the study period. There were significant differences between the first and the fifth weeks in operated limbs ultrasonographically (p < 0.05). The eight-week period is sufficient to assess the effect of various modalities in tendon healing in the collagenase-induced model in the donkey. The development and expansion of collagenase induced tendinitis until week six after confirmation of tendinitis may disturb findings of the healing effect of various modalities in the tendon, in which tendinitis is still expanding and may mask the healing effect of the modalities used.

Immunolocalization of decorin, a small leucin-rich proteoglycan, in the normal and injured horse tendon

The aim of this study was to evaluate the intensity of decorin in normal and the injured equine cadaver limbs. The study was carried out using superficial digital flexor tendon (SDFT) samples harvested from equine cadaver limbs. Randomly assigned left or right equine distal forelimbs were collected in normal (7 - 14 years old ± 2.86 SD) and injured (6 - 16 years old ± 3.64 SD) SDFT. Small pieces of approximately 5 x 5 x 3 mm were collected from normal and the injured areas at the mid-most metacarpal regions and fixed in 4% paraformaldehyde at room temperature. They were routinely prepared for H&E staining in order to confirm whether they were normal or injured. Then they were prepared for immunological assay, the primary and the secondary antibodies were prepared in a standard ratio. The results showed that the distribution of decorin was varied between fascicles and the interfascicular matrix (IFM), and the latter showed greater intensity than the fascicles. The injured tendons showed up-regulation of decorin, it was intensively expressed in all the cases of injured tendon, particularly fascicles showed significant up-regulation when compared to the normal tendon. It was concluded that decorin was varied regionally, and the injured tendons presented a significant up-regulation.

Bovine tendon atomization

Thus far, histotripsy has not successfully fractionated tendon tissues, possibly due to bubbles being of insufficient size to create a pressure-release interface. In this study, a planar tissue-air interface was treated with histotripsy to create a micro-fountain and atomization; particulates ejected from the tendon sample were collected and analyzed histologically to determine whether tissue fractionation was achieved. [Work supported by NSF GRFP DGE1255832 and NIH NIBIB EB027886.]

Platelet-Rich Plasma Releasate Promotes Early Healing in Tendon After Acute Injury.

Background:Acute tendon injury can limit motion and thereby inhibit tendon healing. Positive results have been found after the use of platelet-rich plasma (PRP) to treat tendon injury; however, the early effects of PRP on tendon regeneration are not known.Purpose/Hypothesis:The purpose of this study was to evaluate the effects of PRP releasate (PRPr) on the early stages of tendon healing in a rat partial tenotomy model. It was hypothesized that PRPr can promote early healing of an Achilles tendon in rats.Study Design:Controlled laboratory study.Methods:PRP was prepared by a 2-step method of manual platelet concentration from 10 rats. PRPr was isolated from the clotted preparation after activation by thrombin and was applied to an Achilles tendon on 1 side of 30 rats on the second day after partial tenotomy, with normal saline used as the control on the other side. Achilles tendon samples were harvested 5 and 10 days after tenotomy. At each time point, 15 Achilles tendon samples were obtained, of which 5 samples were evaluated by Masson trichrome staining, apoptosis, and cell proliferation, while the other 10 samples were tested for tensile strength using a material testing machine.Results:Compared with saline-treated control tendons, the PRPr-treated tendons showed increased collagen synthesis near the cut edge and fewer apoptotic cells (P = .01). An immunohistochemical analysis revealed more Ki-67–positive cells but fewer cluster of differentiation (CD) 68+ (ED1+) macrophages in PRPr tendons compared with saline-treated tendons (P < .01). Tendons treated with PRPr also showed higher ultimate tensile strength than those treated with saline (P = .03).Conclusion:PRPr treatment promotes tissue recovery in the early phase of tendon healing by stimulating tendon cell proliferation and collagen production while inhibiting cell apoptosis and CD68+ (ED1+) macrophage infiltration.Clinical Relevance:These findings suggest that with PRPr treatment, higher loads can be applied to the healing tendon at an earlier time, which can help the patient resume activity earlier.

Differences in cellular and microstructural properties of the semitendinosus muscle tendon between young and adult patients

BackgroundPoor outcomes associated with anterior cruciate ligament reconstruction in paediatric patients are a major concern. The tendon structure and its cellular characteristics are key factors that affect the mechanical properties of tendons. This study aimed to evaluate the effects of growth on the cellular and microstructural properties of the tendon of the semitendinosus muscle in humans. MethodsSemitendinosus muscle tendon samples from 76 patients who underwent ligament reconstruction were examined and divided into three groups: immature (10.8 ± 2.7 years old), young (16.5 ± 1.8 years old), and adult (35.2 ± 8.6 years old), based on age and the state of the epiphyseal plate in the distal femur. The number of tendon cells per unit area was assessed, and the major-to-minor-length ratio of the tendon cell nuclei was calculated to evaluate the shape of the nuclei using haematoxylin and eosin staining. The collagen fibril diameter and distribution were determined using electron microscopy. ResultsThe major-to-minor-length ratio of the tendon cell nuclei significantly increased with age (p-value; immature vs. young: 0.018, young vs adult: 0.001, immature vs adult: 0.001). The shape of the tendon cell nuclei was rounder in the immature group and more elongated in the adult group. A significant decrease in the number of tendon cells was observed with age (immature: 565 ± 134/mm2, young: 356 ± 105/mm2, adult: 272 ± 81/mm2; p-value: immature vs young: 0.001, young vs adult: 0.012, immature vs adult: 0.001). The mean fibril diameter in the immature group was significantly smaller (p-value: immature vs young: 0.018, young vs adult: 0.001, immature vs adult: 0.001). The distribution of the collagen fibrils changed from right skewed in the immature group to flat in the adult group. ConclusionsThe characteristics of the tendon cells and the microstructure of collagen in muscle tendons significantly changed with age.

Effects of cyclic loading on the mechanical properties and failure of human patellar tendon

Patellar tendinopathy is a common overuse injury in sports such as volleyball, basketball, and long-distance running. Microdamage accumulation, in response to repetitive loading of the tendon, plays an important role in the pathophysiology of patellar tendinopathy. This damage presents mechanically as a reduction in Young’s modulus and an increase in residual strain. In this study, 19 human patellar tendon samples underwent cyclic testing in load control until failure, segmented by four ramped tests where digital image correlation (DIC) was used to assess anterior surface strain distributions. Ramped tests were performed prior to cyclic testing and at timepoints corresponding to 10%, 20%, and 30% of cyclic stiffness reduction. Young’s modulus significantly decreased and cyclic energy dissipation significantly increased over the course of cyclic testing. The DIC analysis illustrated a heterogeneous strain distribution, with strain concentrations increasing in magnitude and size over the course of cyclic testing. Peak stress and initial peak strain magnitudes significantly correlated with the number of cycles to failure (r2 = 0.65 and r2 = 0.57, respectively, p < 0.001); however, the rates of peak cyclic strain and modulus loss displayed the highest correlations with the number of cycles to failure (r2 = 96% and r2 = 86%, respectively, p < 0.001). The high correlation between the rates of peak cyclic strain and modulus loss suggest that non-invasive methods to continuously monitor tendon strain may provide meaningful predictions of overuse injury in the patellar tendon.

Comparison of polarization sensitive second harmonic generation ‎microscopy techniques for the study of biological tissues

Recently, polarization sensitive Second Harmonic Generation (pSHG) microscopy has become a powerful tool for the study of the noncenterosymmetric biological structures. This is due to the fact that pSHG has some intrinsically benefits such as high resolution and contrast, and it can also penetrate deeply inside the sample in a noninvasive manner. One drawback for the pSHG technique is that the imaging procedure is not fast enough to study in vivo samples or to monitor the dynamics of different tissues. This issue imposes some limitations on using the pSHG technique to study in vivo samples. Fortunately, recently Single Scan polarization sensitive Second Harmonic Generation (SS-pSHG) technique has been introduced as a fast alternative for the conventional pSHG technique. In this article, the results obtained from ex vivo biological samples of starch, human cornea and animal tendon have been compared in a pixel-to-pixel manner using pSHG and SS-pSHG techniques in forward direction. Even though the samples used here are ex vivo, the results of this study promise that the polarization sensitive SHG microscopy techniques have a great potential to study biological tissues in a noninvasive procedure. This issue is more important especially in the cases that samples are in vivo.

Морфологические показатели ахиллова сухожилия у лабораторной крысы

The article reflects the normative morphological and biomechanical parameters of the Achilles tendon in a laboratory rat, and also developed a methodological approach to assessing the structural and functional state of the tendons and its compliance. The micromorphological, micromorphometric and biomechanical data of the tendon in the studied group of animals have been scientifically substantiated. It was shown that the morphological parameters of tendon tissue correlate with its biomechanical characteristics. The experimental model of the study was a laboratory rat (n=10). The material for the study was the Achilles tendon. A comprehensive methodological approach was used, including anatomical preparation, micromorphological studies, micromorphometry, biomechanical testing of tendon samples and statistical data processing. Thus, the indicators of strength and elasticity of the tendon are due to the peculiarities of the tissue architectonics, namely, the mutually parallel unidirectional and dense arrangement of collagen fiber bundles with pronounced interfiber connections and the number of cells of the fibroblastic population.

A method of removing retardance induced by scattering of collagenous fiber bundles

In this work, we report a method of removing scattering induced retardance in polarization sensitive full field optical coherence tomography (PS-FFOCT). First, the Mueller matrix that describes its operation is derived. The thickness invariant retardance induced by the scattering of collagenous fiber bundles is then used to find the accurate values of the birefringence of the layers that consist collagenous fibers. Finally, the initial en face birefringent images of in vitro beef tendon samples are presented to demonstrate the capability of our method.

DSC examination of rotator cuff damage in patients with total shoulder arthroplasty

The assessment of rotator cuff tear prior to shoulder replacement is based on the physical findings and imaging procedures, preferably magnetic resonance imaging (MRI). However, MRI is not always available, and in trauma patients, the CT-scan-based classification of glenohumeral arthritis or tendon damage is generally not applicable. In case of 4-part dislocated proximal humerus fractures the right diagnosis is crucial prior to choose between different type protheses or osteosyntheses. Therefore, there is a need for novel methods for the evaluation of rotator cuff damage. Our aim was to evaluate whether differential scanning calorimetry (DSC) could determine the grade of rotator cuff damage in patients undergoing shoulder replacement. Small samples of rotator cuff tendons of patients undergoing reversed shoulder replacement due to orthopedic or trauma indications were resected during surgery, and thermal parameters were measured using DSC. Radiological evaluation was also performed to classify the degree of rotator cuff damage and glenohumeral arthritis. In case of orthopedic samples, the consequence of advanced tendon damage was well demonstrated by the shape and the running of the curves, compared to the control sample. In trauma samples, the moderately degenerated tendons also exhibited significant difference from the control in the shape of the scans and in the thermal parameters. DSC curves demonstrated a clear difference in the thermal parameters of healthy and pathologic samples. DSC could be a useful additional method in the evaluation of rotator cuff tear arthropathies in future studies.

Increased expression of macrophages and inflammatory cytokines at tendon origin in patients with chronic lateral epicondylitis

The success of anti-inflammatory medications and corticosteroid injections in controlling chronic lateral epicondylitis symptoms suggests an underlying inflammatory pathology that is also causative of the pain experienced by patients; however, evidence regarding inflammatory mediators and cells remains inconclusive. We conducted a case-control study that included a total of 24 participants (10 patients and 14 controls). Extensor carpi radialis brevis tendon samples were obtained from patients, and flexor carpi radialis tendon samples were obtained from control subjects. We then performed immunohistochemical assessment to determine the expression levels of neuropeptides (substance P and calcitonin gene-related peptide), glutamate receptors (N-methyl-d-aspartate receptor type 1 and metabotropic glutamate receptor 5), inflammatory cytokines (interleukin 1α and tumor necrosis factor α), and inflammatory cells (M1 macrophages [CD68], M2 macrophages [CD163 and CD206], T-lymphocytes [CD3], and B-lymphocytes [CD20]). Patients' sampled extensor carpi radialis brevis tendons showed significantly elevated expression levels of neuropeptides, glutamate receptors, and inflammatory cytokines, along with a number of macrophages, compared with controls (P < .001 or P < .0001); however, there were no differences in the number of T- and B-lymphocytes between the 2 groups. The findings of this study showed that inflammation is involved in the pathology of chronic lateral epicondylitis.