Objectives. Platelet-rich plasma (PRP) is being used increasingly often in the clinical setting to treat tendon-related pathologies. Yet the optimal PRP preparations to promote tendon healing in different patient populations are poorly defined. Here, we sought to determine whether increasing the concentration of platelet-derived proteins within a derivative of PRP, platelet lysate (PL), enhances
Aims. Myokine developmental endothelial locus-1 (DEL-1) has been documented to alleviate inflammation and endoplasmic reticulum (ER) stress in various cell types. However, the effects of DEL-1 on inflammation, ER stress, and apoptosis in
Peri-tendinous injection of local anaesthetic,
both alone and in combination with corticosteroids, is commonly performed
in the treatment of tendinopathies. Previous studies have shown
that local anaesthetics and corticosteroids are chondrotoxic, but
their effect on
The purpose of this study was to evaluate the beneficial effects of r-Irisin (IR) on human primary
Aims. The purpose of this study was to evaluate the in vitro effects of apocynin, an inhibitor of nicotinamide adenine dinucleotide phosphate oxidase (NOX) and a downregulator of intracellular reactive oxygen species (ROS), on high glucose-induced oxidative stress on
Objectives. The aim of this study was to investigate the effect of hyperglycaemia on oxidative stress markers and inflammatory and matrix gene expression within tendons of normal and diabetic rats and to give insights into the processes involved in tendinopathy. Methods. Using
Objectives. Platelet-rich fibrin matrix (PRFM) has been proved to enhance
During in vitro sub-culturing,
Introduction. The hierarchical structure of tendon results in a complex mechanical strain environment, with
Introduction. The use of platelet-rich concentrate (PRC) to enhance the healing response in tendon repair is currently an area of considerable interest. Activated platelets release a cocktail of growth factors and ECM regulating molecules. Previous work suggests that
Introduction. Tendinopathies are debilitating and painful conditions. They are believed to result from repetitive overuse, which can create micro-damage that accumulates over time, and initiates a catabolic cell response. The aetiology of tendinopathy remains poorly understood, therefore the ideal treatment remains unclear. However, current data support the use of eccentric exercise as an effective treatment. In a previous study, we have shown that eccentric loading generates perturbations in the tendon at 10Hz, which is not present during other less effective loading regimes. Consequently, we hypothesis that 10Hz loading initiates an increased anabolic response in
Introduction and Aims: Large or recurrent rotator cuff tendon tears are difficult to treat effectively. Collagen bio-scaffolds have become available to reinforce a tendon repair or as an interpositional graft. This study compares the suitability of two collagen bio-scaffolds for autologous
Introduction: Tendon ruptures are increasingly common, repair can be difficult and healing poorly understood. Tissue engineering approaches often require expansion of cell numbers to populate a construct, and maintenance of cell phenotoype is essential for tissue regeneration. Methods: In this study we characterise the phenotype of human Achilles
Introduction. We previously reported that disruption of TGFβ signaling in limb mesenchyme resulted in complete failure of tendon differentiation. Materials and Methods. To bypass this early function and study additional roles of TGFβ signaling in tendon development we disrupted TGFβ signaling in
Large and retracted rotator cuff tendon tears fail to repair, or re-tear following surgical intervention. This study attempted to develop novel tissue engineering approaches using tenocytes-seeded bioscaffolds for tendon reconstruction of massive rotator cuff tendon defect in rabbits. Porcine small intestine submucosa (Restore™) and type I/III collagen bioscaffold (ACI-MaixTM) were chosen as bioscaffold carriers for autologous
Elastic energy-storing tendons including the equine superficial digital flexor tendon (SDFT) and human Achilles tendon significantly increase locomotor efficiency, but suffer high injury rates and experience increased core temperatures during exercise. Tenocytes are linked by gap junctions (GJ) comprised of connexin (Cx) proteins that mediate intercellular communication and are necessary for strain-induced collagen synthesis. The effects of hyperthermia on gap junction intercellular communication (GJIC) are unknown. We investigated the hypothesis that there is a down regulation in GJIC and Cx protein by
Autologous tendon cell injection (ATI) is a promising non-surgical treatment for tendinopathies and tendon tear that address its underlying pathology. The procedure involves harvesting autologous tendon tissue, the isolation of the tendon cells, expansion under quality assured GMP cell laboratory and the injection of the tendon cells via U/S into the degenerative tendon tissue. In clinical practice, the patella (PT) and palmaris longus (PL) tendons are common sites used for tendon tissue biopsy. The objective of this study is to compare the tendon cell quality, identity, purity, doubling time and yield of cells between PT and PL tendons for ATI. Tendon tissue biopsies were harvested from PT via U/S using a 14-gauge needle or resected surgically from the PL tendon. The biopsies were transported to a GMP cell laboratory, where tendon cells were isolated, cultured and expanded for 4 to 6 weeks, and analysed for viability, cell doubling time, cellular characteristics including cell purity, potency and identity (PPI). Tendon samples from 149 patients were analysed (63 PT). Average biopsy weight was 62mg for PT and 119mg for PI (p<0.001). Average cell doubling time (83.9 vs 82.7 hours), cellular yield (16.2 vs 15.2x106), viability (98.7 vs 99.0%) and passage number (3 vs 3) were not significantly different between tendons. Additionally, ddPCR analyses showed no differences of PPI including tendon cell markers of collagen type I, scleraxis and tenomodulin. No post-biopsy complications or contamination were reported for either group. Assessing tendon tissue from palmaris tendon is relatively easier. Tendon tissue biopsy tissue for autologous tendon cell therapy can be obtained from either the PT or PL tendons. Tendon cells isolated from PT and PL were equal in growth characteristics and PPI. There are no differences in the quality of tendon cells isolated from the PT or PL.
The term macromolecular crowding is used to describe equilibria and kinetics of biochemical reactions and biological processes that occur via mutual volume exclusion of macromolecules in a highly crowded structureless medium. In vivo, the extracellular space is heavily crowded by a diverse range of macromolecules and thus, biological processes occur rapidly, whilst in vitro, in the absence of macromolecules, the same processes occur very slowly, if they are initiated at all (1-3). This talk will discuss the concept of macromolecular crowding, alone or in combination with other in vitro microenvironment modulators, in tendon engineering context.
Purpose. Platelet-Rich Plasma (PRP), an autologous derivative of whole blood that contains a supraphysiological concentration of platelets and growth factors. Most published studies have investigated the effect of PRP-conditioned media on cell cultures. We are not aware of any study that has investigated whole PRP with its cellular components on human tissue cultures. This study aims to investigate the effect of PRP on cell migration from human Achilles tendon explants, and the subsequent cellular proliferative effects in culture. Methods. This is an in-vitro study on tendon explants obtained from Achilles tendon rupture patients. The samples were collected in sterile DMEM F12 solution then carefully cut into approximately 1–3mm. 3. sections. Tendon explants were cultured in three media types: 1. 100% PRP; 2. 50% PRP; and 3. 50% fetal calf serum (FCS). 1 and 2 were made up using DMEM F12 media (standard culture medium). Explants and cells were incubated at 37°c in 5% CO. 2. for 48 hours. Results. Images of the explanted tissue were taken using a Nikon TE300 microscope with Retiga CCD camera and cells around each explant were counted. Kruskal-Wallis statistical test showed that 100%PRP and 50%PRP cultured explants have significantly higher number of cells (p ≤0.002 and 0.028 respectively) when compared with 50%FCS cultured explants. Ziva ultrasensitive proliferation assay revealed that 100%PRP significantly increased cell proliferation. In addition, PicoGreen assay showed that DNA content of 100% PRP cultured cells were significantly higher than the control. The concentration of TGF-b1, VEGF, PDGF-AB and IGF-1 growth factors were significantly higher in PRP comparing to 50% FCS medium. Conclusion. Our findings show that whole PRP strongly affect the behaviour of human
Interstitial supraspinatus tears can cause persistent subacromial impingement symptoms despite non operative treatment. Autologous tendon cell injection (ATI) is a non-surgical treatment for tendinopathies and tear. We report a randomised controlled study of ATI compared to corticosteroid injection (CS) as treatment for interstitial supraspinatus tears and tendinopathy. Inclusion criteria were patients with symptom duration > 6 months, MRI confirmed intrasubstance supraspinatus tear, and prior treatment with physiotherapy and ≥ one CS or PRP injection. Participants were randomised to receive ATI to the interstitial tear or corticosteroid injection to the subacromial bursa in a 2:1 ratio, under ultrasound guidance. Assessments of pain (VAS) and function (ASES) were performed at baseline, and 1, 3, 6 and 12 months post treatment. 30 participants (19 randomised to ATI) with a mean age of 50.5 years (10 females) and a mean duration of symptoms of 23.5 months. Baseline VAS pain and ASES scores were comparable between groups. While mean VAS pain scores improved in both groups at 3 months after treatment, pain scores were superior with ATI at 6 months (p=0.01). Mean ASES scores in the ATI group were superior to the CS group at 3 months (p=0.026) and 6 months (p=0.012). Seven participants in the CS group withdrew prior to 12 months due to lack of improvement. At 12 months, mean VAS pain in the ATI group was 1.6 ± 1.3. The improvements in mean ASES scores in the ATI group at 6 and 12 months were greater than the MCID (12.0 points). At 12 months, 95% of ATI participants had an ASES score > the PASS (patient acceptable symptom state). This is the first level one study using ATI to treat interstitial supraspinatus tear. ATI results in a significant reduction in pain and improvement in shoulder function.
Hamstring tendons (HT) represent a widely used autograft for ACL reconstruction. Harvesting, processing and pretensioning procedures together with the time out of the joint could theoretically hamper tendon cells (TCs) viability. The authors hypothesize that HT cells are not impaired at the end of the surgical procedures and their tenogenic phenotype may be strongly improved by exposure to PEMF. Remnants of semitendinosus and gracilis tendons were collected at the end of the surgical procedures before skin closure from 15 healthy donors who underwent ACL reconstruction with autologous hamstring tendons. To isolate TCs, the tendon was minced and digested with 0.3 % type I collagenase and the nucleated cells were plated at a density 5x10E3 cells/cm2 and cultured in chamber slides in differentiation medium composed of DMEM + 5ng/ml basic fibroblast growth factor (b-FGF) for 7, 14, 21 days The following cell cultures were set up: TCs cultured with differentiation medium + exposure to PEMF 8 h/day (PEMF generator system IGEA, intensity of magnetic field = 1.5 mT, frequency = 75 Hz) TCs cultured with differentiation medium without exposure to PEMF At day 0, day 7, day 14 and day 21, immunofluorescence analysis was performed to evaluate the expression of collagen type I, collagen type VI, scleraxis and PCNA (proliferative marker) Subsequently, tendon explant cultures were set up to verify, at day 21, explant viability and the expression of collagen type I, collagen type VI, beta-catenin and PCNASummary:
Methods
Aims. The effects of remnant preservation on the anterior cruciate ligament (ACL) and its relationship with the tendon graft remain unclear. We hypothesized that the co-culture of remnant cells and bone marrow stromal cells (BMSCs) decreases apoptosis and enhances the activity of the hamstring tendons and
Tendinopathy is a tendon pathology often resulting from a failed healing response to tendon injury. Activated protein C (APC) is a natural anti-coagulant with anti-inflammatory and wound healing promoting functions, which are mainly mediated by its receptors, endothelial protein C receptor (EPCR) and protease activated receptors (PARs). This study aimed to determine whether APC stimulates
During aging, tendons demonstrate substantial disruptions in homeostasis, leading to impairments in structure-function. Impaired tendon function contributes to substantial declines quality of life during aging. Aged tendons are more likely to undergo spontaneous rupture, and the healing response following injury is impaired in aged tendons. Thus, there is a need to develop strategies to maintain tendon homeostasis and healing capacity through the lifespan. Tendon cell density sharply declines by ∼12 months of age in mice, and this low cell density is retained in geriatric tendons. Our data suggests that this decline in cellularity initiates a degenerative cascade due to insufficient production of the extracellular matrix (ECM) components needed to maintain tendon homeostasis. Thus, preventing this decline in tendon cellularity has great potential for maintaining tendon health. Single cell RNA sequencing analysis identifies two changes in the aged tendon cell environment. First, aged tendons primarily lose
To address the current challenge of anterior cruciate ligament (ACL) reconstruction, this study is the first to fabricate a braided collagen rope (BCR) which mimics native hamstring for ACL reconstruction. The study aims to evaluate the biological and biomechanical properties of BCR both in vivo and vitro. Rabbit ACL reconstruction model using collagen rope and autograft (hamstring tendon) was conducted. The histological and biomechanical evaluations were conducted at 6-, 12-, 18, 26-week post-operation. In vitro study included cell morphology analysis, cell function evaluation and RNA sequencing of the
Introduction and Objective. Achilles tendon defect is difficult problem for orthopedic surgeon, and therefore the development of new treatments is desirable. Platelet-rich fibrin (PRF), dense fibrin scaffold composed of a fibrin matrix containing many growth factors, is recently used as regenerative medicine preparation. However, few data are available on the usefulness of PRF on Achilles tendon healing after injury. The objective of this study is to examine whether PRF promotes the healing of Achilles tendon defect in vivo and evaluated the effects of PRF on
Introduction and Objective. The rupture of the anterior cruciate ligament is a common sports injury and surgical reconstruction is often required to restore full function of the knee. Hamstring tendons are usually used as autografts. In addition to knee pain and stiffness, infections are feared complications after surgery. Incubation of the autograft in a vancomycin solution until implantation reduced the infection rate by about ten-fold. Recent studies showed no negative effect of vancomycin on the biomechanical properties of porcine tendons. A negative effect of high vancomycin concentrations on chondrocytes and osteoblast is reported, but the effect on tendon and
Early identification of patients at risk for impaired tendon healing and corresponding novel therapeutic approaches are urgent medical needs. This study aimed to clarify the role of CD3+ T-cells during acute Achilles tendon (AT) healing. Blood and hematoma aspirate were taken from 26 patients during AT reconstruction, and additional blood samples were obtained during clinical follow-up at 6, 26 and 52 weeks after surgery. T-cell subsets were analyzed by flow cytometry using CD3, CD4, CD8, CD11a, CD57 and CD28 antibodies. Clinical follow-up included functional tests, MRI assessments, and subjective questionnaires. In vitro, the functional behavior of patient-derived
Tendon injuries present a major clinical challenge, as they necessitate surgical intervention and are prone to fibrotic progression. Despite advances in physical therapy and surgical technique, tendons fail to return to full native functioning, underlining the need for a biological therapeutic to improve tendon healing. Myofibroblasts are activated fibroblasts that participate in the proliferative and remodeling phases of wound healing, and while these matrix-producing cells are essential for proper healing, they are also linked to fibrotic initiation. A subset of
Depletion of Scleraxis-lineage (ScxLin) cells in adult tendon recapitulates age-related decrements in cell density, ECM organization and composition. However, depletion of ScxLin cells improves tendon healing, relative to age-matched wildtype mice, while aging impairs healing. Therefore, we examined whether ScxLin depletion and aging result in comparable shifts in the tendon cell environment and defined the intrinsic programmatic shifts that occur with natural aging, to define the key regulators of age-related healing deficits. ScxLin cells were depleted in 3M-old Scx-Cre+; Rosa-DTRF/+ mice via diphtheria toxin injections into the hindpaw. Rosa-DTRF/+ mice were used as wildtype (WT) controls. Tendons were harvested from 6M-old ScxLin depleted and WT mice, and 21-month-old (21M) C57Bl/6 mice (aged). FDL tendons (n=6) were harvested for single-cell RNAseq, pooled, collagenase digested, and sorted for single cell capture. Data was processed using Cell Ranger and then aligned to the annotated mouse genome (mm10). Filtering, unsupervised cell clustering, and differential gene expression (DEG) analysis were performed using Seurat. Following integration and sub-clustering of the
Cellular therapies play an important role in tendon tissue engineering with
Energy storing tendons such as the human Achilles and equine superficial digital flexor tendon (SDFT) are prone to age-related injury. Tendons have poor healing capacity and a lack of effective treatments can lead to ongoing pain, reduced function and re-injury. It is therefore important to identify the mechanisms underpinning age-related tendinous changes in order to develop more effective treatments. Our recent single cell sequencing data has shown that tendon cell populations have extensive heterogeneity and cells housed in the tendon interfascicular matrix (IFM) are preferentially affected by ageing. There is, however, a lack of established surface markers for cell populations in tendon, limiting the capacity to isolate distinct cell populations and study their contribution to age-related tendon degeneration. Here, we investigate the presence of the cell surface proteins MET proto-oncogene (MET), integrin subunit alpha 10 (ITGA10), fibroblast activation protein alpha (FAP) and platelet derived growth factor receptor alpha (PDGFRA) in the equine SDFT cell populations and their co-localisation with known markers. Using Western blot we validated the specificity of selected antibodies in equine tissue before performing immunohistochemistry to establish the location of the respective proteins in the SDFT. We subsequently used double labelling immunofluorescence with the established mural cell marker desmin (DES) to distinguish between
Objectives. Intra-articular injections of local anaesthetics (LA), glucocorticoids (GC), or hyaluronic acid (HA) are used to treat osteoarthritis (OA). Contrast agents (CA) are needed to prove successful intra-articular injection or aspiration, or to visualize articular structures dynamically during fluoroscopy. Tranexamic acid (TA) is used to control haemostasis and prevent excessive intra-articular bleeding. Despite their common usage, little is known about the cytotoxicity of common drugs injected into joints. Thus, the aim of our study was to investigate the effects of LA, GC, HA, CA, and TA on the viability of primary human chondrocytes and
Adherent cells are known to respond to physical characteristics of their surrounding microenvironment, adapting their cytoskeleton and initiating signaling cascades specific to the type of cue encountered. Scaffolds mimicking native biophysical cues have proven to differentiate stem cells towards tissue-specific lineages and to maintain the phenotype of somatic cells for longer periods of time in culture. Biomaterial-based tendon implants are designed to withstand high physiological loads but often lack the appropriate biochemical, biophysical and biological structure to drive tendon regeneration by populating cells. The objective of this study is to use tendon main component, collagen type I, to create scaffolds that reproduce tendon natural anisotropy and rigidity, in an effort to engineer functional tendon tissue with native organization and strength, able to maintain
Introduction and Objective. Chronic tendinopathy is a multifactorial disease and a common problem in both, athletes and the general population. Mechanical overload and in addition old age, adiposity, and metabolic disorders are among the risk factors for chronic tendinopathy but their role in the pathogenesis is not yet unequivocally clarified. Materials and Methods. Achilles tendons of young (10 weeks) and old (100 weeks) female rats bred for high (HCR) and low (LCR) intrinsic aerobic exercise capacity were investigated. Both Achilles tendons of 28 rats were included and groups were young HCR, young LCR, old HCR, and old LCR (n = 7 tendons per group/method). In this rat model, genetically determined aerobic exercise capacity is associated with a certain phenotype as LCR show higher body weight and metabolic dysfunctions in comparison to HCR. Quantitative real-time PCR (qPCR) was used to evaluate alterations in gene expression. For histological analysis, semi-automated image analysis and histological scoring were performed. Results. Age-related downregulation of
Cellular therapies play an important role in tendon tissue engineering and regenerative medicine with
A tendon is a fibrous connective tissue that acts to transmit tensile forces between muscles and bones. It mainly consists of soluble substance, collagen and small volume of elastic fibres, which are produced by tenoblasts and
Cellular therapies play an important role in tendon tissue engineering with
Tendon injuries are associated with the formation of inferior, disorganized scar tissue at the tendon bone insertion site and high failure rates. Two major processes are discussed being key players: the inflammatory reaction upon tear and the remodeling process of the tendon. In a previous study we demonstrated that the profile of MMPs and TIMPs, being key factors of tendon modeling and remodeling, is altered in
Introduction. Adult tendon injuries occur very frequently, but injured tendon heals very slowly and the mechanisms of the slow-healing response to injury are still largely unknown. Currently, the main barrier is our insufficient understanding of the mechanisms responsible for homeostasis, regeneration and repair of adult tendon. This gap in knowledge translates to a lack of experimental models. Therefore, using the combination of state-of-the-art genetic approaches, we have established novel cell biological tools to advance the understanding of tendon biology. Materials and Methods. Adult mouse tendon progenitor lines and Adult mouse
Rotator cuff repair is performed to treat shoulder pain and disability. Failure of the tendon repair site is common; one strategy to improve healing is to enforce a period of post-operative immobilisation. Immobilisation may have unintended effects on tendon healing. Tenocytes under uniaxial strain form more organised collagen and up regulate expression of proliferative genes. Vitamin C (ascorbic acid), an anti-oxidant that is a co-factor for collagen synthesis, has also been reported to enhance collagen deposition and organisation. The purpose of this study was to compare human
Tendons mainly consist of collagen in order to withstand high tensile forces. Compared to other, high turnover tissues, cellularity and vascularity in tendons are low. Thus, the natural healing process of tendons takes long and can be problematic. In case of injury to the enthesis, the special transition from tendon over cartilage to bone is replaced by a fibrous scar tissue, which remains an unsolved problem in rotator cuff repair. To improve tendon healing, many different approaches have been described using scaffolds, stem cells, cytokines, blood products, gene therapy and others. Despite promising in vitro and in vivo results, translation to patient care is challenging. In clinics however, tendon auto- or allografts remain still first choice to augment tendon healing if needed. Therefore, it is important to understand natural tendon properties and natural tendon healing first. Like in other tissues, senescence of
Cell-based tissue engineering strategies for tendon repair have limited clinical applicability due to delayed extracellular matrix (ECM) deposition and subsequent prolonged culture periods, which lead to tenogenic phenotypic drift. Deposition of ECM in vitro can be enhanced by macromolecular crowding (MMC), a biophysical phenomenon that governs the intra- and extra-cellular milieu of multicellular organisms, which has been described to accelerate ECM deposition in human
Worldwide, tendon disorders are one of the main causes of disability that decrease the quality of life of individuals and represent a substantial economic burden on society. Currently, the main therapies used for tendon injuries are not able to restore tendon functionality, and due to tendons' hypovascular and hypocellular nature, they present a reduced healing capacity, which also limits the success of the available therapies. In order to discover new therapies, extracellular vesicles (EVs), key players in cell-cell communication, have been widely explored for tissue engineering and regenerative medicine applications. Thus, the aim of this study is to assess the role of EVs derived from platelets in stem cell tenogenic commitment using a bioengineered tendon in vitro model for potential use as tendon therapeutic agents. Biomimetic platelet-derived EVs were produced by freeze-thaw cycles of platelets and isolation at different centrifugation speed. To recreate the architecture of tendons, a 3D system consisting of electrospun anisotropic nanofiber scaffolds coated with collagen encapsulating human adipose stem cells (hASCs) and different types of platelet-derived EVs, were produced. Then, the influence of the tendon-mimetic constructs and the distinct EVs populations in the hASCs tenogenic differentiation were assessed over culture time. We observed that the hASCs on the nanofibrous tendon scaffolds, show high cytoskeleton anisotropic organization that is characteristic of
Introduction. Tendons are critical to mobility, and are susceptible to degeneration through injury and ageing. Type I collagen is the most abundant protein in vertebrates; it is the main structural protein of the extracellular matrix in numerous musculoskeletal tissues, including tendons. Type I collagen predominantly is a heterotrimer, which consists of two alpha-1 chains and one alpha-2 chain (α1). 2. (α2) encoded by the COL1A1 and COL1A2 genes, respectively. However, type I collagen can form homotrimers (α1). 3. which are protease-resistant, and are associated with age-related musculoskeletal diseases, fibrotic and connective tissue pathologies. Transforming growth factor beta (TGFβ) enhances collagen (I) gene expression, is involved in tendon mechanobiology and repair processes, while its effect on homotrimer formation is unknown. Our aim is to investigate the relative expressions of collagen (I) α1 and α2 polypeptide chains in
Introduction. Tendon is prone to degeneration through ageing and injury and current therapies are largely ineffective. The recent identification of a cell population within tendon with stem cell-like characteristics holds potential for regeneration of tendon. The local stem cell environment (niche) is important for stem cell maintenance and function. This study aims to characterize extracellular matrix (ECM) components of the stem cell niche in equine tendon, which is prone to age-related degeneration and rupture. Materials and Methods. Putative tendon stem cells (TSCs) were isolated from equine superficial digital flexor tendon by low-density plating and differential adhesion to fibronectin. Cells were analysed by flow cytometry using antibodies to mesenchymal stem cell markers, as well as qRT-PCR for stem cell and tenogenic markers. The multipotency of cells was assessed using tri-lineage differentiation assays. ECM components of the
Background and objectives: Tenocytes change their structure, composition and mechanical properties to adapt to mechanical loading. Voltage gated and mecha-nosensitive ion channels may play a key role in human
The energy-storing human Achilles tendon and equine superficial digital flexor tendon (SDFT) show no adaptation to exercise unlike muscle and bone, and are prone to injury. Injury involves microdamage accumulation until there is sufficient weakening for rupture to occur during normal athletic activity. Anatomically opposing positional tendons, such as the common digital extensor tendon (CDET) in the horse rarely suffer exercise–induced injury. Tenocytes maintain the extra-cellular matrix, but in energy-storing tendons they appear unable to adequately repair microdamage as it occurs. Tenocytes have been classified subjectively into 3 subtypes on the basis of histological nuclear morphology. Long, thin type 1 cells are thought to be less synthetically active than cigar-shaped type 2 cells, but their exact morphology and relative proportions in different tendon sites and ages has not been clearly defined. We hypothesised that
Objectives. Tranexamic acid (TXA) is an anti-fibrinolytic medication commonly used to reduce perioperative bleeding. Increasingly, topical administration as an intra-articular injection or perioperative wash is being administered during surgery. Adult soft tissues have a poor regenerative capacity and therefore damage to these tissues can be harmful to the patient. This study investigated the effects of TXA on human periarticular tissues and primary cell cultures using clinically relevant concentrations. Methods. Tendon, synovium, and cartilage obtained from routine orthopaedic surgeries were used for ex vivo and in vitro studies using various concentrations of TXA. The in vitro effect of TXA on primary cultured
Alarmins- also referred to as damage associated molecular patterns (DAMPS)- are endogenous molecules mobilized in response to tissue damage known to activate the innate immune system and regulate tissue repair and remodelling. The molecular mechanisms that regulate inflammatory and remodelling pathways in tendinopathy are largely unknown therefore identifying early immune effectors is essential to understanding the pathology. S100A8 and S100A9 are low molecular weight calcium binding proteins primarily released by activated phagocytes in an inflammatory setting and also secreted as a heterodimeric complex that exhibits cytokine like functions. Based on our previous investigations we sought evidence of S100A8/A9 expression in human tendinopathy and thereafter, to explore mechanisms whereby S100 proteins may regulate inflammatory mediators and matrix regulation in human
Injury to the core region of energy-storing tendons is a frequent occurrence in both human and equine athletes, the incidence of which increases with age. Such energy-storing tendons include the human Achilles tendon (AT) and the equine superficial digital flexor tendon (SDFT). By definition, energy-storing tendons experience high strains during high-speed athletic activity. In contrast, anatomically opposing tendons (“positional” tendons), such as the common digital extensor tendon (CDET) in the horse and extensor digitorum longus tendon in man act only to transmit muscular force and rarely suffer exercise–induced injury. Functional adaptation of muscle and bone in response to exercise is well – documented, but there has been no convincing evidence to suggest that the energy-storing tendons in adults have the ability to adapt to exercise. We hypothesised that adaptive increases in
The objective was to seek evidence of hypoxia in early human tendinopathy and thereafter, to explore mechanisms whereby tissue hypoxia may regulate apoptosis, inflammatory mediators and matrix regulation in human
Introduction. The two-dimensional (2D) monolayer culture paradigm has limited translational potential to physiological systems; chondrocytes and
All cells exist within a 3D microenvironment where they are exposed to a multitude of mechanobiological cues, from nano-level cell/matrix interactions, to tissue-level mechanical strain. These cues are fundamental to maintaining tissue homeostasis, but when disrupted during disease, can promote pathological outcomes and impair healing. This is particularly true in tendons; 3D load bearing connective tissue structures composed of a complex arrangement of matrix proteins, organised in a highly aligned manner and maintained by tendon cells (tenocytes). When diseased or injured (termed tendinopathy), the tendon begins a journey of poor healing, characterised by mechanically inferior disorganised scar tissue which ultimately results in compromised or total loss of function. In both health and disease, the mechanobiological stimuli experienced by
Mesenchymal stem cells (MSCs), characterised by their self-renewal and multidifferentiation potential, are a favoured cell population for future tissue engineering applications. Differentiation of MSCs towards a specific lineage has been extensively studied, mainly through the use of growth factors or conditioned media. However, growth factor supplementation is a mono-domain approach and considering the number of permutations, it is unlikely to find the optimal cocktail. Although PRPs are used extensively, its use is controversial, and standardization is impossible. Conditions media have various limitations, including how much, when and how effective it is at the time that it would be aspirated. Thus, co-culture systems are at forefront of scientific research and technological innovation. Co-culture system gives access to the complete cell secretome and offers the advantages of autologous therapy. However, several weeks of co-culture are necessary to observe stem cell differentiation. We hypothesize that, by using macromolecular crowding, which has been shown to recapitulate the dense in vivo microenvironment of the extracellular area and enhance matrix deposition in vitro with its excluded volume effect, it will accelerate stem cell differentiation towards tenogenic lineage. Further, we will assess if tendon specific extracellular matrix deposited by
Tranexamic acid (TXA) is an anti-fibrinolytic medication commonly used to reduce peri-operative bleeding. Increasingly, topical administration as an intra-articular injection or peri-operative wash is being administered at concentrations between 10–100mg/ml. This study investigated effects of TXA on human periarticular tissues and primary cell cultures using clinically relevant concentrations. Tendon, synovium and cartilage obtained from routine orthopaedic surgeries were used ex vivo or cultured for in vitro studies using various concentrations of TXA. They were stained with 5-chloromethylfluorescein diacetate and propidium iodide and imaged using confocal microscopy to identify the proportion of live and dead cells. The in vitro effect of TXA on primary cultured
Collagen materials are extensively used in regenerative medicine. However, they still present limitations such as a mono-domain composition and poor mechanical properties. On the other hand, tissue grafts overcome most of these limitations. In addition, the potential of tissue grafts in musculoskeletal tissue engineering has not been fully investigated. Herein, we ventured to assess the potential of a decellularised porcine peritoneum for musculoskeletal applications by comparing its characteristics with a commercial collagen scaffold employed in tendon. Results indicated that the porcine peritoneum had higher mechanical properties and a lower crosslinking ratio (p < 0.01). Furthermore, it presented a lower resistance to collagenase digestion, which suggests a faster remodelling in vivo of the tissue graft. Immunohistochemistry analysis showed a preserved and multicomponent structure in the porcine peritoneum contrary to the collagen matrix, confirming the multifunctional nature of the tissue graft. Regarding the cell-response assessment,
Surgical repair of rotator cuff tears have high failure rates (20–70%), often due to a lack of biological healing. Augmenting repairs with extracellular matrix-based scaffolds is a common option for surgeons, although to date, no commercially available product has proven to be effective. In this study, a novel collagen scaffold was assessed for its efficacy in augmenting rotator cuff repair. The collagen scaffold was assessed in vitro for cytocompatability and retention of
Cell-based tissue engineering strategies for tendon repair have limited clinical applicability due to delayed extracellular matrix (ECM) deposition and subsequent prolonged culture periods, which lead to tenogenic phenotypic drift. Deposition of ECM in vitrocan be enhanced by macromolecular crowding (MMC), a biophysical phenomenon that governs the intra- and extra-cellular milieu of multicellular organisms. 2. , which has been described to accelerate ECM deposition in human
Introduction: Tendinopathy entails pain and degenerative tissue proliferation such as
Summary. Tissue grafts fail to recapitulate native tendon function, imposing the need for development of functional regeneration strategies. Herein, we describe advancements in tendon repair and regeneration using functionalised natural and synthetic devices and scaffold-free cell-based therapies. Introduction. Tendon and ligament injuries constitute an unmet clinical need with approximately 100,000 new cases annually in US alone. Tissue grafts are considered the gold standard in clinical practice. However, allografts and xenografts can lead to potential disease transmission, whilst the limited supply of autografts in severe injuries and degenerative conditions restricts their use. To this end, scaffold and scaffold-free therapies are under development to address the tissue grafts shortage. Herein, we describe biophysical, biochemical and biological methods to maintain tendon derived cell phenotype and/or differentiation of other cell types towards tenogenic lineage; development of tendon-equivalent facsimiles; and ultimately functional neotendon formation. Materials and Methods. Growth factor supplementation was assessed as means to either maintain tendon derived stem cell phenotype or differentiate them towards
Summary Statement. We have shown that integrin mRNA expression is regulated by the application of mechanical load. This indicates that mechanical loading may modify cell sensitivity to perceive further load through increased interaction with the ECM. Introduction. Tendinopathies are a range of diseases characterised by pain and insidious degeneration. Although poorly understood, onset is often associated with physical activity. We have previously investigated the regulation by mechanical strain of metalloproteinase gene expression in human
Anterior cruciate ligament injury is the most common and economically costly sport injuries, frequently requiring expensive surgery and rehabilitation. Post-operative knee septic arthritis represents a serious complication with an incidence rate between 0.14% and 1.7%. A common practice to avoid septic arthritis is the “vancomycin wrap”, consisting in the soaking of the graft for 10–15 minutes within a sterile gauze swab previously saturated with 5 mg/mL vancomycin. Even though several studies have been conducted to investigate vancomycin toxicity on different musculoskeletal tissues or cells, little is known about the effect of such antimicrobial on tendon-derived cells. The aim of this study was to determine the in vitro toxicity of different concentrations of vancomycin at different time points on human primary
Summary Statement. Tendon micromechanics were investigated using 2 methods. When collagen deformation was measured directly, higher levels of inter-fibre sliding were observed than when
Summary. Silver nanoparticles improve the tensile property of the repaired Achilles tendon by modulating the synthesis and deposition of collagen. This makes silver nanoparticles a potential drug for tendon healing process with less undesirable side effect. Introduction. Tendon injury is a common injury that usually takes a long time to fully recover and often lead to problems of joint stiffness and re-rupture due to tissue adhesions and scarring on the repaired tendon respectively. Recently, it has been proven that silver nanoparticles (AgNPs) are capable of regenerating skin tissue with minimal scarring and comparable tensile property to normal skin. Hence, it is hypothesised that AgNPs could also improve the healing in tendon injury as both tissues are predominating with fibroblasts. The objective of this study is to look at the in vitro response of primary
Cell-based therapies require removal of cells from their optimal in vivotissue context and propagation in vitroto attain suitable number. However, bereft of their optimal tissue niche, cells lose their phenotype and with it their function and therapeutic potential. Biophysical signals, such as surface topography and substrate stiffness, and biochemical signals, such as collagen I, have been shown to maintain permanently differentiated cell phenotype and to precisely regulate stem cell lineage commitment (1, 2). Herein, we developed and characterised substrates of variable rigidity and constant nanotopographical features to offer control over cellular functions during ex vivoexpansion. PDMS substrates with varying ratios of monomer to curing agent (0:1, 1:1, 5:1) were fabricated based on established protocols. Grooved substrates were created using a silinated wafer with groove dimensions of 2µm × 2µm × 2µm; planar control groups were created using flat glass. The aforementioned PDMS solutions were poured onto the wafer/glass, cured at 200 ºC and treated with oxygen plasma. Substrates were then investigated with/without collagen I coating. (0.1, 0.5, and 1 mg/ml). Atomic force microscopy (AFM) and optical profilometry were used to assess the topographical features of the substrates. Dynamic mechanical analysis (DMA) was used to determine the mechanical properties of the substrates. The simultaneous effect of surface topography / substrate rigidity on cell phenotype and function was assessed using human permanently differentiated cells (dermal fibroblasts, tenocytes) and stem cells (human bone marrow stem cells) and various morphometric and gene / protein assays. PDMS substrates of varying stiffness (1000 kPa, 130 kPa, 50 kPa) can be made by varying the Sylgard ratio, while maintaining topographical features. Human adult dermal fibroblasts,
Tendon is a bradytrophic and hypovascular tissue, hence, healing remains a major challenge. The molecular key events involved in successful repair have to be unravelled to develop novel strategies that reduce the risk of unfavourable outcomes such as non-healing, adhesion formation, and scarring. This review will consider the diverse pathophysiological features of tendon-derived cells that lead to failed healing, including misrouted differentiation (e.g. de- or transdifferentiation) and premature cell senescence, as well as the loss of functional progenitors. Many of these features can be attributed to disturbed cell-extracellular matrix (ECM) or unbalanced soluble mediators involving not only resident tendon cells, but also the cross-talk with immigrating immune cell populations. Unrestrained post-traumatic inflammation could hinder successful healing. Pro-angiogenic mediators trigger hypervascularization and lead to persistence of an immature repair tissue, which does not provide sufficient mechano-competence. Tendon repair tissue needs to achieve an ECM composition, structure, strength, and stiffness that resembles the undamaged highly hierarchically ordered tendon ECM. Adequate mechano-sensation and -transduction by tendon cells orchestrate ECM synthesis, stabilization by cross-linking, and remodelling as a prerequisite for the adaptation to the increased mechanical challenges during healing. Lastly, this review will discuss, from the cell biological point of view, possible optimization strategies for augmenting Achilles tendon (AT) healing outcomes, including adapted mechanostimulation and novel approaches by restraining neoangiogenesis, modifying stem cell niche parameters, tissue engineering, the modulation of the inflammatory cells, and the application of stimulatory factors. Cite this article:
Adherent cells are known to respond to physical characteristics of their surrounding microenvironment, adapting their cytoskeleton and initiating signaling cascades specific to the type of cue encountered. Scaffolds mimicking native biophysical cues have proven to differentiate stem cells towards tissue-specific lineages and to maintain the phenotype of somatic cells for longer periods of culture time. Although the characteristic anisotropy of tendon tissue is commonly replicated in scaffolds, relevant physical cues such as tendon rigidity or mechanical loading are often neglected. The objective of this study is to use tendons' main extracellular matrix component, collagen type I, to create scaffolds with an anisotropic surface topography and controlled rigidity, in an effort to engineer functional tendon tissue equivalents, with native organization and strength. Porcine collagen type I in solution was treated with one of the following cross-linkers: glutaraldehyde, genipin or 4-arm polyethylene glycol (4SP). The resulting mixture was poured on micro-grooved (2×2×2 μm) or planar polydimethylsiloxane (PDMS) molds and dried in a laminar flow hood to obtain 5 mg/ml collagen films. Surface topography and elastic modulus of the final scaffolds were analyzed using SEM/AFM and rheometry, respectively. Human tendon cells were isolated from adult tendon tissue and cultured on micro-grooved/planar scaffolds for 4, 7 and 10 days. Cell morphology, collagen III and tenascin C expression were analyzed by immunocytochemistry. Among the different cross-linkers used, only the treatment with 4SP resulted in scaffolds with a recognizable micro-grooved surface topography. Precise control over the micro-grooved topography and the rigidity of the scaffolds was achieved by cross-linking the collagen with varying concentrations of 4SP at low pH and temperature. The elastic modulus of the scaffolds cross-linked with the highest concentration of 4SP matched the physiological values reported in developing tendons (∼15 kPa). Around eighty percent of the human tendon cells cultured on the cross-linked collagen films aligned in the direction of the anisotropy for 10 days in culture. At 4 days, tenoyctes cultured on micro-grooved substrates presented a significant higher nuclei aspect ratio than
Summary Statement. This study describes the design and preliminary in vitro testing of a novel patch for the repair of rotator cuff tendon tears. The laminated design incorporates woven and electrospun components. The woven element provides the patch with excellent mechanical strength and the electrospun layer improves cell attachment and promotes cell orientation and diferentiation. Introduction. Aligned nanofibrous electrospun scaffolds have been previously proposed as ideal scaffolds for tendon repair, replicating the anisotropy of tendon and providing a biomimetic design to encourage tissue regeneration (Hakimi et al., 2012). However, such scaffolds are still limited in terms of mechanical properties. This paper presents the design of a novel patch for rotator cuff repair in which the electrospun scaffold is supported by a woven component. Patients & Methods. Aligned polydioxanone (PDO) electrospun scaffolds were produced using a single nozzle electrospinning set-up with a rotating collector. The woven component was created by weaving PDO monofilaments with a manual loom. The woven and non-woven constituents were bound by a non-destructive method which preserves the surface morphology of the electrospun material. For each type of scaffold, a minimum of 3 specimens were tested to failure in tension using Zwick machine at rate of 0.3 mm/min until failure. For in vitro work, human-derived tendon cells were extracted from rotator cuff tendon tissue obtained during surgical repair, with appropriate ethical approval. Cells were cultured on the scaffolds for at least 14 days. Results. The contribution of the woven component to the tensile strength of the assembled patch is about 20 times more when compared to the electrospun scaffold. In vitro work shows that human
Human mesenchymal stem cells (MSCs) are multipotent stem cells with the ability to differentiate into mesoderm-type cells such as osteoblasts, chondroblast,
To test the hypothesis that reseeded anterior cruciate ligament (ACL)-derived cells have a better ability to survive and integrate into tendon extracellular matrix (ECM) and accelerate the ligamentization process, compared to adipose-derived mesenchymal stem cells (ADMSCs). Acellularized tibialis allograft tendons were used. Tendons were randomly reseeded with ACL-derived cells or ADMSCs. ACL-derived cells were harvested and isolated from remnants of ruptured ACLs during reconstruction surgery and cultured at passage three. Cell suspensions (200 µl) containing 2 × 106 ACL-derived cells or ADMSCs were prepared for the purpose of reseeding. At days 1, 3, and 7 post-reseeding, graft composites were assessed for repopulation with histological and immunohistochemical analysis. Matrix protein contents and gene expression levels were analyzed.Aims
Methods
Current cell-based tissue engineering strategies have limited clinical applicability due to the need for large cell numbers and prolonged culture periods that lead to phenotypic drift. In vitro microenvironmental modulators have been proposed to mimic the native tendon. Standard in vitro culture conditions result in delayed extracellular matrix (ECM) deposition, impairing the development of scaffold-free approaches. ECM deposition can be enhanced by macromolecular crowding (MMC), a biophysical phenomenon that governs the milieu of multicellular organisms. We assessed a multifactorial biophysical approach, using MMC and mechanical loading, on different cell sources to determine their suitability for in vitro fabrication of tendon-like tissue. Human dermal fibroblasts (DFs),
A revision for periprosthetic joint infection (PJI) in total hip arthroplasty (THA) has a major effect on the patient’s quality of life, including walking capacity. The objective of this case control study was to investigate the histological and ultrastructural changes to the gluteus medius tendon (GMED) in patients revised due to a PJI, and to compare it with revision THAs without infection performed using the same lateral approach. A group of eight patients revised due to a PJI with a previous lateral approach was compared with a group of 21 revised THAs without infection, performed using the same approach. The primary variables of the study were the fibril diameter, as seen in transmission electron microscopy (TEM), and the total degeneration score (TDS), as seen under the light microscope. An analysis of bacteriology, classification of infection, and antibiotic treatment was also performed.Aims
Methods
R Appleyard, Murray Maxwell Biomechanics Lab, Royal North Shore Hospital, Sydney. The fundamental mechanisms that underlie tendon breakdown are ill understood. There is an emerging hypothesis that altered mechanical strain modulates the metabolism and/or phenotype of
Tenocytes from several mammal species have been shown to be prone to phenotypic drift at early sub-culture passages. In the present study we compared allogenic and xenogenic serum supplementation suitability as a supplement for the in vitro expansion of equine
Rotator cuff tears are common in middle-aged and elderly patients. Despite advances in the surgical repair of rotator cuff tears, the rates of recurrent tear remain high. This may be due to the complexity of the tendons of the rotator cuff, which contributes to an inherently hostile healing environment. During the past 20 years, there has been an increased interest in the use of biologics to complement the healing environment in the shoulder, in order to improve rotator cuff healing and reduce the rate of recurrent tears. The aim of this review is to provide a summary of the current evidence for the use of forms of biological augmentation when repairing rotator cuff tears. Cite this article:
As we grow older, the risk of tendon degeneration and injuries increases, which can result in pain, disability, healthcare cost, and lost productivity. Even after surgical repair the results are often unsatisfactory. The cellular reasons for the differences in the healing potential, however, are not well studied. To get a deeper insight into the biological characteristics of tenocyte-like cells from different patient groups we established a biobank with material from over 150 human donors. The patients/donors suffered from rotator cuff tears and were operated to restore the function. A proportion of the isolated cells showed stem cell-like characteristics and was able to differentiate into the osteoblastic, chondrogenic and adipogenic linage. Investigating the differentiation potential of the cells with regard to donor characteristics, we were able to demonstrate that age, sex but also the “degeneration” has an impact of the cellular potential. A possibility to stimulate the cellular activity is the application of growth factors, as already clinically used for stimulation of bone healing. Therefore, the responsiveness of the cells to the growth factors Bone Morphogenetic protein-2/7 (BMP-2/7) was analysed in vitro. Independent of the donor characteristics, the cells responded to the BMP-stimulation by increased proliferation and collagen-1 synthesis. However, cells isolated from donors with high fatty infiltration of the muscle or older females were less responsive. Looking into the intracellular signalling pathway, the data showed that the BMP-signal is mainly mediated by the canonical-pathway with samd8 playing a major role. This basic research gives first information regarding the differences in
The December 2022 Foot & Ankle Roundup360 looks at: Evans calcaneal osteotomy and multiplanar correction in flat foot deformity; Inflammatory biomarkers in tibialis posterior tendon dysfunction; Takedown of ankle fusions and conversion to total ankle arthroplasty; Surgical incision closure with three different materials; Absorbable sutures are not inferior to nonabsorbable sutures for tendo Achilles repair; Zadek’s osteotomy is a reliable technique for treating Haglund’s syndrome; How to best assess patient limitations after acute Achilles tendon injury; Advances in the management of infected nonunion of the foot and ankle.
Mechanical stimulation is a key factor in the development and healing of tendon-bone insertion. Treadmill training is an important rehabilitation treatment. This study aims to investigate the benefits of treadmill training initiated on postoperative day 7 for tendon-bone insertion healing. A tendon-bone insertion injury healing model was established in 92 C57BL/6 male mice. All mice were divided into control and training groups by random digital table method. The control group mice had full free activity in the cage, and the training group mice started the treadmill training on postoperative day 7. The quality of tendon-bone insertion healing was evaluated by histology, immunohistochemistry, reverse transcription quantitative polymerase chain reaction, Western blotting, micro-CT, micro-MRI, open field tests, and CatWalk gait and biomechanical assessments.Aims
Methods
Rotator cuff (RC) tears are common musculoskeletal injuries which often require surgical intervention. Noninvasive pulsed electromagnetic field (PEMF) devices have been approved for treatment of long-bone fracture nonunions and as an adjunct to lumbar and cervical spine fusion surgery. This study aimed to assess the effect of continuous PEMF on postoperative RC healing in a rat RC repair model. A total of 30 Wistar rats underwent acute bilateral supraspinatus tear and repair. A miniaturized electromagnetic device (MED) was implanted at the right shoulder and generated focused PEMF therapy. The animals’ left shoulders served as controls. Biomechanical, histological, and bone properties were assessed at three and six weeks.Aims
Methods
Introduction. Primary cilia are organelles found singularly on almost every cell in the body, including
Achilles tendinopathy is a common cause of disability. Despite the economic and social relevance of the problem, the causes and mechanisms of Achilles tendinopathy remain unclear. Tendon vascularity, gastrocnemius-soleus dysfunction, age, gender, body weight and height, pes cavus, and lateral ankle instability are considered common intrinsic factors. The essence of Achilles tendinopathy is a failed healing response, with haphazard proliferation of
Purpose of the study: Platelet rich fibrin (PRF) favours proliferation of
Introduction: We studied the extracellular matrix (ECM) of 19 ruptured human Achilles tendons, comparing the tissue composition of specimens taken from area close to the rupture with specimens harvested from an apparently healthy area in the same tendon. The hypothesis was that the metabolism of these molecules is altered in patients with Achilles tendon rupture. Materials and Methods: We compared the gene expression and the protein localization of the main ECM molecules (collagen type I, decorin and versican) including enzymes involved in their metabolism as matrix metallo-proteases (MMP2 and 9) and tissue inhibitory of metal-loproteinase (TIMP 1 and 2) using a Real Time PCR, zymography and FACE analysis. Results: The gene expression of proteoglycans core protein, collagen type I, MMPs and TIMPs is more represented in the area close to the tendon rupture (p<
0.05). The expression of MMPs was confirmed by zymography analysis, showing a marked increase of gelatinolytic activity in area close to the tendon rupture (p<
0.05). The chemical composition of tendon changes showing that in the healthy area the carbohydrate content is higher than the ruptured area (p<
0.05). Discussion/Conclusions: In the ruptured area, the
Purpose: Ultrastructural analysis of PT graft for ACL single bundle reconstruction. Materials and methods: Arthroscopical biopsies for new meniscal lesions at 6-12-24mm-5-10 ys. All cases with IKDC normal/nearly normal and KT2000 excellent/good. Samples prepared with Karnowsky fixing and urani-lacetate solution. Fibril diameter and transversal area measured by LEICA QUIN in 5 cuts randomly selected for each sample. Results: 6 months biopsy showed severe P.T. modifications, with a decrease of larger fibrils, substituted with smaller one with plenty of extra cellular matrix. Oxitalan fibers, macrophagic cells and
Proliferation, migration, and differentiation of anterior cruciate ligament (ACL) remnant and surrounding cells are fundamental processes for ACL reconstruction; however, the interaction between ACL remnant and surrounding cells is unclear. We hypothesized that ACL remnant cells preserve the capability to regulate the surrounding cells’ activity, collagen gene expression, and tenogenic differentiation. Moreover, extracorporeal shock wave (ESW) would not only promote activity of ACL remnant cells, but also enhance their paracrine regulation of surrounding cells. Cell viability, proliferation, migration, and expression levels of Collagen-I (COL-I) A1, transforming growth factor beta (TGF-β), and vascular endothelial growth factor (VEGF) were compared between ACL remnant cells untreated and treated with ESW (0.15 mJ/mm2, 1,000 impulses, 4 Hz). To evaluate the subsequent effects on the surrounding cells, bone marrow stromal cells (BMSCs)’ viability, proliferation, migration, and levels of Type I Collagen, Type III Collagen, and tenogenic gene (Aims
Methods
Summary. Our results prove that Demineralised Cortical Bone (DCB) can be used as biological tendon graft substitute, combined with correct surgical technique and the use of suture bone anchor early mobilisation can be achieved. Introduction. Surgical repair of tendon injuries aims to restore length, mechanical strength and function. In severe injuries with loss of tendon substance a tendon graft or a substitute is usually used to restore functional length. This is usually associated with donor site morbidity, host tissue reactions and lack of remodelling of the synthetic substitutes which may result in suboptimal outcome. In this study we hypothesise that DCB present in biological tendon environment with early mobilisation and appropriate tension will result in remodelling of the DCB into ligament tissue rather that ossification of the DCB at traditional expected. Our preparatory cadaveric study (abstract submitted to CORS 2013) showed that the repair model used in this animal study has sufficient mechanical strength needed for this animal study. Methods. 6 mature female sheep undergone surgical resection of the distal 1 cm of the right patellar tendon and osteotomy of patellar tendon attachment at the tibial tuberosity under general anaesthesia. Repair was done using DCB with 2 suture bone anchor. Animals were allowed immediate mobilisation after surgery and were sacrificed at 12 weeks. The force passing through the operated and non-operated legs was assessed preoperatively and at week 3, week 6, week 9 and week 12 bay walking the animals over a force plate. Radiographs were taken immediately after euthanasia, the Patella-Tendon-tibia constructs were retrieved and pQCT scan was done. Histological analysis included
Summary Statement. A novel biomimetic polydioxanone tendon patch with woven and electrospun components is biocompatible, recapitulates native tendon architecture and creates a tissue-healing microenvironment directed by a subpopulation of regenerative macrophages. The woven component provides tensile strength while the tendon heals. Introduction. There is great interest in the use of biomimetic devices to augment tendon repairs. Ideally, implants improve healing without causing adverse local or systemic reactions. Biocompatibility remains a critical issue prior to implantation into humans, as some implants elicit a foreign body response (FBR) involving inflammation, poor wound healing and even fistulae formation. Additionally, the effect on articular cartilage locally or systemically with placement of a juxta-articular implant has not been examined. The purpose of this study is to test the in vivo biocompatibility of a novel hybrid woven and electrospun polydioxanone patch in a rat tendon transection model. Patients and Methods. Sixty Lewis rats were divided into 4 groups in which the infraspinatus was surgically transected 3 mm from its insertion. Tendons were repaired with a woven and electrospun polydioxanone patch (PDOe) and 5-0 Prolene sutures. Vicryl and Silk patches or a simple Prolene suture repair served as comparators. Animals were sacrificed at 1, 2, 4, 6 and 12 weeks to examine the biocompatibility of the implants. Immunohistochemistry was used to examine macrophage subpopulations and hematoxylin and eosin staining was used to assess foreign-body giant cells and both analyzed with a one-way ANOVA with significance set at p<.05. Articular cartilage was scrutinised with semi-quantitative analysis. Hind paw inflammatory indices were used to determine the systemic effects and biomechanical testing the tensile strength of the materials over time. Results. The PDOe patch remained grossly quiescent at all time-points. There was a severe inflammatory reaction to Vicryl at one and 2-week time-points with gross exudate. Silk patches were associated with larger fibrous capsules at each time point. There were no adverse systemic effects and articular cartilage remained normal with no differences between materials to controls. Immunohistochemistry showed a significantly higher ratio of regenerative to inflammatory macrophages for the PDOe patch compared to other constructs at each time-point and similar to controls. Silk and Vicryl patches had a greater than 10-fold increase in foreign-body giant cells compared to the PDOe patch and controls (p<.05) suggesting incorporation rather than rejection and walling off of the biomaterial. Tensile strength of the PDOe patch increased in the first 2 weeks to greater than 90 N and gradually declined to a mean of 22 N at 12 weeks. Discussion/Conclusion. The novel PDOe patch appears to be biocompatible and illicit very little FBR in this rat tendon injury model. Importantly, there was no joint reaction to the biomaterial which has not been addressed previously. We believe the electrospun component of the patch recapitulates native tendon architecture creating a tissue healing microenvironment directed by a regenerative macrophage subpopulation. These results corroborate earlier in vitro work that showed incorporation of
Introduction: Tendon tissue engineering entails the generation of a highly ordered collagen matrix with several organization scales that confer the tendon its mechanical functionality. Endogenous production of proteoglycans account for the typical microscopic organization in bundles of the tendon extracellular matrix, as they prevent lateral fusion of collagen fibril by binding the shaft of the fibres and promoting tip to tip fusion. The approach developed in this study is to rely on this molecular endogenous production and to induce a supramolecular uniaxial alignment of collagen fibres bundles with the help of specially designed scaffolds under continuous fluid shear stress. Methods: Microchannel chitosan scaffolds were produced by casting 2% chitosan gel on a mould equipped with stainless steel needles array that was imaged by optical coherence tomography with a resolution at ~10microns. From OCT measurements, regularly spaced microchannels with clearly delimited boundaries are obtained inside a microporous core of chitosan. By varying the number and the diameter of needles (from 250 μm (microns)to 500 μm (microns)) different types of microstructure have been produced. Microchannels scaffolds were seeded with primary
Embryonic chick
Summary. In an in vitro tendon cell model, the tendon-specific gene expression up-regulation induced by PEMF negatively correlates with field intensity; moreover repeated lower-intensity PEMF treatments (1.5 mT) provokes a higher release of anti-inflammatory cytokines respect to the single treatment. Introduction. Tendon disorders represent a diagnostic and therapeutic challenge for physicians. Traditional treatments are characterised by a long recovery time and a high occurrence of injury relapses. Despite the growing clinical interest in pulsed electromagnetic fields (PEMFs) few studies on their effect on tendons and ligaments have been conducted. Tendon resident cells (TCs) are a mixed population, made up mostly by
Introduction: The pathogenesis of chronic tendinopathy is unclear. A role for increased apoptosis of
Introduction: New biotechnologies create opportunities for gene therapy to promote rotator cuff healing. We have previously demonstrated that genetically engineered mesenchymal stem cells (MSCs) over expressing BMP-2 and SMAD8 signaling molecule differentiate to
Introduction: The pathogenesis of chronic tendinopathy is unclear. The role of the increased apoptosis of
Introduction: Rotator cuff tears are a common injury which affects both the young athlete and the sedentary elderly alike. This condition is commonly treated with glucocorticoid injections as part of initial management. The effects, however, of these injections on the histology of collagen and the metabolism of tendon fibroblasts are still controversial. Materials and methods: In this study, samples from 19 patients with rotator cuff tears were taken during definitive surgery to manage these tears. There was a history of glucocorticoid injections in all of the patients. The samples were examined in terms of histopathology using light microscopy, in situ hybridization to detect the presence of glucocorticoid receptor mRNA and TUNEL assay to determine the incidence of apoptosis. Results: Light microscopy of hematoxylin-eosin stained samples from the study group showed marked cellularity although there were no signs of inflammation. The nuclei were noted to be rounded and a significant number showed pyknosis. Angiogenesis was also noted in the sections, consistent with previous finding of angio-fibroblastic hyperplasia as a characteristic of tendinosis. Collagen structure was noted to be abnormal, with longitudinal clefts and focal areas of marked disorganization of fibers. In situ hybridization showed a strong signal for glucocorticoid receptor mRNA in all of the samples. TUNEL assay also showed a strong signal for apoptosis of the tendon fibroblasts in the study group as compared to the control group which showed almost no signal. Conclusion: Our results suggest that although an overall picture of hypercellularity is seen in cases of tendinosis and tendon tears, a high percentage of these cells are undergoing apoptosis. This may reflect a natural high rate of turnover of cells during the process of repair or may be due to exogenous factors. Glucocorticoids almost certainly affect metabolism of tendon fibroblasts and subsequently collagen structure as seen by the abundant expression of the receptor mRNA. However, a causal relationship between glucocorticoids and apoptosis of
Introduction: The anterior cruciate ligament (ACL) is the most frequently damaged ligament in the knee joint. The patella tendon autograft is the current replacement of choice, however autografts are not always available and grafting often leads to donor site morbidity. Allogeneic implants may cause an adverse immunological reaction [. 1. ] The aim of this study was to develop an acellular tendon scaffold with the mechanical and biochemical properties of tissue which could be rapidly recellularised for use in tissue engineering of the anterior cruciate ligament. Materials and Methods: Porcine patella tendons were dissected less than 24 hours after slaughter and washed in PBS. The tendons were decellularised using 0.1% (w/ v) SDS for 24 hours. Decellularisation was assessed by haematoxylin and eosin staining and light microscopy. The glycosaminoglycan and hydroxyproline (measure of collagen) content of the scaffold were also assessed quantitatively following decellularisation. Following decellularisation the scaffolds were subject to various levels of ultrasonication in order to modify the acellular scaffold prior to reseeding in an attempt to achieve recellularisation of the scaffold. Denaturation of the collagen within the scaffold following ultrasonication was assessed using the Ą-chymotrypsin assay. Decellularised and ultrasonicated scaffolds were subject to uniaxial tensile loading to failure in a Howden tensile testing machine. The sonicated scaffolds were reseeded with human
Re-rupture is common after primary flexor tendon repair. Characterization of the biological changes in the ruptured tendon stumps would be helpful, not only to understand the biological responses to the failed tendon repair, but also to investigate if the tendon stumps could be used as a recycling biomaterial for tendon regeneration in the secondary grafting surgery. A canine flexor tendon repair and failure model was used. Following six weeks of repair failure, the tendon stumps were analyzed and characterized as isolated tendon-derived stem cells (TDSCs).Objectives
Methods
The long head of the biceps (LHB) is often resected in shoulder surgery and could therefore serve as a cell source for tissue engineering approaches in the shoulder. However, whether it represents a suitable cell source for regenerative approaches, both in the inflamed and non-inflamed states, remains unclear. In the present study, inflamed and native human LHBs were comparatively characterized for features of regeneration. In total, 22 resected LHB tendons were classified into inflamed samples (n = 11) and non-inflamed samples (n = 11). Proliferation potential and specific marker gene expression of primary LHB-derived cell cultures were analyzed. Multipotentiality, including osteogenic, adipogenic, chondrogenic, and tenogenic differentiation potential of both groups were compared under respective lineage-specific culture conditions.Objectives
Methods
Femoroacetabular impingement (FAI) is a potential cause of hip osteoarthritis (OA). The purpose of this study was to investigate the expression profile of matrix metalloproteinases (MMPs) in the labral tissue with FAI pathology. In this study, labral tissues were collected from four FAI patients arthroscopically and from three normal hips of deceased donors. Proteins extracted from the FAI and normal labrums were separately applied for MMP array to screen the expression of seven MMPs and three tissue inhibitors of metalloproteinases (TIMPs). The expression of individual MMPs and TIMPs was quantified by densitometry and compared between the FAI and normal labral groups. The expression of selected MMPs and TIMPs was validated and localized in the labrum with immunohistochemistry.Aims
Methods