Search

Macrophages play an important role in the development and progression of osteoarthritis (OA). The aim of this study was to identify macrophage phenotypes in synovium and monocyte subsets in peripheral blood in C57BL/6 mice by destabilizing the medial meniscus (DMM), and the association of macrophage subsets with OA features. DMM, sham, and non-operated knees were histologically assessed between 1 and 56 days for macrophage polarization states by immunohistochemistry (IHC), cartilage damage, synovial thickening, and osteophytes (n=9 per timepoint). Naive knees (n=6) were used as controls. Monocyte and polarized synovial macrophage subsets were evaluated by flow cytometry. CD64 and CD206 levels on IHC were higher at early timepoints in DMM and sham knees compared to naive knees. iNOS labeling intensity was higher in DMM and sham knees than in naive knees from d3 onwards. CD163 expression was unaltered at all timepoints. Even though macrophage polarization profiles were similar in DMM and sham knees, only in DMM knees the presence of iNOS and CD206 associated with synovial thickness, and CD163 staining inversely correlated with osteophyte presence. At day 14, monocyte subset distribution was different in peripheral blood of DMM compared to sham mice. In conclusion, monocyte subsets in blood and synovial macrophage phenotypes vary after joint surgery. High levels of iNOS+ , CD163+ , and CD206+ cells are found in both destabilized and sham-operated knees, and co-existence with joint instability may be a requirement to initiate and exacerbate OA progression. This article is protected by copyright. All rights reserved.

Objective In osteoarthritis, chondrocytes tend to acquire a hypertrophic phenotype, which contributes to the modification of the extracellular matrix, resulting in permanent cartilage changes. In mouse chondrocytes, pro-inflammatory macrophages and pro-inflammatory cytokines have been shown to stimulate hypertrophy via the activation of the nuclear factor kappa B (NF-κB) pathway. Whether or not this also occurs in human chondrocytes remains unclear. We therefore aimed to investigate whether hypertrophy-like responses in human cartilage are driven mainly by intrinsic inflammatory signaling or shaped by specific macrophage populations. Design Human articular chondrocytes were cultured with pro-inflammatory cytokines or medium conditioned by defined macrophage subsets. Furthermore, the effect of inhibition of NF-κB-dependent gene expression was evaluated using the NF-κB inhibitor SC-514. Hypertrophy was assessed by measuring the transcription level of alkaline phosphatase ( ALPL), type X collagen ( COL10A1), Indian hedgehog ( IHH), and runt-related transcription factor 2 ( RUNX2). Results The expression of hypertrophic genes was not promoted in human chondrocytes by pro-inflammatory cytokines neither pro-inflammatory M(IFNγ + TNFα) macrophages. Inhibition of the NF-κB-dependent gene expression did not affect human articular chondrocyte hypertrophy. However, tissue repair M(IL4) macrophages induced hypertrophy by promoting the expression of COL10A1, RUNX2, and IHH. Conclusion Intrinsic inflammatory signaling activation is not involved in the hypertrophic shift observed in human articular chondrocytes cultured in vitro. However, tissue repair macrophages may contribute to the onset of this detrimental phenotype in human osteoarthritic cartilage, given the effect observed in our experimental models.

Bone-to-soft tissue interfaces are responsible for transferring loads between tissues with significantly dissimilar material properties. The examples of connective soft tissues are ligaments, tendons, and cartilages. Such natural tissue interfaces have unique microstructural properties and characteristics which avoid the abrupt transitions between two tissues and prevent formation of stress concentration at their connections. Here, we review some of the important characteristics of these natural interfaces. The native bone-to-soft tissue interfaces consist of several hierarchical levels which are formed in a highly specialized anisotropic fashion and are composed of different types of heterogeneously distributed cells. The characteristics of a natural interface can rely on two main design principles, namely by changing the local microarchitectural features (e.g., complex cell arrangements, and introducing interlocking mechanisms at the interfaces through various geometrical designs) and changing the local chemical compositions (e.g., a smooth and gradual transition in the level of mineralization). Implementing such design principles appears to be a promising approach that can be used in the design, reconstruction, and regeneration of engineered biomimetic tissue interfaces. Furthermore, prominent fabrication techniques such as additive manufacturing (AM) including 3D printing and electrospinning can be used to ease these implementation processes. Biomimetic interfaces have several biological applications, for example, to create synthetic scaffolds for osteochondral tissue repair.

Without the availability of disease-modifying drugs, there is an unmet therapeutic need for osteoarthritic patients. During osteoarthritis, the homeostasis of articular chondrocytes is dysregulated and a phenotypical transition called hypertrophy occurs, leading to cartilage degeneration. Targeting this phenotypic transition has emerged as a potential therapeutic strategy. Chondrocyte phenotype maintenance and switch are controlled by an intricate network of intracellular factors, each influenced by a myriad of feedback mechanisms, making it challenging to intuitively predict treatment outcomes. In this study, we developed a regulatory network model using knowledge-based and data-driven modelling technologies. The in silico high-throughput screening of (pairwise) perturbations operated with that network model highlighted conditions impacting the hypertrophic switch. Several combinations were tested in a murine cell line and primary chondrocytes to validate the predicted conditions’ potential. Our in silico-in vitro strategy opens a new route for developing osteoarthritis targeting therapies by refining the early stages of drug discovery.

Knee osteoarthritis (OA) is a condition mainly characterized by cartilage degradation. Currently, no effective treatment exists to slow down the progression of OA-related cartilage damage. Selective COX-2 inhibitors may, next to their pain killing properties, act chondroprotective in vivo. To determine whether the route of administration is important for the efficacy of the chondroprotective properties of selective COX-2 inhibitors, a systematic review was performed according to the PRISMA guidelines. Studies investigating OA-related cartilage damage of selective COX-2 inhibitors in vivo were included. Nine of the fourteen preclinical studies demonstrated chondroprotective effects of selective COX-2 inhibitors using systemic administration. Five clinical studies were included and, although in general non-randomized, failed to demonstrate chondroprotective actions of oral selective COX-2 inhibitors. All of the four preclinical studies using bolus intra-articular injections demonstrated chondroprotective actions, while one of the three preclinical studies using a slow release system demonstrated chondroprotective actions. Despite the limited evidence in clinical studies that have used the oral administration route, there seems to be a preclinical basis for considering selective COX-2 inhibitors as disease modifying osteoarthritis drugs when used intra-articularly. Intra-articularly injected selective COX-2 inhibitors may hold the potential to provide chondroprotective effects in vivo in clinical studies.

Objective Free fatty acids (FAs) may influence cartilage metabolism and osteoarthritis (OA) disease progression. It is not clearly studied which FAs are present in the synovial fluid of knee joints and whether there are differences in FA content between nonsymptomatic and OA knee joints. The aim of this study was to investigate the presence of different types of FAs in synovial fluid of both OA- and nonsymptomatic control joints, and to analyze differences between both groups. Design A total of 23 synovial fluid samples were collected from patients with end-stage knee OA undergoing total knee replacement, with approval of the medical ethical committee. As controls, 6 synovial fluid samples were obtained from postmortem donors without any history of joint disease or arthritis. Measurement of free FA concentration was done by mass spectrometry for saturated FAs (SFA), monounsaturated FAs (MUFA), and omega-3 and omega-6 polyunsaturated FAs (n-3 PUFAs and n-6 PUFAs). Results Our measurements demonstrated the presence of SFAs, MUFAs, n-3 and n-6 PUFAs in synovial fluid of both nonsymptomatic and OA knee joints. The n-6/n-3 ratio was significantly lower in the OA group ( P = 0.0005). Arachidonic acid (n-6 PUFA) concentrations were also lower in OA synovial fluid ( P = 0.01), while tetracosadienoic acid ( P = 0.0001) and nervonic acid ( P = 0.001) (MUFAs) were higher in synovial fluid of patients with knee OA. Conclusion Synovial fluid contains a broad spectrum of free FAs. The FAs profile differs between OA and control subjects, including a tendency for less n-6 FAs in OA joints.

Background: Connective tissue progenitors (CTPs) from native bone marrow (BM) or their culture-expanded progeny, often referred to as mesenchymal stem/stromal cells, represents a promising strategy for treatment of cartilage injuries. But the cartilage regeneration capacity of these cells remains unpredictable because of cell heterogeneity. Hypothesis: The harvest technique of BM may highly influence stem cell heterogeneity and, thus, cartilage formation because these cells have distinct spatial localization within BM from the same bone. Study Design: Controlled laboratory study. Methods: CTPs obtained from the femur of patients undergoing total hip replacement by 2 harvest techniques—BM aspiration and BM collection—after bone rasping were immunophenotyped by flow cytometry and evaluated for chondrogenic ability. The spatial localization of different CTP subsets in BM was verified by immunohistochemistry. Results: Cells from the BM after rasping were significantly more chondrogenic than the donor-matched aspirate, whereas no notable difference in their osteogenic or adipogenic potential was observed. The authors then assessed whether distinct immunophenotypically defined CTP subsets were responsible for the different chondrogenic capacity. Cells directly isolated from BM after rasping contained a higher percentage (mean, 7.2-fold) of CD45–CD271+CD56+ CTPs as compared with BM aspirates. The presence of this subset in the harvested BM strongly correlated with chondrogenic ability, showing that CD271+CD56+ cells are enriched in chondroprogenitors. Furthermore, evaluation of these CTP subsets in BM revealed that CD271+CD56+ cells were localized in the bone-lining regions whereas CD271+CD56– cells were found in the perivascular regions. Since the iliac crest remains a frequent site of BM harvest for musculoskeletal regeneration, the authors also compared the spatial distribution of these subsets in trabeculae of femoral head and iliac crest and found CD271+CD56+ bone-lining cells in both tissues. Conclusion: Chondrogenically distinct CTP subsets have distinct spatial localization in BM; hence, the harvest technique of BM determines the efficiency of cartilage formation. Clinical Relevance: The harvest technique of BM may be of major importance in determining the clinical success of BM mesenchymal stem/stromal cells in cartilage repair.

Meniscal damage is, despite its major role in knee osteoarthritis (OA), often neglected in OA animal models. We evaluated structural meniscal degeneration during the course of OA in the murine collagenase-induced OA (CIOA) model. To investigate this, OA was induced in the knee joints of 33 male C57BL/6 mice by an intra-articular injection of 10U collagenase. The mice were sacrificed after 1, 3, 7, 14, 28, and 56 days, and the knees were harvested and processed for histological analysis. As control, six knees were obtained from 16-week-old mice in which no OA was induced. Meniscal damage, meniscal extrusion, and articular cartilage damage were evaluated on thionin-stained sections. Associations between parameters of interest were evaluated with Spearman rho correlation tests. When compared to non-OA knees, meniscal extrusion was visible from day 1 onwards and meniscal degeneration had a tendency to increase over time. The meniscus damage appeared around the same time as articular cartilage damage (day 14–28) and was statistically significantly more pronounced anterior than posterior, and no differences were seen between medial and lateral menisci. Meniscus and articular cartilage damage were moderately associated in the CIOA knees (ρ = 0.57; 95%CI [0.23–0.78]). Our findings suggest that the CIOA model is a valuable model to study the role of meniscal damage during OA progression and can support the development of future preventative treatment strategies.

Obesity is a well-known risk factor for osteoarthritis, but it is unknown what it does on cartilage repair. Here we investigated whether a high fat diet (HFD) influences cartilage repair in a mouse model of cartilage repair. We fed DBA/1 mice control or HFD (60% energy from fat). After 2 weeks, a full thickness cartilage defect was made in the trochlear groove. Mice were sacrificed, 1, 8, and 24 weeks after operation. Cartilage repair was evaluated on histology. Serum glucose, insulin and amyloid A were measured 24 h before operation and at endpoints. Immunohistochemical staining was performed on synovium and adipose tissue to evaluate macrophage infiltration and phenotype. One week after operation, mice on HFD had defect filling with fibroblast-like cells and more cartilage repair as indicated by a lower Pineda score. After 8 weeks, mice on a HFD still had a lower Pineda score. After 24 weeks, no mice had complete cartilage repair and we did not detect a significant difference in cartilage repair between diets. Bodyweight was increased by HFD, whereas serum glucose, amyloid A and insulin were not influenced. Macrophage infiltration and phenotype in adipose tissue and synovium were not influenced by HFD. In contrast to common wisdom, HFD accelerated intrinsic cartilage repair in DBA/1 mice on the short term. Resistance to HFD induced inflammatory and metabolic changes could be associated with accelerated cartilage repair. © 2017 Orthopaedic Research Society. Published by Wiley Periodicals, Inc.

Background: Osteoarthritis (OA) is a degenerative joint disease leading to pain and disability for which no curative treatment exists. A promising biological treatment for OA is intra-articular administration of platelet-rich plasma (PRP). PRP injections in OA joints can relieve pain, although the exact working mechanism is unclear. Purpose: To examine the effects of PRP releasate (PRPr) on pain, cartilage damage, and synovial inflammation in a mouse OA model. Study Design: Controlled laboratory study. Methods: OA was induced unilaterally in the knees of male mice (n = 36) by 2 intra-articular injections of collagenase at days –7 and –5. At day 0, pain was measured by registering weight distribution on the hindlimbs, after which mice were randomly divided into 2 groups. Mice received 3 intra-articular injections of PRP or saline in the affected knee. Seven mice per group were euthanized at day 5 for assessment of early synovial inflammation and cartilage damage. Pain in the remaining mice was registered for a total of 3 weeks. These mice were euthanized at day 21 for assessment of cartilage damage and synovial inflammation on histological evaluation. Antibodies against iNOS, CD163, and CD206 were used to identify different subtypes of macrophages in the synovial membrane. Results: Mice in the PRPr group increased the distribution of weight on the affected joint in 2 consecutive weeks after the start of the treatment ( P < .05), whereas mice in the saline group did not. At day 21, PRPr-injected knees had a thinner synovial membrane ( P < .05) and a trend toward less cartilage damage in the lateral joint compartment ( P = .053) than saline-injected knees. OA knees treated with saline showed less anti-inflammatory (CD206+ and CD163+) cells at day 5 than healthy knees, an observation that was not made in the PRPr-treated group. A higher level of pain at day 7 was associated with a thicker synovial membrane at day 21. The presence of CD206+ cells was negatively associated with synovial membrane thickness. Conclusion: In a murine OA model, multiple PRPr injections reduced pain and synovial thickness, possibly through modulation of macrophage subtypes. Clinical Relevance: PRPr injections in early OA or shortly after joint trauma can reduce pain and synovial inflammation and may inhibit OA development in patients.

Trauma and age-related cartilage disorders represent a major global cause of morbidity, resulting in chronic pain and disability in patients. A lack of effective therapies, together with a rapidly aging population, creates an impressive clinical and economic burden on healthcare systems. In this scenario, experimental therapies based on transplantation or in situ stimulation of skeletal Mesenchymal Stem/progenitor Cells (MSCs) have raised great interest for cartilage repair. Nevertheless, the challenge of guiding MSC differentiation and preventing cartilage hypertrophy and calcification still needs to be overcome. While research has mostly focused on the stimulation of cartilage anabolism using growth factors, several issues remain unresolved prompting the field to search for novel solutions. Recently, inhibition of anti-chondrogenic regulators has emerged as an intriguing opportunity. Anti-chondrogenic regulators include extracellular proteins as well as intracellular transcription factors and microRNAs that act as potent inhibitors of pro-chondrogenic signals. Suppression of these inhibitors can enhance MSC chondrogenesis and production of cartilage matrix. We here review the current knowledge concerning different types of anti-chondrogenic regulators. We aim to highlight novel therapeutic targets for cartilage repair and discuss suitable tools for suppressing their anti-chondrogenic functions. Further effort is needed to unveil the therapeutic perspectives of this approach and pave the way for effective treatment of cartilage injuries in patients. © 2018 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res.

Supplemental Digital Content is available in the text., Background: In the human ear and nose, cartilage plays a key role in establishing its form and function. Interestingly, there is a noticeable paucity on biochemical, structural, and mechanical studies focused on facial cartilage. Such studies are needed to provide elementary knowledge that is fundamental to tissue engineering of cartilage. Therefore, in this study, a comparison is made of the biochemical, structural, and mechanical differences between ear, ala nasi, and septum on the extracellular matrix (ECM) level. Methods: Cartilage samples were harvested from 10 cadaveric donors. Each sample was indented 10 times with a nanoindenter to determine the effective Young’s modulus. Structural information of the cartilage was obtained by multiple-photon laser scanning microscopy capable of revealing matrix components at subcellular resolution. Biochemistry was performed to measure glycosaminoglycan (GAG), DNA, elastin, and collagen content. Results: Significant differences were seen in stiffness between ear and septal cartilage (P = 0.011) and between ala nasi and septal cartilage (P = 0.005). Elastin content was significantly higher in ear cartilage. Per cartilage subtype, effective Young’s modulus was not significantly correlated with cell density, GAG, or collagen content. However, in septal cartilage, low elastin content was associated with higher stiffness. Laser microscopy showed a distinct difference between ear cartilage and cartilage of nasal origin. Conclusion: Proposed methods to investigate cartilage on the ECM level provided good results. Significant differences were seen not only between ear and nasal cartilage but also between the ala nasi and septal cartilage. Albeit its structural similarity to septal cartilage, the ala nasi has a matrix stiffness comparable to ear cartilage.

Background Obesity is associated with the development and progression of osteoarthritis (OA). Although the infrapatellar fat pad (IFP) could be involved in this association, due to its intracapsular localization in the knee joint, there is currently little known about the effect of obesity on the IFP. Therefore, we investigated cellular and molecular body mass index (BMI)-related features in the IFP of OA patients. Methods Patients with knee OA (N = 155, 68% women, mean age 65 years, mean (SD) BMI 29.9 kg/m2 (5.7)) were recruited: IFP volume was determined by magnetic resonance imaging in 79 patients with knee OA, while IFPs and subcutaneous adipose tissue (SCAT) were obtained from 106 patients undergoing arthroplasty. Crown-like structures (CLS) were determined using immunohistochemical analysis. Adipocyte size was determined by light microscopy and histological analysis. Stromal vascular fraction (SVF) cells were characterized by flow cytometry. Results IFP volume (mean (SD) 23.6 (5.4) mm3) was associated with height, but not with BMI or other obesity-related features. Likewise, volume and size of IFP adipocytes (mean 271 pl, mean 1933 μm) was not correlated with BMI. Few CLS were observed in the IFP, with no differences between overweight/obese and lean individuals. Moreover, high BMI was not associated with higher SVF immune cell numbers in the IFP, nor with changes in their phenotype. No BMI-associated molecular differences were observed, besides an increase in TNFα expression with high BMI. Macrophages in the IFP were mostly pro-inflammatory, producing IL-6 and TNFα, but little IL-10. Interestingly, however, CD206 and CD163 were associated with an anti-inflammatory phenotype, were the most abundantly expressed surface markers on macrophages (81% and 41%, respectively) and CD163+ macrophages had a more activated and pro-inflammatory phenotype than their CD163- counterparts. Conclusions BMI-related features usually observed in SCAT and visceral adipose tissue could not be detected in the IFP of OA patients, a fat depot implicated in OA pathogenesis. Electronic supplementary material The online version of this article (doi:10.1186/s13075-017-1395-9) contains supplementary material, which is available to authorized users.

We studied the effects of intra-articularly injected bone marrow derived mesenchymal stem cells (MSCs), as well as freshly isolated bone marrow mononuclear cells (BMMNCs), on pain, cartilage damage, bone changes and inflammation in an in-vivo rat osteoarthritis (OA) model. OA was induced unilaterally by injection of mono-iodoacetate (MIA) and allowed to develop for 3 weeks. Then, animals were treated by intra-articular injection with MSCs, BMMNCs, or saline as a control. Four weeks later, pain was assessed with an incapitance tester, subchondral bone alterations were measured with µCT and cartilage quality and joint inflammation were assessed by histological analysis. Animals treated with MSCs distributed significantly more weight to the affected limb after treatment, which was not observed in the other groups. No statistically significant differences between treatment groups regarding cartilage damage, subchondral bone alterations and synovial inflammation were observed. Additional cell tracking experiments indicated adequate intra-articular cell injection and cell survival up to 2 weeks. In our OA model, injected MSCs were able to reduce MIA induced pain, as measured by an increased weight distribution to the affected limb. No statistically significant effects of the cellular therapies on structural damage and synovial inflammation were found.

Objective: Stiffening of the joint is a feature of knee osteoarthritis (OA) that can be caused by fibrosis of the synovium. The infrapatellar fat pad (IPFP) present in the knee joint produces immune-modulatory and angiogenic factors. The goal of the present study was to investigate whether the IPFP can influence fibrotic processes in synovial fibroblasts, and to determine the role of transforming growth factor β (TGFβ) and prostaglandin F2α (PGF2α ) in these processes. Methods: Batches of fat-conditioned medium (FCM) were made by culturing pieces of IPFP obtained from the knees of 13 patients with OA. Human OA fibroblast-like synoviocytes (FLS) (from passage 3) were cultured in FCM with or without inhibitors of TGFβ/activin receptor-like kinase 5 or PGF2α for 4 days. The FLS were analyzed for production of collagen and expression of the gene for procollagen-lysine, 2-oxoglutarate 5-dioxygenase 2 (PLOD2; encoding lysyl hydroxylase 2b, an enzyme involved in collagen crosslinking) as well as the genes encoding α-smooth muscle actin and type I collagen α1 chain. In parallel, proliferation and migration of the synoviocytes were analyzed. Results: Collagen production and PLOD2 gene expression by the FLS were increased 1.8-fold (P < 0.05) and 6.0-fold (P < 0.01), respectively, in the presence of FCM, relative to control cultures without FCM. Moreover, the migration and proliferation of synoviocytes were stimulated by FCM. Collagen production was positively associated with PGF2α levels in the FCM (R = 0.89, P < 0.05), and inhibition of PGF2α levels reduced the extent of FCM-induced collagen production and PLOD2 expression. Inhibition of TGFβ signaling had no effect on the profibrotic changes. Conclusion: These results indicate that the IPFP can contribute to the development of synovial fibrosis in the knee joint by increasing collagen production, PLOD2 expression, cell proliferation, and cell migration. In addition, whereas the findings showed that TGFβ is not involved, the more recently discovered profibrotic factor PGF2α appears to be partially involved in the regulation of profibrotic changes.

Background: Mesenchymal stem cells (MSCs) are promising candidates as a cell-based therapy for osteoarthritis (OA), although current results are modest. Pre-treatment of MSCs before application might improve their therapeutic efficacy. Hypothesis: Pre-treatment of MSCs with inflammatory factors or hypoxia will improve their migration and adhesion capacities toward OA-affected tissues. Study Design: Controlled laboratory study. Methods: We used real-time polymerase chain reaction to determine the effects of different fetal calf serum (FCS) batches, platelet lysate (PL), hypoxia, inflammatory factors, factors secreted by OA tissues, and OA synovial fluid (SF) on the expression of 12 genes encoding chemokine or adhesion receptors. Migration of MSCs toward factors secreted by OA tissues was studied in vitro, and attachment of injected MSCs was evaluated in vivo in healthy and OA knees of male Wistar rats. Results: Different FCS batches, PL, or hypoxia did not influence the expression of the migration and adhesion receptor genes. Exposure to inflammatory factors altered the expression of CCR1, CCR4, CD44, PDGFRα, and PDGFRβ. MSCs migrated toward factors secreted by OA tissues in vitro. Neither pre-treatment with inflammatory factors nor the presence of OA influenced MSC migration in vitro or adhesion in vivo. Conclusion: Factors secreted by OA tissues increase MSC migration in vitro. In vivo, no difference in MSC adhesion was found between OA and healthy knees. Pre-treatment with inflammatory factors influenced the expression of migration and adhesion receptors of MSCs but not their migration in vitro or adhesion in vivo. Clinical Relevance: To improve the therapeutic capacity of intra-articular injection of MSCs, they need to remain intra-articular for a longer period of time. Pre-treatment of MSCs with hypoxia or inflammatory factors did not increase the migration or adhesion capacity of MSCs and will therefore not likely prolong their intra-articular longevity. Alternative approaches to prolong the intra-articular presence of MSCs should be developed to increase the therapeutic effect of MSCs in OA.

Background Magnetic resonance imaging (MRI) is increasingly used for research in hand osteoarthritis, but imaging the thin cartilage layers in the hand joints remains challenging. We therefore assessed the accuracy of MRI in detecting cartilage loss in patients with symptomatic osteoarthritis of the first carpometacarpal (CMC1) joint. Methods Twelve patients scheduled for trapeziectomy to treat severe symptomatic osteoarthritis of the CMC1 joint underwent a preoperative high resolution 3D spoiled gradient (SPGR) MRI scan. Subsequently, the resected trapezium was evaluated histologically. The sections were scored for cartilage damage severity (Osteoarthritis Research Society International (OARSI) score), and extent of damage (percentage surface area). Each MRI scan was scored for the area of normal cartilage, partial cartilage loss and full cartilage loss. The percentages of the total surface area with any cartilage loss and full-thickness cartilage loss were calculated using MRI and histological evaluation. Results MRI and histological evaluation both identified large areas of overall cartilage loss. The median (IQR) surface area of any cartilage loss on MRI was 98% (82–100%), and on histological assessment 96% (87–98%). However, MRI underestimated the extent of full-thickness cartilage loss. The median (IQR) surface area of full-thickness cartilage loss on MRI was 43% (22–70%), and on histological evaluation 79% (67–85%). The difference was caused by a thin layer of high signal on the articulating surface, which was interpreted as damaged cartilage on MRI but which was not identified on histological evaluation. Conclusions Three-dimensional SPGR MRI of the CMC1 joint demonstrates overall cartilage damage, but underestimates full-thickness cartilage loss in patients with advanced osteoarthritis.

Fibrates are used as lipid-lowering drugs to prevent cardiovascular pathology. Fibrates are ligands of peroxisome proliferator-activated receptor α (PPARα). Besides altering lipid metabolism, PPARα ligands exert anti-inflammatory effects on various cell types. In this study, we hypothesized that PPARα agonists exert beneficial effects on osteoarthritis (OA) and rheumatoid arthritis (RA) by their local anti-inflammatory effects, but also by their systemic influences. A systematic literature search of Medline and EMBASE databases was performed up to August 2011. The main search items were osteoarthritis, rheumatoid arthritis, peroxisome proliferator-activated receptor alpha and fibrates. Inclusion criteria were in vivo or in vitro studies regarding humans or animals in which the effects of PPARα ligands were studied. Six in vivo human studies, four in vivo animal studies and seven in vitro studies were included. The in vivo human studies showed all beneficial clinical effects of PPARα ligands, but studies were small and only four were randomized. Ligands for PPARα significantly reduced pain, swelling of the joints and decreased systemic inflammatory markers. In vitro and in vivo animal studies indicate that PPARα agonists inhibit bone resorption, and reduce inflammatory and destructive responses in cartilage and synovium. PPARα agonists such as fibrates should be considered as potential therapeutic strategy for RA. There is no clinical evidence for their use in OA, although in vitro studies indicate that PPARα agonists demonstrate different joint-protective effects locally, and systemic effects on inflammation, serum lipid levels and vascular pathology. Animal studies should be performed and after confirmation of the protective effects of PPARα, large randomized controlled trials could investigate fibrates in OA and RA.

Purpose: To determine if T1 rho mapping can be used as an alternative to delayed gadolinium-enhanced magnetic resonance imaging of cartilage (dGEMRIC) in the quantification of cartilage biochemical composition in vivo in human knees with osteoarthritis. Materials and Methods: This study was approved by the institutional review board. Written informed consent was obtained from all participants. Twelve patients with knee osteoarthritis underwent dGEMRIC and T1 rho mapping at 3.0 T before undergoing total knee replacement. Outcomes of dGEMRIC and T1 rho mapping were calculated in six cartilage regions of interest. Femoral and tibial cartilages were harvested during total knee replacement. Cartilage sulphated glycosaminoglycan (sGAG) and collagen content were assessed with dimethylmethylene blue and hydroxyproline assays, respectively. A four-dimensional multivariate mixed-effects model was used to simultaneously assess the correlation between outcomes of dGEMRIC and T1 rho mapping and the sGAG and collagen content of the articular cartilage. Results: T1 relaxation times at dGEMRIC showed strong correlation with cartilage sGAG content (r = 0.73; 95% credibility interval [CI] = 0.60, 0.83) and weak correlation with cartilage collagen content (r = 0.40; 95% CI: 0.18, 0.58). T1r relaxation times did not correlate with cartilage sGAG content (r = 0.04; 95% CI: 20.21, 0.28) or collagen content (r = 20.05; 95% CI = 20.31, 0.20). Conclusion: dGEMRIC can help accurately measure cartilage sGAG content in vivo in patients with knee osteoarthritis, whereas T1 rho mapping does not appear suitable for this purpose. Although the technique is not completely sGAG specific and requires a contrast agent, dGEMRIC is a validated and robust method for quantifying cartilage sGAG content in human osteoarthritis subjects in clinical research. (C) RSNA, 2015

Objective Adipose tissue is known to release inflammatory cytokines and growth factors. In this exploratory study, the authors examined whether the infrapatellar fat pad (IPFP) closely located to cartilage in the knee joint can affect cartilage metabolism. In addition, the authors analysed whether the macrophage types present in IPFP could explain the effect on cartilage. Methods IPFP explants obtained during total knee replacement of 29 patients with osteoarthritis (OA) were used to make fat-conditioned medium (FCM). Explants of bovine cartilage were cultured with or without FCM. Nitric oxide (NO) and glycosaminoglycan release and gene expression of matrix-degrading enzymes in cartilage were analysed. To stimulate catabolic processes in the cartilage, the authors added interleukin 1β, and the effect of six FCMs was evaluated. The presence of different types of macrophages (CD68+, CD86+ and CD206+) in OA IPFPs was compared with subcutaneous adipose tissue samples and IPFP samples from patients with an anterior cruciate ligament rupture. Results FCM alone reduced NO and glycosaminoglycan release and matrix metalloproteinase (MMP)1 gene expression by the cartilage. Moreover, when catabolic conditions were enhanced with interleukin 1β, FCM inhibited NO production as well as MMP1 and MMP3 gene expression and increased collagen type II gene expression. Significantly more CD206+ cells were present in OA IPFP samples than in subcutaneous fat or anterior cruciate ligament IPFP samples. Conclusion In contrast to the authors' expectations, medium conditioned by end-stage OA IPFP inhibited catabolic processes in cartilage. CD206+ cells present in the IPFPs used for making the FCM might have contributed to the inhibition of catabolic processes in the cartilage.

The increasing average age in developed societies is paralleled by an increase in the prevalence of many age-related diseases such as osteoarthritis (OA), which is characterized by deformation of the joint due to cartilage damage and increased turnover of subchondral bone. Consequently, deficiency in DNA repair, often associated with premature aging, may lead to increased pathology of these two tissues. To examine this possibility, we analyzed the bone and cartilage phenotype of male and female knee joints derived from 52- to 104-week-old WT C57Bl/6 and trichothiodystrophy (TTD) mice, who carry a defect in the nucleotide excision repair pathway and display many features of premature aging. Using micro-CT, we found bone loss in all groups of 104-week-old compared to 52-week-old mice. Cartilage damage was mild to moderate in all mice. Surprisingly, female TTD mice had less cartilage damage, proteoglycan depletion, and osteophytosis compared to WT controls. OA severity in males did not significantly differ between genotypes, although TTD males had less osteophytosis. These results indicate that in premature aging TTD mice age-related changes in cartilage were not more severe compared to WT mice, in striking contrast with bone and many other tissues. This segmental aging character may be explained by a difference in vasculature and thereby oxygen load in cartilage and bone. Alternatively, a difference in impact of an anti-aging response, previously found to be triggered by accumulation of DNA damage, might help explain why female mice were protected from cartilage damage. These findings underline the exceptional segmental nature of progeroid conditions and provide an explanation for pro- and anti-aging features occurring in the same individual.

Objective. In osteoarthritis (OA), changes occur in both cartilage and subchondral bone. The subchondral bone plate facilitates normal cross-talk between articular cartilage and trabecular subchondral bone, and adaptive changes in the plate due to OA may therefore disturb cross-talk homeostasis. To investigate these changes over time, we examined the cartilage-subchondral bone interface using a combined approach of histologic analysis and in vivo microfocal computed tomography. Methods. Sixteen-week-old male C57BL/6 mice (n = 32) received intraarticular injections of collagenase in 1 joint to induce instability-related OA and received saline injections in the contralateral knee joint (control joint). At 2, 4, 6, 10, and 14 weeks after injection, changes in the tibial subchondral bone plate and subchondral trabeculae were analyzed. Results. Two weeks after injection, collagenase-injected joints had significantly more cartilage damage and osteophytosis than did control joints. Osteoclast activity directly underneath the subchondral bone plate was significantly elevated in collagenase-injected joints compared to control joints (mean +/- SEM osteoclast surface/bone surface 11.07 +/- 0.79% versus 7.60 +/- 0.81%), causing the plate to become thinner and creating a large increase in subchondral bone plate porosity (mean +/- SEM cumulative porosity volume 0.05 +/- 0.04 x 10(-3) mm(3) in control joints versus 2.52 +/- 0.69 x 10(-3) mm(3) in collagenase-injected joints). Four weeks after injection, the previously formed perforations disappeared, coinciding with a significant rise in osteoblast activity in the subchondral trabecular bone in collagenase-injected joints compared to control joints (mean +/- SEM bone formation rate/bone surface 0.62 +/- 0.13 mu m(3)/mu m(2) per day versus 0.30 +/- 0.03 mu m(3)/mu m(2) per day). Conclusion. The current study is the first to provide quantitative longitudinal data on the dynamic changes in the subchondral bone plate after OA induction. The development of plate perforations may enhance mutual interaction between subchondral trabeculae, bone marrow cells, and the articular cartilage in OA.

Objective. Incidence of OA rises steeply in women of age >50 years; the climacteric period for women. The simultaneous occurrence of these events suggests an association between OA and changes in female hormonal aspects. This systematic review studies the assumed association between OA and aspects concerning the fertile period (duration, endogenous hormones, age at menarche/menopause) and the menopause [menopausal status, years since menopause (YSM) and surgical menopause]. Methods. Medline and EMBASE were searched for articles assessing associations between hand/hip/knee OA and female hormonal aspects. Methodological quality was assessed systematically, and results were summarized in a best-evidence synthesis. Results. Sixteen studies were included in the present study. For most hormonal aspects no association was found. Conflicting evidence was found for an association of age at menarche with Herberden's nodes (HNs) and hand ROA, YSM with knee ROA and ovariectomy with hip OA. An increased risk was seen for low estradiol serum levels in the early follicular phase with incident knee ROA, age at menarche being >= 11 years old with total hip replacement, being post-menopausal and YSM with the presence of HN. A protective effect was seen for age at menopause being >= 52 years with total knee replacement. Evidence level was limited for all. Conclusions. The assumed relationship between the female hormonal aspects and OA was not clearly observed in this review. The relationship is perhaps too complex, or other aspects, yet to be determined, play a role in the increased incidence in women aged >50 years.

Since the first cell therapeutic study to repair articular cartilage defects in the knee in 1994, several clinical studies have been reported. An overview of the results of clinical studies did not conclusively show improvement over conventional methods, mainly because few studies reach level I of evidence for effects on middle or long term. However, these explorative trials have provided valuable information about study design, mechanisms of repair and clinical outcome and have revealed that much is still unknown and further improvements are required. Furthermore, cellular and molecular studies using new technologies such as cell tracking, gene arrays and proteomics have provided more insight in the cell biology and mechanisms of joint surface regeneration. Besides articular cartilage, cartilage of other anatomical locations as well as progenitor cells are now considered as alternative cell sources. Growth Factor research has revealed some information on optimal conditions to support cartilage repair. Thus, there is hope for improvement. In order to obtain more robust and reproducible results, more detailed information is needed on many aspects including the fate of the cells, choice of cell type and culture parameters. As for the clinical aspects, it becomes clear that careful selection of patient groups is an important input parameter that should be optimized for each application. In addition, the study outcome parameters should be improved. Although reduced pain and improved function are, from the patient's perspective, the most important outcomes, there is a need for more structure/tissue-related outcome measures. Ideally, criteria and/or markers to identify patients at risk and responders to treatment are the ultimate goal for these more sophisticated regenerative approaches in joint surface repair in particular, and regenerative medicine in general.

Background Treatment of midportion Achilles tendinopathy is hampered by limited knowledge of the pathophysiology. Hypothesis Chondrogenic differentiation of tendon cells might take place in midportion Achilles tendinopathy and could be used as a target for drug treatment. An in vitro model for chondrogenic differentiation would be useful to evaluate existing and future treatment opportunities. Study Design Descriptive and controlled laboratory study. Methods Perioperatively harvested tissue from human midportion Achilles tendinotic lesions and healthy Achilles tendons was analyzed by microscopy and real-time reverse transcription polymerase chain reaction. In vitro chondrogenic differentiation of tendon explants was induced using transforming-growth-factor beta. This model was modulated by removing the chondrogenic stimulus or adding triamcinolone or platelet-rich plasma. Results Midportion Achilles tendinotic lesions had increased glycosaminoglycan staining and more rounded cell nuclei. Chondrogenic markers (sex-determining region Y)–box9, aggrecan, collagen 2, and RUNT-related transcription factor 2 were upregulated, but collagen 10 was not. Nondegenerative tendon explants cultured on chondrogenic medium had higher expression of aggrecan, collagen 2, and collagen 10 but not (sex-determining region Y)–box9 and RUNT-related transcription factor 2. Removing the chondrogenic stimulus decreased expression of aggrecan, collagen 2, and collagen 10. Both triamcinolone and platelet-rich plasma influenced the chondrogenic gene expression pattern in the in vitro model. Conclusion Chondrogenic differentiation is present in midportion Achilles tendinopathy. An in vitro model to study this chondrogenic differentiation was developed. Clinical Relevance This model can be used to investigate chondrogenic differentiation as a possible target for drug treatment, contributing to the development of more successful mechanism-based treatment opportunities.

Rozendaal RM; Koes BW; Van Osch GJ; Uitterlinden EJ; Garling EH; Willemsen SP; Ginai AZ; Verhaar JA; Weinans H; Bierma-Zeinstra SM. Het effect van glucosaminesulfaat op de progressie van heupartrose. Huisarts Wet 2008;51(11):535-41. Inleiding Het effect van glucosaminesulfaat op artrose is omstreden. Om meer duidelijkheid te krijgen voerden we een geblindeerd, gerandomiseerd, placebo-gecontroleerd onderzoek uit bij eerstelijns patienten met heupartrose. We onderzochten of glucosaminesulfaat effect heeft op de symptomen en de progressie van artrose. Methoden We randomiseerden in huisartsenpraktijken 222 patienten met heupartrose. Zij kregen 2 jaar lang eenmaal daags 1500 mg orale glucosaminesulfaat of een placebo. De patienten moesten voldoen aan een van de criteria voor heupartrose van het American College of Rheumatology. Primaire uitkomstmaten waren pijn- en functiescores over 24 maanden en gewrichtsspleetafname na 24 maanden. De belangrijkste secundaire uitkomstmaten waren pijn, functie en stijfheid na 3, 12 en 24 maanden. Resultaten Bij aanvang waren de demografische en klinische variabelen in beide groepen vergelijkbaar. Na 24 maanden zagen we geen verschillen in pijn: –1,54 (95%-BI –5,43-2,36) en functie: –2,01 (95%-BI –5,38-1,36). Ook de gewrichtsspleetversmalling was na 24 maanden vergelijkbaar met –0,029 (95%-BI –0,122-0,064). Tot slot vonden we geen verschillen in de secundaire uitkomstmaten. Conclusie Glucosaminesulfaat bestrijdt de symptomen en progressie van heupartrose niet beter dan een placebo.

BACKGROUND: With accumulating knowledge on osteoarthritis development, the next step is to focus on possibilities for primary prevention. METHODS: In a 2 x 2 factorial design, the effects of a diet-and-exercise program and of oral glucosamine sulfate (double blind and placebo-controlled) on the incidence of knee osteoarthritis were evaluated in a high-risk group of 407 middle-aged women with a body mass index >= 27 kg/m(2) without clinical signs of knee osteoarthritis at baseline (ISRCTN 42823086). Primary outcome was the incidence of knee osteoarthritis, defined as Kellgren & Lawrence grade >= 2, joint space narrowing of >= 1.0 mm, or clinical knee osteoarthritis (clinical and radiographic American College of Rheumatology criteria) after 2.5 years. RESULTS: After 2.5 years, only 10% of all subjects were lost to follow-up, and 17% of all knees showed incident knee osteoarthritis. Accounting for the significant interaction between the interventions, no significant main effect of either intervention was found. Independently, both interventions alone showed indications of reduced knee osteoarthritis incidence (odds ratio [OR] 0.69; 95% CI, 0.39-1.21 for the diet-and-exercise program and OR 0.60; 95% CI, 0.31-1.12 for the glucosamine intervention). These effects were neutralized in subjects receiving both interventions (OR 0.97; 95% CI, 0.55-1.71). CONCLUSIONS: No significant main effects of the diet-and-exercise program and of glucosamine sulfate were found on incident knee osteoarthritis. Nevertheless, this trial provides valuable insights for future trial design for preventive osteoarthritis studies. (C) 2015 Elsevier Inc. All rights reserved.

Objectives: Surgical manipulation of cartilage tissue is associated with chondrocyte death in the wound edges that hinders integration. The objective of this study was to evaluate the effect of a short course of treatment of a cartilage graft with a combination of hyaluronidase and collagenase on chondrocyte density and integrative capacity. Methods: Cartilage explants were treated with enzymes for various time periods and at various concentrations. A central core was punched out of a larger explant, treated with enzymes, reimplanted, and placed subcutaneously in athymic mice. The number of chondrocytes in the wound edges was counted, and the integrative capacity of the grafts was evaluated by histology. Results: Treatment with collagenase for 48 hours led to a significant increase in the number of vital chondrocytes and restored it to normal after 14 days of culture. Treatment with hyaluronidase and collagenase for 48 hours further increased chondrocyte densities to supranormal values. Shortening the treatment to 1 hour restored the chondrocyte density to normal after 14 days of culture. In vivo integration experiments showed increased chondrocyte densities in treated wound edges and extracellular matrix fibers crossing over from enzyme-treated parts to untreated parts. Conclusions: Short-duration treatment of a cartilage graft with a combination of hyaluronidase and collagenase increases cell density at wound edges and promotes integrative repair.

Summary Objective: An anterior cricoid split (ACS) causes an immediate distortion of the cricoid cartilage resulting in an anterior gap due to retraction of the cut ends. The objective of this animal study is to investigate: (1) to what extent the distortion after ACS is influenced by non-cartilaginous structures like tunica elastica, membranes, ligaments and muscles, which are connected to the cricoid; (2) how distortion is changing with further development; (3) in what way the distortion is affected by scoring of the internal surface of the cricoid; and (4) whether an immediate or late injury-induced distortion is related to age. Methods: Surgical interventions were performed in 20 young (8 weeks of age, 1300–1600 g) and 5 adult (28 weeks of age, 3500–4000 g) New Zealand White rabbits. The immediate effects were measured, and then the animals were followed for 20 weeks to study the long-term effects of the various procedures. Results: (1) The gap, immediately following an ACS, increased after additional transection of the cricothyroid ligament and the cricotracheal membrane, and even more when the cricovocal membrane was elevated from the inner surface of the cricoid arch. (2) The degree of distortion after various interventions in young animals appeared to increase substantially during further growth. (3) When the above-mentioned successive surgical steps were combined with scoring of the internal surface of the cricoid arch, a marked malformation of the split cricoid did develop with warping of the cut ends in lateral direction and a latero-cephalic rotation, the latter due to the action of the cricothyroid muscles. (4) The immediate distortion appeared to be similar in young and adult animals. During a follow-up of 20 weeks, a progressive distortion of the split cricoid ring was observed in the young growing rabbits. In adult animals, no significant progression of the distortion was found. Conclusions: The immediate and long-term distortion of the split cricoid is determined by the release of intrinsic forces of the cartilage, and extrinsic forces from non-cartilaginous structures like ligaments, muscles, membranes and tunica elastica.

Cartilage can be shaped by scoring. In an exploratory study in living adult animals, this phenomenon was demonstrated in cartilage of the nasal septum. Bending was observed immediately after superficial scoring of the cartilage surface, and the cartilage always warped in the direction away from the scored side. The scored piece of cartilage still showed its initially distorted shape 10 weeks after primary surgery. In ex vivo experiments, a clear relation between incision depth and bending of septal cartilage was observed. Under these controlled conditions, the variation between different septa was small. Deformation of the septal specimens was increased by introducing single superficial incisions deepening to half the thickness of the cartilage. A positive correlation between incision depth and bending was demonstrated. A model was used to accurately predict the degree of bending of the cartilage after making an incision of a particular depth. Hence, the effect of cartilage scoring can be predicted. Because the results of this controlled study showed excellent reproducibility for different septa, it is expected that this model can be extrapolated to human nasal septum cartilage. This would enable the surgeon to better predict the result of cartilage scoring, either preoperatively or perioperatively.

Background: Cartilage tissue engineering can offer promising solutions for restoring cartilage defects in the head and neck area and has the potential to overcome limitations of current treatments. However, to generate a construct of reasonable size, large numbers of chondrocytes are required, which limits its current applicability. Therefore, the authors evaluate the suitability of a combination of cells for cartilage regeneration: bone marrow-derived mesenchymal stem cells and ear or nasal chondrocytes. Methods: Human bone marrow-derived mesenchymal stem cells were encapsulated in alginate hydrogel as single-cell-type populations or in combination with bovine ear chondrocytes or nasal chondrocytes at an 80:20 ratio. Constructs were either cultured in vitro or implanted directly subcutaneously into mice. Cartilage formation was evaluated with biochemical and biomechanical analyses. The use of a xenogeneic coculture system enabled the analyses of the contribution of the individual cell types using species-specific gene-expression analyses. Results: In vivo, human bone marrow-derived mesenchymal stem cells/bovine ear chondrocytes or human bone marrow-derived mesenchymal stem cells/bovine nasal chondrocytes contained amounts of cartilage components similar to those of constructs containing chondrocytes only (i.e., bovine ear and nasal chondrocytes). In vitro, species-specific gene-expression analyses demonstrated that aggrecan was expressed by the chondrocytes only, which suggests a more trophic role for human bone marrow-derived mesenchymal stem cells. Furthermore, the additional effect of human bone marrow-derived mesenchymal stem cells was more pronounced in combination with bovine nasal chondrocytes. Conclusions: By supplementing low numbers of bovine ear or nasal chondrocytes with human bone marrow-derived mesenchymal stem cells, the authors were able to engineer cartilage constructs with properties similar to those of constructs containing chondrocytes only. This makes the procedure more feasible for future applicability in the reconstruction of cartilage defects in the head and neck area because fewer chondrocytes are required. CLINICAL QUESTIONS/LEVEL OF EVIDENCE: Therapeutic, V.

Cartilage structures from the head and neck possess a certain but limited capacity to heal after injury. This capacity is accredited to the perichondrium. In this study, the role of the inner (cambium) and the outer (fibrous) layers of the perichondrium in cartilage wound healing in vitro is investigated. For the first time, the possibility of selectively removing the outer perichondrium layer is presented. Using rabbit ears, three different conditions were created: cartilage explants with both perichondrium layers intact, cartilage explants with only the outer perichondrium layer dissected, and cartilage explants with both perichondrium layers removed. The explants were studied after 0, 3, 7, 14, and 21 days of in vitro culturing using histochemistry and immunohistochemistry for Ki-67, collagen type II, transforming growth factor beta 1 (TGFbeta1), and fibroblast growth factor 2 (FGF2). When both perichondrium layers were not disturbed, fibrous cells grew over the cut edges of the explants from day 3 of culture on. New cartilage formation was never observed in this condition. When only the outer perichondrium layer was dissected from the cartilage explants, new cartilage formation was observed around the whole explant at day 21. When both perichondrium layers were removed, no alterations were observed at the wound surfaces. The growth factors TGFbeta1 and FGF2 were expressed in the entire perichondrium immediately after explantation. The expression gradually decreased with time in culture. However, the expression of TGFbeta1 remained high in the outer perichondrium layer and the layer of cells growing over the explant. This indicates a role for TGFbeta1 in the enhancement of fibrous overgrowth during the cartilage wound-healing process. The results of this experimental in vitro study demonstrate the dual role of perichondrium in cartilage wound healing. On the one hand, the inner layer of the perichondrium, adjacent to the cartilage, provides (in time) cells for new cartilage formation. On the other hand, the outer layer rapidly produces fibrous overgrowth, preventing the good cartilage-to-cartilage connection necessary to restore the mechanical function of the structure.

The current White paper summarizes the discussions and exchange of experiences during the first European Interdisciplinary Summit on Cell-Based ATMPs held in Vienna, Austria, May 02-03, 2013. The meeting was supported by the Research Networking Programme REMEDIC (regenerative medicine) funded by the European Science Foundation and by the British Medical Research Council. To improve the competitiveness of Europe in the field of cell-based Advanced Medicinal Therapy Products (ATMPs), the following key issues were identified during the meeting: removal of national hurdles in the European Union, harmonization of national and subnational differences in Hospital Exemption rules, improved treatment algorithms for reimbursement, better knowledge on the mode of action, predictive preclinical efficacy and safety testing, need for innovative systems for preclinical testing, appropriate product characterization, manufacturing with cost of goods in mind, and appropriate design of clinical trials. ispartof: Tissue Engineering: Part A vol:20 issue:19 pages:2549-2554 ispartof: location:United States status: published

Tendinopathy and idiopathic osteoarthritis (OA) are prevalent in middle-aged active individuals and represent a significant disease burden. Both disorders are associated with overloading of musculoskeletal tissues and both respond well to mechanotherapy. Other shared risk factors include genetic predisposition, obesity and specific age.1 ,2 Both disorders have a multifactorial pathogenesis. Tendon and cartilage both consist of an extracellular matrix with mainly collagen (type I and II respectively), proteoglycans and sparse distribution of specialised cells. The key histopathological feature of tendinopathy and OA is extracellular matrix degeneration. The 2015 study on tendon structural changes in patients with diabetes in BJSM by de Jonge et al 3 points to similarities between tendinopathy and OA, which we frequently notice in our collaborative tendon and OA research group. These similarities between degenerative tendinopathy and OA may have clinical implications. Below, we would like to display some examples. ### Role of advanced glycation end products Advanced glycation end products (AGEs) accumulate in connective tissues of patients with type 2 diabetes. De Jonge et al 3 showed more tendon structure disorganisation in individuals with …

Tissue Engineering. Part B, Reviews, 21 (2), ISSN:1937-3368, ISSN:1937-3376

A pedicled auricular perichondrial flap wrapped around trabecular demineralized bovine bone matrix can generate an autologous cartilage graft. In earlier experimental studies, it was demonstrated that this graft could be used for nasal and cricoid reconstruction. It was assumed that the vascularization of the perichondrial flap was obligatory, but it was never proven that the flap should be pedicled. Moreover, for clinical use, the dimensions of the auricle would set restrictions to the size of the graft generated. Therefore, the possibility to generate cartilage with a composite graft of a free perichondrial flap wrapped around demineralized bovine bone matrix, by using young New Zealand White rabbits, was studied. This composite graft was implanted at poorly (subcutaneously in the abdominal wall; n = 12), fairly (subcutaneously in the pinna; n = 12), and well-vascularized sites (quadriceps muscle; n = 12). As a control, trabecular demineralized bovine bone matrix was implanted without perichondrial cover. Half of these grafts (n = 6) were harvested after 3 weeks, and the remaining grafts (n = 6) after 6 weeks of implantation. In histologic sections of these grafts, the incidence of cartilage formation was scored. Furthermore, the amount of newly formed cartilage was calculated by computerized histomorphometry. Trabecular demineralized bovine bone matrix without perichondrial cover demonstrated early resorption; no cartilage or bone was formed. In demineralized bovine bone matrix wrapped in perichondrium, early cartilage formed after 3 weeks at well- and fairly vascularized sites. No cartilage could be detected in grafts placed at a poorly vascularized site after 3 weeks; minimal cartilage formed after 6 weeks. In summary, the highest incidence of cartilage formed when trabecular demineralized bovine bone matrix was wrapped either in a pedicled auricular perichondrial flap or in a free perichondrial flap, which was placed at a well-vascularized site. Second, a significantly higher percentage of the total area of the graft was cartilaginized at well-vascularized sites after 3 weeks. The newly generated cartilage contained collagen type II and proteoglycans with hyaluronic acid binding regions, whereas collagen type I was absent, indicating the presence of hyaline cartilage. This study demonstrates that new cartilage suitable for a graft can be generated by free perichondrial flaps, provided that the site of implantation is well vascularized. Consequently, the size of such a graft is no longer limited to the dimensions of the auricle.

This study was performed to determine the various processes involved in the behaviour of hyaline cartilage during the wound healing period after trauma or surgery of vulnerable structures like the nasal septal cartilage and the cricoid. The results of different procedures (perpendicular and parallel to the cartilage surface) in young and young-adult animals were analyzed: septal incision at different locations (young-old), cricoid split (young-old), suturing cartilage, closing defects with autologous cartilage (young), biomaterials (young) and newly engineered cartilage in 4- and 24-week-old rabbits (series of ten animals). Cartilage of the young rabbit and child have similar hyaline cartilage with a varying distribution in thickness. Thinner areas are more susceptible to malformations. Incisions through younger cartilage give rise to some new cartilage formation covered by a new layer of perichondrium: through older, differentiated cartilage the incision causes superficial but permanent necrosis. Edges of cut cartilage mostly do heal by formation of fibrous junctions. This forms a weak spot, sensitive to deviations. The same fate goes for the healing between the autologous graft and the surrounding pre-existent cartilage. Trauma parallel to the surface, leads to inconsistent quantity of neocartilage. With ageing the wound healing and regenerative capacities decrease. In general, biomaterials are less accepted by the surrounding tissues and would impede further growth. Only newly engineered, and thus less differentiated (younger) cartilage of hyaline nature, appeared to be well accepted at the interface with the edges of a cartilage defect. There are indications that the release of growth factors might play a role in cartilage wound healing. In the child as well as the adult, wound healing of hyaline cartilage structures is incomplete, and surgery remains 'experimental' surgery. The clinical implications of gradual loss of the regenerative capacity of hyaline cartilage should be further investigated.

Introduction Articular cartilage needs sulfated-glycosaminoglycans (sGAGs) to withstand high pressures while mechanically loaded. Chondrocyte sGAG synthesis is regulated by exposure to compressive forces. Moderate physical exercise is known to improve cartilage sGAG content and might protect against osteoarthritis (OA). This study investigated whether rat knee joints with sGAG depleted articular cartilage through papain injections might benefit from moderate exercise, or whether this increases the susceptibility for cartilage degeneration. Methods sGAGs were depleted from cartilage through intraarticular papain injections in the left knee joints of 40 Wistar rats; their contralateral joints served as healthy controls. Of the 40 rats included in the study, 20 rats remained sedentary, and the other 20 were subjected to a moderately intense running protocol. Animals were longitudinally monitored for 12 weeks with in vivo micro-computed tomography (μCT) to measure subchondral bone changes and single-photon emission computed tomography (SPECT)/CT to determine synovial macrophage activation. Articular cartilage was analyzed at 6 and 12 weeks with ex vivo contrast-enhanced μCT and histology to measure sGAG content and cartilage thickness. Results All outcome measures were unaffected by moderate exercise in healthy control joints of running animals compared with healthy control joints of sedentary animals. Papain injections in sedentary animals resulted in severe sGAG-depleted cartilage, slight loss of subchondral cortical bone, increased macrophage activation, and osteophyte formation. In running animals, papain-induced sGAG-depleted cartilage showed increased cartilage matrix degradation, sclerotic bone formation, increased macrophage activation, and more osteophyte formation. Conclusions Moderate exercise enhanced OA progression in papain-injected joints and did not protect against development of the disease. This was not restricted to more-extensive cartilage damage, but also resulted in pronounced subchondral sclerosis, synovial macrophage activation, and osteophyte formation., Arthritis Research & Therapy, 16 (1), ISSN:1465-9905, ISSN:1465-9913, ISSN:1478-6362, ISSN:1478-6354

Adipose tissue-derived mesenchymal stem cells (ASC) are of great interest as a cellular therapeutic agent for regenerative and immunomodulatory purposes. The function of ASC adapts to environmental conditions, such as oxygen tension. Oxygen levels within tissues are typically much lower than under standard culture conditions and ASC used for therapy therefore encounter a change from normoxic to hypoxic conditions. The effect of hypoxia on the regenerative potential of ASC has been investigated in a number of studies. The effect of hypoxia on the immunomodulatory function of ASC, however, remains to be determined. In the present study the effect of hypoxic (1% oxygen) culture conditions on human ASC was examined. ASC showed no signs of toxicity under low oxygen levels and no major immunophenotypical changes were observed, apart from a down regulation of the marker CD105. Oxygen tension had no effect on the proliferation of ASC and colony forming unit (CFU) efficiency remained the same under 1% and 20% oxygen. Under both oxygen levels ASC were capable of strong upregulation of the immunomodulatory molecules indolamine 2,3-dioxygenase (IDO) and programmed death ligand-1 (PD-L1) upon stimulation with IFN- and TNF-, and, in addition, IDO activity as measured by the accumulation of L-kynurenine was not affected under hypoxia. The ability of ASC to inhibit anti-CD3/CD28 stimulated CD4+ and CD8+ T cell proliferation was enhanced under hypoxic conditions.The results of the present study demonstrate that the immunosuppressive capacity of ASC is maintained under hypoxic conditions. These findings are important for the therapeutic use of ASC and may be applied for the in vitro generation of ASC with improved functionality for therapeutic use.

The outcome of surgical interventions is largely depending on the quality of wound healing of the tissues. In children, a second aspect of paramount importance is the effects on further growth.

Background: In diseased joints, the catabolic environment results in progressive joint damage. Mesenchymal stem cells (MSCs) can have immunomodulatory effects by secreting anti-inflammatory factors. To exert these effects, MSCs need to be triggered by pro-inflammatory cytokines. To explore the potential of MSCs as a treatment for diseased joints, we studied the effect of synovial fluid (SF) from donors with different joint diseases and donors without joint pathology on the immunomodulatory capacities of human MSCs in vitro. We hypothesized that SF of diseased joints influences the immunomodulatory effects of MSCs. Materials and Methods: MSCs were cultured in medium with SF of six osteoarthritis (OA) or six rheumatoid arthritis (RA) donors and three donors without joint pathology were used as control. Gene expressions of IL-6, HGF, TNFa, TGFb1, and indoleamine 2,3-dioxygenase (IDO) were analyzed. l-kynurenine concentration in conditioned medium (CM) by MSCs with SF was determined as a measure of IDO activity by MSCs. Furthermore, the effect of CM with SF on proliferation of activated lymphocytes was analyzed. Results: Addition of SF significantly up-regulated the mRNA expression of IL-6 and IDO in MSCs. SF(OA) induced significantly higher expression of IDO than SF(control), although no difference in IDO activity of the MSCs could be shown with a l-kynurenine assay. Medium conditioned by MSCs with SF(OA or RA) suppressed activated lymphocyte proliferation in vitro more than medium conditioned by MSCs without SF or with SF(control). Discussion: SF can influence the expression of genes involved in immunomodulation by MSCs and the effect on lymphocyte proliferation. We found indications for disease-specific differences between SFs but the variation between donors, even within one disease group was high. These data warrant further research to examine the potential application of MSC therapy in arthritic joints.

Background Infrapatellar fat pad (IPFP) might be involved in osteoarthritis (OA) by production of cytokines. It was hypothesised that production of cytokines is sensitive to environmental conditions. Objectives To evaluate cytokine production by IPFP in response to interleukin (IL)1b and investigate the ability to modulate this response with an agonist for peroxisome proliferator activated receptor alpha (PPAR alpha), which is also activated by lipid-lowering drugs such as fibrates. Methods Cytokine secretion of IPFP was analysed in the medium of explant cultures of 29 osteoarthritic patients. IPFP (five donors) and synovium (six donors) were cultured with IL-1b and PPAR alpha agonist Wy14643. Gene expression of IL-1b, monocyte chemoattractant protein (MCP1), (IL-6, tumour necrosis factor (TNF)alpha, leptin, vascular endothelial growth factor (VEGF), IL-10, prostaglandin-endoperoxide synthase (PTGS)2 and release of TNF alpha, MCP1 and prostaglandin E-2 were compared with unstimulated IPFP and synovium explants. Results IPFP released large amounts of inflammatory cytokines, adipokines and growth factors. IL-1b increased gene expression of PTGS2, TNF alpha, IL-1b, IL-6 and VEGF and increased TNF alpha release in IPFP. MCP1, leptin, IL-10 gene expression and MCP1, leptin and PGE(2) release did not increase significantly. Synovium responded to IL-1b similarly to IPFP, except for VEGF gene expression. Wy14643 decreased gene expression of PTGS2, IL-1b, TNF alpha, MCP1, VEGF and leptin in IPFP explants and IL-1b, TNF alpha, IL-6, IL-10 and VEGF in synovium that responded to IL-1b. Conclusion IPFP is an active tissue within the joint. IPFP cytokine production is increased by IL-1b and decreased by a PPAR alpha agonist. The effects were similar to effects seen in synovium. Fibrates may represent a potential disease-modifying drug for OA by modulating inflammatory properties of IPFP and synovium.

Introduction This study aimed to determine whether, as in osteoarthritis, increased levels of interleukin-6 (IL-6) are present in the synovial fluid of patients with symptomatic cartilage defects and whether this IL-6 affects cartilage regeneration as well as the cartilage in the degenerated knee. Methods IL-6 concentrations were determined by ELISA in synovial fluid and in conditioned media of chondrocytes regenerating cartilage. Chondrocytes were obtained from donors with symptomatic cartilage defects, healthy and osteoarthritic donors. The effect of IL-6 on cartilage regeneration and on metabolism of the resident cartilage in the knee was studied by both inhibition of endogenous IL-6 and addition of IL-6, in a regeneration model and in osteoarthritic explants in the presence of synovial fluid, respectively. Readout parameters were DNA and glycosaminoglycan (GAG) content and release. Differences between controls and IL-6 blocked or supplemented samples were determined by univariate analysis of variance using a randomized block design. Results Synovial fluid of patients with symptomatic cartilage defects contained more IL-6 than synovial fluid of healthy donors (P = 0.001) and did not differ from osteoarthritic donors. IL-6 production of osteoarthritic chondrocytes during cartilage regeneration was higher than that of healthy and defect chondrocytes (P < 0.001). Adding IL-6 increased GAG production by healthy chondrocytes and decreased GAG release by osteoarthritic chondrocytes (P < 0.05). Inhibition of IL-6 present in osteoarthritic synovial fluid showed a trend towards decreased GAG content of the explants (P = 0.06). Conclusions Our results support a modest anabolic role for IL-6 in cartilage matrix production. Targeting multiple cytokines, including IL-6, may be effective in improving cartilage repair in symptomatic cartilage defects and osteoarthritis.

Background Bone grafts are required to repair large bone defects after tumour resection or large trauma. The availability of patients' own bone tissue that can be used for these procedures is limited. Thus far bone tissue engineering has not lead to an implant which could be used as alternative in bone replacement surgery. This is mainly due to problems of vascularisation of the implanted tissues leading to core necrosis and implant failure. Recently it was discovered that embryonic stem cells can form bone via the endochondral pathway, thereby turning in-vitro created cartilage into bone in-vivo. In this study we investigated the potential of human adult mesenchymal stem cells to form bone via the endochondral pathway. Methods MSCs were cultured for 28 days in chondrogenic, osteogenic or control medium prior to implantation. To further optimise this process we induced mineralisation in the chondrogenic constructs before implantation by changing to osteogenic medium during the last 7 days of culture. Results After 8 weeks of subcutaneous implantation in mice, bone and bone marrow formation was observed in 8 of 9 constructs cultured in chondrogenic medium. No bone was observed in any samples cultured in osteogenic medium. Switch to osteogenic medium for 7 days prevented formation of bone in-vivo. Addition of β-glycerophosphate to chondrogenic medium during the last 7 days in culture induced mineralisation of the matrix and still enabled formation of bone and marrow in both human and rat MSC cultures. To determine whether bone was formed by the host or by the implanted tissue we used an immunocompetent transgenic rat model. Thereby we found that osteoblasts in the bone were almost entirely of host origin but the osteocytes are of both host and donor origin. Conclusions The preliminary data presented in this manuscript demonstrates that chondrogenic priming of MSCs leads to bone formation in vivo using both human and rat cells. Furthermore, addition of β-glycerophosphate to the chondrogenic medium did not hamper this process. Using transgenic animals we also demonstrated that both host and donor cells played a role in bone formation. In conclusion these data indicate that in-vitro chondrogenic differentiation of human MSCs could lead to an alternative and superior approach for bone tissue engineering.

Objective: To investigate the association between weight or body mass index (BMI) and the development of hand osteoarthritis. Methods: Systematic review of observational studies. Medical databases were searched up to April 2008. Articles that presented data on the association between weight and hand osteoarthritis were selected. The qualities of these studies were then assessed by two independent reviewers using a 19 criteria scoring system. Using the mean scores of all studies as a cut-off value, the studies were deemed as high or low quality. Study quality and study designs were combined to determine the level of evidence using best-evidence synthesis, which consisted of fi ve levels of evidence. Results: From the 25 studies included, two had cohort, three case-control and 20 cross-sectional study designs. Fifteen studies were considered high-quality studies. Of these high-quality studies, one cohort, two case-control and seven cross-sectional studies showed a positive association between weight or BMI and hand osteoarthritis. Based on three high-quality studies with preferred study designs (one cohort and two case-control) with a positive association, the level of evidence of the association between overweight and developing hand osteoarthritis is moderate. The approximate risk ratio of this association is 1.9. Conclusion: Weight or BMI is associated with the development of hand osteoarthritis. The level of evidence of published studies is moderate according to best-evidence synthesis. Further high-quality cohort or case-control studies are needed to elucidate the role of weight in hand osteoarthritis.

Introduction: Oestrogen depletion may influence onset and/or progression of osteoarthritis. We investigated in an ovariectomized mouse model the impact of oestrogen loss and oestrogen supplementation on articular cartilage and subchondral bone in tibia and patella, and assessed bone changes in osteoarthritis development. Methods: C3H/HeJ mice were divided into four groups: sham-operated, oestrogen depletion by ovariectomy (OVX), OVX with estradiol supplementation (OVX+E) and OVX with bisphosphonate (OVX+BP). Each mouse had one knee injected with low-dose iodoacetate (IA), and the contralateral knee was injected with saline. Cartilage was analysed histologically 12 weeks postsurgery; bone changes were monitored over time using in vivo micro-computed tomography. Results: In tibiae, OVX alone failed to induce cartilage damage, but OVX and IA combination significantly induced cartilage damage. In patellae, OVX alone induced significant cartilage damage, which was enhanced by IA. In both tibiae and patellae, OVX in combination with IA significantly decreased subchondral cortical thickness in an additive manner. OVX+E and OVX+BP inhibited tibial and patellar subchondral cortical thinning, inhibited patellar and tended to diminish tibial cartilage damage. In patellae, IA interacted with BP, leading to increased subchondral cortical and trabecular bone. Conclusions: This study demonstrates the significance of oestrogen for articular cartilage and subchondral bone and maintenance of healthy joints, supporting an etiological role for altered oestrogen signaling in osteoarthritis either by directly affecting cartilage or increasing susceptibility for an osteoarthritis trigger. The data strongly support the concept of involvement of subchondral bone plate in osteoarthritis.

Contains fulltext : 81091.pdf (Publisher’s version ) (Closed access) OBJECTIVE: To investigate whether porous titanium can provide a better support for revascularization of a mucosal graft ideal for tracheal reconstruction. In patients with laryngotracheal stenosis or tumor, the mucosa with supporting structures can be damaged, resulting in a defect that has to be reconstructed. Autologous tissues like cartilage and mucosa have been used for reconstruction. The main problem has been incomplete mucosal reepithelialization. DESIGN: In the first experiment, porous titanium or ear cartilage was combined with mucosa and implanted subcutaneously in athymic mice for different periods of time. In the second experiment, using rabbits, surgically created defects were reconstructed with porous titanium and mucosa on a pedicled fascia flap using a 2-stage procedure. The implants were analyzed with emphasis on angiogenesis and mucosal survival. SUBJECTS: Male New Zealand white rabbits and nude athymic mice (BALB-c nu/nu). RESULTS: Normal mucosa having a submucosal layer with vital cells was noted on top of the titanium. Multiple blood vessels were observed extending from the muscle layer through the titanium. Cytokeratin expression was detected in the suprabasal and basal layers of the mucosal epithelium. In contrast, the mucosa on cartilage showed no vital cells and no cytokeratin expression. In the rabbit experiment, all animals survived the reconstruction. The titanium was well integrated to the adjacent tracheal cartilage and surrounding tissues, supporting a fully vital mucosa. CONCLUSIONS: Porous titanium is an inert biomaterial that provides support and allows easy revascularization of a mucosal graft. Titanium, in combination with viable autologous tissues, is a good alternative for tracheal reconstruction.

Background The effectiveness of glucosamine sulfate as a symptom and disease modifier for osteoarthritis is still under debate. Objective To assess whether glucosamine sulfate has an effect on the symptoms and structural progression of hip osteoarthritis during 2 years of treatment. Design Randomized, controlled trial. Setting Primary care in the Netherlands. Patients 222 patients with hip osteoarthritis who were recruited by their general practitioner. Patients were eligible if they met the American College of Rheumatology clinical criteria for hip osteoarthritis. Intervention 2 years of treatment with 1500 mg of oral glucosamine sulfate or placebo once daily. Measurements Primary outcome measures were Western Ontario and McMaster Universities (WOMAC) pain and function subscales over 24 months and joint space narrowing after 24 months. The main secondary outcome measures were WOMAC pain, function, and stiffness after 3, 12, and 24 months. Results At baseline, both groups were similar in demographic and clinical variables. Overall, WOMAC pain did not differ (mean difference [glucosamine sulfate minus placebo], -1.54 [95% CI, -5.43 to 2.36]), nor did WOMAC function (mean difference, -2.01 [CI, -5.38 to 1.36]). Joint space narrowing also did not differ after 24 months (mean difference, -0.029 [CI, -0.122 to 0.064]). Only 1 of the sensitivity analyses, based on extreme assumptions regarding missing assessments due to total hip replacement, provided results consistent with a glucosamine effect. Limitations Twenty patients had total hip replacement during the trial. Half of the patients had a Kellgren and Lawrence score of 1. Conclusion Glucosamine sulfate was no better than placebo in reducing symptoms and progression of hip osteoarthritis. International Standard Randomised Controlled Trial Number: ISRCTN54513166.

Background This study evaluates changes in peri-articular bone in two canine models for osteoarthritis: the groove model and the anterior cruciate ligament transection (ACLT) model. Methods Evaluation was performed at 10 and 20 weeks post-surgery and in addition a 3-weeks time point was studied for the groove model. Cartilage was analysed, and architecture of the subchondral plate and trabecular bone of epiphyses was quantified using micro-CT. Results At 10 and 20 weeks cartilage histology and biochemistry demonstrated characteristic features of osteoarthritis in both models (very mild changes at 3 weeks). The groove model presented osteophytes only at 20 weeks, whereas the ACLT model showed osteophytes already at 10 weeks. Trabecular bone changes in the groove model were small and not consistent. This contrasts the ACLT model in which bone volume fraction was clearly reduced at 10 and 20 weeks (15–20%). However, changes in metaphyseal bone indicate unloading in the ACLT model, not in the groove model. For both models the subchondral plate thickness was strongly reduced (25–40%) and plate porosity was strongly increased (25–85%) at all time points studied. Conclusion These findings show differential regulation of subchondral trabecular bone in the groove and ACLT model, with mild changes in the groove model and more severe changes in the ACLT model. In the ACLT model, part of these changes may be explained by unloading of the treated leg. In contrast, subchondral plate thinning and increased porosity were very consistent in both models, independent of loading conditions, indicating that this thinning is an early response in the osteoarthritis process.