Cartilage damage in the haemophilic joints: pathophysiology, diagnosis and management

Intra-articular bleeding affects the metabolism and repair of articular cartilage. Biomechanical data have shown that blood causes harmful effects on overall cartilage function under loading conditions. Therefore, haemophilic patients suffering a haemarthrosis should be subjected to blood aspiration (arthrocentesis) to prevent cartilage damage. MRI and ultrasonography have shown themselves to be excellent noninvasive tools for the evaluation of early cartilage damage that remains undetectable by conventional radiography in haemophilic patients. Prophylaxis with the deficient factor can prevent cartilage deterioration and reduce the incidence of joint haemorrhage in children with haemophilia. Radiosynovectomy has proved to be a highly effective procedure to decrease both the frequency and the severity of recurrent intra-articular bleeding episodes. Nowadays, the most usual surgical procedures for treating articular cartilage defects (cartilage repair) include abrasion chondroplasty, microfracture, mosaicplasty, autologous chondrocyte implantation (ACI), and matrix-induced ACI. In small defects (<2-4 cm(2)), ostechondral autograft or microfracture are the recommended options. In large defects (>2-4 cm(2)), ACI or osteochondral allograft are indicated. However, these techniques have not been applied in haemophilic patients because inflammatory conditions and advanced degenerative change (>50% joint space narrowing) are contraindications for cartilage repair. Thus, prevention of cartilage damage is paramount in haemophilia. The definitive remedy for advanced cartilage damage is either (knee or hip) replacement or (ankle) arthrodesis. Primary prophylaxis and radiosynovectomy are the best alternatives at our disposal to protect our patients against cartilage damage and arthropathy in haemophilic joints.     

Surgical approaches to the repair of cartilage defects

Traumatic defects in articular cartilage are common in the young athletic population. They may occur in association with other injuries to the knee, particularly anterior cruciate ligament disruption. We understand that both theoretically and clinically, these defects may lead to an increased incidence of ongoing painful symptoms in the short term and degenerative joint disease in the long term. The orthopedic surgeon has several options to deal with theses injuries. The choice is dependent on the size and position of the lesion in the knee and any associated pathology. The most commonly practised methods aim to evoke a ‘repair’ response of fibrocartilage formation. This often helps in the short term, but the fibrocartilage degenerates over time, resulting in the return of symptoms. These ‘repair’ methods can be classified as: 1. Marrow stimulation techniques– these include abrasion chondroplasty, subchondral drilling and microfracture techniques. 2. Scaffold induced repair techniques. More recently, attempts to ‘re‐generate’ normal articular cartilage have been introduced to clinical practice. These are: 1. Mosaicplasty– autogenous osteochondral plug transplantation. 2. Autologous chondrocyte implantation (ACI)– this involves the harvest and culturing of autologous chondrocytes and then re‐implantation via injection under a periosteal or porcine collagen patch. The newest technology allow implantation of the collagen patch which has had chondrocytes cultured within its structure. The results of these autologous chondrocyte implantation show encouraging short to medium term results clinically. 3. Some orthopaedic centres have recently been advocating ‘articular cartilage paste grafting’– this is a simple technique based upon the theory that a paste of autogenous articular cartilage and subchondral bone should contain chondrocytes, stem cells and growth factors in its own scaffold. Orthopedic surgeons await with interest the outcome of pre‐clinical work in examining the use of growth factors, scaffold technology and gene therapy in helping with the clinical problem of articular cartilage defects.     

Platelet lysate 3D scaffold supports mesenchymal stem cell chondrogenesis: An improved approach in cartilage tissue engineering

Articular lesions are still a major challenge in orthopedics because of cartilage's poor healing properties. A major improvement in therapeutics was the development of autologous chondrocytes implantation (ACI), a biotechnology-derived technique that delivers healthy autologous chondrocytes after in vitro expansion. To obtain cartilage-like tissue, 3D scaffolds are essential to maintain chondrocyte differentiated status. Currently, bioactive 3D scaffolds are promising as they can deliver growth factors, cytokines, and hormones to the cells, giving them a boost to attach, proliferate, induce protein synthesis, and differentiate. Using mesenchymal stem cells (MSCs) differentiated into chondrocytes, one can avoid cartilage harvesting. Thus, we investigated the potential use of a platelet-lysate-based 3D bioactive scaffold to support chondrogenic differentiation and maintenance of MSCs. The MSCs from adult rabbit bone marrow (n?=?5) were cultivated and characterized using three antibodies by flow cytometry. MSCs (1?×?10⁵) were than encapsulated inside 60?µl of a rabbit platelet-lysate clot scaffold and maintained in Dulbecco's Modified Eagle Medium Nutrient Mixture F-12 supplemented with chondrogenic inductors. After 21 days, the MSCs-seeded scaffolds were processed for histological analysis and stained with toluidine blue. This scaffold was able to maintain round-shaped cells, typical chondrocyte metachromatic extracellular matrix deposition, and isogenous group formation. Cells accumulated inside lacunae and cytoplasm lipid droplets were other observed typical chondrocyte features. In conclusion, the usage of a platelet-lysate bioactive scaffold, associated with a suitable chondrogenic culture medium, supports MSCs chondrogenesis. As such, it offers an alternative tool for cartilage engineering research and ACI.     

Technology insight: adult mesenchymal stem cells for osteoarthritis therapy

Despite the high prevalence and morbidity of osteoarthritis (OA), an effective treatment for this disease is currently lacking. Restoration of the diseased articular cartilage in patients with OA is, therefore, a challenge of considerable appeal to researchers and clinicians. Techniques that cause multipotent adult mesenchymal stem cells (MSCs) to differentiate into cells of the chondrogenic lineage have led to a variety of experimental strategies to investigate whether MSCs instead of chondrocytes can be used for the regeneration and maintenance of articular cartilage. MSC-based strategies should provide practical advantages for the patient with OA. These strategies include use of MSCs as progenitor cells to engineer cartilage implants that can be used to repair chondral and osteochondral lesions, or as trophic producers of bioactive factors to initiate endogenous regenerative activities in the OA joint. Targeted gene therapy might further enhance these activities of MSCs. Delivery of MSCs might be attained by direct intra-articular injection or by graft of engineered constructs derived from cell-seeded scaffolds; this latter approach could provide a three-dimensional construct with mechanical properties that are congruous with the weight-bearing function of the joint. Promising experimental and clinical data are beginning to emerge in support of the use of MSCs for regenerative applications.     

Cell-based cartilage repair: illusion or solution for osteoarthritis

PURPOSE OF REVIEW: Regeneration of damaged articular cartilage remains one of the most challenging problems in orthopedic surgery. Distinct surgical procedures were developed for the repair of focal cartilage defects and this review will focus on recent aspects of cell-based healing approaches that aim to achieve restoration of normal joint function by regenerating hyaline cartilage. RECENT FINDINGS: Surgical techniques are rapidly developing, and include resorbable biomaterials and expanded human mesenchymal stem cells to avoid disadvantages conferred by periosteal flaps and autologous chondrocytes. While expansion of mesenchymal stem cells seems to be safe and applicable, some concern exists about the stability of mesenchymal stem cells set to path to become chondrocytes, since common in-vitro protocols of chondrogenesis induce a program related to endochondral ossification which may finally yield only transient cartilage. SUMMERY: Bone marrow-stimulating techniques and autologous chondrocyte transplantation confer pain relief to the patients, and are superior to no treatment. Similar in their clinical outcome, they induce fibrocartilaginous repair tissue which may mature towards hyaline cartilage over time. Gained knowledge in the regulation of chondrogenesis, the role of host cell recruitment, transplanted cells, defect-filling materials and the influence of factors from subchondral bone will help to improve surgical procedures to allow their application to larger defects and patients with advanced signs of osteoarthritis.     

Pathogenesis of haemophilic synovitis: experimental studies on blood-induced joint damage

Summary.  Hemarthrosis is a common manifestation of haemophilia, and joint arthropathy remains a frequent complication. Even though the exact mechanisms related to blood-induced joint disease have not yet been fully elucidated, it is likely that iron deposition in the synovium induces an inflammatory response that causes not only immune system activation but also stimulates angiogenesis. This process ultimately results in cartilage and bone destruction. Investigating the processes that occur in the early stages of blood-induced joint disease in humans has been very limited. Therefore, the use of haemophilic animal models is critical to augment the understanding of this phenomenon. This article discusses three cellular regulators (p53, p21 and TRAIL) induced in synovial tissue that are important for iron metabolism. A cartilage remodelling programme induced by the release of cytokines and growth factors that result in articular damage is also discussed. Full elucidation of the pathogenesis of haemophilic joint disease is required to identify new avenues for prevention and therapy.     

Osteoarthritic chondrocyte–secreted morphogens induce chondrogenic differentiation of human mesenchymal stem cells

Objective

The potential of stem cells to repair compromised cartilage tissue, such as in osteoarthritis (OA), depends strongly on how transplanted cells respond to factors secreted from the residing OA chondrocytes. This study was undertaken to determine the effect of morphogenetic signals from OA chondrocytes on chondrogenic differentiation of human mesenchymal stem cells (MSCs).

Methods

The effect of OA chondrocyte–secreted morphogens on chondrogenic differentiation of human MSCs was evaluated using a coculture system involving both primary and passaged OA chondrocytes. The findings were compared against findings for human MSCs cultured in OA chondrocyte–conditioned medium. Gene expression analysis, biochemical assays, and immunofluorescence staining were used to characterize the chondrogenic differentiation of human MSCs. Mass spectrometry analysis was used to identify the soluble factors. Numerical analysis was carried out to model the concentration profile of soluble factors within the human MSC–laden hydrogels.

Results

The human MSCs cocultured with primary OA chondrocytes underwent chondrogenic differentiation even in the absence of growth factors; however, the same effect could not be mimicked using OA chondrocyte–conditioned medium or expanded cells. Additionally, the cocultured environment down‐regulated hypertrophic differentiation of human MSCs. Mass spectrometry analysis demonstrated cell–cell communication and chondrocyte phenotype–dependent effects on cell‐secreted morphogens.

Conclusion

The experimental findings, along with the results of the numerical analysis, suggest a crucial role of soluble morphogens and their local concentrations in the differentiation pattern of human MSCs in a 3‐dimensional environment. The concept of using a small number of chondrocytes to promote chondrogenic differentiation of human MSCs while preventing their hypertrophic differentiation could be of great importance in formulating effective stem cell–based cartilage repair.

     

Physiopathology of haemophilic arthropathy

Summary.  Haemophilic arthropathy, which shares some clinical and biological injury characteristics with rheumatoid arthritis, is characterized by two main features: chronic proliferative synovitis and cartilage destruction. It is the consequence of repeated extravasation of blood into joint cavities, but its exact pathogenesis, particularly with regard to early changes in the joint, is still incompletely understood. This review presents recent findings obtained in experiments performed in vitro and using animal models, which have improved our knowledge of the pathogenesis of haemophilic arthropathy. These experimental studies show that haemophilic arthropathy is a multifactorial event in which the deposit of iron in the joints appears to exert a central role. First, iron may promote the apoptosis of chondrocytes by catalysing the formation of oxygen metabolites; this may explain the fact that intra-articular blood exerts a directly harmful effect on cartilage before, and independent of synovial changes. Secondly, iron may also act on the synovial membrane by favouring its proliferation through the induction of proto-oncogenes involved in cellular proliferation and stimulation of inflammatory cytokines as well as abrogation of apoptosis. These two processes, one degenerative and cartilage-mediated, the other inflammatory and synovium-mediated could occur in parallel or sequentially. Overall, it may be expected that these experimental results will yield new therapeutic strategies capable of effectively preventing the occurrence of this still serious and common complication in patients with severe haemophilia.     

Premature induction of hypertrophy during in vitro chondrogenesis of human mesenchymal stem cells correlates with calcification and vascular invasion after ectopic transplantation in SCID mice

OBJECTIVE: Functional suitability and phenotypic stability of ectopic transplants are crucial factors in the clinical application of mesenchymal stem cells (MSCs) for articular cartilage repair, and might require a stringent control of chondrogenic differentiation. This study evaluated whether human bone marrow-derived MSCs adopt natural differentiation stages during induction of chondrogenesis in vitro, and whether they can form ectopic stable cartilage that is resistant to vascular invasion and calcification in vivo. METHODS: During in vitro chondrogenesis of MSCs, the expression of 44 cartilage-, stem cell-, and bone-related genes and the deposition of aggrecan and types II and X collagen were determined. Similarly treated, expanded articular chondrocytes served as controls. MSC pellets were allowed to differentiate in chondrogenic medium for 3-7 weeks, after which the chondrocytes were implanted subcutaneously into SCID mice; after 4 weeks in vivo, samples were evaluated by histology. RESULTS: The 3-stage chondrogenic differentiation cascade initiated in MSCs was primarily characterized by sequential up-regulation of common cartilage genes. Premature induction of hypertrophy-related molecules (type X collagen and matrix metalloproteinase 13) occurred before production of type II collagen and was followed by up-regulation of alkaline phosphatase activity. In contrast, hypertrophy-associated genes were not induced in chondrocyte controls. Whereas control chondrocyte pellets resisted calcification and vascular invasion in vivo, most MSC pellets mineralized, in spite of persisting proteoglycan and type II collagen content. CONCLUSION: An unnatural pathway of differentiation to chondrocyte-like cells was induced in MSCs by common in vitro protocols. MSC pellets transplanted to ectopic sites in SCID mice underwent alterations related to endochondral ossification rather than adopting a stable chondrogenic phenotype. Further studies are needed to evaluate whether a more stringent control of MSC differentiation to chondrocytes can be achieved during cartilage repair in a natural joint environment.     

Sonography for assessment of haemophilic arthropathy in children: a systematic protocol

Radiological imaging of joints in children with haemophilia is important to detect abnormalities, grade their severity and monitor the effects of treatment. Scoring systems for staging haemophilic arthropathy have been developed based on plain film or magnetic resonance imaging (MRI) findings. Radiographs alone may be inadequate for evaluating joint disease in children with haemophilia on prophylaxis while MRI may be difficult to access and require the child to be sedated. Sonography can be a useful complementary modality in the evaluation of haemophilic arthropathy that is readily available and does not require the child to be sedated. In this paper, we briefly review the current imaging scales available for the assessment of haemophilic arthropathy and present a systematic protocol for sonographic assessment of the knee and ankle in haemophilic children along with examples of findings in joint effusion/hemarthrosis, synovial hypertrophy and cartilage loss. Also, we correlate the ultrasound findings with the corresponding MRI images demonstrating the anatomic planes used for imaging acquisition. Sonography is a promising technique for the assessment of soft tissue changes which are the earliest findings in haemophilic arthropathy. Further investigation is required for evaluation of osteochondral changes given limitations of sonography in this regard and in minimizing operator dependency, especially if applied in multicentric clinical trials.     

Pathogenesis of haemophilic arthropathy

Summary.   The pathogenetic mechanism of haemophilic arthropathy is multifactorial and includes degenerative cartilage-mediated and inflammatory synovium-mediated components. Intra-articular blood first has a direct effect on cartilage, as a result of the iron-catalysed formation of destructive oxygen metabolites (resulting in chondrocyte apoptosis), and subsequently affects the synovium, in addition to haemosiderin-induced synovial triggering. Both processes occur in parallel, and while they influence each other they probably do not depend on each other. This concept resembles degenerative joint damage as found in osteoarthritis as well as inflammatory processes in rheumatoid arthritis. These processes finally result in a fibrotic and destroyed joint.     

细胞凋亡在家兔正常软骨化骨过程中作用的电镜观察

目的通过对家兔软骨细胞超微结构的观察,探讨细胞凋亡在正常软骨细胞向软骨分化过程中的作用。方法采用透视电镜,检测5周龄正常家兔肋软骨细胞超微结构的变化。结果超微结构显示,软骨细胞的骨化过程是渐进过程,从静止区到骨化区,软骨细胞的形态、细胞核及各种细胞器的变化是逐渐增殖活跃到凋亡出现,且细胞的凋亡从增殖带和肥大带交接处开始出现。结论家兔肋软骨生长板软骨细胞从静止区到骨化区细胞的增殖和分化是一个渐进的过程,在此过程中凋亡可能起着重要的作用。     

Tissue engineering and osteoarthritis

Articular cartilage lesions predispose to the development of early osteoarthritis. Most current surgical techniques give rise to the formation of fibrocartilage with biochemical and biomechanical properties inferior to those or articular cartilage. Tissue engineering could offer a modern alternative to the treatment of these lesions and in this way, prevent the development of early osteoarthritis in young active patients. Different tissue engineering approaches rely on the current use of autologous chondrocytes, or the potential use of mesenchymal stem cells. Other variables rely on the type of scaffold to use such as synthetic biodegradable polymers, fibrin or collagen-derived scaffolds of different sources, bovine, porcine, rat tail, etc, in the form of gels, sponges, mesh, etc, and all of these with or without growth factors. The use of autologous chondrocytes is a reality at the present time, whether injected under a periosteum patch or seeded on collagen. However, most investigators and biotech companies are in search of onestep surgical procedures, for which reason stem cells have to be kept in mind, as well as systems that will allow arthroscopic implantation.     

Corticosteroid treatment induces chondrocyte apoptosis in an experimental arthritis model and in chondrocyte cultures

OBJECT: In order to examine the mechanisms involved in steroid-induced arthropathy after intra-articular corticosteroid injection, a histological examination was performed in vivo using severe combined immunodeficiency (SCID) mice that were implanted with human articular cartilage into the back (SCID/hu model). In addition, the effect of corticosteroids on chondrocyte apoptosis was evaluated in vitro using cultured human chondrocytes. METHOD: Human articular cartilage was obtained during knee surgery and implanted subcutaneously into the backs of SCID mice. One month later, weekly injections of corticosteroid (hydrocortisone acatate: 1 mg/0.2 ml, triamcinolone acetonide: 0.2 mg/0.2 ml, dexamethasone acetate: 0.1 mg/0.2 ml) in the subcutaneous cavity around the grafted cartilage in SCID mice were initiated. After six weeks of treatment, the grafted cartilage pieces were removed from the SCID mice and examined histologically. Chondrocyte apoptosis after corticosteroid treatment was also investigated using cultured human chondrocytes. RESULT: In the corticosteroid treated, grafted articular cartilage, apoptotic chondrocytes were apparent in the superficial and middle layers of cartilage. But a reduced intensity of Safranin O staining was not remarkable. In the cultured chondrocytes, apoptotic changes were also observed after corticosteroid treatment. CONCLUSION: Corticosteroid treatment induces chondrocyte apoptosis and it may be important to understand the steroid-induced arthropathy.     

Current management of cartilage defects: a review

Cartilage defects are a significant cause of morbidity and diminished quality of life, often leading to osteoarthritis (OA). Pain relief, restoration of joint function, and prevention or delay of the onset of OA are the aims of management, and initial treatment is usually conservative but temporary. Recent advances in understanding cartilage biology and the use of diagnostic imaging techniques have, however, allowed more aggressive approaches to cartilage repair which include: arthroscopic lavage with or without debridement; marrow stimulation procedures; implantation of autologous cells or tissue; and knee reconstruction. The role of these techniques in the clinician's effort to match treatment to a patient's needs and expectations is reviewed.     

Osteoarthritis. Emerging evidence for cell interactions in the breakdown and remodeling of cartilage

Interactions among the cells of joint components appear to contribute to the dynamic events associated with breakdown of the cartilage matrix and remodeling of the articular surface in osteoarthritis. The mediator interleukin-1 may be one of the stimuli that induce release of hydrolytic factors from synovial membrane cells and chondrocytes, which contribute to the degradation of collagen and proteoglycans in the cartilage matrix. The remodeling process is associated with chondrocyte proliferation and vascular and cellular ingrowth from subchondral bone with osteophyte formation. It is postulated that growth factors isolated from cartilage and bone may contribute to repair and remodeling of the articular end of the joint.     

Chondral injuries

Chondral injures are present in up to 10 to 12% of all individuals. When symptomatic, chondral lesions manifest in knee pain, swelling, and loss of function. Cartilage loss may be partial or complete, and it may affect one or multiple locations. The natural history of untreated lesions most likely results in increased disability and progression of cartilage loss. Lesions are classified according to location, depth, and size. Nonsurgical treatment modalities include oral medications, injections, bracing, or physical therapy. Surgical treatment ranges from arthroscopic debridement to implantation of autologous chondrocytes beneath a periosteal patch covering the lesion. The patient's symptoms, age, activity level, and lesion characteristics must be considered and matched with a suitable procedure.     

Synovium in haemophilic arthropathy

Summary. Synovium is an essential component of the joint and plays a critical role in maintaining a balance between physiological processes and pathological changes in the joint. Recurrent intra-articular bleeding as occur in haemophilia induce pathological synovial changes in the joint. From a certain point on, synovitis inevitably plays a major role in joint destruction, although in the early phase of haemophilic arthropathy its role may be secondary to cartilage damage as a result of the direct effects of blood on cartilage. The changed haemosiderotic, synovial tissue produces catabolic cytokines and enzymes harmful for cartilage.     

Fibroblast-like synoviocyte-chondrocyte interaction in cartilage degradation

OBJECTIVE: In vitro models for joint diseases often focus on a single cell type, such as chondrocytes in osteoarthritis (OA) or fibroblast-like synoviocytes (synoviocytes) in rheumatoid arthritis (RA). However, these joint diseases affect the whole joint and interaction between chondrocytes and synoviocytes may play an important role in disease pathology. The current study was designed to study the use of the alginate recovered chondrocyte method as a model for cartilage degradation and to study interaction between chondrocytes and synoviocytes. METHODS: Bovine chondrocytes were cultured in alginate beads for 1 week, subsequently chondrons were retrieved and seeded into transwells. Every two days cartilage-slices were analysed for proteoglycan content (colorimetric, Blyscan GAG kit), collagen content (HPLC) and collagen HP and LP crosslinking (HPLC). For degradation experiments, monocultures of cartilage-slices labelled with (35)S and cocultures with synoviocytes were stimulated with IL-1beta or TNF-alpha. After 7 days, (35)S release was measured taken as a measure of cartilage degradation. RESULTS: After biochemical analysis, three week old cartilage-like slices were chosen to perform cartilage-degradation experiments. Synoviocytes were able to induce cartilage degradation only in the presence of living chondrocytes. In addition, the cytokines interleukin 1 (IL-1beta) and tumor necrosis factor (TNF-alpha) were only able to induce cartilage degradation by chondrocytes, not by synoviocytes. CONCLUSION: These data indicate that the alginate recovered chondrocyte method provides a novel model for cartilage degradation in which the interaction between synoviocytes and chondrocytes can be studied.     

Stage oriented surgical cartilage therapy. Current situation

Chondral or osteochondral lesions are typical injuries in orthopaedics and traumatology. Since there is no regeneration of damaged articular cartilage, these lesions can lead to premature osteoarthritis. Therefore, an adequate therapy for these injuries is an important goal. Nowadays, common methods in cartilage therapy are procedures for the recruitment of mesenchymal stem cells: autologous osteochondral transplantation and autologous chondrocyte transplantation. Currently, autologous osteochondral transplantation is the only procedure that allows the replacement of the defect with hyaline cartilage. However, this procedure has the problem of donor-site morbidity and limited availability of transplants. Stem cell recruiting procedures and autologous chondrocyte transplantation normally achieve a regeneration of the defect with only fibrocartilage tissue, but both can achieve good medium-term clinical results. Each of these therapeutic principles has certain major indications. In order to select an adequate therapy, the classification of chondral or osteochondral lesion is needed. From a multiplicity of classification systems, those of the ICRS are of particular clinical relevance.