Treatment of experimental equine osteoarthritis by in vivo delivery of the equine interleukin-1 receptor antagonist gene

Evaluation of intramuscularly administered sodium pentosan polysulfate for treatment of experimentally induced osteoarthritis in horses

OBJECTIVE

To assess clinical, radiographic, histologic, and biochemical effects of sodium pentosan polysulfate (NaPPS) administered IM for treatment of experimentally induced osteoarthritis in horses.

ANIMALS

18 horses.

PROCEDURES

Osteoarthritis was induced arthroscopically in 1 middle carpal joint of all horses. Nine horses received NaPPS (3 mg/kg, IM) on study days 15, 22, 29, and 36. Nine control horses received the same volume of saline (0.9% NaCl) solution IM on study days 15, 22, 29, and 36. Clinical, radiographic, gross, histologic, histochemical, and biochemical findings as well as findings of synovial fluid analysis were evaluated.

RESULTS

No adverse treatment-related events were detected. Induced osteoarthritis caused a substantial increase in lameness, response to flexion, joint effusion, radiographic findings, synovial membrane inflammation, and articular cartilage fibrillation. Articular cartilage fibrillation was substantially reduced by NaPPS treatment, and concentrations of chondroitin sulfate 846 epitope were significantly increased in the synovial fluid of osteoarthritic and non-osteoarthritic joints of treated horses.

CONCLUSIONS AND CLINICAL RELEVANCE

Results indicated that NaPPS has some beneficial disease-modifying effects and may be a therapeutic option for osteoarthritis in horses.

Self-assembling nanoparticles for intra-articular delivery of anti-inflammatory proteins

Intra-articular delivery of therapeutics to modulate osteoarthritis (OA) is challenging. Delivery of interleukin-1 receptor antagonist (IL-1Ra), the natural protein inhibitor of IL-1, to modulate IL-1-based inflammation through gene therapy or bolus protein injections has emerged as a promising therapy for OA. However, these approaches suffer from rapid clearance and reduced potency over time. Nano/microparticles represent a promising strategy for overcoming the shortcomings of intra-articular drug delivery. However, these delivery vehicles are limited for delivery of protein therapeutics due to their hydrophobic character, low drug loading efficiency, and harsh chemical conditions during particle processing. We designed a new block copolymer that assembles into submicron-scale particles and provides for covalently tethering proteins to the particle surface for controlled intra-articular protein delivery. This block copolymer self-assembles into 300 nm-diameter particles with a protein tethering moiety for surface covalent conjugation of IL-1Ra protein. This copolymer particle system efficiently bound IL-1Ra and maintained protein bioactivity in vitro. Furthermore, particle-tethered IL-1Ra bound specifically to target synoviocyte cells via surface IL-1 receptors. Importantly, IL-1Ra nanoparticles inhibited IL-1-mediated signaling to equivalent levels as soluble IL-1Ra. Finally, the ability of nanoparticles to retain IL-1Ra in the rat stifle joint was evaluated by in vivo imaging over 14 days. IL-1Ra-tethered nanoparticles significantly increased the retention time of IL-1Ra in the rat stifle joint over 14 days with enhanced IL-1Ra half-life (3.01 days) compared to that of soluble IL-1Ra (0.96 days) and without inducing degenerative changes in cartilage structure or composition.

Impact of inflammation on the osteoarthritic niche: implications for regenerative medicine

Osteoarthritis (OA) is the most common form of arthritis worldwide and is the sixth leading cause of disability. It costs the UK economy approximately 1% of gross national product per annum. With an aging population, the cost of chronic conditions such as OA continues to rise. Historically, treatments for OA have been limited to painkillers, physiotherapy and joint injections. When these fail, patients are referred for joint replacement surgery. With the advent of tissue engineering strategies aimed at generating new bone and cartilage for repair of osteochondral defects, there has been considerable interest in exploiting these techniques to devise new treatments for OA. To date, little consideration has been given to the OA niche and attendant inflammatory milieu for any regenerative skeletal strategy. This review highlights the importance of understanding the osteoarthritic niche in order to modify existing tissue engineering and regenerative medicine strategies for the future treatment of OA.

Benefits of recombinant adeno-associated virus (rAAV)-mediated insulinlike growth factor I (IGF-I) overexpression for the long-term reconstruction of human osteoarthritic cartilage by modulation of the IGF-I axis

Administration of therapeutic genes to human osteoarthritic (OA) cartilage is a potential approach to generate effective, durable treatments against this slow, progressive disorder. Here, we tested the ability of recombinant adeno-associated virus (rAAV)-mediated overexpression of human insulinlike growth factor (hIGF)-I to reproduce an original surface in human OA cartilage in light of the pleiotropic activities of the factor. We examined the proliferative, survival and anabolic effects of the rAAV-hIGF-I treatment in primary human normal and OA chondrocytes in vitro and in explant cultures in situ compared with control (reporter) vector delivery. Efficient, prolonged IGF-I secretion via rAAV stimulated the biological activities of OA chondrocytes in all the systems evaluated over extended periods of time, especially in situ, where it allowed for the long-term reconstruction of OA cartilage (at least for 90 d). Remarkably, production of high, stable amounts of IGF-I in OA cartilage using rAAV advantageously modulated the expression of central effectors of the IGF-I axis by downregulating IGF-I inhibitors (IGF binding protein [IGFBP]-3 and IGFBP4) while up-regulating key potentiators (IGFBP5, the IGF-I receptor and downstream mitogen-activated protein kinase/extracellular signal-regulated kinase 1/2 [MAPK/ERK-1/2] and phosphatidylinisitol-3/Akt [PI3K/Akt] signal transduction pathways), probably explaining the enhanced responsiveness of OA cartilage to IGF-I treatment. These findings show the benefits of directly providing an IGF-I sequence to articular cartilage via rAAV for the future treatment of human osteoarthritis.

Effects of intraarticular IL1-Ra for acute anterior cruciate ligament knee injury: a randomized controlled pilot trial (NCT00332254)

OBJECTIVE

To evaluate the clinical effectiveness of intraarticular IL-1 receptor antagonist (IL-1Ra) for anterior cruciate ligament (ACL) tear.

METHODS

Eleven patients with acute ACL tear confirmed by magnetic resonance imaging (MRI) were randomized to receive a single intraarticular injection of IL-1Ra (anakinra 150 mg, n = 6) or equal volume of saline placebo (1 ml, n = 5). The double-blinded treatment was administered a mean 2 weeks after injury. Synovial fluid (SF) (n = 9 patients) and sera (all patients) were available at baseline (prior to injection) and immediately prior to surgery (mean 35 days later) and analyzed for SF IL-1α, IL-1β, IL-1Ra and serum hyaluronan (HA), an indicator of synovial inflammation. The primary outcome, standardized Knee Injury and Osteoarthritis Outcome Score (KOOS) questionnaire, was obtained at 0 (baseline), 4, and 14 days after injection.

RESULTS

Compared with placebo, the IL-1Ra group had substantially greater improvement in key outcomes over 14 days (KOOS pain P = 0.001; activities of daily living P = 0.0015; KOOS sports function P = 0.0026; KOOS quality of life (QOL) P = 0.0048; and total KOOS P < 0.0001). There were no adverse reactions in either group. SF IL-1α (P = 0.05) and serum HA (P = 0.03), but not IL-1β, or IL-1Ra, decreased significantly in the IL-1Ra but not the placebo treated patients. Compared with placebo, IL-1α was borderline significantly different in the IL-1Ra treated group (P = 0.06).

CONCLUSIONS

Administered within the first month following severe knee injury, IL-1Ra reduced knee pain and improved function over a 2-week interval. This promising proof of concept study provides a new paradigm for studies of acute joint injury and suggests that a larger follow-up study is warranted.

Efficacy of infliximab in a rabbit model of osteoarthritis

The purpose of this study was to investigate the efficacy of intra-articular injection of infliximab in a rabbit model of osteoarthritis. In 30 New Zealand white rabbits, the cruciate ligaments and medial menisci were resected using the Hulth technique. Eight weeks postsurgery, the animals were randomly divided into three groups, and each group was given monthly intra-articular injections (0.5 ml) of 10 mg/ml infliximab, 20 mg/ml infliximab, or saline, respectively. After 3 months, the results were assessed by macroscopic observation, histological evaluation, and measurement of the levels of interleukin-1β, tumor necrosis factor-α, and nitric oxide in the synovial fluid. In the two groups of rabbits administered infliximab (10 or 20 mg/ml), the pathological changes were more attenuated than in the group administered saline. Mankin scores in the rabbits administered infliximab 10 mg/ml (2.7 ± 0.9) or infliximab 20 mg/ml (2.4 ± 0.7) were significantly lower than in the control group (6.4 ± 1.2) (p <0.05). The tumor necrosis factor-α and nitric oxide contents of the synovial fluid were also decreased significantly in the rabbits administered infliximab at both concentrations compared with the saline-injected rabbits (p <0.05). Administration of infliximab did not change the levels of interleukin-1β in the synovial fluid. Similar results were obtained for all analyses with the two concentrations of infliximab tested. This study demonstrates that intra-articular injections of infliximab can protect against the development of experimentally induced osteoarthritis.

Stem cells and gene therapy for cartilage repair

Cartilage defects represent a common problem in orthopaedic practice. Predisposing factors include traumas, inflammatory conditions, and biomechanics alterations. Conservative management of cartilage defects often fails, and patients with this lesions may need surgical intervention. Several treatment strategies have been proposed, although only surgery has been proved to be predictably effective. Usually, in focal cartilage defects without a stable fibrocartilaginous repair tissue formed, surgeons try to promote a natural fibrocartilaginous response by using marrow stimulating techniques, such as microfracture, abrasion arthroplasty, and Pridie drilling, with the aim of reducing swelling and pain and improving joint function of the patients. These procedures have demonstrated to be clinically useful and are usually considered as first-line treatment for focal cartilage defects. However, fibrocartilage presents inferior mechanical and biochemical properties compared to normal hyaline articular cartilage, characterized by poor organization, significant amounts of collagen type I, and an increased susceptibility to injury, which ultimately leads to premature osteoarthritis (OA). Therefore, the aim of future therapeutic strategies for articular cartilage regeneration is to obtain a hyaline-like cartilage repair tissue by transplantation of tissues or cells. Further studies are required to clarify the role of gene therapy and mesenchimal stem cells for management of cartilage lesions.

Are we moving in the right direction with osteoarthritis drug discovery?

INTRODUCTION

The success of targeted biologic therapy against rheumatoid arthritis has meant that much research has been devoted to investigating the pathophysiology of osteoarthritis, in the hope of defining novel therapeutic targets. Osteoarthritis has long been thought of mainly as a degenerative disease of cartilage, with secondary bony damage and osteophytes. However, in recent years, the importance of the synovium, and in particular the synovial macrophages, has been highlighted in both in vitro and in vivo studies.

AREAS COVERED

The recent progress in osteoarthritis drug discovery, particularly with regard to the search for therapeutic targets for this disease and the development of disease-modifying anti-osteoarthritic drugs is critically assessed. Some important recent research with regard to possible therapeutic targets in osteoarthritis drug discovery is highlighted.

EXPERT OPINION

The concept that synovial macrophages and macrophage-produced cytokines, may play a role in driving inflammatory and destructive signalling pathways in osteoarthritis, is of importance for drug discovery in this disease, in spite of disappointing results from early studies of anti-cytokine strategies in osteoarthritis clinical trials. There is also an abundance of potential downstream therapeutic targets in osteoarthritis, including the matrix metalloproteinases, the aggrecanases, iNOS and elements of the Wnt pathway.

Effects of extracorporeal shock wave therapy and polysulfated glycosaminoglycan treatment on subchondral bone, serum biomarkers, and synovial fluid biomarkers in horses with induced osteoarthritis

OBJECTIVE

To evaluate effects of extracorporeal shock wave therapy (ESWT) and polysulfated glycosaminoglycan treatment (PSGAGT) on subchondral bone (SCB), serum biomarkers, and synovial fluid biomarkers in horses with induced osteoarthritis.

ANIMALS

24 healthy 2- to 3-year-old horses.

PROCEDURES

An osteochondral fragment was created on the distal aspect of the radial carpal bone in 1 middle carpal joint of each horse. Horses were randomly allocated to receive local application of ESWT (days 14 and 28; n = 8), PSGAGT (IM, q 4 d for 28 days; 8), or a sham ESWT probe (placebo; days 14 and 28; 8). Serum biomarkers were measured every 7 days, and synovial fluid biomarkers were measured every 14 days. Bone density was measured by use of computed tomography on days 0 and 70, and microdamage and bone formation variables were compared among groups at the end of the study (day 70).

RESULTS

There was no significant effect of ESWT or PSGAGT on any bone variable. Serum osteocalcin concentration was significantly greater in horses that received ESWT, compared with placebo-treated horses, and serum concentration of the C-terminal telopeptide of type I collagen was significantly higher in horses that received ESWT, compared with placebo- and PSGAG-treated horses. Concentrations of the synovial fluid epitope CS846 were significantly higher in joints with osteoarthritis treated with ESWT CONCLUSIONS AND CLINICAL RELEVANCE: Treatment of osteoarthritis with ESWT had no effect on SCB but did induce increases in serum biomarkers indicative of bone remodeling. Treatment of osteoarthritis with PSGAG had no effect on SCB or biomarkers.

A randomized, double-blind study of AMG 108 (a fully human monoclonal antibody to IL-1R1) in patients with osteoarthritis of the knee

Introduction

AMG 108 is a fully human, immunoglobulin subclass G2 (IgG2) monoclonal antibody that binds the human interleukin-1 (IL-1) receptor type 1, inhibiting the activity of IL-1a and IL-1b. In preclinical studies, IL-1 inhibition was shown to be beneficial in models of osteoarthritis (OA). The purpose of this two-part study was to evaluate the safety and pharmacokinetics (PK; Part A) and clinical effect (Part B) of AMG 108 in a double-blind, placebo-controlled, multiple-dose study in patients with OA of the knee.

Methods

In Part A, patients received placebo or AMG 108 subcutaneously (SC; 75 mg or 300 mg) or intravenously (IV; 100 mg or 300 mg) once every 4 weeks for 12 weeks; in Part B, patients received placebo or 300 mg AMG 108 SC, once every 4 weeks for 12 weeks. The clinical effect of AMG 108 was measured in Part B by using the Western Ontario and McMaster Universities (WOMAC) osteoarthritis index pain score.

Results

In Part A, 68 patients were randomized, and 64 received investigational product. In Part B, 160 patients were randomized, and 159 received investigational product. AMG 108 was well tolerated. Most adverse events (AEs), infectious AEs, serious AEs and infections, as well as withdrawals from the study due to AEs occurred at similar rates in both active and placebo groups. One death was reported in an 80-year-old patient (Part A, 300 mg IV AMG 108; due to complications of lobar pneumonia). AMG 108 serum concentration-time profiles exhibited nonlinear PK. The AMG 108 group in Part B had statistically insignificant but numerically greater improvement in pain compared with the placebo group, as shown by the WOMAC pain scores (median change, -63.0 versus -37.0, respectively).

Conclusions

The safety profile of AMG 108 SC and IV was comparable with placebo in patients with OA of the knee. Patients who received AMG 108 showed statistically insignificant but numerically greater improvements in pain; however, minimal, if any, clinical benefit was observed.

Trial Registration

This study is registered with ClinicalTrials.gov with the identifier NCT00110942.

Gene Therapy for Cartilage Repair

The concept of using gene transfer strategies for cartilage repair originates from the idea of transferring genes encoding therapeutic factors into the repair tissue, resulting in a temporarily and spatially defined delivery of therapeutic molecules to sites of cartilage damage. This review focuses on the potential benefits of using gene therapy approaches for the repair of articular cartilage and meniscal fibrocartilage, including articular cartilage defects resulting from acute trauma, osteochondritis dissecans, osteonecrosis, and osteoarthritis. Possible applications for meniscal repair comprise meniscal lesions, meniscal sutures, and meniscal transplantation. Recent studies in both small and large animal models have demonstrated the applicability of gene-based approaches for cartilage repair. Chondrogenic pathways were stimulated in the repair tissue and in osteoarthritic cartilage using genes for polypeptide growth factors and transcription factors. Although encouraging data have been generated, a successful translation of gene therapy for cartilage repair will require an ongoing combined effort of orthopedic surgeons and of basic scientists.

Evaluation of the ability of two transfection reagents to deliver small interfering RNA molecules to equine and guinea pig cartilage in vitro

OBJECTIVE

To evaluate 2 commercially available transfection reagents for transfection efficiency and distribution of small interfering RNA (siRNA) molecules to chondrocytes in monolayer cultures and full-thickness cartilage explants from guinea pigs and horses.

SAMPLE

Cartilage explants from 5 one-month-old and 3 adult guinea pigs and 5 adult clinically normal horses.

PROCEDURES

Monolayer chondrocytes and uniform cartilage explants were exposed to 1 of 2 siRNA transfection complexes according to manufacturers' protocols (1μM [1×]). Additionally, monolayer chondrocytes were exposed to 2× the suggested amount of a proprietary siRNA molecule. Full-thickness cartilage explants were treated with 1× (1μM), 2× (2μM), and 4× (4μM) or 1× (0.13μM), 4× (0.52μM), and 8× (1.04μM) the recommended concentrations of the proprietary siRNA and the cationic liposome siRNA, respectively, in equivalent media volumes. Use of fluorescent siRNA duplexes allowed quantification of transfected cells via flow cytometry and direct visualization of the depth and distribution of in situ transfection via fluorescent microscopy.

RESULTS

With both transfection reagents, > 90% of monolayer chondrocytes were transfected. In explants, only use of the proprietary molecule achieved > 50% transfection efficiency, whereas use of the cationic liposome achieved < 20%. Only the proprietary molecule-treated cartilage consistently contained fluorescent cells throughout all zones; the cationic liposome-transfected chondrocytes were restricted to explant surfaces.

CONCLUSIONS AND CLINICAL RELEVANCE

Robust transfection of chondrocytes in monolayer was achieved with both reagents, but only use of the proprietary molecule attained effective full-thickness transfection of explants that may allow relevant transcript reduction via RNAi.

Temporal expression and tissue distribution of interleukin-1β in two strains of guinea pigs with varying propensity for spontaneous knee osteoarthritis

OBJECTIVE

To provide a comprehensive immunohistochemical (IHC) map of the temporal expression and tissue distribution of interleukin-1β (IL-1β) through progression of osteoarthritis (OA) in two strains of guinea pigs with varying propensity for spontaneous knee joint disease.

METHODS

OA-prone Hartley and OA-resistant Strain 13 guinea pigs were collected at 60, 120, 180, 240, 360, and 480 days of age (N=4 animals per strain per date). IHC was performed on whole joint preparations; the distribution of IL-1β expression on coronal sections was mapped, semi-quantitatively scored, and correlated to OA grade using Mankin criteria with guinea pig-specific modifications. OA and IHC indices were compared among times and between strains using the Kruskal-Wallis one-way analysis of variance by ranks followed by Dunn's post test.

RESULTS

OA indices for both strains increased from 60 to 480 days of age; a statistically higher score (P ≤ 0.01) was found in Hartley animals at 180, 240, 360, and 480 days. At 60 days of age, IL-1β expression was detected in cartilage, menisci, synovium, and subchondral bone in both strains. Persistent and statistically increased (P<0.05) IL-1β expression was found in these same tissues in Hartley animals at 120 and 180 days, while Strain 13 animals demonstrated a significant reduction in positive immunostaining. Statistical differences in IHC indices between strains beyond 240 days of age were restricted to synovium (days 240 and 480) and subchondral bone (days 360 and 480).

CONCLUSIONS

As expected, histologic OA proceeded in an accelerated manner in Hartley animals relative to Strain 13 animals. The OA-prone strain did not demonstrate reduced IL-1β expression during adult maturity as occurred in the OA-resistant strain, and this persistent expression may have corresponded to early incidence of OA. Future interventional studies are warranted to explore whether dysregulation of IL-1β expression may contribute to premature onset of spontaneous disease in the Hartley guinea pig.

Mesenchymal stem cells and osteoarthritis: remedy or accomplice?

Multipotent mesenchymal stromal or stem cells (MSCs) are likely to be agents of connective tissue homeostasis and repair. Because the hallmark of osteoarthritis (OA) is degeneration and failure to repair connective tissues it is compelling to think that these cells have a role to play in OA. Indeed, MSCs have been implicated in the pathogenesis of OA and, in turn, progression of the disease has been shown to be therapeutically modulated by MSCs. This review discusses current knowledge on the potential of both marrow- and local joint-derived MSCs in OA, the mode of action of the cells, and possible effects of the osteoarthritic niche on the function of MSCs. The use of stem cells for repair of isolated cartilage lesions and strategies for modulation of OA using local cell delivery are discussed as well as therapeutic options for the future to recruit and appropriately activate endogenous progenitors and/or locally systemically administered MSCs in the early stages of the disease. The use of gene therapy protocols, particularly as they pertain to modulation of inflammation associated with the osteoarthritic niche, offer an additional option in the treatment of this chronic disease. In summary, elucidation of the etiology of OA and development of technologies to detect early disease, allied to an increased understanding of the role MSCs in aging and OA, should lead to more targeted and efficacious treatments for this debilitating chronic disease in the future.

Effects of adenovirus-mediated bFGF, IL-1Ra and IGF-1 gene transfer on human osteoarthritic chondrocytes and osteoarthritis in rabbits

The study investigated the effects of adenovirus-mediated gene transfection of basic fibroblast growth factor (bFGF), bFGF combined with interleukin-1 receptor antagonist protein (IL-Ra) and/or insulin-like growth factor-1 (IGF-1) both in human osteoarthritis (OA) chondrocytes and rabbits OA model. Human OA chondrocytes were delivered by adenovirus-mediated bFGF, IL-Ra and IGF-1 vectors, respectively. Chondrocyte proliferation, glycosaminoglycan (GAG) content, expression of type II collagen, ADAMTS-5, MMP-13, MMP-3 and TIMP-1 were determined. Rabbit OA model was induced by anterior cruciate ligament transaction (ACLT) in knees. Adenoviral vectors encoding human bFGF, IL-Ra and IGF-1 were injected intraarticularly into the knee joints after ACLT. The effects of adenovirus-mediated gene transfection on rabbit OA were evaluated. In vitro, the transfected genes were expressed in cell supernatant of human OA chondrocytes. AdbFGF group significantly promoted chondrocyte proliferation, and increased GAG and type II collagen synthesis than in the OA group. As two or three genes were transfected in different combinations, there was significant enhancement on the GAG content, type II collagen synthesis, and TIMP-1 levels, while ADAMTS-5, MMP-13, and MMP-3 levels were reduced. In vivo, the transfected genes were expressed in synovial fluid of rabbits. Intraarticular delivery of bFGF enhanced the expression of type II collagen in cartilage and decreased cartilage Mankin score compared with the OA control group (P=0.047; P<0.01, respectively). Multiple-gene transfection in different combinations showed better results than bFGF transfection alone. This study suggests that bFGF gene transfection is effective in treating experimental OA. Multiple gene transfection has better biologic effects on OA.

Getting arthritis gene therapy into the clinic

Gene transfer technologies enable the controlled, targeted and sustained expression of gene products at precise anatomical locations, such as the joint. In this way, they offer the potential for more-effective, less-expensive treatments of joint diseases with fewer extra-articular adverse effects. A large body of preclinical data confirms the utility of intra-articular gene therapy in animal models of rheumatoid arthritis and osteoarthritis. However, relatively few clinical trials have been conducted, only one of which has completed phase II. This article summarizes the status in 2010 of the clinical development of gene therapy for arthritis, identifies certain constraints to progress and suggests possible solutions.

Effect of self-assembling peptide, chondrogenic factors, and bone marrow-derived stromal cells on osteochondral repair

OBJECTIVE

The goal of this study was to test the ability of an injectable self-assembling peptide (KLD) hydrogel with or without chondrogenic factors (CF) and allogeneic bone marrow stromal cells (BMSCs) to stimulate cartilage regeneration in a full-thickness, critically-sized, rabbit cartilage defect model in vivo. We used CF treatments to test the hypotheses that CF would stimulate chondrogenesis and matrix production by cells migrating into acellular KLD (KLD+CF) or by BMSCs delivered in KLD (KLD+CF+BMSCs).

DESIGN

Three groups were tested against contralateral untreated controls: KLD, KLD+CF, and KLD+CF+BMSCs, n=6-7. Transforming growth factor-β1 (TGF-β1), dexamethasone, and insulin-like growth factor-1 (IGF-1) were used as CF pre-mixed with KLD and BMSCs before injection. Evaluations included gross, histological, immunohistochemical and radiographic analyses.

RESULTS

KLD without CF or BMSCs showed the greatest repair after 12 weeks with significantly higher Safranin-O, collagen II immunostaining, and cumulative histology scores than untreated contralateral controls. KLD+CF resulted in significantly higher aggrecan immunostaining than untreated contralateral controls. Including allogeneic BMSCs+CF markedly reduced the quality of repair and increased osteophyte formation compared to KLD-alone.

CONCLUSIONS

These data show that KLD can fill full-thickness osteochondral defects in situ and improve cartilage repair as shown by Safranin-O, collagen II immunostaining, and cumulative histology. In this small animal model, the full-thickness critically-sized defect provided access to the marrow, similar in concept to abrasion arthroplasty or spongialization in large animal models, and suggests that combining KLD with these techniques may improve current practice.

Cartilage biology, pathology, and repair

Osteoarthritis is one of the most common forms of musculoskeletal disease and the most prominent type of arthritis encountered in all countries. Although great efforts have been made to investigate cartilage biology and osteoarthritis pathology, the treatment has lagged behind that of other arthritides, as there is a lack of effective disease-modifying therapies. Numerous approaches for dealing with cartilage degradation have been tried, but enjoyed very little success to develop approved OA treatments with not only symptomatic improvement but also structure-modifying effect. In this review we discuss the most recent findings regarding the regulation of cartilage biology and pathology and highlight their potential therapeutic values.

Role of proinflammatory cytokines in the pathophysiology of osteoarthritis

Osteoarthritis (OA) is associated with cartilage destruction, subchondral bone remodeling and inflammation of the synovial membrane, although the etiology and pathogenesis underlying this debilitating disease are poorly understood. Secreted inflammatory molecules, such as proinflammatory cytokines, are among the critical mediators of the disturbed processes implicated in OA pathophysiology. Interleukin (IL)-1β and tumor necrosis factor (TNF), in particular, control the degeneration of articular cartilage matrix, which makes them prime targets for therapeutic strategies. Animal studies provide support for this approach, although only a few clinical studies have investigated the efficacy of blocking these proinflammatory cytokines in the treatment of OA. Apart from IL-1β and TNF, several other cytokines including IL-6, IL-15, IL-17, IL-18, IL-21, leukemia inhibitory factor and IL-8 (a chemokine) have also been shown to be implicated in OA and could possibly be targeted therapeutically. This Review discusses the current knowledge regarding the role of proinflammatory cytokines in the pathophysiology of OA and addresses the potential of anticytokine therapy in the treatment of this disease.

The OARSI histopathology initiative - recommendations for histological assessments of osteoarthritis in the horse

OBJECTIVE

Equine models of osteoarthritis (OA) have been used to investigate pathogenic pathways of OA and evaluate therapeutic candidates for naturally occurring equine OA which is a significant clinical disease in the horse. This review focuses on the macroscopic and microscopic criteria for assessing naturally occurring OA in the equine metacarpophalangeal joint as well as the osteochondral fragment-exercise model of OA in the equine middle carpal joint.

METHODS

A review was conducted of all published OA studies using horses and the most common macroscopic and microscopic scoring systems were summarized. Recommendations regarding methods of OA assessment in the horse have been made based on published studies.

RESULTS

A modified Mankin scoring system is recommended for semi-quantitative histological assessment of OA in horses due to its already widespread use and similarity to other scoring systems. Recommendations are also provided for histological scoring of synovitis and macroscopic lesions of OA as well as changes in the calcified cartilage and subchondral bone of naturally occurring OA.

CONCLUSIONS

The proposed system for assessment of equine articular tissues provides a useful method to quantify OA change. It is believed that addition of quantitative tracing onto plastic and macroscopic measurement as recently described would be an improvement for overall assessment of articular cartilage change.

Clinical responses to gene therapy in joints of two subjects with rheumatoid arthritis

This paper provides the first evidence of a clinical response to gene therapy in human arthritis. Two subjects with rheumatoid arthritis received ex vivo, intraarticular delivery of human interleukin-1 receptor antagonist (IL-1Ra) cDNA. To achieve this, autologous synovial fibroblasts were transduced with a retrovirus, MFG-IRAP, carrying IL-1Ra as the transgene, or remained as untransduced controls. Symptomatic metacarpophalangeal (MCP) joints were injected with control or transduced cells. Joints were clinically evaluated on the basis of pain; the circumference of MCP joint 1 was also measured. After 4 weeks, joints underwent surgical synovectomy. There were no adverse events in either subject. The first subject responded dramatically to gene transfer, with a marked and rapid reduction in pain and swelling that lasted for the entire 4 weeks of the study. Remarkably, joints receiving IL-1Ra cDNA were protected from flares that occurred during the study period. Analysis of RNA recovered after synovectomy revealed enhanced expression of IL-1Ra and reduced expression of matrix metalloproteinase-3 and IL-1beta. The second subject also responded with reduced pain and swelling. Thus, gene transfer to human, rheumatoid joints can be accomplished safely to produce clinical benefit, at least in the short term. Using this ex vivo procedure, the transgene persisted within the joint for at least 1 month. Further clinical studies are warranted.

Treatment of knee osteoarthritis with Orthokine-derived autologous conditioned serum

Osteoarthritis (OA) is the most prevalent arthritis in the world with increasing numbers of people expected to acquire the disease as the population ages. Therapies commonly used to manage the disease have limited efficacy and some carry significant risks. Current data suggest that the anti-inflammatory cytokine IL-1 receptor antagonist (IL-1Ra) can alter the inflammatory response and cartilage erosion present in OA. Intra-articular gene expression of IL-1Ra has shown promising results in animal models to provide symptomatic improvement and minimize osteoarthritic changes. Orthogen AG (Dusseldorf, Germany) has developed a method to produce an autologous conditioned serum (ACS) rich in IL-1Ra marketed as Orthokine. Study participants treated with ACS have improved pain and function; however, these results are preliminary and need confirmation. If ongoing trials prove that ACS can retard cartilage degeneration and reduce inflammation, the management of OA would be dramatically altered, perhaps providing a mechanism to prevent the disease or at least its progression.

[IL-1 antagonists]

Interleukin (IL)-1 plays an important role not only in the mediation of inflammation but also in the destruction of cartilage and bone. Together with TNF-alpha it is one of the most important cytokines in the pathogenesis of rheumatoid arthritis (RA) and juvenile idiopathic arthritis (JIA). The first IL-1 antagonist to be approved for RA was Anakinra, an IL-1 receptor antagonist. Anakinra appears to be less effective for RA than TNF blockers. Hence, Anakinra is rarely used for the treatment of RA, but more for the treatment of IL-1-mediated diseases such as autoinflammatory syndromes, adult-onset Still's disease and systemic onset JIA. Two newer IL-1 antagonists have recently been approved for the treatment of CAPS (cryopyrin-associated periodic syndromes): Canakinumab, a fully human IL-1beta antibody, and rilonacept, a fusion protein consisting of the ligand-binding domain of the IL-1 receptor and the IL-1-receptor accessory protein, bound to human IgG1. For RA, there is only one proof-of-concept study to date with canakinumab. There are no prospective data for the treatment of patients with RA who did not respond to or tolerate TNF antagonists; in a retrospective analysis, only 8% of anti-TNF pretreated patients achieved an ACR 20 response.

Remodelling of human osteoarthritic cartilage by FGF-2, alone or combined with Sox9 via rAAV gene transfer

Compensating for the loss of extracellular cartilage matrix, as well as counteracting the alterations of the chondrocyte phenotype in osteoarthritis are of key importance to develop effective therapeutic strategies against this disorder. In the present study, we analysed the benefits of applying a potent gene combination to remodel human osteoarthritic (OA) cartilage. We employed the promising recombinant adeno-associated virus (rAAV) vector to deliver the mitogenic fibroblast growth factor 2 (FGF-2) factor, alone or simultaneously with the transcription factor Sox9 as a key activator of matrix synthesis, to human normal and OA articular chondrocytes. We evaluated the effects of single (FGF-2) or combined (FGF-2/SOX9) transgene expression upon the regenerative activities of chondrocytes in three dimensional cultures in vitro and in cartilage explants in situ. Single overexpression of FGF-2 enhanced the survival and proliferation of both normal and OA chondrocytes, without stimulating the matrix synthetic processes in the increased pools of cells. The mitogenic properties of FGF-2 were maintained when SOX9 was co-overexpressed and concomitant with an increase in the production of proteoglycans and type-II collagen, suggesting that the transcription factor was capable of counterbalancing the effects of FGF-2 on matrix accumulation. Also important, expression of type-X collagen, a marker of hypertrophy strongly decreased following treatment by the candidate vectors. Most remarkably, the levels of activities achieved in co-treated human OA cartilage were similar to or higher than those observed in normal cartilage. The present findings show that combined expression of candidate factors in OA cartilage can re-establish key features of normal cartilage and prevent the pathological shift of metabolic homeostasis. These data provide further motivation to develop coupled gene transfer approaches via rAAV for the treatment of human OA.

Cytokine profile of autologous conditioned serum for treatment of osteoarthritis, in vitro effects on cartilage metabolism and intra-articular levels after injection

INTRODUCTION

Intraarticular administration of autologous conditioned serum (ACS) recently demonstrated some clinical effectiveness in treatment of osteoarthritis (OA). The current study aims to evaluate the in vitro effects of ACS on cartilage proteoglycan (PG) metabolism, its composition and the effects on synovial fluid (SF) cytokine levels following intraarticular ACS administration.

METHODS

The effect of conditioned serum on PG metabolism of cultured OA cartilage explants was compared to unconditioned serum. The effect of serum conditioning on levels of interleukin-1beta (IL-1beta), IL-4, IL-6, IL-10, IL-13, interferon gamma (IFN-gamma), tumor necrosis factor alpha (TNF-alpha), osteoprotegerin (OPG), oncostatin M (OSM), interleukin-1 receptor (IL-1ra) and transforming growth factor beta (TGF-beta) were measured by multiplex ELISA. As TNF-alpha levels were found to be increased in conditioned serum, the effect of TNF-alpha inhibition by etanercept on PG metabolism was studied in cartilage explants cultured in the presence of conditioned serum. Furthermore, cytokine levels in SF were measured three days after intraarticular ACS injection in OA patients to verify their retention time in the joint space.

RESULTS

PG metabolism was not different in the presence of conditioned serum compared to unconditioned serum. Levels of the anti-inflammatory cytokines IL-1ra, TGF-beta, IL-10 as well as of pro-inflammatory cytokines IL-1beta, IL-6, TNF-alpha and OSM were increased. IL-4, IL-13 and IFN-gamma levels remained similar, while OPG levels decreased. TNF-alpha inhibition did not influence PG metabolism in cartilage explant culture in the presence of conditioned serum. Although OPG levels were higher and TGF-beta levels were clearly lower in ACS than in SF, intraarticular ACS injection in OA patients did not result in significant changes in these cytokine levels.

CONCLUSIONS

ACS for treatment of osteoarthritis contains increased levels of anti-inflammatory as well as pro-inflammatory cytokines, in particular TNF-alpha, but conditioned serum does not seem to have a net direct effect on cartilage metabolism, even upon inhibition of TNF-alpha. The fast intraarticular clearance of cytokines in the injected ACS may explain the limited effects found previously in vivo.

Osteoarthritis: can anti-cytokine therapy play a role in treatment?

Osteoarthritis (OA) is the most common joint disorder worldwide, and it has an enormous socioeconomic impact both in the United States and throughout the world. The degree of articular inflammation is usually associated with the disease's progression, indicating that this process could contribute to articular damage. IL-1 beta and anti-TNF alpha are the two major cytokines players in the physiopathology of OA. Hence, we aimed to review the current literature on the effects of IL-1 and TNF-alpha neutralization as a new OA therapy. In vitro and experimental models showed a reduction in cartilage destruction with IL-1 inhibition therapy by IL-1 receptor antagonists (IL-1Ra). Despite this favorable evidence in animal models, studies on the inhibition of IL-1R in humans are still scarce. Although there is clear evidence that TNF-alpha plays a role in the pathophysiology of OA, only a few experimental trials have investigated the efficacy of blocking this pro-inflammatory cytokine in the treatment of OA. So far, the few studies available in humans using anti-TNF-alpha and IL-1 receptor antagonist are not remarkable, suggesting that further investigation and new therapeutic approaches are needed.

Dynamic compression stimulates proteoglycan synthesis by mesenchymal stem cells in the absence of chondrogenic cytokines

The objective of this study was to evaluate the effect of dynamic compression on mesenchymal stem cell (MSC) chondrogenesis. Dynamic compression was applied to agarose hydrogels seeded with bone marrow-derived adult equine MSCs. In the absence of the chondrogenic cytokine transforming growth factor beta (TGFbeta), dynamic compression applied for 12 h per day led to significantly greater proteoglycan synthesis than in unloaded TGFbeta-free cultures, although at a rate that was approximately 20% to 35% of unloaded TGFbeta cultures. These data suggest that the emergence of aggrecan dominated a chondrogenic response to loading as increases in proteoglycan synthesis. Cross-sectional analyses were conducted to subjectively identify potential spatial distributions of heterogeneous differentiation. In loaded samples, cell viability and metachromatic staining was low near the porous compression platen interface but increased with depth, reaching levels in the lower portion of the hydrogel that resembled unloaded TGFbeta cultures. These results suggest that the combination of high hydrostatic pressure and low dynamic strain and fluid flow had a stronger effect on chondrogenesis than did low hydrostatic pressure coupled with high dynamic strain and fluid flow. Next, the 12-h per day loading protocol was applied in the presence of TGFbeta. Biosynthesis in loaded cultures was less than in unloaded TGFbeta samples. Taken together, these data suggest that the duration of loading necessary to stimulate mechanoinduction of MSCs may not be optimal for neo-tissue accumulation in the presence of chondrogenic cytokines.

Antioxidant capacity and oxidative damage determination in synovial fluid of chronically damaged equine metacarpophalangeal joint

In order to determine oxidative stress in equine joints with degenerative processes, we analyzed synovial fluid (SF) antioxidant capacity and the concentration of oxidative damage biomarkers in healthy and chronically damaged metacarpophalangeal joints. SF samples were collected from joints of thirty 2-5 year-old crossbreed male equine, macroscopically classified at post mortem inspection and later histologically confirmed. The antioxidant capacity was determined measuring uric acid and the concentration of sulfhydryl groups and the total radical trapping antioxidant potential (TRAP). The oxidative damage was determined by assessing malondialdehyde (MDA) and carbonyl protein concentration. TRAP was significantly higher (p < 0.05) in the group with chronic damage (CD). The sulfhydryl groups and concentration of uric acid did not show significant difference between the groups (p > 0.05). Although carbonyl concentration did not show significant difference between groups, it was slightly higher in the group with CD (p = 0.05009). Concentration of MDA did not show significant difference (p > 0.05) between groups. The observed significant increase in TRAP in the group with CD could be related to the participation of components other than protein, sulfhydryl groups, or uric acid coming from degenerating joint tissues. These findings could be helpful for a better understanding of the oxidative stress role in equine joints with chronic degenerative process.

Evaluation of adipose-derived stromal vascular fraction or bone marrow-derived mesenchymal stem cells for treatment of osteoarthritis

The purpose of this study was the assessment of clinical, biochemical, and histologic effects of intraarticular administered adipose-derived stromal vascular fraction or bone marrow-derived mesenchymal stem cells for treatment of osteoarthritis. Osteoarthritis was induced arthroscopically in the middle carpal joint of all horses, the contralateral joint being sham-operated. All horses received treatment on Day 14. Eight horses received placebo treatment and eight horses received adipose-derived stromal vascular fraction in their osteoarthritis-affected joint. The final eight horses were treated the in osteoarthritis-affected joint with bone marrow-derived mesenchymal stem cells. Evaluations included clinical, radiographic, synovial fluid analysis, gross, histologic, histochemical, and biochemical evaluations. No adverse treatment-related events were observed. The model induced a significant change in all but two parameters, no significant treatment effects were demonstrated, with the exception of improvement in synovial fluid effusion PGE2 levels with bone marrow-derived mesenchymal stem cells when compared to placebo. A greater improvement was seen with bone marrow-derived mesenchymal stem cells when compared to adipose-derived stromal vascular fraction and placebo treatment. Overall, the findings of this study were not significant enough to recommend the use of stem cells for the treatment of osteoarthritis represented in this model.

[Molecular tools to remodel osteoarthritic articular cartilage : growth, transcription, and signaling factors]

Osteoarthritis (OA) is a chronic disorder of the diarthrodial joints, mostly characterized by gradual deterioration of the articular cartilage. This disease still has no effective treatment. An emerging strategy for treating OA is based on molecular concepts using growth factors, transcription factors, and signaling molecules in light of their effects on the restoration of cartilage integrity. Recent studies have demonstrated that overexpression of such candidate molecules using direct gene transfer or ex vivo protocols is capable of stimulating cell proliferation and matrix synthesis in normal human and OA cartilage explants in vitro as well as in animal models in vivo. As a result, the structure of the articular cartilage can be improved. More insights into the pathophysiology of human OA and further studies in animal models are needed, however, to facilitate clinical translation of these molecular approaches. In conclusion, recent experimental findings permit cautious optimism, holding promise for treating human OA in the future.

Evaluation of the effect of extracorporeal shock wave treatment on experimentally induced osteoarthritis in middle carpal joints of horses

OBJECTIVE-To assess the clinical, biochemical, and histologic effects of extracorporeal shock wave therapy (ESWT) in the treatment of horses with experimentally induced osteoarthritis (OA). ANIMALS-Twenty-four 2- to 3-year-old horses without evidence of lameness. PROCEDURES-OA was induced arthroscopically in 1 middle carpal joint of each horse. Fourteen days after induction of OA, horses were treated with a sham ESWT probe (placebo; n = 8), polysulfated glycosaminoglycan (PSGAG) administered IM every 4 days for 28 days as a positive control treatment (8), or ESWT administered on days 14 and 28 with a focused shock wave unit (8). Evaluations included clinical assessments of degree of lameness every 2 weeks and weekly synovial fluid analyses. Horses were euthanized 70 days after induction of OA, and gross pathologic and histologic examinations of cartilage and synovial membrane specimens were performed at necropsy. A generalized linear mixed model was used to compare outcomes among treatment groups. RESULTS-No adverse treatment-related events were detected in any horse. The degree of lameness in horses treated with ESWT improved significantly, compared with the degree of lameness in placebo- or PSGAG-treated horses. No disease-modifying effects were evident in results for synovial fluid, synovial membranes, or cartilage from the ESWT- or PSGAG-treated horses. CONCLUSIONS AND CLINICAL RELEVANCE-Although a disease-modifying effect of ESWT was not detected, the significant clinical effect of ESWT suggested that this modality should be considered for treatment of horses with OA in combination with another modality that does affect the disease process.

Joint injury and osteoarthritis: soluble mediators in the course and treatment of cartilage pathology

Osteoarthritis is a disabling disease of the aging generation, which results in loss of quality of life and increased healthcare costs. Cytokines appear to play an important role in the cartilaginous degeneration characterizing the pathological process. Increasing experience is being gained with cytokine-modulating therapies aimed at interfering with effects of chondrodegradative cytokines in the synovial fluid. Although in vitro and in vivo effectiveness of several of these therapies has been demonstrated, clinical effectiveness remains disputable, which may be related to the low levels of inflammatory cytokines found in osteoarthritic joints. By contrast, directly after joint trauma, which has been shown to predipose to early osteoarthritis, synovial fluid cytokine levels are strongly increased. Cytokine-modulating therapies, however, have hardly been considered for this indication. Increased knowledge of intra-articular soluble mediators correlating with cartilage pathology will lead to further development of cytokine-modulating products and, eventually, to effective inhibition of cartilage degeneration, in both the osteoarthritic as well as injured joints.

Evaluation of polysulfated glycosaminoglycan or sodium hyaluronan administered intra-articularly for treatment of horses with experimentally induced osteoarthritis

OBJECTIVE

To assess clinical, biochemical, and histologic effects of polysulfated glycosaminoglycan (PSGAG) or sodium hyaluronan administered intra-articularly in treatment of horses with experimentally induced osteoarthritis.

ANIMALS

24 horses.

PROCEDURES

Osteoarthritis was induced arthroscopically in 1 middle carpal joint of all horses. Eight horses received hyaluronan (20 mg) and amikacin (125 mg) intra-articularly on study days 14, 21, and 28. Eight horses received PSGAG (250 mg) and amikacin (125 mg) intra-articularly on study days 14, 21, and 28. Eight control horses received 2 mL of saline (0.9% NaCl) solution and amikacin (125 mg) intra-articularly on study days 14, 21, and 28. Clinical, radiographic, synovial fluid analysis, gross, histologic, histochemical, and biochemical findings were evaluated.

RESULTS

No adverse treatment-related events were detected. Induced osteoarthritis caused a substantial change in lameness, response to flexion, joint effusion, and radiographic findings, and of these, synovial fluid effusion was reduced with PSGAG, compared with control horses. No changes in clinical signs were seen with PSGAG or hyaluronan, compared with control horses. Histologically, the degree of synovial membrane vascularity and subintimal fibrosis was significantly reduced with PSGAG treatment, compared with controls. Histologically, significantly less fibrillation was seen with hyaluronan treatment, compared with controls.

CONCLUSIONS AND CLINICAL RELEVANCE

Results indicated that PSGAG and hyaluronan had beneficial disease-modifying effects and are viable therapeutic options for osteoarthritis in horses.

Evaluation of topically administered diclofenac liposomal cream for treatment of horses with experimentally induced osteoarthritis

OBJECTIVE

To assess the clinical, biochemical, and histologic effects of topically administered diclofenac liposomal cream (DLC) in the treatment of horses with experimentally induced osteoarthritis.

ANIMALS

24 horses.

PROCEDURES

Osteoarthritis was induced arthroscopically in 1 middle carpal joint of all horses. Eight horses treated with DLC were given 7.3 g twice daily via topical application. Eight horses treated with phenylbutazone were given 2 g orally once daily. Eight control horses received no treatment. Evaluations included clinical, radiographic, magnetic resonance imaging, synovial fluid, gross, and histologic examinations as well as histochemical and biochemical analyses.

RESULTS

No adverse treatment-related events were detected. Horses that were treated with DLC or phenylbutazone had significant clinical improvement of lameness, unlike the control horses. Treatment with DLC induced significant improvement in staining and total articular glycosaminoglycan content, compared with no treatment. Treatment with phenylbutazone induced significant reduction in synovial fluid prostaglandin E2 concentration, compared with DLC and no treatment. Treatment with DLC induced significantly less radial carpal bone sclerosis and overall gross cartilage erosion, compared with phenylbutazone.

CONCLUSIONS AND CLINICAL RELEVANCE

Results indicated that DLC had both clinical sign-modifying and disease-modifying effects. Only clinical sign-modifying effects were detected in association with phenylbutazone administration. Treatment with DLC had significant beneficial effects, compared with phenylbutazone, and no detrimental effects. Results suggested that DLC is a viable therapeutic option for horses with osteoarthritis.

Inflammatory mediators and cartilage biomarkers in synovial fluid after a single inflammatory insult: a longitudinal experimental study

INTRODUCTION

Inflammation is an important feature of many joint diseases, and levels of cartilage biomarkers measured in synovial fluid may be influenced by local inflammatory status. Little is known about the magnitude and time course of inflammation-induced changes in cartilage tissue turnover as measured in vivo by synovial fluid markers. We aimed to study temporal changes in concentrations of inflammatory mediators, matrix metalloproteinase activity and cartilage biomarkers over 1 week in joints with experimentally induced inflammation.

METHODS

Localized inflammation was induced in the intercarpal joint of six horses by sterile injection of 0.5 ng lipopolysaccharide, and synovial fluid was collected at post-injection hours (PIH) 0, 8, 24 and 168. Concentrations of inflammatory mediators (prostaglandin E2, substance P, and bradykinin), general matrix metalloproteinase activity and markers of collagen II turnover (CPII and C2C) as well as aggrecan turnover (CS846 and glycosaminoglycans) were measured with appropriate assays. One-way analysis of variance on repeated measures was used to analyze differences in synovial fluid marker levels over time.

RESULTS

Lipopolysaccharide-injection led to a sharp rise in prostaglandin E2 at PIH 8, while substance P, bradykinin and matrix metalloproteinase activity showed more sustained increases at PIH 8 and 24. Glycosaminoglycan release paralleled changes in the CS846 epitope, with an increase by PIH 8, a peak at PIH 24, and return to baseline by PIH 168. For type II collagen, a parallel time course between catabolic (C2C) and anabolic (CPII) markers was also observed, but the time course differed from that seen for proteoglycan markers: collagen II markers peaked later, at PIH 24, and were still elevated over baseline at PIH 168.

CONCLUSIONS

A primary intra-articular inflammatory insult, characterized by local release of peptide and lipid mediators and matrix metalloproteinase activation, can alter synovial fluid levels of proteoglycan biomarkers as early as 8 hours post-induction, and can lead to sustained rises in collagen II biomarkers during at least 1 week after onset.

Orthopedic gene therapy in 2008

Orthopedic disorders, although rarely fatal, are the leading cause of morbidity and impose a huge socioeconomic burden. Their prevalence will increase dramatically as populations age and gain weight. Many orthopedic conditions are difficult to treat by conventional means; however, they are good candidates for gene therapy. Clinical trials have already been initiated for arthritis and the aseptic loosening of prosthetic joints, and the development of bone-healing applications is at an advanced, preclinical stage. Other potential uses include the treatment of Mendelian diseases and orthopedic tumors, as well as the repair and regeneration of cartilage, ligaments, and tendons. Many of these goals should be achievable with existing technologies. The main barriers to clinical application are funding and regulatory issues, which in turn reflect major safety concerns and the opinion, in some quarters, that gene therapy should not be applied to nonlethal, nongenetic diseases. For some indications, advances in nongenetic treatments have also diminished enthusiasm. Nevertheless, the preclinical and early clinical data are impressive and provide considerable optimism that gene therapy will provide straightforward, effective solutions to the clinical management of several common debilitating disorders that are otherwise difficult and expensive to treat.

Autologous conditioned serum (Orthokine) is an effective treatment for knee osteoarthritis

OBJECTIVE

Osteoarthritis (OA) is prevalent and difficult to treat. Autologous conditioned serum (ACS), marketed under the trade name Orthokine, is a novel, injectable antiarthritic derived from the patient's own blood. The present study is the first time ACS has undergone a controlled clinical trial.

METHOD

We investigated 376 patients with knee OA in a prospective, randomized, patient- and observer-blinded, placebo-controlled trial using an intention-to-treat analysis (ITT). The clinical effects of ACS were compared to hyaluronan (HA) and saline (placebo) as assessed by patient-administered outcome instruments (Western Ontario and McMaster Universities osteoarthritis index, global patient assessment, visual analog scale, Short-Form 8) after 7, 13 and 26 weeks. After 104 weeks an observer-blinded follow-up was carried out. Frequency and severity of adverse events were used as safety parameters.

RESULTS

In all treatment groups, intra-articular injections produced a reduction in symptoms as well as an improvement in quality of life. However, the effects of ACS were significantly superior to those of HA and saline for all outcome measures and time points, and improvements were clinically relevant; there were no differences between the effects of HA and saline. The frequency of adverse events was comparable in the ACS and saline groups, but higher in the HA group.

CONCLUSION

The data demonstrate that ACS injection considerably improves clinical signs and symptoms of OA. It remains to be determined whether ACS is disease-modifying, chondroprotective, or chondroregenerative.

Gene therapy of the rheumatic diseases: 1998 to 2008

During the decade since the launch of Arthritis Research, the application of gene therapy to the rheumatic diseases has experienced the same vicissitudes as the field of gene therapy as a whole. There have been conceptual and technological advances and an increase in the number of clinical trials. However, funding has been unreliable and a small number of high-profile deaths in human trials, including one in an arthritis gene therapy trial, have provided ammunition to skeptics. Nevertheless, steady progress has been made in a number of applications, including rheumatoid arthritis and osteoarthritis, Sjögren syndrome, and lupus. Clinical trials in rheumatoid arthritis have progressed to phase II and have provided the first glimpses of possible efficacy. Two phase I protocols for osteoarthritis are under way. Proof of principle has been demonstrated in animal models of Sjögren syndrome and lupus. For certain indications, the major technological barriers to the development of genetic therapies seem to have been largely overcome. The translational research necessary to turn these advances into effective genetic medicines requires sustained funding and continuity of effort.

Effects of exercise vs experimental osteoarthritis on imaging outcomes

OBJECTIVE

To identify changes in imaging outcomes in a controlled model of osteoarthritis (OA) vs exercise.

METHOD

Sixteen 2-year-old horses were randomly assigned to an exercise control (n=8) or an exercise OA (n=8) group. All horses had middle carpal joints arthroscopically explored and an osteochondral fragment was induced in one middle carpal joint of the OA group. All horses were treadmill exercised for the duration of the study (91 days). Clinical, radiographic, nuclear scintigraphic, computed tomographic and magnetic resonance imaging (MRI) examinations were performed and outcomes of these were compared between groups. Imaging results were correlated to clinical, biomarker and gross pathologic results.

RESULTS

The OA group had significant increases in clinical outcomes and most imaging parameters. Specifically, the OA group showed significant increases in radiographic lysis and nuclear scintigraphic uptake. There was very little change in subchondral bone density, but a significant change in subchondral bone edema. Radiographic lysis, radial carpal bone edema and nuclear scintigraphy were strongly correlated with clinical changes and radial carpal bone edema was strongly correlated with changes in Type I and Type II collagen found in the synovial fluid.

CONCLUSIONS

OA induced significant changes in imaging parameters beyond the adaptation seen with exercise. Bone edema detected with MRI was closely correlated with collagen biomarkers detected in the synovial fluid.

Perspectives on the use of gene therapy for chronic joint diseases

Advances in molecular and cellular biology have identified a wide variety of proteins including targeted cytokine inhibitors, immunomodulatory proteins, cytotoxic mediators, angiogenesis inhibitors, and intracellular signalling molecules that could be of great benefit in the treatment of chronic joint diseases, such as osteo- and rheumatoid arthritis. Unfortunately, protein-based drugs are difficult to administer effectively. They have a high rate of turnover, requiring frequent readministration, and exposure in non-diseased tissue can lead to serious side effects. Gene transfer technologies offer methods to enhance the efficacy of protein-based therapies, enabling the body to produce these molecules locally at elevated levels for extended periods. The proof of concept of gene therapies for arthritis has been exhaustively demonstrated in multiple laboratories and in numerous animal models. This review attempts to condense these studies and to discuss the relative benefits and limitations of the methods proposed and to discuss the challenges toward translating these technologies into clinical realities.

Animal models for target diseases in gene therapy--using DNA and siRNA delivery strategies

Nanoparticles, including lipopolyamines leading to lipoplexes, liposomes, and polyplexes are targeted drug carrier systems in the current search for a successful delivery system for polynucleic acids. This review is focused on the impact of gene and siRNA delivery for studies of efficacy, pharmacodynamics, and pharmacokinetics within the setting of the wide variety of in vivo animal models now used. This critical appraisal of the recent literature sets out the different models that are currently being investigated to bridge from studies in cell lines through towards clinical reality. Whilst many scientists will be familiar with rodent (murine, fecine, cricetine, and musteline) models, few probably think of fish as a clinically relevant animal model, but zebrafish, madake, and rainbow trout are all being used. Larger animal models include rabbit, cat, dog, and cow. Pig is used both for the prevention of foot-and-mouth disease and human diseases, sheep is a model for corneal transplantation, and the horse naturally develops arthritis. Non-human primate models (macaque, common marmoset, owl monkey) are used for preclinical gene vector safety and efficacy trials to bridge the gap prior to clinical studies. We aim for the safe development of clinically effective delivery systems for DNA and RNAi technologies.

Changes in synovial fluid and serum biomarkers with exercise and early osteoarthritis in horses

OBJECTIVE

To discriminate between changes in biomarkers with exercise compared to changes in biomarkers with osteoarthritis (OA) in exercising horses.

METHOD

Sixteen, 2-year-old horses were randomly assigned either to an exercise-alone (n=8) or OA-affected (also exercised) (n=8) group. All horses had both mid-carpal joints arthroscoped and OA induced in one mid-carpal joint in the OA-affected joints of OA-affected horses. Two weeks after surgery all horses commenced a strenuous exercise program on a high-speed treadmill. Clinical outcomes and synovial fluid and serum biomarkers, were evaluated weekly. Synovial and serum biomarkers evaluated were epitope CS846 (CS846), epitope CPII (CPII), glycosaminoglycans (GAGs), epitope Col CEQ (Col CEQ) (a marker of type II collagen degradation), type I and II collagen degradation fragments (C1,2C), osteocalcin, C-terminal of bone type I collagen (CTX1), type I collagen (Col I) and (synovial fluid only of cartilage) prostaglandin E2 (PGE2) levels. Horses were euthanized at day 91 and their joints assessed grossly, histopathologically, and histochemically.

RESULTS

Exercise induced a significant increase in synovial fluid CS846, CPII, GAG, Col CEQ, C1,2C, osteocalcin and Col I concentrations. There was a significant increase in synovial fluid CS846, CPII, Col CEQ, C1,2C, osteocalcin, Col I and PGE2 concentrations in OA-affected joints compared to exercise-alone joints. The concentration of serum CS846, CPII, GAG, osteocalcin, C1,2C and Col I increased with exercise. For each of these biomarkers there was also a statistically significant increase in serum biomarker levels in OA-affected horses compared to exercise-alone horses.

CONCLUSIONS

Six synovial fluid and serum biomarkers were useful in separating early experimental OA from exercise alone but synovial fluid CTX1 and serum Col CEQ and CTX1 were not.