Effect of Intra-Articular Sprifermin vs Placebo on Femorotibial Joint Cartilage Thickness in Patients With Osteoarthritis: The FORWARD Randomized Clinical Trial

The inflammatory endotype in osteoarthritis: Reflections from the 2024 OARSI clinical trials symposium (CTS) with a special emphasis on feasibility for clinical development

Objective

The inflammatory endotype is arguably one of the most well-established endotype in osteoarthritis (OA). While endotyping holds promise for advancing drug development, numerous potential challenges must be considered, addressed and resolved before successful clinical outcomes can be achieved.

Design

Since 2017, the Osteoarthritis Research Society International (OARSI) has hosted the Clinical Trials Symposium (CTS). Each year, OARSI and the CTS steering committee encourage discussions on selected topics among a broad range of stakeholders, including regulators, drug developers, clinicians, clinical researchers, biomarker specialists, and basic scientists, with the aim of advancing drug development in the OA field.

Results

This report highlights the ongoing tension between academia's "blue ocean" strategy and the feasibility-driven approach of drug developers, all within the context of scientific efforts to find effective solutions. Understanding the needs, goals, constraints, and opportunities of all involved stakeholders is crucial for defining optimal drug development strategies for OA.

Conclusion

A multidisciplinary, collaborative approach is essential for developing effective OA treatments, balancing scientific discovery with regulatory and clinical feasibility.

Efficacy of intra-articular injections for the treatment of osteoarthritis: A narrative review

Osteoarthritis (OA) is a prevalent degenerative joint disease characterized by progressive cartilage loss, inflammation, and joint dysfunction. With profound effects on joint function and quality of life, OA imposes a substantial socio-economic burden. As of now, OA remains incurable, lacking approved medications, regenerative therapies, or procedures that can halt the progressive destruction of the joint. Intraarticular (IA) injections have emerged as a cornerstone in the management of knee OA, offering localized minimally invasive therapeutic options. Traditional IA therapies, including corticosteroids and hyaluronic acid (HA), primarily aim to reduce pain but lack regenerative capacity. Biologic IA therapies for knee OA including autologous blood-derived products like platelet-rich plasma (PRP), bone marrow aspirate concentrate (BMAC) and mesenchymal stromal cells (MSCs) have become more commonly used. Finally, newer IA therapies such as fibroblast growth factor 18 and gene therapy are being investigated. In this review, we highlight the current evidence around IA injections for the treatment of knee OA.

FGF18 induces chondrogenesis and anti-osteoarthritic effects in a mouse model for TMJ degeneration

OBJECTIVE

Temporomandibular Joint Osteoarthritis (TMJ-OA) is a degenerative disease characterized by progressive loss of cartilage and subchondral bone sclerosis. Currently there are no effective treatments for TMJ-OA. FGF18 is a member of the fibroblast growth factor family with essential roles for chondrogenesis, selectively binding to FGFR3 receptor. Studies have reported FGF18 attenuates cartilage degradation. Whereas the anti-osteoarthritic effects of FGF18 in the articular cartilage are known, the effects of FGF18 in a TMJ fibrocartilage degeneration mouse model remain to be determined. The goal of this project was to determine the effects of intra-articular injections of FGF18 in a mouse model for TMJ degeneration.

METHOD

Prosthesis tubes were bonded at the left lower incisor of 6-week-old triple collagen transgenic mice (Col1a1XCol2a1XCol10a1), creating unilateral crossbite and degeneration of the TMJ fibrocartilage. Six weeks after placement of prosthesis tubes, experimental and control mice received intra-articular injections of rmFGF18 (5µg/week) or saline, respectively, for 3 weeks.

RESULTS

Mice receiving saline intra-articular injections presented with a thinner cartilage layer with decreased proteoglycan distribution and Edu positive cells (chondrocyte proliferation marker), while mice injected with rmFGF18 presented with significant increased fibrocartilage thickness, remarkable proteoglycan distribution and chondrocyte proliferation, suggesting healing of the induced degeneration. Furthermore, reversal of the TMJ degeneration achieved by rmFGF18 injection was accompanied by a substantial reduction in Noggin (antagonist of BMP signaling), increase in TIMP1 (inhibitor of metalloproteinases such as MMP13) and decrease in MMP13 expression.

CONCLUSION

Our results postulate FGF18 as a powerful growth factor for the healing of TMJ fibrocartilage.

Chasing the target: reports from the Advances in Targeted Therapies meeting, 2024

OBJECTIVES

The Advances in Targeted Therapies annual meeting brings together experts within the field of rheumatology and immunology to highlight and discuss the latest scientific developments and needs in the field. The objective is to highlight unmet scientific needs in the field of rheumatology.

METHODS

The 24th annual Advances in Targeted Therapies meeting convened with more than 100 international clinicians and scientific researchers in rheumatology, immunology, and other specialities relating to all aspects of immune-mediated inflammatory diseases. During the meeting, we held 5 rheumatologic disease-specific discussion sections consisting of experts in each field. These groups included rheumatoid arthritis (RA), psoriatic arthritis (PsA), axial spondyloarthritis (axSpA), osteoarthritis (OA), and systemic lupus erythematosus (SLE). In each group, experts were asked to identify the top 2 to 3 most important overarching and disease-specific scientific unmet needs to be addressed in the next 5 years.

RESULTS

The overarching themes across disciplines included the need for precision medicine, improved classification of disease states, and the further identification of targets and associated therapies, including the potential role of chimeric antigen receptor (CAR) T cell therapies. Within RA, the group highlighted the lack of precision medicine and the need for better biomarkers. Further, the lack of targeted therapies against fibroblasts in RA was discussed, with the potential impact of targeting fibroblasts early in the disease as an unmet need. For PsA, there is a continued need for a better definition of disease endotypes and for the categorisation of those with complex and difficult-to-treat (D2T) diseases. The development of bispecific molecules and combination therapeutic approaches remain a high priority. For axSpA, the disease-modifying characteristics of nonsteroid anti-inflammatory drugs need further evaluation, as does the treatment of residual pain and fatigue frequently in the disease. In OA, new therapeutic targets remain an unmet need, and the discussion group prioritised potential experimental strategies that could lead to innovative therapeutic targets. Elucidating the specific signalling and target cells responsible for, or inhibiting, repair will be essential for developing targeted therapies. SLE experts emphasised the need to identify the most predictive biological contributions to disease progression in patients with early clinical precursors of SLE. The role of CAR T cell therapy must be further investigated, along with ancillary biologic studies (eg, immune system profiling) that provide critical insights into disease pathogenesis. Further, there is a need to determine the relationship of patient-relevant symptoms to the pathophysiology of SLE and identify new therapeutic targets for these symptoms.

CONCLUSIONS

There remain many unmet needs on the road to precision medicine with regard to identifying disease endotypes and biomarkers for disease progression or therapeutic response. For most diseases discussed, a strong unmet need remains with regard to identifying new targets and therapies for those with refractory or D2T disease. The ability to prevent or cure rheumatic disease remains the ultimate unmet need in rheumatology.

Acupotomy Ameliorates KOA Related Chondrocyte Premature Senescence Through YAP/FOXD1 Pathway

Purpose

Premature senescence of chondrocytes is a typical lesion of knee osteoarthritis (KOA). Abnormal cartilage stress can inhibit the mechanosensitive Yes-associated protein (YAP) / transcription factor forkhead box D1 (FOXD1) pathway, which is related to premature senescence of chondrocytes, thereby accelerating the progression of the lesion. This study aims to investigate whether acupotomy intervention could inhibit the premature senescence of chondrocytes and protect the cartilage of KOA rabbits.

Methods

18 male New Zealand rabbits were randomly divided into 3 groups (n = 6 each): control, KOA, and KOA + acupotomy (KOA+Apo). KOA, KOA+Apo rabbits were modeled by modified Videman's method for 6 weeks. After modeling, the KOA+Apo groups were subjected to acupotomy once a week for 3 weeks on the muscles around the left hind knee. The modified Lequesne MG score and passive range of motion (PROM) were used to evaluate the general condition and exercise ability of rabbits. Cartilage degeneration was detected by safranin O-fast green staining and transmission electron microscope(TEM). Type II collagen (Col-II) and aggrecan by immunohistochemistry (IHC), IL-7 and MMP-13 by Enzyme-Linked Immunosorbent Assay (ELISA), and p53, Rb1, p - YAP, YAP, FOXD1 by IHC, Western blot, or RT - PCR.

Results

Acupotomy effectively curbed cartilage degeneration and chondrocyte premature senescence in KOA rabbits. Mechanistically, it cut IL - 7 and MMP-13 levels, easing the inflammatory milieu and extracellular matrix degradation. It also regulated p53 and Rb1, controlling cell - cycle progression. Crucially, acupotomy upregulated the YAP/FOXD1 pathway, which, by affecting downstream genes, modulated IL - 7, MMP-13, p53, and Rb1 levels, acting as a pivotal molecular link in its regulatory effects.

Conclusion

Acupotomy may protect KOA rabbits' cartilage by inhibiting chondrocytes premature senescence via the YAP/FOXD1 pathway, offering a new theoretical basis for treating mechanically - induced KOA.

Advancements in regenerative medicine: a comprehensive review of stem cell and growth factor therapies for osteoarthritis

Osteoarthritis (OA) is a widely encountered degenerative joint disorder marked by gradual cartilage deterioration, inflammation, and pain, which collectively impose considerable strain on global healthcare systems. While traditional therapies typically offer relief from symptoms, they do not tackle the core pathophysiological aspects of the disease. Regenerative medicine has recently risen as a promising field for addressing OA, capitalizing on the regenerative capabilities of stem cells and growth factors to foster tissue healing and renewal. This thorough review delves into the most recent progress in stem cell and growth factor treatments for OA, covering preclinical studies, clinical trials, and novel technological developments. We discuss the diverse origins of stem cells, such as mesenchymal stem cells (MSCs), induced pluripotent stem cells (iPSCs), and adipose-derived stem cells (ASCs), underscoring their therapeutic actions and effectiveness in both preclinical and clinical environments. Moreover, we explore contributions of growth factors like transforming growth factor (TGF)-β, platelet-derived growth factor (PDGF), and insulin-like growth factor (IGF) in modifying OA's pathology and enhancing tissue restoration. Additionally, this review discusses the hurdles and constraints tied to current regenerative strategies, including the standardization of cell sources, the refinement of delivery techniques, and considerations for long-term safety. By meticulously assessing the latest research outcomes and technological breakthroughs, this review aims to shed light on the potential of stem cell and growth factor therapies as forthcoming therapeutic options for OA, thereby propelling forward the domain of regenerative medicine and enhancing clinical results for individuals afflicted with this incapacitating ailment.

Multifaceted imaging strategies for clinical trials of knee osteoarthritis-a tightly interlinked value and precision chain

Osteoarthritis is a debilitating, whole-organ disease that involves all osteoarticular tissues. No effective treatments have yet been approved by the regulatory agencies for modifying the natural history of this disease and its structural progression. In this whitepaper, we will summarize concepts of "multi-faceted" (multi-contrast) magnetic resonance imaging (MRI), with a focus on its application in osteoarthritis clinical trials. The process described here encompasses a tightly interlinked value and precision chain, where all elements must be aligned seamlessly for the trial to succeed. The procedure should begin with careful patient characterization and selection, potentially aided by (multifaceted) imaging, so that the disease (sub-) types in these potential participant will match the mechanism of action (MOA) of the medical investigational product (i.e., the drug studied). This should be followed by a comprehensive yet efficient MRI acquisition protocol, employing sequences with various contrasts that permit the characterization of imaging-based joint pathologies and evaluation of the drug's MOA. Suitable image analysis tools must be employed, ideally adhering to regulatory compliance standards. Multiple validated endpoints can be derived from the various (multifaceted) contrasts, to be potentially combined to multi-component or composite endpoints, based on stringent a-priori rules. In conclusion, a robust value and precision chain needs to be fully functional for a disease-modifying osteoarthritis trial to be successful. Participant selection must be mindful of the drug's MOA, and a well-aligned and custom-tailored "multifaceted" image acquisition protocol, suitable image analysis tools, and meaningful endpoints should be in place, which should match the specific image contrasts.

Stem and progenitor cells in the synovial joint as targets for regenerative therapy

Damage to articular cartilage, tendons, ligaments and entheses as a result of trauma, degeneration or inflammation in rheumatic diseases is prevalent. Regenerative medicine offers promising strategies for repairing damaged tissues, with the aim of restoring both their structure and function. While these strategies have traditionally relied on tissue engineering approaches using exogenous cells, interventions based on the activation of endogenous repair mechanisms are an attractive alternative. Key to advancing such approaches is a comprehensive understanding of the diversity of the stem and progenitor cells that reside in the adult synovial joint and how they function to repair damaged tissues. Advances in developmental biology have provided a lens through which to understand the origins, identities and functions of these cells, and insights into the roles of stem and progenitor cells in joint tissue repair, as well as their complex relationship with fibroblasts, have emerged. Integration of knowledge obtained through studies using advanced single-cell technologies will be crucial to establishing unified models of cell populations, lineage hierarchies and their molecular regulation. Ultimately, a more complete understanding of how cells repair tissues in adult life will guide the development of innovative pro-regenerative drugs, which are poised to enter clinical practice in musculoskeletal medicine.

Aberrant anabolism hinders constructive metabolism of chondrocytes by pharmacotherapy in osteoarthritis

Osteoarthritis (OA) is a highly prevalent and disabling disease with an unmet therapeutic need. The characteristic cartilage loss and alteration of other joint structures result from a complex interaction of multiple risk factors, with mechanical overload consistently playing a central role. This overload generates an inflammatory response in the cartilage due to the activation of the innate immune response in chondrocytes, which occurs through various cellular mechanisms. Moreover, risk factors associated with obesity, being overweight, and metabolic syndrome enhance the inflammatory response both locally and systemically. OA chondrocytes, the only cells present in articular cartilage, are therefore inflamed and initiate an anabolic process in an attempt to repair the damaged tissue, which ultimately results in an aberrant and dysfunctional process. Under these circumstances, where the cartilage continues to be subjected to chronic mechanical stress, proposing a treatment that stimulates the chondrocytes' anabolic response to restore tissue structure does not appear to be a therapeutic target with a high likelihood of success. In fact, anabolic drugs proposed for the treatment of OA have yet to demonstrate efficacy. By contrast, multiple therapeutic strategies focused on pharmacologically managing the inflammatory component, both at the joint and systemic levels, have shown promise. Therefore, prioritizing the control of chronic innate pro-inflammatory pathways presents the most viable and promising therapeutic strategy for the effective management of OA. As research continues, this approach may offer the best opportunity to alleviate the burden of this incapacitating disease.

Frontal plane mechanical leg alignment estimation from knee x-rays using deep learning

Objective

Lower limb malalignment can complicate symptoms and accelerate knee osteoarthritis (OA), necessitating consideration in study population selection. In this study, we develop and validate a deep learning model that classifies leg alignment as "normal" or "malaligned" from knee antero-posterior (AP)/postero-anterior (PA) radiographs alone, using an adjustable hip-knee-ankle (HKA) angle threshold.

Material and methods

We utilized 8878 digital radiographs, including 6181 AP/PA full-leg x-rays (LLRs) and 2697 AP/PA knee x-rays (2292 with positioning frame, 405 without). The model's evaluation involved two steps: In step 1, the model's predictions on knee images cropped from LLRs were compared against the ground truth from the original LLRs. In step 2, the model was tested on knee AP radiographs, using corresponding same-day LLRs as a proxy for ground truth.

Results

The model effectively classified alignment, with step one achieving sensitivity and specificity of 0.92 for a threshold of 7.5°, and 0.90 and 0.85 for 5°. For positioning frame images, step two showed a sensitivity of 0.85 and specificity of 0.81 for 7.5°, and 0.79 and 0.74 for 5°. For non-positioning frame images, sensitivity and specificity were 0.91 and 0.83 for 7.5°, and 0.9 and 0.86 for 5°.

Conclusion

The model developed in this study accurately classifies lower limb malalignment from AP/PA knee radiographs using adjustable thresholds, offering a practical alternative to LLRs. This can enhance the precision of study population selection and patient management.

Which Endpoints Should be Applied in Interventional Trials? -: From Single Uni-dimensional Assessment Tailored to a Drug's Mechanism of Action to Multi-Component Measures and Multi-Domain Composites

Objective

A vast array of structural/imaging and clinical endpoints/outcomes are available today to osteoarthritis epidemiologists or trialists. Which assessments are best suited for which studies remains unsettled. When several assessments are available, these may be analyzed together (simultaneously or hierarchically), using statistical modeling and adjustment. Or, alternatively, they may be combined to form more complex multi-component or composite (potentially multi-domain) endpoints/outcomes. This review describes such concepts and their challenges, using examples from current osteoarthritis imaging research.

Design

A narrative, non-systematic literature search (PubMed and others) was conducted, and informal consultations were held with experts in the field. The identified concepts and experimental findings were then organized to present an integrated framework.

Results

Single imaging assessments can encompass one (uni-dimensional) or more (multi-dimensional) structures. Integration of image assessments of one structure/tissue across anatomical locations provides aggregate measures. This can also be created across heterogeneous (multi-dimensional) types of assessments (multi-component/composite), either within an area (such as imaging - single domain) or across broader areas of health and well-being (multi-domain). Weighting, standardization, and (clinical) usefulness are crucial characteristics of multi-component/composite endpoints. Examples of these concepts are here provided in the context of osteoarthritis imaging.

Conclusions

Options for multi-component/composite endpoints in osteoarthritis research are virtually infinite. Smart research strategies are required to explore and validate these vast possibilities, with appropriate statistical treatment being paramount. A one-size/endpoint-fits-all approach will likely fail in observational and interventional studies. Imaging assessment needs to be tailored to both the drug's unique mechanism of action, and to the participants' morpho-type.

Regression to the mean for physical function and quality of life in clinical trials for symptomatic knee osteoarthritis

OBJECTIVE

To estimate the size of regression to the mean (RTM) for common patient-reported outcomes in trials for knee osteoarthritis (OA).

DESIGN

Longitudinal cohort study; we included participants of the Osteoarthritis Initiative who fulfilled typical inclusion criteria for enrolment in a trial. These included: age 40-79 years, symptomatic knee OA, Kellgren-Lawrence grade 2-3, use of pain medication more than half the days of a month in past 12 months, numerical rating scale pain of 4 to 9. We studied observed changes in WOMAC physical function and KOOS quality of life (QOL).

RESULTS

We identified 547 subjects who fulfilled inclusion criteria on at least one annual follow-up between year 1 and year 8. The mean level of physical function and QOL at each follow-up time point was similar, about 18 and about 51, respectively. However, at the time of theoretical inclusion in a trial, the mean levels in the same subjects were 23 and 43, respectively (both worse scores). The mean improvement in physical function between inclusion and 1 and 2 years later, respectively, was 2.5 (95% confidence interval 1.7 to 3.2) and 3.1 (2.3 to 3.8). The corresponding improvement in QOL was 2.7 (1.7 to 3.7) and 4.2 (3.1 to 5.3).

CONCLUSION

RTM in trials for knee OA is likely to explain improvement in physical function and QOL, not only in knee pain. RTM often misleads investigators to overinterpret effectiveness as RTM neither represents improvement from the intervention nor placebo effect from the intervention and its context.

Exploring a novel outcome measure of symptom progression in knee osteoarthritis utilizing a large randomized trial

OBJECTIVES

Explore a newly defined composite measure of symptom progression for knee osteoarthritis (KOA) in a large, randomized study of a potential disease-modifying osteoarthritis drug (DMOAD).

DESIGN

Using longitudinal KOA studies, a potential composite endpoint of time to symptom progression was defined as the first occurrence of worsening of Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) Pain of ≥10 points with no improvement (≤9 point decrease) in WOMAC Function (0-100 scale). A post hoc analysis explored discrimination and association with structural outcomes in the sprifermin FORWARD trial through Years 3 and 5. All treatment arms of the intent-to-treat population were analyzed.

RESULTS

Among the 549 FORWARD participants, 442 (80.5%) completed Year 3, and 378 (68.9%) completed Year 5. Sprifermin showed dose-dependent benefits in the time to symptom progression at Year 3 with hazard ratio (95% CI) for each sprifermin treatment arm vs placebo as follows: 100 μg every 6 months (Q6M), 0.51 (0.28, 0.93); 100 μg Q12M, 0.69 (0.40, 1.20); 30 μg Q6M, 0.89 (0.53, 1.50); and 30 μg Q12M, 0.80 (0.47, 1.35). Similar findings were seen through Year 5 and for a subgroup based on modern clinical trial inclusion criteria. There were increased numbers of knee replacements in symptom progressors (n=8, 5.6%) vs non-progressors (n=7, 1.7%).

CONCLUSIONS

The symptom progression endpoint discriminated between placebo and treatment responses in a post hoc analysis of a Phase 2 investigational DMOAD KOA trial. The endpoint requires validation and further exploration in DMOAD clinical trials.

TRIAL NUMBER

NCT01919164.

Filtered and unfiltered lipoaspirates reveal novel molecular insights and therapeutic potential for osteoarthritis treatment: a preclinical in vitro study

Introduction

Orthobiologics, such as autologous nanofat, are emerging as a potential treatment option for osteoarthritis (OA), a common degenerative joint causing pain and disability in the elderly. Nanofat, a minimally processed human fat graft rich in stromal vascular fraction (SVF) secretory factors, has shown promise in relieving pain. This study aimed to elucidate the molecular mechanisms underlying nanofat treatment of OA-affected cells and compare two filtration systems used for nanofat preparation.

Methods

Chondrocytes and synoviocytes were isolated from articular cartilage and synovium of 22 OA-patients. Lipoaspirates from 13 OA-patients were emulsified using the Adinizer® or Lipocube™ Nano filter systems to generate nanofat. The fluid phase of SVF from both filtered and unfiltered lipoaspirates was applied to OA-affected cells. Luminex multiplex ELISA were performed with lipoaspirates and cell supernatants alongside functional assays evaluating cell migration, proliferation, metabolic activity, and senescence.

Results

A total of 62 cytokines, chemokines, growth factors, neuropeptides, matrix-degrading enzymes, and complement components were identified in lipoaspirates. Among these, significant concentration differences were observed for TIMP-2, TGF-ß3, and complement component C3 between the filtered and unfiltered samples. Nanofat enhanced chondrocyte proliferation and migration, as well as synoviocyte migration and metabolic activity, while reducing chondrocyte metabolic activity. Pain-related factors like β-NGF, MCP-1, Substance P, VEGF, and αCGRP were reduced, while anti-inflammatory TGF-β1+3 increased and pro-inflammatory cytokines (IL-5, IL-7, IL-15, and IFN-γ) decreased. Nanofat also elevated secretion of complement components and TIMPs in both cell types. Notably, our results revealed no significant differences in cellular effects between sSVF filtered using the Adinizer® and Lipocube™ Nano systems, as well as compared to unfiltered sSVF.

Discussion

Here, we provide first insights into how autologous nanofat therapy may ameliorate OA by enhancing chondrocyte proliferation and synoviocyte migration while modulating inflammatory and pain-related factors. However, further research is needed to determine its effects on cartilage regeneration.

Advances and Challenges in the Pursuit of Disease-Modifying Osteoarthritis Drugs: A Review of 2010-2024 Clinical Trials

Background/Objectives: Osteoarthritis (OA) is a highly prevalent, degenerative joint disease capable of causing severe pain and impaired mobility. Current treatments mitigate symptoms but do not cure the disease. The development of a disease-modifying osteoarthritis drug (DMOAD) could improve patient outcomes by slowing, halting, or reversing joint damage. Many DMOADs have progressed to clinical trials, but very few have made a significant impact, and none have been approved for clinical use. The purpose of this review is to present an update on the current status of DMOADs with a particular focus on results published since 2010. Methods: A comprehensive search was conducted within PubMed and ClinicalTrials.gov for novel DMOADs enrolled in phase II and III clinical trials between 1 January 2010 and 1 July 2024. Results: Eleven DMOAD candidates are reviewed and critically analyzed for their potential benefit in OA treatment-Lorecivivint (SM04690), TissueGene-C, Cindunistat (SD-6010), Sprifermin, UBX0101, TPX-100, GLPG1972/S201086, Lutikizumab (ABT-981), SAR113945, MIV-711, and LNA043-and relevant challenges to their development are discussed. Conclusions: Six DMOADs have demonstrated statistically significant evidence of a structural or symptomatic benefit without major safety concerns in phase II and III randomized controlled trials post-2010.

Delivery of FGF18 using mRNA-LNP protects the cartilage against degeneration via alleviating chondrocyte senescence

BACKGROUND

Osteoarthritis (OA) is a degenerative joint disease with an immense unmet medical need. FGF18 protein is a potential regenerative factor for cartilage repair. However, traditional protein delivery methods have limited efficacy due to the short lifetime and shallow infiltration.

RESULTS

In this work, we discovered that lipid nanoparticle (LNP) can infiltrate and deliver FGF18 mRNA deeper in the cartilage than proteins. After mRNA UTR optimization and chemical modification, the expression of FGF18 can last up to 6 days in the cartilage. Furthermore, delivering FGF18 mRNA activates FOXO3a-autophagy pathway, which protects against chondrocyte degeneration and senescence. Local intra-articular injection of FGF18 mRNA-LNP significantly alleviates OA symptoms in DMM and senile OA models. Sustained expression and accessibility of FGF18-mRNA to deeper chondrocytes makes LNP-mRNA more effective than FGF18 recombinant protein.

CONCLUSIONS

In summary, this study presents a novel approach superior to recombinant protein alone and holds promise as a new therapeutic strategy for OA.

Porcine-Derived Chondroitin Sulfate Sodium Alleviates Osteoarthritis in HTB-94 Cells and MIA-Induced SD Rat Models

Osteoarthritis (OA) is a chronic disease characterized by cartilage degradation, leading to bone friction, inflammation, stiffness, pain, and reduced mobility. This study investigates the therapeutic effects of porcine-derived chondroitin sulfate sodium (CS) on OA symptoms at both cellular and animal levels. In vitro study, HTB-94 chondrocytes were treated with inflammatory stimuli and CS (10, 50, 100, and 200 μg/mL) to assess the release of inflammatory mediators and the expression of genes and proteins related to cartilage synthesis and degradation. In vivo study, an MIA-induced OA rat model was used, and CS (62, 124, and 248 mg/kg b.w.) was orally administered for 4 weeks. Key parameters, such as exercise capacity, micro-CT, histological evaluation of joint tissues, serum inflammatory markers, and the expression of mRNA and proteins (inflammatory, cartilage synthesis and degradation, and apoptosis markers), were analyzed. Porcine-derived CS significantly reduced PGE2, NO, and extracellular matrix degradation marker (COMP and CTX-II) levels and increased the expression of cartilage synthesis-related genes and proteins in both HTB-94 cells and the MIA-induced rats. Additionally, CS modulated cartilage degradation pathways and notably inhibited apoptosis in vivo. The effects of porcine CS were comparable to the NSAID ibuprofen, demonstrating its potential as an anti-inflammatory and chondroprotective agent for OA management and dietary supplementation.

Osteoarthritis

Osteoarthritis is a heterogeneous disorder that is increasingly prevalent largely due to aging and obesity, resulting in a major disease burden worldwide. Knowledge about the underlying aetiology has improved, with increased understanding of the role of genetic factors, the microbiome, and existence of different pain mechanisms. However, this knowledge has not yet been translated into new treatment options. New evidence has questioned the efficacy of recommended treatments, such as therapeutic exercise programmes and the focus on weight loss, but managing obesity and maintaining activity remain important for the prevention and management of osteoarthritis. Approaches should consider individual and cultural preferences and resource availability to increase patient and community engagement, and optimise outcomes worldwide. Most of the focus has been on established osteoarthritis where management is primarily directed at relieving symptoms. The search for the much needed effective treatments that improve both symptoms and structure, often referred to as disease-modifying osteoarthritic drugs, is ongoing. Promising data indicate that targeting inflammation is effective in hand osteoarthritis.

Therapeutic Controlled Release Strategies for Human Osteoarthritis

Osteoarthritis is a progressive, irreversible debilitating whole joint disease that affects millions of people worldwide. Despite the availability of various options (non-pharmacological and pharmacological treatments and therapy, orthobiologics, and surgical interventions), none of them can definitively cure osteoarthritis in patients. Strategies based on the controlled release of therapeutic compounds via biocompatible materials may provide powerful tools to enhance the spatiotemporal delivery, expression, and activities of the candidate agents as a means to durably manage the pathological progression of osteoarthritis in the affected joints upon convenient intra-articular (injectable) delivery while reducing their clearance, dissemination, or side effects. The goal of this review is to describe the current knowledge and advancements of controlled release to treat osteoarthritis, from basic principles to applications in vivo using therapeutic recombinant molecules and drugs and more innovatively gene sequences, providing a degree of confidence to manage the disease in patients in a close future.

Bioactive peptides and proteins for tissue repair: microenvironment modulation, rational delivery, and clinical potential

Bioactive peptides and proteins (BAPPs) are promising therapeutic agents for tissue repair with considerable advantages, including multifunctionality, specificity, biocompatibility, and biodegradability. However, the high complexity of tissue microenvironments and their inherent deficiencies such as short half-live and susceptibility to enzymatic degradation, adversely affect their therapeutic efficacy and clinical applications. Investigating the fundamental mechanisms by which BAPPs modulate the microenvironment and developing rational delivery strategies are essential for optimizing their administration in distinct tissue repairs and facilitating clinical translation. This review initially focuses on the mechanisms through which BAPPs influence the microenvironment for tissue repair via reactive oxygen species, blood and lymphatic vessels, immune cells, and repair cells. Then, a variety of delivery platforms, including scaffolds and hydrogels, electrospun fibers, surface coatings, assisted particles, nanotubes, two-dimensional nanomaterials, and nanoparticles engineered cells, are summarized to incorporate BAPPs for effective tissue repair, modification strategies aimed at enhancing loading efficiencies and release kinetics are also reviewed. Additionally, the delivery of BAPPs can be precisely regulated by endogenous stimuli (glucose, reactive oxygen species, enzymes, pH) or exogenous stimuli (ultrasound, heat, light, magnetic field, and electric field) to achieve on-demand release tailored for specific tissue repair needs. Furthermore, this review focuses on the clinical potential of BAPPs in facilitating tissue repair across various types, including bone, cartilage, intervertebral discs, muscle, tendons, periodontal tissues, skin, myocardium, nervous system (encompassing brain, spinal cord, and peripheral nerve), endometrium, as well as ear and ocular tissue. Finally, current challenges and prospects are discussed.

Association between type III collagen degradation and local tissue damage of a single joint

Objective

The development of disease-modifying drugs is limited by OA's heterogeneity and the challenge of defining clinical endpoints. Serological biomarkers are considered potential surrogate endpoints, but their contribution from single joints to systemic levels in OA patients is unclear. In this exploratory study we longitudinally assessed systemic biomarker levels' response to tissue damage and healing before and after surgery in patients undergoing knee or hip joint replacement revision for aseptic failure. Patients with chronic pain associated with a prior hip or knee arthroplasty, but not receiving revision surgery were included as control.

Method

The serological biomarker of MMP mediated type III collagen degradation C3M, associated with synovial tissue degradation, was measured at baseline before revision surgery, after revision surgery and at a 6-month follow-up in 48 patients with aseptic loosening of a knee or hip prosthesis and in 18 patients with chronic pain from a hip or knee prosthesis. Longitudinal changes in biomarkers were modeled using linear mixed models.

Results

No differences between the aseptic loosening and chronic pain groups were observed at baseline. Revision surgery in the aseptic loosening group led to a swift increase in C3M, which normalized within 2-3 months. No changes in biomarker level were observed in chronic pain patients over three months.

Conclusion

These findings suggest that tissue damage in a single joint significantly impacts systemic biomarker levels and underscores the relevance of systemic biomarkers in assessing local tissue remodeling.

A comprehensive review of phase 2/3 trials in osteoarthritis: an expert opinion

INTRODUCTION

Osteoarthritis (OA) is a chronic, degenerative, and debilitating disease associated with significant long-term morbidity and disability. The pathogenesis of OA is not completely understood but involves an interplay between environmental risk factors, joint mechanics, abnormal pain pathways and upregulation of inflammatory signaling pathways. Current therapeutic options for patients are limited to conservative management, minimal pharmacological options or surgical management, with significant caveats to all approaches.

AREAS COVERED

In this review, we have set out to investigate current phase II/III clinical trials by undertaking a PubMed search. Examined clinical trials have explored a myriad of potential therapeutics from conventional disease-modifying anti-rheumatic drugs and biologics usually used in the treatment of inflammatory arthritides, to more novel approaches targeting inflammatory pathways implicated in OA, cartilage degeneration or pain pathways.

EXPERT OPINION

Unfortunately, most completed phase II/III clinical trials have shown little impact on patient pain scores, with the exception of the traditional DMARD methotrexate and Sprifermin. Methotrexate has been shown to be beneficial when used in the correct patient cohort (MRI proven synovitis). Sprifermin has the longest follow-up data of 5 years and has been shown to reduce loss of MRI-measured cartilage thickness and pain scores.

Unbiased analysis of knee cartilage thickness change over three years after sprifermin vs. placebo treatment - A post-hoc analysis from the phase 2B FORWARD study

Objective

Post-treatment cartilage morphometry in the FORWARD study was performed without blinding to MRI acquisition order, involving potential reader bias. Here we obtained unbiased estimates of cartilage change post-treatment, reading year (Y)2 and Y5 MRIs with blinding to time point. We studied whether post-treatment cartilage thickness change differed between sprifermin- and placebo-treated knees.

Methods

FORWARD was a 5-year randomized control trial in 549 knee osteoarthritis patients. Here, Y2/Y5 images were analyzed with blinding to relative temporal order and treatment group. Cartilage change during Y2→Y5 was obtained in 337 participants: n ​= ​57 treated with placebo intra-articular injections every 6 months (q6M); n ​= ​69 with 30 ​μg sprifermin every 12 months (q12 ​M), n ​= ​67 with 30 ​μg q6M, n ​= ​73 with 100 ​μg q12 ​M, and n ​= ​71 with 100 ​μg q6M between baseline (BL) and 18 ​M. Total femorotibial joint (TFTJ) cartilage thickness was the primary analytic focus.

Results

TFTJ cartilage thickness change during Y2→Y5 was -26μm (SD64; 95%CI -32,-19) across the cohort; no statistically significant difference (p ​= ​0.80) was observed between Sprifermin treated or placebo arms (one-way ANOVA). All groups lost cartilage, but the treatment-related difference in cartilage thickness in Sprifermin arms relative to placebo at Y2 was maintained until Y5. Annualized cartilage change in placebo participants was -8.2 ​μm (SD21; 95%CI -14,-2.5) during Y2→Y5 vs. -5.4 ​μm (SD27; 95%CI -13,1.8) during BL→Y2; no significant difference was identified (t-test).

Conclusion

FORWARD is the first study evaluating post-treatment benefits of a potential disease modifying osteoarthritis drug. Cartilage thickness gained with 100 ​μg sprifermin at Y2 is maintained to Y5 and thus appears viable and sustainable.This is a post-hoc analysis of the FORWARD trial: ClinicalTrials.gov Identifier: NCT01919164.

The collagenase-induced osteoarthritis (CIOA) model: Where mechanical damage meets inflammation

Objective

To characterize inflammatory and mechanical changes in the collagenase-induced OA (CIOA) model in rats.

Design

Skeletally mature, 6-month-old Wistar rats received unilateral intraarticular injections of saline, 500 U or 1000 U of collagenase on days 0 and 2 of the study. Joint tissues were harvested on either day 4 or 70 to evaluate the acute and long-term changes. Blood biomarkers, gait asymmetry and mechanical hyperalgesia were assessed repeatedly up until day 70.

Results

The intraarticular injection of collagenase triggered an increase in cartilage degeneration and bone resorption over time, particularly for 1000 U. Similarly, mild synovitis was observed on day 70 with an increased number of synovial lining cells, increased fibrosis, and infiltration of peripheral macrophages. Mechanistically, these findings were linked to a dose-related mechanical weakening of the anterior cruciate ligament (ACL), which caused persistent joint destabilization throughout the study. Furthermore, the collagenase injection triggered acute inflammation and swelling of the synovium on day 4 and an acute systemic inflammatory response with increased cytokine and peripheral blood immune cell levels. While mild synovitis persisted until day 70, the systemic inflammatory response returned to control levels after 8 days. Similarly, the observed acute changes in gait and mechanical hyperalgesia also returned to baseline after 21 days.

Conclusion

By evaluating inflammatory and mechanical factors at different doses and timepoints, our characterization enables a more targeted study design and increases the clinical relevance of future studies involving the CIOA model.

Exosome-Integrated Hydrogels for Bone Tissue Engineering

Exosome-integrated hydrogels represent a promising frontier in bone tissue engineering, leveraging the unique biological properties of exosomes to enhance the regenerative capabilities of hydrogels. Exosomes, as naturally occurring extracellular vesicles, carry a diverse array of bioactive molecules that play critical roles in intercellular communication and tissue regeneration. When combined with hydrogels, these exosomes can be spatiotemporally delivered to target sites, offering a controlled and sustained release of therapeutic agents. This review aims to provide a comprehensive overview of the recent advancements in the development, engineering, and application of exosome-integrated hydrogels for bone tissue engineering, highlighting their potential to overcome current challenges in tissue regeneration. Furthermore, the review explores the mechanistic pathways by which exosomes embedded within hydrogels facilitate bone repair, encompassing the regulation of inflammatory pathways, enhancement of angiogenic processes, and induction of osteogenic differentiation. Finally, the review addresses the existing challenges, such as scalability, reproducibility, and regulatory considerations, while also suggesting future directions for research in this rapidly evolving field. Thus, we hope this review contributes to advancing the development of next-generation biomaterials that synergistically integrate exosome and hydrogel technologies, thereby enhancing the efficacy of bone tissue regeneration.

Fluctuation of Bone Marrow Lesions and Inflammatory MRI Markers over 2 Years and Concurrent Associations with Quantitative Cartilage Loss

OBJECTIVE

To assess whether change of semiquantitatively magnetic resonance imaging (MRI)-defined bone marrow lesions (BMLs) and inflammatory markers is associated with change in quantitatively-assessed cartilage loss in the femorotibial joint (FTJ) in knees with radiographic osteoarthritis (OA) over 24 months.

DESIGN

Participants were included from the IMI-APPROACH and the Osteoarthritis Initiative FNIH studies. Semiquantitative MRI assessment was performed for BMLs, Hoffa- and effusion-synovitis. Quantitative cartilage thickness measurements were performed manually. Definitions of change included number of subregions with BMLs, change in sum and change in maximum increase in size. Change in Hoffa-synovitis and effusion-synovitis was categorized in addition. Between-group comparisons regarding cartilage loss in the FTJ, medial and lateral compartments were performed using analysis of variance (ANOVA).

RESULTS

A total of 629 participants were included. Knees without any BMLs at baseline (BL) and follow-up (FU) had significantly less cartilage loss compared to the other subgroups. Change in both directions in the sum score of BMLs was associated with increased rates of cartilage loss. Maximum increase in size of BMLs was associated with increased rates of cartilage loss (FTJ increase by 2 grades -0.183 mm, 95% CI [-0.335, -0.031], by 3 grades -0.306 mm, [-0.511, -0.101]). Worsening of Hoffa-synovitis was associated with increased rates of cartilage loss.

CONCLUSION

Knees without BMLs at BL and FU showed lowest rates of cartilage loss. Knees with an increase in BML size showed increased rates of concurrent cartilage loss. Approaches with the aim to inhibit BML development, avoidance of increase in size and avoidance of Hoffa-synovitis worsening may have beneficial effects on cartilage loss.

Is detection of disease-modifying osteoarthritis drug treatment more effective when performing cartilage morphometry without blinding to MR image acquisition order?

OBJECTIVE

We here explore whether observed treatment effects of a putative disease-modifying osteoarthritis drug (DMOAD) are greater when cartilage morphometry is performed with rather than without knowledge of magnetic resonance imaging (MRI) acquisition order (unblinded/blinded to time point).

METHODS

In the FORWARD (FGF-18 Osteoarthritis Randomized Controlled Trial with Administration of Repeated Doses) randomized controlled trial, 549 knee osteoarthritis patients were randomized 1:1:1:1:1 to three once-weekly intra-articular injections of placebo, 30 µg sprifermin every 6 or 12 months (M), or 100 µg every 6/12 M. After year 2, cartilage segmentation of BL through 24 M MRIs was performed, with blinding to acquisition order. After year 5, 24 and 60 M MRIs were analyzed together, with unknown relative order, but with segmented BL images as reference (24 M unblinded vs. BL), by the same operators. Total femorotibial joint cartilage thickness (TFTJ_ThC) change was obtained for 352 participants analyzed under both conditions.

RESULTS

Twenty-four-month data read unblinded to order revealed a -35 ± 44 µm lower TFTJ_ThC than blinded analysis (all groups: lower/upper bounds -120/+51 µm; correlation r2 = 97%). With unblinded analysis, the placebo group lost -46 ± 57 µm TFTJ_ThC over 24 M, whereas 100 µg/every 6 M lost -2.2 ± 73 µm (difference =44 µm [95% CI: 22, 66]). With blinded analysis, placebo lost -11 ± 53 µm, whereas 100 µg/every 6 M gained 30 ± 62 µm (difference = 40 µm [95% CI: 21, 60]). 100 µg sprifermin injected every 6 M showed statistically significant (p < 0.001) treatment effects on TFTJ_ThC, with Cohen D = -0.66 for unblinded and D = -0.69 for blinded analysis.

CONCLUSIONS

These results do not reveal that detection of proposed DMOAD treatment is enhanced with MRIs read unblinded to order; rather, the sensitivity is similar to blinded analysis. Choices on blinded vs. unblinded analysis may thus be based on other criteria.

Harnessing Peptide-Based Hydrogels for Enhanced Cartilage Tissue Engineering

Cartilage tissue engineering remains a formidable challenge due to its complex, avascular structure and limited regenerative capacity. Traditional approaches, such as microfracture, autografts, and stem cell delivery, often fail to restore functional tissue adequately. Recently, there has been a surge in the exploration of new materials that mimic the extracellular microenvironment necessary to guide tissue regeneration. This review investigates the potential of peptide-based hydrogels as an innovative solution for cartilage regeneration. These hydrogels, formed via supramolecular self-assembly, exhibit excellent properties, including biocompatibility, ECM mimicry, and controlled biodegradation, making them highly suitable for cartilage tissue engineering. This review explains the structure of cartilage and the principles of supramolecular and peptide hydrogels. It also delves into their specific properties relevant to cartilage regeneration. Additionally, this review presents recent examples and a comparative analysis of various peptide-based hydrogels used for cartilage regeneration. The review also addresses the translational challenges of these materials, highlighting regulatory hurdles and the complexities of clinical application. This comprehensive investigation provides valuable insights for biomedical researchers, tissue engineers, and clinical professionals aiming to enhance cartilage repair methodologies.

Sexual dimorphism in articular tissue anatomy - Key to understanding sex differences in osteoarthritis?

OBJECTIVE

Osteoarthritis (OA) prevalence and incidence varies between women and men, but it is unknown whether this follows sex-specific differences in systemic factors (e.g. hormones) and/or differences in pre-morbid joint anatomy. We recognize that classifications of sex within humans cannot be reduced to female/male, but given the lack of literature on non-binary individuals, this review is limited to the sexual dimorphism of articular morphotypes.

METHODS

Based on a Pubmed search using relevant terms, and input from experts, we selected articles based on the authors' judgment of their relevance, interest, originality, and scientific quality; no "hard" bibliometric measures were used to evaluate their quality or importance. Focus was on clinical rather than pre-clinical studies, with most (imaging) data being available for the knee joint.

RESULTS

After introducing "sexual dimorphism", the specific literature on articular morphotypes is reviewed, structured by: radiographic joint space width (JSW), meniscus, ligaments, articular cartilage morphology, articular cartilage composition and deformation, and articular tissue response to treatment.

CONCLUSIONS

Sex-specific differences were clearly observed for JSW, meniscus damage, ligament size, and cartilage morphometry (volume, thickness, and surface areas) but not for cartilage composition. Ligament and cartilage measures were smaller in women even after matching for confounders. Taken together, the findings indicate that female (knee) joints may be structurally more vulnerable and at greater risk of OA. The "one size/sex fits all" approach must be abandoned in OA research, and all observational and interventional studies should report their results for sex-specific strata, at least in pre-specified secondary or post-hoc analyses.

What is New in Osteoarthritis Imaging?

Osteoarthritis (OA) is the leading joint disorder globally, affecting a significant proportion of the population. Recent studies have changed our understanding of OA, viewing it as a complex pathology of the whole joint with a multifaceted etiology, encompassing genetic, biological, and biomechanical elements. This review highlights the role of imaging in diagnosing and monitoring OA. Today's role of radiography is discussed, while also elaborating on the advances in computed tomography and magnetic resonance imaging, discussing semiquantitative methods, quantitative morphologic and compositional techniques, and giving an outlook on the potential role of artificial intelligence in OA research.

Gaining Insight into Updated MR Imaging for Quantitative Assessment of Cartilage Injury in Knee Osteoarthritis

PURPOSE OF THE REVIEW

Knee Osteoarthritis (KOA) entails progressive cartilage degradation, reviewed via MRI for morphology, biochemical composition, and microtissue alterations, discussing clinical advantages, limitations, and research applicability.

RECENT FINDINGS

Compositional MRI, like T2/T2* mapping, T1rho mapping, gagCEST, dGEMRIC, sodium imaging, diffusion-weighted imaging, and diffusion-tensor imaging, provide insights into cartilage injury in KOA. These methods quantitatively measure collagen, glycosaminoglycans, and water content, revealing important information about biochemical compositional and microstructural alterations. Innovative techniques like hybrid multi-dimensional MRI and diffusion-relaxation correlation spectrum imaging show potential in depicting initial cartilage changes at a sub-voxel level. Integration of automated image analysis tools addressed limitations in manual cartilage segmentation, ensuring robust and reproducible assessments of KOA cartilage. Compositional MRI techniques reveal microstructural changes in cartilage. Multi-dimensional MR imaging assesses biochemical alterations in KOA-afflicted cartilage, aiding early degeneration identification. Integrating artificial intelligence enhances cartilage analysis, optimal diagnostic accuracy for early KOA detection and monitoring.

Ultrasound Imaging in Knee Osteoarthritis: Current Role, Recent Advancements, and Future Perspectives

While conventional radiography and MRI have a well-established role in the assessment of patients with knee osteoarthritis, ultrasound is considered a complementary and additional tool. Moreover, the actual usefulness of ultrasound is still a matter of debate in knee osteoarthritis assessment. Despite that, ultrasound offers several advantages and interesting aspects for both current clinical practice and future perspectives. Ultrasound is potentially a helpful tool in the detection of anomalies such as cartilage degradation, osteophytes, and synovitis in cases of knee osteoarthritis. Furthermore, local diagnostic and minimally invasive therapeutic operations pertaining to knee osteoarthritis can be safely guided by real-time ultrasound imaging. We are constantly observing a growing knowledge and awareness among radiologists and other physicians, concerning ultrasound imaging. Ultrasound studies can be extremely useful to track the response to various therapies. For this specific aim, tele-ultrasonography may constitute an easy tool aiding precise and repeated follow-up controls. Moreover, raw radio-frequency data from US backscattering signals contain more information than B-mode imaging. This paves the way for quantitative in-depth analyses of cartilage, bone, and other articular structures. Overall, ultrasound technologies and their rapid evolution have the potential to make a difference at both the research and clinical levels. This narrative review article describes the potential of such technologies and their possible future implications.

FGF18 encoding circular mRNA-LNP based on glycerolipid engineering of mesenchymal stem cells for efficient amelioration of osteoarthritis

Mesenchymal stem cells (MSCs) exhibit substantial potential for osteoarthritis (OA) therapy through cartilage regeneration, yet the realization of optimal therapeutic outcomes is hampered by their limited intrinsic reparative capacities. Herein, MSCs are engineered with circular mRNA (cmRNA) encoding fibroblast growth factor 18 (FGF18) encapsulated within lipid nanoparticles (LNP) derived from a glycerolipid to facilitate OA healing. A proprietary biodegradable and ionizable glycerolipid, TG6A, with branched tails and five ester bonds, forms LNP exhibiting above 9-fold and 41-fold higher EGFP protein expression in MSCs than commercial LNP from DLin-MC3-DMA and ALC-0315, respectively. The introduction of FGF18 not only augmented the proliferative capacity of MSCs but also upregulated the expression of chondrogenic genes and glycosaminoglycan (GAG) content. Additionally, FGF18 enhanced the production of proteoglycans and type II collagen in chondrocyte pellet cultures in a three-dimensional culture. In an OA rat model, transplantation with FGF18-engineered MSCs remarkably preserved cartilage integrity and facilitated functional repair of cartilage lesions, as evidenced by thicker cartilage layers, reduced histopathological scores, maintenance of zone structure, and incremental type II collagen and extracellular matrix (ECM) deposition. Taken together, our findings suggest that TG6A-based LNP loading with cmRNA for engineering MSCs present an innovative strategy to overcome the current limitations in OA treatment.

Prospects of Disease-Modifying Osteoarthritis Drugs

Osteoarthritis (OA) causes a massive disease burden with a global prevalence of nearly 23% in 2020 and an unmet need for adequate treatment, given a lack of disease-modifying drugs (DMOADs). The author reviews the prospects of active DMOAD candidates in the phase 2/3 clinical trials of drug development pipeline based on key OA pathogenetic mechanisms directed to inflammation-driven, bone-driven, and cartilage-driven endotypes. The challenges and possible research opportunities are stated in terms of the formulation of a research question known as the PICO approach: (1) population, (2) interventions, (3) comparison or placebo, and (4) outcomes.

The dual amylin and calcitonin receptor agonist KBP-336 elicits a unique combination of weight loss, antinociception and bone protection - a novel disease-modifying osteoarthritis drug

BACKGROUND

Despite the extensive research to provide a disease-modifying osteoarthritis drug (DMOAD), there is still no approved DMOAD. Dual amylin and calcitonin receptor agonists (DACRA) can provide metabolic benefits along with antinociceptive and potential structural preserving effects. In these studies, we tested a DACRA named KBP-336 on a metabolic model of OA in meniscectomised (MNX) rats.

METHODS

We evaluated KBP-336's effect on pain-like symptoms in Sprague Dawley (SD) rats on high-fat diet (HFD) that underwent meniscectomy using the von Frey test to measure the 50% paw withdrawal threshold (PWT) and analyzed using one-way ANOVA. Short in vivo studies and in vitro cell receptor expression systems were used to illustrate receptor pharmacology.

RESULTS

After 30 weeks on HFD, including an 8-week treatment, female MNX animals receiving KBP-336 4.5 nmol/Kg/72 h had lower body weight and smaller adipose tissues than their vehicle-treated counterparts. After 20 weeks on HFD, including an 8-week treatment, male rats receiving KBP-336 had lower body weight than the vehicle group. In both the female and male rats, the MNX groups on KBP-336 treatment had a higher PWT than the vehicle-treated MNX group. Aiming to identify the receptor influencing pain alleviation, KBP-336 was compared to the long-acting human calcitonin (hCTA). Single-dose studies on 12-week-old male rats showed that hCTA lowers CTX-I without affecting food intake, confirming its calcitonin receptor selectivity. On the metabolic OA model with 18 weeks of HFD, including 6-week treatment, hCTA at 100 nmol/Kg/24 h and KBP-336 at 0.5, 1.5, and 4.5 nmol/Kg/72 h produced significantly higher PWT in MNX animals compared to MNX animals on vehicle treatment. hCTA and KBP-336 at 0.5 nmol/Kg did not affect body weight and fat tissues.

CONCLUSION

Overall, KBP-336 improved the pain observed in the metabolic OA model. Calcitonin receptor activation proved to be essential in this antinociceptive effect.

Role of signaling pathways in age-related orthopedic diseases: focus on the fibroblast growth factor family

Fibroblast growth factor (FGF) signaling encompasses a multitude of functions, including regulation of cell proliferation, differentiation, morphogenesis, and patterning. FGFs and their receptors (FGFR) are crucial for adult tissue repair processes. Aberrant FGF signal transduction is associated with various pathological conditions such as cartilage damage, bone loss, muscle reduction, and other core pathological changes observed in orthopedic degenerative diseases like osteoarthritis (OA), intervertebral disc degeneration (IVDD), osteoporosis (OP), and sarcopenia. In OA and IVDD pathologies specifically, FGF1, FGF2, FGF8, FGF9, FGF18, FGF21, and FGF23 regulate the synthesis, catabolism, and ossification of cartilage tissue. Additionally, the dysregulation of FGFR expression (FGFR1 and FGFR3) promotes the pathological process of cartilage degradation. In OP and sarcopenia, endocrine-derived FGFs (FGF19, FGF21, and FGF23) modulate bone mineral synthesis and decomposition as well as muscle tissues. FGF2 and other FGFs also exert regulatory roles. A growing body of research has focused on understanding the implications of FGF signaling in orthopedic degeneration. Moreover, an increasing number of potential targets within the FGF signaling have been identified, such as FGF9, FGF18, and FGF23. However, it should be noted that most of these discoveries are still in the experimental stage, and further studies are needed before clinical application can be considered. Presently, this review aims to document the association between the FGF signaling pathway and the development and progression of orthopedic diseases. Besides, current therapeutic strategies targeting the FGF signaling pathway to prevent and treat orthopedic degeneration will be evaluated.

A Bionic Thermosensitive Sustainable Delivery System for Reversing the Progression of Osteoarthritis by Remodeling the Joint Homeostasis

Although the pathogenesis of osteoarthritis (OA) is unclear, inflammatory cytokines are related to its occurrence. However, few studies focused on the therapeutic strategies of regulating joint homeostasis by simultaneously remodeling the anti-inflammatory and immunomodulatory microenvironments. Fibroblast growth factor 18 (FGF18) is the only disease-modifying OA drug (DMOAD) with a potent ability and high efficiency in maintaining the phenotype of chondrocytes within cell culture models. However, its potential role in the immune microenvironment remains unknown. Besides, information on an optimal carrier, whose interface and chondral-biomimetic microenvironment mimic the native articular tissue, is still lacking, which substantially limits the clinical efficacy of FGF18. Herein, to simulate the cartilage matrix, chondroitin sulfate (ChS)-based nanoparticles (NPs) are integrated into poly(D, L-lactide)-poly(ethylene glycol)-poly(D, L-lactide) (PLEL) hydrogels to develop a bionic thermosensitive sustainable delivery system. Electrostatically self-assembled ChS and ε-poly-l-lysine (EPL) NPs are prepared for the bioencapsulation of FGF18. This bionic delivery system suppressed the inflammatory response in interleukin-1β (IL-1β)-mediated chondrocytes, promoted macrophage M2 polarization, and inhibited M1 polarization, thereby ameliorating cartilage degeneration and synovitis in OA. Thus, the ChS-based hydrogel system offers a potential strategy to regulate the chondrocyte-macrophage crosstalk, thus re-establishing the anti-inflammatory and immunomodulatory microenvironment for OA therapy.

Pharmacotherapy for osteoarthritis-related pain: current and emerging therapies

INTRODUCTION

Osteoarthritis (OA) related pain has affected millions of people worldwide. However, the current pharmacological options for managing OA-related pain have not achieved a satisfactory effect.

AREAS COVERED

This narrative review provides an overview of the current and emerging drugs for OA-related pain. It covers the drugs' mechanism of action, safety, efficacy, and limitations. The National Library of Medicine (PubMed) database was primarily searched from 2000 to 2024.

EXPERT OPINION

Current treatment options are limited and suboptimal for OA pain management. Topical nonsteroidal anti-inflammatory drugs (NSAIDs) are the recognized and first-line treatment in the management of OA-related pain, and other drugs are inconsistent recommendations by guidelines. Emerging treatment options are promising for OA-related pain, including nerve growth factor (NGF) inhibitors, ion channel inhibitors, and calcitonin gene-related peptide (CGRP) antagonists. Besides, drugs repurposing from antidepressants and antiepileptic analgesics are shedding light on the management of OA-related pain. The management of OA-related pain is challenging as pain is heterogeneous and subjective. A more comprehensive strategy combined with non-pharmacological therapy needs to be considered, and tailored management options to individualized patients.

Early cartilage lesion and 5-year incident joint surgery in knee osteoarthritis patients: a retrospective cohort study

OBJECTIVE

to investigate the association between cartilage lesion-related features observed in knee osteoarthritis (OA) patients' first MRI examination and incident knee surgery within 5 years. Additionally, to assess the predictive value of these features for the incident knee surgery.

METHODS

We identified patients diagnosed with knee OA and treated at our institution between January 2015 and January 2018, and retrieved their baseline clinical data and first MRI examination films from the information system. Next, we proceeded to determine joint space narrowing grade, cartilage lesion size grade, cartilage full-thickness loss grade and cartilage lesion sum score for the medial and lateral compartments, respectively. Generalized linear regression models examined the association of these features with 5-year incident knee surgery. Positive and negative predictive values (PPVs and NPVs) were determined referring to 5-year incident knee surgery.

RESULTS

Totally, 878 participants (knees) were found eligible to form the study population. Within the 5 years, surgery was performed on 61 knees. None of the cartilage-related features had been found significantly associated with incident surgery. The results were similar for medial and lateral compartments. The PPVs were low for all the features.

CONCLUSIONS

Among symptomatic clinically diagnosed OA knees, cartilage lesions observed in the first MRI examinations were not found to be associated with the occurrence of joint surgery within a 5-year period. All these cartilage-related features appear to have no additional value in predicting 5-year incident joint surgery.

The evolving landscape of gene therapy strategies for the treatment of osteoarthritis

OBJECTIVES

Significant advances have been made in our understanding of osteoarthritis (OA) pathogenesis; however, no disease-modifying therapies have been identified. This review will summarize the gene therapy landscape, its initial successes for OA, and possible challenges using recent studies and examples of gene therapies in clinical trials.

DESIGN

This narrative review has three major sections: 1) vector systems for OA gene therapy, 2) current and emerging targets for OA gene therapy, and 3) considerations and future directions.

RESULTS

Gene therapy is the strategy by which nucleic acids are delivered to treat and reverse disease progression. Specificity and prolonged expression of these nucleic acids are achieved by manipulating promoters, genes, and vector systems. Certain vector systems also allow for the development of combinatorial nucleic acid strategies that can be delivered in a single intraarticular injection - an approach likely required to treat the complexity of OA pathogenesis. Several viral and non-viral vector-based gene therapies are in clinical trials for OA, and many more are being evaluated in the preclinical arena.

CONCLUSIONS

In a post-coronavirus disease 2019 (COVID-19) era, the future of gene therapy for OA is certainly promising; however, the majority of preclinical validation continues to focus heavily on post-traumatic models and changes in only cartilage and subchondral bone. To ensure successful translation, new candidates in the preclinical arena should be examined against all joint tissues as well as pain using diverse models of injury-, obesity-, and age-induced disease. Lastly, consideration must be given to strategies for repeat administration and the cost of treatment owing to the chronic nature of OA.

30 Years of MRI-based cartilage & bone morphometry in knee osteoarthritis: From correlation to clinical trials

OBJECTIVE

The first publication on morphometric analysis of articular cartilage using magnetic resonance imaging (MRI) in 1994 set the scene for a game change in osteoarthritis (OA) research. The current review highlights milestones in cartilage and bone morphometry, summarizing the rapid progress made in imaging, its application to understanding joint (patho-)physiology, and its use in interventional clinical trials.

METHODS

Based on a Pubmed search of articles from 1994 to 2023, the authors subjectively selected representative work illustrating important steps in the development or application of magnetic resonance-based cartilage and bone morphometry, with a focus on studies in humans, and on the knee. Research on OA-pathophysiology is addressed only briefly, given length constraints. Compositional and semi-quantitative assessment are not covered here.

RESULTS

The selected articles are presented in historical order as well as by content. We review progress in the technical aspects of image acquisition, segmentation and analysis, advances in understanding tissue growth, physiology, function, and adaptation, and a selection of clinical trials examining the efficacy of interventions on knee cartilage and bone. A perspective is provided of how lessons learned may be applied to future research and clinical management.

CONCLUSIONS

Over the past 30 years, MRI-based morphometry of cartilage and bone has contributed to a paradigm shift in understanding articular tissue physiology and OA pathophysiology, and to the development of new treatment strategies. It is likely that these technologies will continue to play a key role in the development and (accelerated) approval of therapy, potentially targeted to different OA phenotypes.

Injectable Microgels with Hybrid Exosomes of Chondrocyte-Targeted FGF18 Gene-Editing and Self-Renewable Lubrication for Osteoarthritis Therapy

Abnormal silencing of fibroblast growth factor (FGF) signaling significantly contributes to joint dysplasia and osteoarthritis (OA); However, the clinical translation of FGF18-based protein drugs is hindered by their short half-life, low delivery efficiency and the need for repeated articular injections. This study proposes a CRISPR/Cas9-based approach to effectively activate the FGF18 gene of OA chondrocytes at the genome level in vivo, using chondrocyte-affinity peptide (CAP) incorporated hybrid exosomes (CAP/FGF18-hyEXO) loaded with an FGF18-targeted gene-editing tool. Furthermore, CAP/FGF18-hyEXO are encapsulated in methacrylic anhydride-modified hyaluronic (HAMA) hydrogel microspheres via microfluidics and photopolymerization to create an injectable microgel system (CAP/FGF18-hyEXO@HMs) with self-renewable hydration layers to provide persistent lubrication in response to frictional wear. Together, the injectable CAP/FGF18-hyEXO@HMs, combined with in vivo FGF18 gene editing and continuous lubrication, have demonstrated their capacity to synergistically promote cartilage regeneration, decrease inflammation, and prevent ECM degradation both in vitro and in vivo, holding great potential for clinical translation.

A perspective on the evolution of semi-quantitative MRI assessment of osteoarthritis: Past, present and future

OBJECTIVE

This perspective describes the evolution of semi-quantitative (SQ) magnetic resonance imaging (MRI) in characterizing structural tissue pathologies in osteoarthritis (OA) imaging research over the last 30 years.

METHODS

Authors selected representative articles from a PubMed search to illustrate key steps in SQ MRI development, validation, and application. Topics include main scoring systems, reading techniques, responsiveness, reliability, technical considerations, and potential impact of artificial intelligence (AI).

RESULTS

Based on original research published between 1993 and 2023, this article introduces available scoring systems, including but not limited to Whole-Organ Magnetic Resonance Imaging Score (WORMS) as the first system for whole-organ assessment of the knee and the now commonly used MRI Osteoarthritis Knee Score (MOAKS) instrument. Specific systems for distinct OA subtypes or applications have been developed as well as MRI scoring instruments for other joints such as the hip, the fingers or thumb base. SQ assessment has proven to be valid, reliable, and responsive, aiding OA investigators in understanding the natural history of the disease and helping to detect response to treatment. AI may aid phenotypic characterization in the future. SQ MRI assessment's role is increasing in eligibility and safety evaluation in knee OA clinical trials.

CONCLUSIONS

Evidence supports the validity, reliability, and responsiveness of SQ MRI assessment in understanding structural aspects of disease onset and progression. SQ scoring has helped explain associations between structural tissue damage and clinical manifestations, as well as disease progression. While AI may support human readers to more efficiently perform SQ assessment in the future, its current application in clinical trials still requires validation and regulatory approval.

Unmet need in rheumatology: reports from the Advances in Targeted Therapies meeting, 2023

The Advances in Targeted Therapies meets annually, convening experts in the field of rheumatology to both provide scientific updates and identify existing scientific gaps within the field. To review the major unmet scientific needs in rheumatology. The 23rd annual Advances in Targeted Therapies meeting convened with more than 100 international basic scientists and clinical researchers in rheumatology, immunology, infectious diseases, epidemiology, molecular biology and other specialties relating to all aspects of immune-mediated inflammatory diseases. We held breakout sessions in five rheumatological disease-specific groups including: rheumatoid arthritis (RA), psoriatic arthritis (PsA), axial spondyloarthritis (axSpa), systemic lupus erythematosus (SLE), systemic sclerosis (SSc) and vasculitis, and osteoarthritis (OA). In each group, experts were asked to identify and prioritise current unmet needs in clinical and translational research. An overarching theme across all disease states is the continued need for clinical trial design innovation with regard to therapeutics, endpoint and disease endotypes. Within RA, unmet needs comprise molecular classification of disease pathogenesis and activity, pre-/early RA strategies, more refined pain profiling and innovative trials designs to deliver on precision medicine. Continued scientific questions within PsA include evaluating the genetic, immunophenotypic, clinical signatures that predict development of PsA in patients with psoriasis, and the evaluation of combination therapies for difficult-to-treat disease. For axSpA, there continues to be the need to understand the role of interleukin-23 (IL-23) in pathogenesis and the genetic relationship of the IL-23-receptor polymorphism with other related systemic inflammatory diseases (eg, inflammatory bowel disease). A major unmet need in the OA field remains the need to develop the ability to reliably phenotype and stratify patients for inclusion in clinical trials. SLE experts identified a number of unmet needs within clinical trial design including the need for allowing endpoints that reflect pharmacodynamic/functional outcomes (eg, inhibition of type I interferon pathway activation; changes in urine biomarkers). Lastly, within SSc and vasculitis, there is a lack of biomarkers that predict response or disease progression, and that allow patients to be stratified for therapies. There remains a strong need to innovate clinical trial design, to identify systemic and tissue-level biomarkers that predict progression or response to therapy, endotype disease, and to continue developing therapies and therapeutic strategies for those with treatment-refractory disease. This document, based on expert consensus, should provide a roadmap for prioritising scientific endeavour in the field of rheumatology.

Chondrocyte membrane-coated nanoparticles promote drug retention and halt cartilage damage in rat and canine osteoarthritis

Osteoarthritis (OA) is a chronic joint disease characterized by progressive degeneration of articular cartilage. A challenge in the development of disease-modifying drugs is effective delivery to chondrocytes. The unique structure of the joint promotes rapid clearance of drugs through synovial fluid, and the dense and avascular cartilage extracellular matrix (ECM) limits drug penetration. Here, we show that poly(lactide-co-glycolic acid) nanoparticles coated in chondrocyte membranes (CM-NPs) were preferentially taken up by rat chondrocytes ex vivo compared with uncoated nanoparticles. Internalization of the CM-NPs was mediated primarily by E-cadherin, clathrin-mediated endocytosis, and micropinocytosis. These CM-NPs adhered to the cartilage ECM in rat knee joints in vivo and penetrated deeply into the cartilage matrix with a residence time of more than 34 days. Simulated synovial fluid clearance studies showed that CM-NPs loaded with a Wnt pathway inhibitor, adavivint (CM-NPs-Ada), delayed the catabolic metabolism of rat and human chondrocytes and cartilage explants under inflammatory conditions. In a surgical model of rat OA, drug-loaded CM-NPs effectively restored gait, attenuated periarticular bone remodeling, and provided chondroprotection against cartilage degeneration. OA progression was also mitigated by CM-NPs-Ada in a canine model of anterior cruciate ligament transection. These results demonstrate the feasibility of using chondrocyte membrane-coated nanoparticles to improve the pharmacokinetics and efficacy of anti-OA drugs.

A review of advanced hydrogels for cartilage tissue engineering

With the increase in weight and age of the population, the consumption of tobacco, inappropriate foods, and the reduction of sports activities in recent years, bone and joint diseases such as osteoarthritis (OA) have become more common in the world. From the past until now, various treatment strategies (e.g., microfracture treatment, Autologous Chondrocyte Implantation (ACI), and Mosaicplasty) have been investigated and studied for the prevention and treatment of this disease. However, these methods face problems such as being invasive, not fully repairing the tissue, and damaging the surrounding tissues. Tissue engineering, including cartilage tissue engineering, is one of the minimally invasive, innovative, and effective methods for the treatment and regeneration of damaged cartilage, which has attracted the attention of scientists in the fields of medicine and biomaterials engineering in the past several years. Hydrogels of different types with diverse properties have become desirable candidates for engineering and treating cartilage tissue. They can cover most of the shortcomings of other treatment methods and cause the least secondary damage to the patient. Besides using hydrogels as an ideal strategy, new drug delivery and treatment methods, such as targeted drug delivery and treatment through mechanical signaling, have been studied as interesting strategies. In this study, we review and discuss various types of hydrogels, biomaterials used for hydrogel manufacturing, cartilage-targeting drug delivery, and mechanosignaling as modern strategies for cartilage treatment.

Imaging Biomarkers of Osteoarthritis

Currently no disease-modifying osteoarthritis drug has been approved for the treatment of osteoarthritis (OA) that can reverse, hold, or slow the progression of structural damage of OA-affected joints. The reasons for failure are manifold and include the heterogeneity of structural disease of the OA joint at trial inclusion, and the sensitivity of biomarkers used to measure a potential treatment effect.This article discusses the role and potential of different imaging biomarkers in OA research. We review the current role of radiography, as well as advances in quantitative three-dimensional morphological cartilage assessment and semiquantitative whole-organ assessment of OA. Although magnetic resonance imaging has evolved as the leading imaging method in OA research, recent developments in computed tomography are also discussed briefly. Finally, we address the experience from the Foundation for the National Institutes of Health Biomarker Consortium biomarker qualification study and the future role of artificial intelligence.

From biochemical markers to molecular endotypes of osteoarthritis: a review on validated biomarkers

INTRODUCTION

Osteoarthritis (OA) affects over 500 million people worldwide. OA patients are symptomatically treated, and current therapies exhibit marginal efficacy and frequently carry safety-risks associated with chronic use. No disease-modifying therapies have been approved to date leaving surgical joint replacement as a last resort. To enable effective patient care and successful drug development there is an urgent need to uncover the pathobiological drivers of OA and how these translate into disease endotypes. Endotypes provide a more precise and mechanistic definition of disease subgroups than observable phenotypes, and a panel of tissue- and pathology-specific biochemical markers may uncover treatable endotypes of OA.

AREAS COVERED

We have searched PubMed for full-text articles written in English to provide an in-depth narrative review of a panel of validated biochemical markers utilized for endotyping of OA and their association to key OA pathologies.

EXPERT OPINION

As utilized in IMI-APPROACH and validated in OAI-FNIH, a panel of biochemical markers may uncover disease subgroups and facilitate the enrichment of treatable molecular endotypes for recruitment in therapeutic clinical trials. Understanding the link between biochemical markers and patient-reported outcomes and treatable endotypes that may respond to given therapies will pave the way for new drug development in OA.