Biomarkers for identifying the early phases of osteoarthritis secondary to medial patellar luxation in dogs

Exploring the Potential of Non-Cellular Orthobiologic Products in Regenerative Therapies for Stifle Joint Diseases in Companion Animals

Stifle joint diseases present a significant challenge in companion animals that often lead to hind limb lameness, with osteoarthritis being a prevalent degenerative condition causing pain and reduced mobility. Regenerative medicine offers a promising avenue for improving treatment outcomes, with a range of emerging therapies showing potential to alleviate symptoms and promote joint health. Among these, hyaluronic acid and platelet-rich plasma have been widely used as intra-articular treatments to enhance joint lubrication, reduce inflammation, and provide symptomatic relief. Interleukin-1 receptor antagonist protein, autologous conditioned serum, and autologous protein solution represent the next generation of regenerative therapies, offering more disease-modifying effects by inhibiting key mediators of joint inflammation. More recently, the MSC-derived secretome has emerged as an innovative, cell-free approach that leverages the diverse bioactive factors secreted by MSCs to support tissue repair and modulate inflammation. This review highlights the evidence base behind these non-cellular orthobiologic treatments for stifle joint disease, aiming to inform veterinary practitioners and owners about available options and their efficacy in supporting conventional treatments.

Outcome of surgical correction of medial patellar luxation in dogs weighing less than 10 kg

BACKGROUND

Various trochleoplasty techniques, including trochlear wedge recession (TWR) and trochlear block recession (TBR), are used to treat dogs with medial patellar luxation (MPL). However, the objective outcomes of these surgical procedures are underreported.

METHODS

Medical records were obtained for dogs weighing less than 10 kg that underwent either TWR or TBR and tibial tuberosity transposition to address grade I-III MPL. Long-term (at least 1 year after the last procedure) follow-up included orthopaedic and radiographic examinations, such as osteoarthritis score (OAS), ground reaction force (GRF) analysis and canine brief pain inventory (CBPI).

RESULTS

Overall, 20 dogs (26 stifles) were followed up in the long term. Minor postoperative complications, medial patellar reluxation (MPR) and intermittent lameness occurred in 46.15%, 19.23% and 15% of the dogs, respectively. MPR occurred only in TWR-treated stifles, while mean OAS increased in all groups. Using the CBPI, the owners perceived an excellent or very good outcome in 95% of dogs.

LIMITATIONS

The limitations of the study include its retrospective observational nature, a lack of randomisation and a small sample size.

CONCLUSION

Surgical treatment resulted in a favourable outcome. GRF analysis could detect subtle differences in weight bearing in dogs treated for MPL, which might not be apparent clinically. There might be a higher risk for reluxation for TWR. However, a larger-scale prospective study would be required to find which treatment is superior.

Secreted Factors and Extracellular Vesicles Account for the Immunomodulatory and Tissue Regenerative Properties of Bone-Marrow-Derived Mesenchymal Stromal Cells for Osteoarthritis

Bone-marrow-derived mesenchymal stromal cells (BMSCs) showed therapeutic potential in the treatment of musculoskeletal diseases, including osteoarthritis (OA). Their soluble mediators and extracellular vesicles (EVs), which make up the secretome, suppress immune response, attenuate inflammation and promote cartilage repair. EVs, as well as the whole secretome, have been investigated as cell free approaches for OA although, to date, a disease-tailored molecular fingerprint is missing. In this study, soluble mediators and miRNAs were sifted in the BMSCs' secretome and EVs, respectively, and analyzed in the frame of cell types and factors involved in OA. The majority of identified molecules repress the activation of immune cells and the production of OA-related inflammatory mediators, as well as promote cartilage protection by acting on both chondrocytes homeostasis and extracellular matrix-degrading enzymes. These data provide the molecular ground for the therapeutic potential of BMSCs for regenerative applications for OA and support the use of secretome or EVs as cell-free applications in joint diseases.

RNA-seq based integrative analysis of potential crucial genes and pathways associated with patellar instability

Patellar instability (PI) is a common knee injury in adolescents, but the crucial biomarkers and molecular mechanisms associated with it remain unclear. We established a PI mouse model and investigated PI-related changes in gene expression by RNA sequencing (RNA-seq). Differentially expressed gene (DEG) analysis and enrichment analysis were performed to identify crucial genes and pathways associated with PI. Subsequently, a protein-protein interaction, DEG-miRNA, DEG-transcription factors, and DEG-drug interaction networks were constructed to reveal hub genes, molecular mechanism, and potential drugs for PI. Finally, the reliability of the sequencing results was confirmed by real-time quantitative polymerase chain reaction (RT-qPCR) and immunohistochemistry. Upon comparison with the control group, 69 genes were differently expressed in PI, including 17 upregulated and 52 downregulated ones. The DEGs were significantly enriched in Janus kinase (JAK)/signal transducer and activator of transcription (STAT) signaling pathway and immune responses. The protein–protein interaction network identified ten PI-related hub genes, all of which are involved in the JAK/STAT signaling pathway or inflammation-related pathways. DEG-miRNA and DEG-transcription factor networks offered new insights for regulating DEGs post-transcriptionally. We also determined potential therapeutic drugs or molecular compounds that could restore dysregulated expression of DEGs via the DGIdb database. RT-qPCR results were consistent with the RNA-seq, confirming the reliability of the sequencing data. Immunohistochemistry results suggested that JAK1 and STAT3 expression was increased in PI. Our study explored the potential molecular mechanisms in PI, provided promising biomarkers and suggested a molecular basis for therapeutic targets for this condition.

Evidence of acrolein in synovial fluid of dogs with osteoarthritis as a potential inflammatory biomarker

BACKGROUND

Acrolein is a known pro-inflammatory toxic aldehyde, propagating cellular damage and tissue inflammation in humans and animal models of various diseases. Osteoarthritis (OA) has a significant inflammatory component; however, presence of acrolein in synovial fluid of joints with OA has not been previously reported. The first aim of this study was to evaluate evidence of acrolein in the synovial fluid of dogs with OA as well as in Control joints. The second aim was to determine if evidence of acrolein can be detected in synovial fluid samples that have been in a frozen state for long periods of time.

METHODS

In this pilot clinical study, synovial fluid samples were prospectively collected (i.e., New samples) from a single joint of both clinically healthy (New Control, n = 5) and dogs with OA (New OA, n = 16) and frozen until the time of analysis. Additionally, frozen synovial fluid samples from a biobank (i.e., Old samples) were used to evaluate ability to detect evidence of acrolein in long-term stored samples (median of 4.89 years) in Old Control (n = 5) and Old OA (n = 5) samples. Measurements of acrolein in all synovial fluid samples was based on detection of its major protein adduct, N ε - (3-formyl-3, 4-dehydropiperidino)lysine (FDP-lysine), using the western blot method. Synovial fluid matrix metalloproteinase 2 (MMP2) was measured in all samples using the western blot method as a positive control of OA inflammation.

RESULTS

Acrolein-lysine adduct was detected in both Control (n = 10) and OA (n = 21) groups in both Old and New samples. Acrolein-lysine adduct and MMP2 were detectable at a lower level in the Old compared to New synovial fluid samples; however, the differences were not statistically significant (p > 0.1). The measured MMP2 levels were significantly higher in the OA compared to Control group samples (p = 0.033), but not for acrolein-lysine adduct (p = 0.30).

CONCLUSIONS

This study confirmed evidence of acrolein in canine synovial fluid of both OA and Control groups. Freezing of synovial fluid for up to 5 years does not appear to significantly affect the ability to detect acrolein-lysine adduct and MMP2 in these samples.

Cartilage Protective and Immunomodulatory Features of Osteoarthritis Synovial Fluid-Treated Adipose-Derived Mesenchymal Stem Cells Secreted Factors and Extracellular Vesicles-Embedded miRNAs

Intra-articular administration of adipose-derived mesenchymal stem cells (ASCs), either in vitro expanded or within adipose tissue-based products obtained at point-of-care, has gained popularity as innovative regenerative medicine approach for osteoarthritis (OA) treatment. ASCs can stimulate tissue repair and immunomodulation through paracrine factors, both soluble and extracellular vesicles (EV) embedded, collectively defining the secretome. Interaction with the degenerative/inflamed environment is a crucial factor in understanding the finely tuned molecular message but, to date, the majority of reports have described ASC-secretome features in resting conditions or under chemical stimuli far from the in vivo environment of degenerated OA joints. In this report, the secretory profile of ASCs treated with native synovial fluid from OA patients was evaluated, sifting 200 soluble factors and 754 EV-embedded miRNAs. Fifty-eight factors and 223 EV-miRNAs were identified, and discussed in the frame of cartilage and immune cell homeostasis. Bioinformatics gave a molecular basis for M2 macrophage polarization, T cell proliferation inhibition and T reg expansion enhancement, as well as cartilage protection, further confirmed in an in vitro model of OA chondrocytes. Moreover, a strong influence on immune cell chemotaxis emerged. In conclusion, obtained molecular data support the regenerative and immunomodulatory properties of ASCs when interacting with osteoarthritic joint environment.

Amniotic membrane-mesenchymal stromal cells secreted factors and extracellular vesicle-miRNAs: Anti-inflammatory and regenerative features for musculoskeletal tissues

Human amniotic membrane‐derived mesenchymal stromal cells (hAMSCs) are easily obtained in large quantities and free from ethical concerns. Promising therapeutic results for both hAMSCs and their secreted factors (secretome) were described by several in vitro and preclinical studies, often for treatment of orthopedic disorders such as osteoarthritis (OA) and tendinopathy. For clinical translation of the hAMSC secretome as cell‐free therapy, a detailed characterization of hAMSC‐secreted factors is mandatory. Herein, we tested the presence of 200 secreted factors and 754 miRNAs in extracellular vesicles (EVs). Thirty‐seven cytokines/chemokines were identified at varying abundance, some of which involved in both chemotaxis and homeostasis of inflammatory cells and in positive remodeling of extracellular matrix, often damaged in tendinopathy and OA. We also found 336 EV‐miRNAs, 51 of which accounted for more than 95% of the genetic message. A focused analysis based on miRNAs related to OA and tendinopathy showed that most abundant EV‐miRNAs are teno‐ and chondro‐protective, able to induce M2 macrophage polarization, inhibit inflammatory T cells, and promote Treg. Functional analysis on IL‐1β treated tenocytes and chondrocytes resulted in downregulation of inflammation‐associated genes. Overall, presence of key regulatory molecules and miRNAs explain the promising therapeutic results of hAMSCs and their secretome for treatment of musculoskeletal conditions and are a groundwork for similar studies in other pathologies. Furthermore, identified molecules will pave the way for future studies aimed at more sharply predicting disease‐targeted clinical efficacy, as well as setting up potency and release assays to fingerprint clinical‐grade batches of whole secretome or purified components.

Emerging Technologies and Platforms for the Immunodetection of Multiple Biochemical Markers in Osteoarthritis Research and Therapy

Biomarkers, especially biochemical markers, are important in osteoarthritis (OA) research, clinical trials, and drug development and have potential for more extensive use in therapeutic monitoring. However, they have not yet had any significant impact on disease diagnosis and follow-up in a clinical context. Nevertheless, the development of immunoassays for the detection and measurement of biochemical markers in OA research and therapy is an active area of research and development. The evaluation of biochemical markers representing low-grade inflammation or extracellular matrix turnover may permit OA prognosis and expedite the development of personalized treatment tailored to fit particular disease severities. However, currently detection methods have failed to overcome specific hurdles such as low biochemical marker concentrations, patient-specific variation, and limited utility of single biochemical markers for definitive characterization of disease status. These challenges require new and innovative approaches for development of detection and quantification systems that incorporate clinically relevant biochemical marker panels. Emerging platforms and technologies that are already on the way to implementation in routine diagnostics and monitoring of other diseases could potentially serve as good technological and strategic examples for better assessment of OA. State-of-the-art technologies such as advanced multiplex assays, enhanced immunoassays, and biosensors ensure simultaneous screening of a range of biochemical marker targets, the expansion of detection limits, low costs, and rapid analysis. This paper explores the implementation of such technologies in OA research and therapy. Application of novel immunoassay-based technologies may shed light on poorly understood mechanisms in disease pathogenesis and lead to the development of clinically relevant biochemical marker panels. More sensitive and specific biochemical marker immunodetection will complement imaging biomarkers and ensure evidence-based comparisons of intervention efficacy. We discuss the challenges hindering the development, testing, and implementation of new OA biochemical marker assays utilizing emerging multiplexing technologies and biosensors.

Secreted Factors and EV-miRNAs Orchestrate the Healing Capacity of Adipose Mesenchymal Stem Cells for the Treatment of Knee Osteoarthritis

Mesenchymal stem cells (MSCs) derived from adipose tissue and used either as expanded cells or minimally manipulated cell preparations showed positive clinical outcomes in regenerative medicine approaches based on tissue restoration and inflammation control, like in osteoarthritis (OA). Recently, MSCs’ healing capacity has been ascribed to the large array of soluble factors, including soluble cytokines/chemokines and miRNAs conveyed within extracellular vesicles (EVs). Therefore, in this study, 200 secreted cytokines, chemokines and growth factors via ELISA, together with EV-embedded miRNAs via high-throughput techniques, were scored in adipose-derived MSCs (ASCs) cultivated under inflammatory conditions, mimicking OA synovial fluid. Both factors (through most abundantly expressed TIMP1, TIMP2, PLG and CTSS) and miRNAs (miR-24-3p, miR-222-3p and miR-193b-3p) suggested a strong capacity for ASCs to reduce matrix degradation activities, as those activated in OA cartilage, and switch synovial macrophages, often characterized by an M1 inflammatory polarization, towards an M2 phenotype. Moreover, the crucial importance of selecting the target tissue is discussed, showing how a focused search may greatly improve potency prediction and explain clinical outcomes. In conclusion, herein presented data shed light about the way ASCs regulate cell homeostasis and regenerative pathways in an OA-resembling environment, therefore suggesting a rationale for the use of MSC-enriched clinical products, such as stromal vascular fraction and microfragmented adipose tissue, in joint pathologies.

Kartogenin inhibits pain behavior, chondrocyte inflammation, and attenuates osteoarthritis progression in mice through induction of IL-10

Osteoarthritis (OA) is a major degenerative joint condition that causes articular cartilage destruction. It was recently found that enhancement of chondroclasts and suppression in Treg cell differentiation are involved in the pathogenesis of OA. Kartogenin (KGN) is a small drug-like molecule that induces chondrogenesis in mesenchymal stem cells (MSCs). This study aimed to identify whether KGN can enhance severe pain behavior and improve cartilage repair in OA rat model. Induction of OA model was loaded by IA-injection of MIA. In the OA rat model, treatment an intra-articular injection of KGN. Pain levels were evaluated by analyzing PWL and PWT response in animals. Histological analysis and micro-CT images of femurs were used to analyze cartilage destruction. Gene expression was measured by real-time PCR. Immunohistochemistry was analyzed to detect protein expression. KGN injection significantly decreased pain severity and joint destruction in the MIA-induced OA model. KGN also increased mRNA levels of the anti-inflammatory cytokine IL-10 in OA patients’ chondrocytes stimulated by IL-1β. Decreased chondroclast expression, and increased Treg cell expression. KGN revealed therapeutic activity with the potential to reduce pain and improve cartilage destruction. Thus, KGN could be a therapeutic molecule for OA that inhibits cartilage damage.

Review of Soluble Biomarkers of Osteoarthritis: Lessons From Animal Models

Objective Osteoarthritis (OA) is one of the leading causes of disability within the adult population. Currently, its diagnosis is mainly based on clinical examination and standard radiography. To date, there is no way to detect the disease at a molecular level, before the appearance of structural changes and symptoms. So an attractive alternative for monitoring OA is the measurement of biochemical markers in blood, urine, or synovial fluid, which could reflect metabolic changes in joint tissue and therefore disease onset and progression. Animal models are relevant to investigate the early stage of OA and metabolic changes occurring in joint tissues. The goal of this narrative review is to summarize the scientific data available in the literature on soluble biomarkers in animal models of OA. Design A literature search was conducted using the PubMed/Medline and Scopus databases between February 1995 and December 2015. All original articles, systematic and narrative reviews published in French or in English were considered. Results We summarized the data of 69 studies and proposed a classification scheme for OA biomarkers in animal studies, largely inspired by the BIPEDS classification. Conclusions Studies about biomarkers and animal models indicate that some markers could be valuable to monitor OA progression and assess therapeutic response in some animal models.

Transient expression of the diseased phenotype of osteoarthritic chondrocytes in engineered cartilage

Due to the degradation of osteoarthritic (OA) cartilage in post-traumatic OA (PTOA), these tissues are challenging to study and manipulate in vitro. In this study, chondrocytes isolated from either PTOA (meniscal-release (MR) model) or normal (contralateral limb) cartilage of canine knee joints were used to form micropellets to assess the maintenance of the OA chondrocyte phenotype in vitro. Media samples from the micropellet cultures were used to measure matrix metalloproteinase (MMP), chemokine, and cytokine concentrations. Significant differences in matrix synthesis were observed as a function of disease with OA chondrocytes generally synthesizing more extracellular matrix with increasing time in culture. No donor dependent differences were detected. Luminex multiplex analysis of pellet culture media showed disease and time-dependent differences in interleukin (IL)-8, keratinocyte chemoattractant (KC)-like protein, MMP-1, MMP-2, and MMP-3, which are differentially expressed in OA. This memory of their diseased phenotype persists for the first 2 weeks of culture. These results demonstrate the potential to use chondrocytes from an animal model of OA to study phenotype alterations during the progression and treatment of OA. © 2016 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 35:829-836, 2017.

Animal models of osteoarthritis: classification, update, and measurement of outcomes

Osteoarthritis (OA) is one of the most commonly occurring forms of arthritis in the world today. It is a debilitating chronic illness causing pain and immense discomfort to the affected individual. Significant research is currently ongoing to understand its pathophysiology and develop successful treatment regimens based on this knowledge. Animal models have played a key role in achieving this goal. Animal models currently used to study osteoarthritis can be classified based on the etiology under investigation, primary osteoarthritis, and post-traumatic osteoarthritis, to better clarify the relationship between these models and the pathogenesis of the disease. Non-invasive animal models have shown significant promise in understanding early osteoarthritic changes. Imaging modalities play a pivotal role in understanding the pathogenesis of OA and the correlation with pain. These imaging studies would also allow in vivo surveillance of the disease as a function of time in the animal model. This review summarizes the current understanding of the disease pathogenesis, invasive and non-invasive animal models, imaging modalities, and pain assessment techniques in the animals.

Mechanotransduction pathways in bone pathobiology

The skeleton is subject to dynamic changes throughout life and bone remodeling is essential for maintenance of bone functionality. The cell populations which predominantly participate in bone and cartilage remodeling, namely osteocytes, osteoblasts, osteoclasts and chondrocytes sense and respond to external mechanical signals and via a series of molecular cascades control bone metabolism and turnover rate. The aforementioned process, known as mechanotransduction, is the underlying mechanism that controls bone homeostasis and function. A wide array of cross-talking signaling pathways has been found to play an important role in the preservation of bone and cartilage tissue health. Moreover, alterations in bone mechanotransduction pathways, due to genetic, hormonal and biomechanical factors, are considered responsible for the pathogenesis of bone and cartilage diseases. Extensive research has been conducted and demonstrated that aberrations in mechanotransduction pathways result in disease-like effects, however only few signaling pathways have actually been engaged in the development of bone disease. The aim of the present review is to present these signaling molecules and cascades that have been found to be mechano-responsive and implicated in bone disease development, as revealed by research in the last five years. In addition, the role of these molecules as prognostic or diagnostic disease markers and their potential as therapeutic targets are also discussed.

Chondroprotective potential of Phyllanthus amarus Schum. & Thonn. in experimentally induced cartilage degradation in the explants culture model

Phyllanthus amarus Schum. & Thonn. (P. amarus) has been reported to exhibit anti-inflammation and antiarthritis properties leading to our interest to examine its beneficial effect in osteoarthritis. Thus, this study aimed to explore the chondroprotective potential of P. amarus extract (PAE) and its major compounds, phyllanthin and hypophyllanthin, in a cartilage explant model. Various concentrations of P. amarus extract, phyllanthin and hypophyllanthin, were treated on porcine articular cartilage explants induced with 25 ng/ml of interleukin-1 beta (IL-1β). After 4 days of incubation, the culture medium was measured for the release of sulfate glycosaminoglycans (s-GAGs) and matrix metalloproteinase-2 (MMP-2) activity by DMMB binding assay and zymography, respectively. The explant tissues were analyzed for the remaining of uronic acid content by colorimetric assay and stained with safranin-O for investigation of proteoglycan content. Cell viability of this model was evaluated by lactate dehydrogenase (LDH) assay. Chondroprotective potential of PAE and the major components against IL-1β-induced cartilage explant degradation were revealed by the decreased s-GAGs level and MMP-2 activity in culture medium consistent with an increase in uronic acid and proteoglycan contents in the explants when compared to the IL-1β treatment. These results agreed with those of diacerein and sesamin which used as positive controls. In addition, better chondroprotective activities of P. amarus crude extracts than those of the purified components were disclosed in this study. Hence, this is a pioneering study presenting the chondroprotective potential of PAE which may augment its application for therapeutic use as an antiarthritic agent.

Diverse expression of selected cytokines and proteinases in synovial fluid obtained from osteoarthritic and healthy human knee joints

Background

Osteoarthritis (OA) is defined by signs and symptoms of inflammation within the affected joint. The aim of this study is to determine the mRNA expression levels of selected cytokines and matrix-metalloproteinases of cells found in synovial fluid (SF) obtained from osteoarthritic knee joints compared to healthy controls.

Methods

SF was obtained from 40 patients undergoing total knee arthroplasty due to evident OA and from 10 healthy controls. Expression of TNF-α, IL-1β, MMP-1 and MMP-3 was assayed among both groups by performing qPCR. Patients were configured concerning age, gender and BMI.

Results

IL-1β, MMP-1 and MMP-3 showed significantly higher expression among the OA group compared to control (P < 0.001). Strong correlation appeared between expression of MMP-1 and MMP-3 among OA patients (r = 0.856); no correlation was found between age, gender or BMI and cytokine/proteinase expression. Expression of IL-1β, MMP-1 and MMP-3 within SF was elevated in OA-patients.

Conclusion

Consequently, cells within SF expressing cytokines and proteinases may play a relevant role in the progression of joint destruction. Considering the fact that SF in an OA joint comprises abnormal amounts of detrimental bioactive proteins, temporary clearance, dilution or suppression/modulation by means of lavage or disease-modifying medication may be promising to constitute interim relief or even postpone disease progression due to decreased inflammatory and/or degrading activity within the articular environment.