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

Supramolecular 3 in 1: A Lubrication and Co-Delivery System for Synergistic Advanced Osteoarthritis Therapy

The complexity, heterogeneity, and drug resistance of diseases necessitate a shift in therapeutic paradigms from monotherapy to combination therapy, which could augment treatment efficiency. Effective treatment of advanced osteoarthritis (OA) requires addressing three key factors contributing to its deterioration: chronic joint inflammation, lubrication dysfunction, and cartilage-tissue degradation. Herein, we present a supramolecular nanomedicine of multifunctionality via molecular recognition and self-assembly. The employed macrocyclic carrier, zwitterion-modified cavitand (CV-2), not only accurately loads various drugs but also functions as a therapeutic agent with lubricating properties for the treatment of OA. Kartogenin (KGN), a drug for articular cartilage regeneration and protection, and flurbiprofen (FP), an anti-inflammatory agent, were coloaded onto CV-2 assembly, forming a supramolecular nanomedicine KGN&FP@CV-2. The three-in-one combination therapy of KGN&FP@CV-2 addresses the three pathological features for treating OA collectively, and thus provides long-term therapeutic benefits for OA through sustained drug release and intrinsic lubrication in vivo. The multifunctional integration of macrocyclic delivery and therapeutics provides a simple, flexible, and universal platform for the synergistic treatment of diseases involving multiple drugs.

Kartogenin delivery systems for biomedical therapeutics and regenerative medicine

Kartogenin, a small and heterocyclic molecule, has emerged as a promising therapeutic agent for incorporation into biomaterials, owing to its unique physicochemical and biological properties. It holds potential for the regeneration of cartilage-related tissues in various common conditions and injuries. Achieving sustained release of kartogenin through appropriate formulation and efficient delivery systems is crucial for modulating cell behavior and tissue function. This review provides an overview of cutting-edge kartogenin-functionalized biomaterials, with a primarily focus on their design, structure, functions, and applications in regenerative medicine. Initially, we discuss the physicochemical properties and biological functions of kartogenin, summarizing the underlying molecular mechanisms. Subsequently, we delve into recent advancements in nanoscale and macroscopic materials for the carriage and delivery of kartogenin. Lastly, we address the opportunities and challenges presented by current biomaterial developments and explore the prospects for their application in tissue regeneration. We aim to enhance the generation of insightful ideas for the development of kartogenin delivery materials in the field of biomedical therapeutics and regenerative medicine by providing a comprehensive understanding of common preparation methods.

Targeting multiple disease hallmarks using a synergistic disease-modifying drug combination ameliorates osteoarthritis via inhibition of senescence and inflammation

AIMS

Osteoarthritis (OA), is a debilitating disease characterized by progressive cartilage degradation, synovial inflammation, and chondrocyte senescence. Various treatment agents independently targeting these hallmarks have been investigated. However, due to the complex multifaceted nature of OA, no disease-modifying osteoarthritis drugs are clinically available. In an attempt to overcome this, we developed a combinatorial approach and demonstrated the efficacy of TsC [Tissue inhibitor of metalloproteinase-3 (TIMP3) + sulfated carboxymethylcellulose (sCMC)] and piperlongumine (PL) combination for the amelioration of OA in a goat ex vivo OA model.

MAIN METHODS

The efficacy of the drug combination was evaluated using the goat ex vivo OA explant model and results were validated in clinically relevant human OA cartilage explants. The chondroprotective effects were evaluated in terms of reduced inflammation and cartilage matrix loss, reduction in chondrosenescence, and reduced oxidative stress.

KEY FINDINGS

A combination of TsC and PL (TsC-PL) significantly reduced inflammation, cartilage matrix loss, chondrosenescence, and oxidative stress in the goat ex vivo OA model and showed chondroprotective effects. Further, similar chondroprotective effects were observed in human OA cartilage. Additionally, the coefficient of drug interaction analysis indicated that the combination of TsC and PL had a synergistic effect in reducing matrix degrading proteases and inflammation (goat ex vivo OA model) and Reactive oxygen species (ROS) production (human OA cartilage).

SIGNIFICANCE

Combinatorial treatment with TsC and PL demonstrated potential disease-modifying effects for the treatment of osteoarthritis via inhibition of inflammation and senescence and supports the usage of treatment strategies targeting multiple pathological factors of OA simultaneously.

Hydrogel-Loaded Exosomes: A Promising Therapeutic Strategy for Musculoskeletal Disorders

Clinical treatment strategies for musculoskeletal disorders have been a hot research topic. Accumulating evidence suggests that hydrogels loaded with MSC-derived EVs show great potential in improving musculoskeletal injuries. The ideal hydrogels should be capable of promoting the development of new tissues and simulating the characteristics of target tissues, with the properties matching the cell-matrix constituents of autologous tissues. Although there have been numerous reports of hydrogels loaded with MSC-derived EVs for the repair of musculoskeletal injuries, such as intervertebral disc injury, tendinopathy, bone fractures, and cartilage injuries, there are still many hurdles to overcome before the clinical application of modified hydrogels. In this review, we focus on the advantages of the isolation technique of EVs in combination with different types of hydrogels. In this context, the efficacy of hydrogels loaded with MSC-derived EVs in different musculoskeletal injuries is discussed in detail to provide a reference for the future application of hydrogels loaded with MSC-derived EVs in the clinical treatment of musculoskeletal injuries.

Applications of Silk Fibroin in Human and Veterinary Medicine

The properties of silk make it a promising material for medical applications, both in human and veterinary medicine. Its predominant amino acids, glycine and alanine, exhibit low chemical reactivity, reducing the risk of graft rejection, a notable advantage over most synthetic polymers. Hence, silk is increasingly used as a material for 3D printing in biomedicine. It can be used to build cell scaffolding with the desired cytocompatibility and biodegradability. In combination with gelatine, silk can be used in the treatment of arthritis, and as a hydrogel, to regenerate chondrocytes and mesenchymal cells. When combined with gelatine and collagen, it can also make skin grafts and regenerate the integumentary system. In the treatment of bone tissue, it can be used in combination with polylactic acid and hydroxyapatite to produce bone clips having good mechanical properties and high immunological tolerance. Furthermore, silk can provide a good microenvironment for the proliferation of bone marrow stem cells. Moreover, research is underway to produce artificial blood vessels using silk in combination with glycidyl methacrylate. Silk vascular grafts have demonstrated a high degree of patency and a satisfactory degree of endothelial cells coverage.

Undenatured type II collagen and its role in improving osteoarthritis

Osteoarthritis (OA) is a degenerative joint disease, affecting 32.5 million US adults or 242 million people worldwide. There is no cure for OA. Many animal and clinical trials showed that oral administration of undenatured type II collagen could significantly reduce the incidence of OA or alleviate the symptoms of articular cartilage. Type II collagen is an important component of cartilage matrix. This article reviewed research progress of undenatured type II collagen including its methods of extraction and preparation, structure and characterization, solubility, thermal stability, gastrointestinal digestive stability, its role in improving OA, and the mechanism of its action in improving OA. Type II collagen has been extensively explored for its potential in improving arthritis. Methods of extraction of type II collagen are inefficient and tedious. The method of limited enzymatic hydrolysis is mainly used to prepare soluble undenatured type II collagen (SC II). The solubility, thermal and gastrointestinal digestive stability of SC II are affected by the sources of raw material, pH, salt ions, and temperature. Oral administration of undenatured type II collagen improves OA, whereas its activity is affected by the sources, degree of denaturalization, intervention methods and doses. However, the influence of the structure of undenatured type II collagen on its activity and the mechanism are unclear. The findings in this review support that undenatured type II collagen can be used in the intervention or auxiliary intervention of patients with OA.

Potential Joint Protective and Anti-Inflammatory Effects of Integrin αvβ3 in IL-1β-Treated Chondrocytes Cells

In osteoarthritis (OA), the articular cartilage covering the articular surface of the bone wears out, exposing the subchondral bone, and the synovial membrane surrounding the joint becomes inflamed, causing pain and deformity. OA causes pain, stiffness, and swelling, and discomfort in the knee when climbing stairs is a typical symptom. Although drug development studies are conducted to treat these inflammatory joint diseases, it is difficult to find conclusive research results which could reduce inflammation and slow cartilage tear. The development of drugs to relieve inflammatory pain often utilizes inflammatory triggers. Interleukins, one of the proteins in the limelight as pro-inflammatory factors, are immune-system-stimulating factors that promote the body's fight against harmful factors such as bacteria. In this study, inflammation was induced in Chondrocytes cells (Chon-001 cells) with IL-1β and then treated with integrin αvβ3 to show anti-inflammatory and chondrogenesis effects. Integrin αvβ3 was not toxic to Chon-001 cells in any concentration groups treated with or without IL-1β. COX-2 and iNOS, which are major markers of inflammation, were significantly reduced by integrin αvβ3 treatment. Expressions of p-ERK, p-JNK, and p-p38 corresponding to the MAPKs signaling pathway and p-IκBα and p-p65 corresponding to the NF-κB signaling pathway were also decreased in a dose-dependent manner upon integrin αvβ3 treatment, indicating that inflammation was inhibited, whereas treatment with integrin αvβ3 significantly increased the expression of ALP, RUNX2, BMP2, BMP4, Aggrecan, SOX9, and COL2A1, suggesting that osteogenesis and chondrogenesis were induced. These results suggest that integrin αvβ3 in-duces an anti-inflammatory effect, osteogenesis, and chondrogenesis on IL-1β-induced Chon-001 cells.

Kartogenin potentially protects temporomandibular joints from collagenase-induced osteoarthritis via core binding factor β and runt-related transcription factor 1 binding - A rat model study

Background/purpose

Temporomandibular joint (TMJ) osteoarthritis (TMJOA) is a chronic disease with progressive destruction of articular cartilage. This study aimed to explore the therapeutic effects of kartogenin on TMJOA via promoting the binding of core binding factor β (CBFβ) and runt-related transcription factor 1 (RUNX1).

Materials and methods

Type II collagenase was injected into 35 8-week-old male Sprague Dawley rat TMJs to establish the TMJOA model. Kartogenin, or the CBFβ-RUNX1 complex inhibitor (Ro5-3335), was also delivered via intra-articular injection. Subchondral bone was analyzed by MicroCT. The hematoxylin-eosin, Safranin O, and toluidine blue O staining were used to observe histopathology. Immunohistochemical staining of proliferating cell nuclear antigen (PCNA), caspase-3 (CASP3), interleukin-1β (IL-1β), and collagen II (COL2) was performed.

Results

TMJOA was established in rats by intra-articular injection of type II collagenase. The condylar cartilage and subchondral bone were damaged, with decreased PCNA and COL2 and increased CASP3 and IL-1 (P < .001). Compared with the OA group, kartogenin alleviated the destruction of cartilage and subchondral bone, rescued the expression of PCNA and COL2, and decreased the expression of CASP3 and IL-1β (P < .01). Ro5-3335 did not aggravate the pathology of TMJOA but neutralized the therapeutic effects of kartogenin on TMJOA.

Conclusion

Kartogenin has a potential therapeutic effect on TMJOA via promoting the CBFβ-RUNX1 binding.

Kartogenin-enhanced dynamic hydrogel ameliorates intervertebral disc degeneration via restoration of local redox homeostasis

INTRODUCTION

Over-activation of oxidative stress due to impaired antioxidant functions in nucleus pulpous (NP) has been identified as a key factor contributing to intervertebral disc degeneration (IVDD). While Kartogenin (KGN) has previously demonstrated antioxidant properties on articular cartilage against osteoarthritis, its effects on NP degeneration have yet to be fully understood.

OBJECTIVES

This study aimed to investigate the protective effects of KGN on nucleus pulpous cells (NPCs) against an inflammatory environment induced by interleukin (IL)-1β, as well as to explore the therapeutic potential of KGN-enhanced dynamic hydrogel in preventing IVDD.

METHODS

NPCs were isolated from rat caudal IVDs and subjected to treatment with KGN at varying concentrations (ranging from 0.01 to 1 ​μM) in the presence of IL-1β. The expression of extracellular matrix (ECM) anabolism markers was quantitatively assessed at both the mRNA and protein levels. Additionally, intracellular reactive oxygen species and antioxidant enzyme expression were evaluated, along with the role of nuclear factor erythroid 2-related factor 2 (NRF2). Based on these findings, a dynamic self-healing hydrogel loaded with KGN was developed through interconnecting networks. Subsequently, KGN-enhanced dynamic hydrogel was administered into rat caudal IVDs that had undergone puncture injury, followed by radiographic analysis and immunohistochemical staining to evaluate the therapeutic efficacy.

RESULTS

In vitro treatments utilizing KGN were observed to maintain ECM synthesis and inhibit catabolic activities in IL-1β-stimulated NPCs. The mechanism behind this protective effect of KGN on NPCs was found to involve the asctivation of NRF2 and downstream antioxidant enzymes, including glutathione peroxidase 1 and heme oxygenase 1. This was further supported by the loss of both antioxidant and anabolic effects upon pharmacological inhibition of NRF2. Furthermore, a self-healing hydrogel was developed and loaded with KGN to achieve localized and sustained release of the compound. The injection of KGN-enhanced hydrogel effectively ameliorated the degradation of NP ECM and mitigated inflammation in a rat model of puncture-induced IVDD.

CONCLUSIONS

Our results indicate that KGN exhibits potential as a therapeutic agent for NP degeneration, and that KGN-enhanced dynamic hydrogel represents a novel approach for treating IVDD by restoring redox homeostasis in NP.The translational potential of this article: The dysregulation of oxidant and antioxidant balance has been shown to impede the repair and regeneration of NP, thereby hastening the progression of IVDD following injury. The present investigation has demonstrated that the sustained release of KGN promotes the synthesis of ECM in vitro and mitigates the progression of IVDD in vivo by restoring redox equilibrium, thereby presenting a novel therapeutic candidate based on the antioxidant properties of KGN for the treatment of IVDD.

Multiple roles of ALK3 in osteoarthritis

Osteoarthritis (OA) is a chronic degenerative joint disease characterized by progressive cartilage degradation, synovial membrane inflammation, osteophyte formation, and subchondral bone sclerosis. Pathological changes in cartilage and subchondral bone are the main processes in OA. In recent decades, many studies have demonstrated that activin-like kinase 3 (ALK3), a bone morphogenetic protein receptor, is essential for cartilage formation, osteogenesis, and postnatal skeletal development. Although the role of bone morphogenetic protein (BMP) signalling in articular cartilage and bone has been extensively studied, many new discoveries have been made in recent years around ALK3 targets in articular cartilage, subchondral bone, and the interaction between the two, broadening the original knowledge of the relationship between ALK3 and OA. In this review, we focus on the roles of ALK3 in OA, including cartilage and subchondral bone and related cells. It may be helpful to seek more efficient drugs or treatments for OA based on ALK3 signalling in future.

Recent development in multizonal scaffolds for osteochondral regeneration

Osteochondral (OC) repair is an extremely challenging topic due to the complex biphasic structure and poor intrinsic regenerative capability of natural osteochondral tissue. In contrast to the current surgical approaches which yield only short-term relief of symptoms, tissue engineering strategy has been shown more promising outcomes in treating OC defects since its emergence in the 1990s. In particular, the use of multizonal scaffolds (MZSs) that mimic the gradient transitions, from cartilage surface to the subchondral bone with either continuous or discontinuous compositions, structures, and properties of natural OC tissue, has been gaining momentum in recent years. Scrutinizing the latest developments in the field, this review offers a comprehensive summary of recent advances, current hurdles, and future perspectives of OC repair, particularly the use of MZSs including bilayered, trilayered, multilayered, and gradient scaffolds, by bringing together onerous demands of architecture designs, material selections, manufacturing techniques as well as the choices of growth factors and cells, each of which possesses its unique challenges and opportunities.

Pelargonidin ameliorates inflammatory response and cartilage degeneration in osteoarthritis via suppressing the NF-κB pathway

Pelargonidin (PG), a derivative of anthocyanins, has anti-oxidant and anti-inflammatory properties. Herein, the protective effect and the mechanism of PG in counteract the osteoarthritis (OA) progression were needed to further evaluate. In the current study, C57BL/6 mice was induced by destabilization of medial meniscus (DMM) surgery to establish the OA model. Primary chondrocytes were acquired from the knee cartilage of newborn mice. Then, PG was administrated to OA mice and IL-1β-stimulated chondrocytes to evaluate its protective effects, respectively. Results uncovered that no conspicuous cytotoxic effects were observed when chondrocytes were treated with PG at a concentration lower than 40 μM for 24-72h. Thus, 10 μM, 20 μM, and 40 μM PG were chosen for subsequent experiments in vitro. Then, we observed that 10, 20, and 40 μM PG reduced the levels of IL-6, TNF-α, COX-2 and iNOS in chondrocytes. In line, PG inhibited the IL-1β-induced ECM catabolism in chondrocytes, as evidenced by deepening toluidine blue staining, increased expression of Collagen II, and decreased expressions of ADAMTS5 and MMP13. Moreover, PG also reduced the IL-1β-stimulated p-p65 overexpression and nuclear translocation of p65 in chondrocytes. In vivo, Safranin O/Fast green and HE staining showed that articular cartilage surface morphology was basically smooth and complete after PG treatment for 8 weeks. Similarly, OARSI scores and MMP13 expression were apparently decreased, whereas Aggrecan expression was elevated in PG-treated mice 8 weeks after DMM surgery. In conclusion, PG can effectively ameliorate inflammatory reactions and cartilage degeneration via suppressing the NF-κB pathway, thereby restraining the OA progression.

Recent Advances in Small Molecule Inhibitors for the Treatment of Osteoarthritis

Osteoarthritis refers to a degenerative disease with joint pain as the main symptom, and it is caused by various factors, including fibrosis, chapping, ulcers, and loss of articular cartilage. Traditional treatments can only delay the progression of osteoarthritis, and patients may need joint replacement eventually. As a class of organic compound molecules weighing less than 1000 daltons, small molecule inhibitors can target proteins as the main components of most drugs clinically. Small molecule inhibitors for osteoarthritis are under constant research. In this regard, by reviewing relevant manuscripts, small molecule inhibitors targeting MMPs, ADAMTS, IL-1, TNF, WNT, NF-κB, and other proteins were reviewed. We summarized these small molecule inhibitors with different targets and discussed disease-modifying osteoarthritis drugs based on them. These small molecule inhibitors have good inhibitory effects on osteoarthritis, and this review will provide a reference for the treatment of osteoarthritis.

Integrated gradient tissue-engineered osteochondral scaffolds: Challenges, current efforts and future perspectives

The osteochondral defect repair has been most extensively studied due to the rising demand for new therapies to diseases such as osteoarthritis. Tissue engineering has been proposed as a promising strategy to meet the demand of simultaneous regeneration of both cartilage and subchondral bone by constructing integrated gradient tissue-engineered osteochondral scaffold (IGTEOS). This review brought forward the main challenges of establishing a satisfactory IGTEOS from the perspectives of the complexity of physiology and microenvironment of osteochondral tissue, and the limitations of obtaining the desired and required scaffold. Then, we comprehensively discussed and summarized the current tissue-engineered efforts to resolve the above challenges, including architecture strategies, fabrication techniques and in vitro/in vivo evaluation methods of the IGTEOS. Especially, we highlighted the advantages and limitations of various fabrication techniques of IGTEOS, and common cases of IGTEOS application. Finally, based on the above challenges and current research progress, we analyzed in details the future perspectives of tissue-engineered osteochondral construct, so as to achieve the perfect reconstruction of the cartilaginous and osseous layers of osteochondral tissue simultaneously. This comprehensive and instructive review could provide deep insights into our current understanding of IGTEOS.

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Providing main challenges to establish integrated gradient osteochondral scaffold.

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Discussing the current tissue-engineered efforts to resolve the above challenges.

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Highlighting construct techniques, and evaluation index and methods of IGTEOS.

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Discussing the future perspectives to achieve perfect osteochondral reconstruction.

An Injectable Hydrogel Scaffold Loaded with Dual-Drug/Sustained-Release PLGA Microspheres for the Regulation of Macrophage Polarization in the Treatment of Intervertebral Disc Degeneration

Due to the unique physical characteristics of intervertebral disc degeneration (IVDD) and the pathological microenvironment that it creates, including inflammation and oxidative stress, effective self-repair is impossible. During the process of intervertebral disc degeneration, there is an increase in the infiltration of M1 macrophages and the secretion of proinflammatory cytokines. Here, we designed a novel injectable composite hydrogel scaffold: an oligo [poly (ethylene glycol) fumarate]/sodium methacrylate (OPF/SMA) hydrogel scaffold loaded with dual-drug/sustained-release PLGA microspheres containing IL-4 (IL-4-PLGA) and kartogenin (KGN-PLGA). This scaffold exhibited good mechanical properties and low immunogenicity while also promoting the sustained release of drugs. By virtue of the PLGA microspheres loaded with IL-4 (IL-4-PLGA), the composite hydrogel scaffold induced macrophages to transition from the M1 phenotype into the M2 phenotype during the early induced phase and simultaneously exhibited a continuous anti-inflammatory effect through the PLGA microspheres loaded with kartogenin (KGN-PLGA). Furthermore, we investigated the mechanisms underlying the immunomodulatory and anti-inflammatory effects of the composite hydrogel scaffold. We found that the scaffold promoted cell proliferation and improved cell viability in vitro. While ensuring mechanical strength, this composite hydrogel scaffold regulated the local inflammatory microenvironment and continuously repaired tissue in the nucleus pulposus via the sequential release of drugs in vivo. When degenerative intervertebral discs in a rat model were injected with the scaffold, there was an increase in the proportion of M2 macrophages in the inflammatory environment and higher expression levels of type II collagen and aggrecan; this was accompanied by reduced levels of MMP13 expression, thus exhibiting long-term anti-inflammatory effects. Our research provides a new strategy for promoting intervertebral disc tissue regeneration and a range of other inflammatory diseases.

A single-cell mass cytometry platform to map the effects of preclinical drugs on cartilage homeostasis

No disease-modifying drug exists for osteoarthritis (OA). Despite success in animal models, candidate drugs continue to fail in clinical trials owing to the unmapped interpatient heterogeneity and disease complexity. We used a single-cell platform based on cytometry by time-of-flight (cyTOF) to precisely outline the effects of candidate drugs on human OA chondrocytes. OA chondrocytes harvested from patients undergoing total knee arthroplasty were treated with 2 drugs, an NF-κB pathway inhibitor, BMS-345541, and a chondroinductive small molecule, kartogenin, that showed preclinical success in animal models for OA. cyTOF conducted with 30 metal isotope-labeled antibodies parsed the effects of the drugs on inflammatory, senescent, and chondroprogenitor cell populations. The NF-κB pathway inhibition decreased the expression of p-NF-κB, HIF2A, and inducible NOS in multiple chondrocyte clusters and significantly depleted 4 p16ink4a-expressing senescent populations, including NOTCH1+STRO1+ chondroprogenitor cells. While kartogenin also affected select p16ink4a-expressing senescent clusters, there was a less discernible effect on chondroprogenitor cell populations. Overall, BMS-345541 elicited a uniform drug response in all patients, while only a few responded to kartogenin. These studies demonstrate that a single-cell cyTOF-based drug screening platform can provide insights into patient response assessment and patient stratification.

Interleukin-10 family members: Biology and role in the bone and joint diseases

Interleukin (IL)-10 family cytokines include IL-10, IL-19, IL-20, IL-22, IL-24, IL-26, IL-28A, IL-28B, and IL-29. These cytokines play crucial regulatory roles in various biological reactions and diseases. In recent years, several studies have shown that the IL-10 family plays a vital role in bone and joint diseases, including bone metabolic diseases, fractures, osteoarthritis, rheumatoid arthritis, and bone tumors. Herein, the recent progress on the regulatory role of IL-10 family of cytokines in the occurrence and development of bone and joint diseases has been summarized. This review will provide novel directions for immunotherapy of bone and joint diseases.

The Role of Interleukin-4 and Interleukin-10 in Osteoarthritic Joint Disease: A Systematic Narrative Review

OBJECTIVE

A fusion protein of interleukin-4 and interleukin-10 (IL4-10 FP) was developed as a disease-modifying osteoarthritis drug (DMOAD), and chondroprotection, anti-inflammation, and analgesia have been suggested. To better understand the mechanisms behind its potential as DMOAD, this systematic narrative review aims to assess the potential of IL-4, IL-10 and the combination of IL-4 and IL-10 for the treatment of osteoarthritis. It describes the chondroprotective, anti-inflammatory, and analgesic effects of IL-4, IL-10, and IL4-10 FP.

DESIGN

PubMed and Embase were searched for publications that were published from 1990 until May 21, 2021 (moment of search). Key search terms were: Osteoarthritis, Interleukin-4, and Interleukin-10. This yielded 2,479 hits, of which 43 were included in this review.

RESULTS

IL-4 and IL-10 showed mainly protective effects on osteoarthritic cartilage in vitro and in vivo, as did IL4-10 FP. Both cytokines showed anti-inflammatory effects, but also proinflammatory effects. Only in vitro IL4-10 FP showed purely anti-inflammatory effects, indicating that proinflammatory effects of one cytokine can be counteracted by the other when given as a combination. Only a few studies investigated the analgesic effects of IL-4, IL-10 or IL4-10 FP. In vitro, IL-4 and IL4-10 FP were able to decrease pain mediators. In vivo, IL-4, IL-10, and IL4-10 FP were able to reduce pain.

CONCLUSIONS

In conclusion, this review describes overlapping, but also different modes of action for the DMOAD effects of IL-4 and IL-10, giving an explanation for the synergistic effects found when applied as combination, as is the case for IL4-10 FP.

Single-Dose Intra-Cartilage Delivery of Kartogenin Using a Cationic Multi-Arm Avidin Nanocarrier Suppresses Cytokine-Induced Osteoarthritis-Related Catabolism

OBJECTIVE

Kartogenin (KGN) has proven as a both chondrogenic and chondroprotective drug for osteoarthritis (OA) therapy. However, being a small hydrophobic molecule, KGN suffers from rapid joint clearance and inability to penetrate cartilage to reach chondrocytes following intra-articular administration. As such multiple high doses are needed that can lead to off-target effects including stimulation and tissue outgrowth. Here we design charge-based cartilage targeting formulation of KGN by using a multi-arm cationic nano-construct of Avidin (mAv) that can rapidly penetrate into cartilage in high concentrations owing to weak-reversible electrostatic binding interactions with negatively charged aggrecan-glycosaminoglycans (GAGs) and form an extended-release drug depot such that its therapeutic benefit can be reaped in just a single dose.

DESIGN

We synthesized 2 novel formulations, one with a releasable ester linker (mAv-OH-KGN, release half-life ~58 h) that enables sustained KGN release over 2 weeks and another with a non-releasable amide linker (mAv-NH-KGN) that relies on mAv's ability to be uptaken and endocytosed by chondrocytes for drug delivery. Their effectiveness in suppressing cytokine-induced catabolism was evaluated in vitro using cartilage explant culture model.

RESULTS

A single 100 μM dose of cartilage homing mAv-KGN was significantly more effective in suppressing cytokine-induced GAG loss, cell death, inflammatory response and in rescuing cell metabolism than a single dose of free KGN; multiple doses of free KGN were needed to match this therapeutic response.

CONCLUSION

mAv mediated delivery of KGN is promising and can facilitate clinical translation of KGN for OA treatment with only a single dose.

Thermosensitive Hydrogel Loaded with Primary Chondrocyte-Derived Exosomes Promotes Cartilage Repair by Regulating Macrophage Polarization in Osteoarthritis

BACKGROUND

Intra-articular injection is a classic strategy for the treatment of early osteoarthritis (OA). However, the local delivery of traditional therapeutic agents has limited benefits for alleviating OA. Exosomes, an important type of extracellular nanovesicle, show great potential for suppressing cartilage destruction in OA to replace drugs and stem cell-based administration.

METHODS

In this study, we developed a thermosensitive, injectable hydrogel by in situ crosslinking of Pluronic F-127 and hyaluronic acid, which can be used as a slow-release carrier to durably retain primary chondrocyte-derived exosomes at damaged cartilage sites to effectively magnify their reparative effect.

RESULTS

It was found that the hydrogel can sustainedly release exosomes, positively regulate chondrocytes on the proliferation, migration and differentiation, as well as efficiently induce polarization of M1 to M2 macrophages. Intra-articular injection of this exosomes-incorporated hydrogel significantly prevented cartilage destruction by promoting cartilage matrix formation. This strategy also displayed a regenerative immune phenotype characterized by a higher infiltration of CD163⁺ regenerative M2 macrophages over CD86⁺ M1 macrophages in synovial and chondral tissue, with a concomitant reduction in pro-inflammatory cytokines (TNF-α, IL-1β, and IL-6) and increase in anti-inflammatory cytokine (IL-10) in synovial fluid.

CONCLUSION

Our results demonstrated that local sustained-release primary chondrocyte-derived exosomes may relieve OA by promoting the phenotypic transformation of macrophages from M1 to M2, which suggesting a great potential for the application in OA.

Icariin-Loaded Hydrogel Regulates Bone Marrow Mesenchymal Stem Cell Chondrogenic Differentiation and Promotes Cartilage Repair in Osteoarthritis

Intra-articular injection of mesenchymal stem cells is a potential therapeutic strategy for cartilage protection and symptom relief for osteoarthritis (OA). However, controlling chondrogenesis of the implanted cells in the articular cavity remains a challenge. In this study, hydrogels containing different concentrations of icariin were prepared by in situ crosslinking of hyaluronic acid and Poloxamer 407. This injectable and thermoresponsive hydrogel, as a 3D cell culture system, showed good biocompatibility with chondrocytes and bone marrow mesenchymal stem cells (BMSCs), as well as promoted proliferation and chondrogenesis of BMSCs through the Wnt/β-catenin signaling pathway. Intra-articular injection of this kind of BMSC-loaded composite hydrogel can significantly prevent cartilage destruction by inducing chondrogenic differentiation of BMSCs, and relieve pain through regulating the expression of inflammatory cytokines (e.g., IL-10 and MMP-13) in the OA model. Incorporating BMSCs into this novel icariin-loaded hydrogel indicates a more superior efficacy than the single BMSC injection, which suggests a great potential for its application in OA.

Confirmation of inhibitingTLR4/MyD88/NF-κB Signalling Pathway by Duhuo Jisheng Decoction on Osteoarthritis: A Network Pharmacology Approach-Integrated Experimental Study

This study was conducted to identify whether the TLR4/MyD88/NF-κB signalling pathway plays a vital role in osteoarthritis (OA) treatment with Duhuo Jisheng Decoction (DHJSD) on the basis of a network pharmacology approach (NPA)-integrated experiment. Two experiments were conducted as follow: NPA for DHJSD using six OA-related gene series and the key pathway was screened out using NPA. NPA identified a vital role for the TLR4/MyD88/NF-κB signalling pathway in OA treatment with DHJSD, the conventional western blot analysis and qPCR confirmed it. Furthermore, changes of miR-146a-5p and miR-34a-5p in the cellular models were recovered by DHJSD administration, which synergistically contributed to OA therapy. The toll-like receptor signalling pathway and the NF-κB signalling pathway were meaningfully enriched by the miRNA-regulated gene pathways. This study identified and confirmed the TLR4/MyD88/NF-κB signalling pathway is an essential inflammatory signalling pathway in the DHJSD underlying OA treatment. The results provide a basis for further evaluation of the regulatory mechanism of the drug’s efficacy in treating OA.

Integration of a miniaturized DMMB assay with high-throughput screening for identifying regulators of proteoglycan metabolism

Defective biosynthesis or function of proteoglycans causes pathological conditions in a variety of tissue systems. Osteoarthritis (OA) is a prevalent degenerative joint disorder characterized by progressive cartilage destruction caused by imbalanced proteoglycan synthesis and degradation. Identifying agents that regulate proteoglycan metabolism may benefit the development of OA-modifying therapeutics. High-throughput screening (HTS) of chemical libraries has paved the way for achieving this goal. However, the implementation and adaptation of HTS assays based on proteoglycan measurement remain underexploited. Using primary porcine chondrocytes as a model, we report a miniaturized dimethyl-methylene blue (DMMB) assay, which is commonly used to quantitatively evaluate sulfated glycosaminoglycan (GAG) content, with an optimized detection range and reproducibility and its integration with HTS. Treatment with TGF-β1 and IL1-α, known as positive and negative proteoglycan regulators, respectively, supported the assay specificity. A pre-test of chemical screening of 960 compounds identified both stimulators (4.48%) and inhibitors (6.04%) of GAG production. Fluorophore-assisted carbohydrate electrophoresis validated the activity of selected hits on chondroitin sulfate expression in an alginate culture system. Our findings support the implementation of this simple colorimetric assay in HTS to discover modifiers of OA or other diseases related to dysregulated proteoglycan metabolism.

A green-lipped mussel reduces pain behavior and chondrocyte inflammation and attenuated experimental osteoarthritis progression

The green-lipped mussel (GLM) contains novel omega-3 polyunsaturated fatty acids, which exhibit anti-inflammatory and joint-protecting properties. Osteoarthritis (OA) is a degenerative joint disease characterized by a progressive loss of cartilage; oxidative stress plays a role in the pathogenesis of OA. The objectives of this study were to investigate the in vivo effects of the GLM on pain severity and cartilage degeneration using an experimental rat OA model, and to explore the mode of action of GLM. OA was induced in rats by intra-articular injection of monosodium iodoacetate (MIA) into the knee. Oral GLM was initiated on the day after 3dyas of MIA injection. Limb nociception was assessed by measuring the paw withdrawal latency and threshold. Samples were analyzed both macroscopically and histologically. Immunohistochemistry was used to investigate the expression of interleukin-1β (IL-1β), IL-6, nitrotyrosine, and inducible nitric oxide synthase (iNOS) in knee joints. Also, the GLM was applied to OA chondrocyte, and the expression on catabolic marker and necroptosis factor were evaluated by real-time polymerase chain reaction. Administration of the GLM improved pain levels by preventing cartilage damage and inflammation. GLM significantly attenuated the expression levels of mRNAs encoding matrix metalloproteinase-3 (MMP-3), MMP-13, and ADAMTS5 in IL-1β-stimulated human OA chondrocytes. GLM decreased the expression levels of the necroptosis mediators RIPK1, RIPK3, and the mixed lineage kinase domain-like protein (MLKL) in IL-1β-stimulated human OA chondrocytes. Thus, GLM reduced pain and cartilage degeneration in rats with experimentally induced OA. The chondroprotective properties of GLM included suppression of oxidative damage and inhibition of catabolic factors implicated in the pathogenesis of OA cartilage damage. We suggest that GLM may usefully treat human OA.

Low-Molecular-Weight Collagen Peptide Ameliorates Osteoarthritis Progression through Promoting Extracellular Matrix Synthesis by Chondrocytes in a Rabbit Anterior Cruciate Ligament Transection Model

This study examined whether the oral administration of low-molecular-weight collagen peptide (LMCP) containing 3% Gly-Pro-Hyp with >15% tripeptide (Gly-X-Y) content could ameliorate osteoarthritis (OA) progression using a rabbit anterior cruciate ligament transection (ACLT) model of induced OA and chondrocytes isolated from a patient with OA. Oral LMCP administration (100 or 200 mg/kg/day) for 12 weeks ameliorated cartilage damage and reduced the loss of proteoglycan compared to the findings in the ACLT control group, resulting in dose-dependent (p < 0.05) improvements of the OARSI score in hematoxylin & eosin (H&E) and Safranin O staining. In microcomputed tomography analysis, LMCP also significantly (p < 0.05) suppressed the deterioration of the microstructure in tibial subchondral bone during OA progression. The elevation of IL-1βand IL-6 concentrations in synovial fluid following OA induction was dose-dependently (p < 0.05) reduced by LMCP treatment. Furthermore, immunohistochemistry illustrated that LMCP significantly (p < 0.05) upregulated type II collagen and downregulated matrix metalloproteinase-13 in cartilage tissue. Consistent with the in vivo results, LMCP significantly (p < 0.05) increased the mRNA expression of COL2A1 and ACAN in chondrocytes isolated from a patient with OA regardless of the conditions for IL-1βinduction. These findings suggest that LMCP has potential as a therapeutic treatment for OA that stimulates cartilage regeneration.

Effects of photobiomodulation and a physical exercise program on the expression of inflammatory and cartilage degradation biomarkers and functional capacity in women with knee osteoarthritis: a randomized blinded study

BACKGROUND

The knee osteoarthritis (OA) is a joint disease characterized by degradation of articular cartilage that leads to chronic inflammation. Exercise programs and photobiomodulation (PBM) are capable of modulating the inflammatory process of minimizing functional disability related to knee OA. However, their association on the concentration of biomarkers related to OA development has not been studied yet. The aim of the present study is to investigate the effects of PBM (via cluster) with a physical exercise program in functional capacity, serum inflammatory and cartilage degradation biomarkers in patients with knee OA.

METHODS

Forty-two patients were randomly allocated in 3 groups: ESP: exercise + sham PBM; EAP: exercise + PBM and CG: control group. Six patients were excluded before finished the experimental period. The analyzed outcomes in baseline and 8-week were: the Western Ontario and McMaster Universities Osteoarthritis (WOMAC) and the evaluation of serum biomarkers concentration (IL-1β, IL-6, IL-8, IL-10 e TNF-α, and CTX-II).

RESULTS

An increase in the functional capacity was observed in the WOMAC total score for both treated groups (p < 0.001) and ESP presents a lower value compared to CG (p < 0.05) the 8-week post-treatment. In addition, there was a significant increase in IL-10 concentration of EAP (p < 0.05) and higher value compared to CG (p < 0.001) the 8-week post-treatment. Moreover, an increase in IL-1β concentration was observed for CG (p < 0.05). No other difference was observed comparing the other groups.

CONCLUSION

Our data suggest that the physical exercise therapy could be a strategy for increasing functional capacity and in association with PBM for increasing IL-10 levels in OA knee individuals.

TRIAL REGISTRATION

ReBEC (RBR-7t6nzr).

Novel NFκB Inhibitor SC75741 Mitigates Chondrocyte Degradation and Prevents Activated Fibroblast Transformation by Modulating miR-21/GDF-5/SOX5 Signaling

Osteoarthritis (OA) is a common articular disease manifested by the destruction of cartilage and compromised chondrogenesis in the aging population, with chronic inflammation of synovium, which drives OA progression. Importantly, the activated synovial fibroblast (AF) within the synovium facilitates OA through modulating key molecules, including regulatory microRNAs (miR's). To understand OA associated pathways, in vitro co-culture system, and in vivo papain-induced OA model were applied for this study. The expression of key inflammatory markers both in tissue and blood plasma were examined by qRT-PCR, western blot, immunohistochemistry, enzyme-linked immunosorbent assay (ELISA) and immunofluorescence assays. Herein, our result demonstrated, AF-activated human chondrocytes (AC) exhibit elevated NFκB, TNF-α, IL-6, and miR-21 expression as compared to healthy chondrocytes (HC). Importantly, AC induced the apoptosis of HC and inhibited the expression of chondrogenesis inducers, SOX5, TGF-β1, and GDF-5. NFκB is a key inflammatory transcription factor elevated in OA. Therefore, SC75741 (an NFκB inhibitor) therapeutic effect was explored. SC75741 inhibits inflammatory profile, protects AC-educated HC from apoptosis, and inhibits miR-21 expression, which results in the induced expression of GDF-5, SOX5, TGF-β1, BMPR2, and COL4A1. Moreover, ectopic miR-21 expression in fibroblast-like activated chondrocytes promoted osteoblast-mediated differentiation of osteoclasts in RW264.7 cells. Interestingly, in vivo study demonstrated SC75741 protective role, in controlling the destruction of the articular joint, through NFκB, TNF-α, IL-6, and miR-21 inhibition, and inducing GDF-5, SOX5, TGF-β1, BMPR2, and COL4A1 expression. Our study demonstrated the role of NFκB/miR-21 axis in OA progression, and SC75741's therapeutic potential as a small-molecule inhibitor of miR-21/NFκB-driven OA progression.

Intra-Articular Injection of miR-29a-3p of BMSCs Promotes Cartilage Self-Repairing and Alleviates Pain in the Rat Osteoarthritis

BACKGROUND

Stem cells intra-articular injection stagey indicated a potential therapeutic effect on improving the pathological progress of osteoarthritis (OA). However, the long-term effect of stem cells intra-articular injection on the cartilage regeneration remains unclear. miR-29a-3p is predicted to be a critical target for inhibiting insulin-like growth factor-1 expression and may aggravate the progression of OA.

METHODS

In this study, we investigated the therapeutic efficacy of intra-articular injection of bone marrow mesenchymal stem cells (BMSCs) transfected with miR-29a-3p inhibitor in OA.

RESULTS

miR-29a-3p inhibitor transfection did not influence cell viability of BMSCs, while the chondrogenic differentiation potential of BMSCs was significantly improved. Interestingly, intra-articular injection of BMSCs with miR-29a-3p inhibition significantly prevented articular cartilage degeneration by up-regulating the expression of Sox 9, Col-2a1, aggrecan and down-regulating the expression of matrix metalloproteinase, as well as relieved pain in OA.

CONCLUSION

The double effects on cartilage protection and pain relief indicated a great potential of intra-articular injection of miR-29a-3p inhibitor-transfected BMSCs for the treatment of OA.

Chondrogenic Potential of Dental-Derived Mesenchymal Stromal Cells

The field of tissue engineering has revolutionized the world in organ and tissue regeneration. With the robust research among regenerative medicine experts and researchers, the plausibility of regenerating cartilage has come into the limelight. For cartilage tissue engineering, orthopedic surgeons and orthobiologists use the mesenchymal stromal cells (MSCs) of various origins along with the cytokines, growth factors, and scaffolds. The least utilized MSCs are of dental origin, which are the richest sources of stromal and progenitor cells. There is a paradigm shift towards the utilization of dental source MSCs in chondrogenesis and cartilage regeneration. Dental-derived MSCs possess similar phenotypes and genotypes like other sources of MSCs along with specific markers such as dentin matrix acidic phosphoprotein (DMP) -1, dentin sialophosphoprotein (DSPP), alkaline phosphatase (ALP), osteopontin (OPN), bone sialoprotein (BSP), and STRO-1. Concerning chondrogenicity, there is literature with marginal use of dental-derived MSCs. Various studies provide evidence for in-vitro and in-vivo chondrogenesis by dental-derived MSCs. With such evidence, clinical trials must be taken up to support or refute the evidence for regenerating cartilage tissues by dental-derived MSCs. This article highlights the significance of dental-derived MSCs for cartilage tissue regeneration.

Intra-articular Injection of Kartogenin-Enhanced Bone Marrow-Derived Mesenchymal Stem Cells in the Treatment of Knee Osteoarthritis in a Rat Model

BACKGROUND

In this study, we investigated the in vitro and in vivo chondrogenic capacity of kartogenin (KGN)-enhanced bone marrow-derived mesenchymal stem cells (BMSCs) for cartilage regeneration.

PURPOSE

To determine (1) whether functionalized nanographene oxide (NGO) can effectively deliver KGN into BMSCs and (2) whether KGN would enhance BMSCs during chondrogenesis in vitro and in vivo in an animal model.

STUDY DESIGN

Controlled laboratory study.

METHODS

Functionalized NGO with line chain amine-terminated polyethylene glycol (PEG) and branched polyethylenimine (BPEI) were used to synthesize biocompatible NGO-PEG-BPEI (PPG) and for loading hydrophobic KGN molecules noncovalently via π-π stacking and hydrophobic interactions (PPG-KGN). Then, PPG-KGN was used for the intracellular delivery of hydrophobic KGN by simple mixing and co-incubation with BMSCs to acquire KGN-enhanced BMSCs. The chondrogenic efficacy of KGN-enhanced BMSCs was evaluated in vitro. In vivo, osteoarthritis (OA) was induced by anterior cruciate ligament transection in rats. A total of 5 groups were established: normal (OA treated with nothing), phosphate-buffered saline (PBS; intra-articular injection of PBS), PPG-KGN (intra-articular injection of PPG-KGN), BMSCs (intra-articular injection of BMSCs), and BMSCs + PPG-KGN (intra-articular injection of PPG-KGN-preconditioned BMSCs). At 6 and 9 weeks after the surgical induction of OA, the rats received intra-articular injections of PPG-KGN, BMSCs, or KGN-enhanced BMSCs. At 14 weeks after the surgical induction of OA, radiographic and behavioral evaluations as well as histological analysis of the knee joints were performed.

RESULTS

The in vitro study showed that PPG could be rapidly uptaken in the first 4 hours after incubation, reaching saturation at 12 hours and accumulating in the lysosome and cytoplasm of BMSCs. Thus, PPG-KGN could enhance the efficiency of the intracellular delivery of KGN, which showed a remarkably high chondrogenic differentiation capacity of BMSCs. When applied to an OA model of cartilage injuries in rats, PPG-KGN-preconditioned BMSCs contributed to protection from joint space narrowing, pathological mineralization, OA development, and OA-induced pain, as well as improved tissue regeneration, as evidenced by radiographic, weightbearing, and histological findings.

CONCLUSION

Our results demonstrate that KGN-enhanced BMSCs showed markedly improved capacities for chondrogenesis and articular cartilage repair. We believe that this work demonstrates that a multifunctional nanoparticle-based drug delivery system could be beneficial for stem cell therapy. Our results present an opportunity to reverse the symptoms and pathophysiology of OA.

CLINICAL RELEVANCE

The intracellular delivery of KGN to produce BMSCs with enhanced chondrogenic potential may offer a new approach for the treatment of OA.

Osteochondral Tissue Engineering: The Potential of Electrospinning and Additive Manufacturing

The socioeconomic impact of osteochondral (OC) damage has been increasing steadily over time in the global population, and the promise of tissue engineering in generating biomimetic tissues replicating the physiological OC environment and architecture has been falling short of its projected potential. The most recent advances in OC tissue engineering are summarised in this work, with a focus on electrospun and 3D printed biomaterials combined with stem cells and biochemical stimuli, to identify what is causing this pitfall between the bench and the patients' bedside. Even though significant progress has been achieved in electrospinning, 3D-(bio)printing, and induced pluripotent stem cell (iPSC) technologies, it is still challenging to artificially emulate the OC interface and achieve complete regeneration of bone and cartilage tissues. Their intricate architecture and the need for tight spatiotemporal control of cellular and biochemical cues hinder the attainment of long-term functional integration of tissue-engineered constructs. Moreover, this complexity and the high variability in experimental conditions used in different studies undermine the scalability and reproducibility of prospective regenerative medicine solutions. It is clear that further development of standardised, integrative, and economically viable methods regarding scaffold production, cell selection, and additional biochemical and biomechanical stimulation is likely to be the key to accelerate the clinical translation and fill the gap in OC treatment.

Electroacupuncture Relieves Pain and Attenuates Inflammation Progression Through Inducing IL-10 Production in CFA-Induced Mice

The therapeutic effect of electroacupuncture (EA) on inflammatory pain has been well recognized clinically, but the mechanism is unclear. Interleukin-10 (IL-10), which is produced by regulatory T (Treg) cell, is a key anti-inflammatory cytokine for relieving inflammatory pain. Therefore, the aim of this study is to investigate whether EA could inhibit CFA-induced pain and attenuate inflammation progression by regulating the activation of immunocyte and inducing the expression of IL-10. In this study, mice were treated with EA (2/100 Hz, 2 mA) for five consecutive days after 1 day of CFA injection. The behavioral tests were measured and analyzed after the daily EA treatment; then, hind paw, spinal cord, and spleen tissues were prepared for assessment. The results showed that EA treatment significantly increased the mechanical threshold and thermal latency after CFA injection and boosted the expression of IL-10 in paw and spinal cord tissues. EA treatment promoted Treg cells; suppressed macrophage and neutrophils cells; reduced the expression of IL-1β, NLRP3, and TNF-α; and ultimately relieved inflammatory pain. The findings suggested that the analgesic and anti-inflammatory effect of EA treatment could be partially associated with suppression of pro-inflammatory cytokines mediated by induction of IL-10.

Identification of the Key Role of NF-κB Signaling Pathway in the Treatment of Osteoarthritis With Bushen Zhuangjin Decoction, a Verification Based on Network Pharmacology Approach

This study aimed to identify whether the NF-κB signaling pathway plays a key role in the treatment of osteoarthritis (OA) with Bushen Zhuangjin Decoction (BZD) based on a typical network pharmacology approach (NPA). Four sequential experiments were performed: 1) conventional high-performance liquid chromatography (HPLC), 2) preliminary observation of the therapeutic effects of BZD, 3) NPA using three OA-related gene expression profiles, and 4) verification of the key pathway identified by NPA. Only one HPLC-verified compound (paeoniflorin) was identified from the candidate compounds discovered by NPA. The genes verified in the preliminary observation were also identified by NPA. NPA identified a key role for the NF-κB signaling pathway in the treatment of OA with BZD, which was confirmed by conventional western blot analysis. This study identified and verified NF-κB signaling pathway as the most important inflammatory signaling pathway involved in the mechanisms of BZD for treating OA by comparing the NPA results with conventional methods. Our findings also indicate that NPA is a powerful tool for exploring the molecular targets of complex herbal formulations, such as BZD.

Encapsulated Mesenchymal Stromal Cell Microbeads Promote Endogenous Regeneration of Osteoarthritic Cartilage Ex Vivo

The anti-inflammatory secretome of mesenchymal stromal cells (MSCs) is lucrative for the treatment of osteoarthritis (OA), a disease characterized by low-grade inflammation. However, the precise effects of the MSC secretome on patient-derived OA tissue is lacking. To investigate these effects, alginate encapsulated MSCs are co-cultured with patient-derived OA cartilage explants for 8 days. Proteoglycan distribution in OA cartilage explants examined by Safranin O staining is markedly improved when cultured with MSC microbeads as compared to control OA explants cultured alone. Total sulfated glycosaminoglycan (sGAG) content in OA explants is significantly increased upon co-culture with MSC microbeads on day 8. The sGAG released into the culture media is unchanged by the presence of MSC microbeads, suggesting de novo sGAG synthesis in OA explants. Co-culture with MSC microbeads increased the DNA content and Ki67+ cells in OA explants, indicating proliferation. An increase in secreted cytokines IL-10, HGF, and sFAS assessed by multiplex cytokine assay, increased TIMP1 levels, and reduction in percent apoptotic cells in OA explants is noted. Together, data demonstrates that paracrine factors secreted by alginate encapsulated MSCs microbeads in response to OA cartilage, create an anabolic, proliferative, and anti-apoptotic microenvironment inducing endogenous regeneration in clinically relevant, patient-derived OA cartilage.

Cartilage tissue engineering for obesity-induced osteoarthritis: Physiology, challenges, and future prospects

Osteoarthritis (OA) is a multifactorial joint disease with pathological changes that affect whole joint tissue. Obesity is acknowledged as the most influential risk factor for both the initiation and progression of OA in weight-bearing and non-weight-bearing joints. Obesity-induced OA is a newly defined phenotypic group in which chronic low-grade inflammation has a central role. Aside from persistent chronic inflammation, abnormal mechanical loading due to increased body weight on weight-bearing joints is accountable for the initiation and progression of obesity-induced OA. The current therapeutic approaches for OA are still evolving. Tissue-engineering-based strategy for cartilage regeneration is one of the most promising treatment breakthroughs in recent years. However, patients with obesity-induced OA are often excluded from cartilage repair attempts due to the abnormal mechanical demands, altered biomechanical and biochemical activities of cells, persistent chronic inflammation, and other obesity-associated factors. With the alarming increase in the number of obese populations globally, the need for an innovative therapeutic approach that could effectively repair and restore the damaged synovial joints is of significant importance for this sub-population of patients. In this review, we discuss the involvement of the systemic and localized inflammatory response in obesity-induced OA and the impact of altered mechanical loading on pathological changes in the synovial joint. Moreover, we examine the current strategies in cartilage tissue engineering and address the critical challenges of cell-based therapies for OA. Besides, we provide examples of innovative ways and potential strategies to overcome the obstacles in the treatment of obesity-induced OA.

THE TRANSLATIONAL POTENTIAL OF THIS ARTICLE

Altogether, this review delivers insight into obesity-induced OA and offers future research direction on the creation of tissue engineering-based therapies for obesity-induced OA.

DUSP5 suppresses interleukin-1β-induced chondrocyte inflammation and ameliorates osteoarthritis in rats

Osteoarthritis (OA) is a chronic degenerative joint disease characterized by deterioration of articular cartilage. Dual specificity phosphatase 5 (DUSP5), a member of the DUSP subfamily, is known to regulate cellular inflammation. Here, we studied the relationship between DUSP5 and OA by knockdown and overexpression DUSP5, respectively. Results from in vitro experiments demonstrated that the knockdown of DUSP5 increased interleukin-1β (IL-1β)-induced expression of inflammatory genes, such as inducible nitric oxide synthase (iNOS), cyclooxygenase 2 (COX2), and matrix metalloproteinases (MMPs) in chondrocytes, whereas it decreased the expression of anti-inflammatory genes, such as tissue inhibitor of metalloproteinase 3 (TIMP3) and IL-10. Conversely, the overexpression of DUSP5 suppressed the IL-1β-induced expression of iNOS, COX-2, and MMPs, and upregulated the expression of TIMP3 and IL-10. Moreover, knockdown of DUSP5 enhanced the IL-1β-induced activation of NF-κB and ERK pathways, whereas its overexpression inhibited these pathways. DUSP5 overexpression prevented cartilage degeneration in a rat OA model, while its knockdown reversed that effect. Our findings reveal that DUSP5 suppresses IL-1β-induced chondrocyte inflammation by inhibiting the NF-κB and ERK signaling pathways and ameliorates OA.

Herbal Composition LI73014F2 Alleviates Articular Cartilage Damage and Inflammatory Response in Monosodium Iodoacetate-Induced Osteoarthritis in Rats

The aim of this study was to determine the anti-osteoarthritic effects of LI73014F2, which consists of Terminalia chebula fruit, Curcuma longa rhizome, and Boswellia serrata gum resin in a 2:1:2 ratio, in the monosodium iodoacetate (MIA)-induced osteoarthritis (OA) rat model. LI73014F2 was orally administered once per day for three weeks. Weight-bearing distribution and arthritis index (AI) were measured once per week to confirm the OA symptoms. Synovial membrane, proteoglycan layer, and cartilage damage were investigated by histological examination, while synovial fluid interleukin-1β level was analyzed using a commercial kit. Levels of pro-inflammatory mediators/cytokines and matrix metalloproteinases (MMPs) in the cartilage tissues were investigated to confirm the anti-osteoarthritic effects of LI73014F2. LI73014F2 significantly inhibited the MIA-induced increase in OA symptoms, synovial fluid cytokine, cartilage damage, and expression levels of pro-inflammatory mediators/cytokines and MMPs in the articular cartilage. These results suggest that LI73014F2 exerts anti-osteoarthritic effects by regulating inflammatory cytokines and MMPs in MIA-induced OA rats.

The emerging landscape of nanotheranostic-based diagnosis and therapy for osteoarthritis

Osteoarthritis (OA) is a common degenerative disease involving numerous joint tissues and cells, with a growing rate in prevalence that ultimately results in a negative social impact. Early diagnosis, OA progression monitoring and effective treatment are of significant importance in halting OA process. However, traditional imaging techniques lack sensitivity and specificity, which lead to a delay in timely clinical intervention. Additionally, current treatments only slow the progression of OA but have not meet the largely medical need for disease-modifying therapy. In order to overcome the above-mentioned problems and improve clinical efficacy, nanotheranostics has been proposed on OA remedy, which has confirmed success in animal models. In this review, different imaging targets-based nanoprobe for early and timely OA diagnosis is first discussed. Second, therapeutic strategies delivered by nanosystem are summarized as much as possible. Their advantages and the potential for clinical translation are detailed discussed. Third, nanomedicine simultaneously combined with the imaging for OA treatment is introduced. Nanotheranostics dynamically tracked the OA treatment outcomes to timely and individually adjust therapy. Finally, future prospects and challenges of nanotechnology-based OA diagnosis, imaging and treatment are concluded and predicted. It is believed that nanoprobe and nanomedicine will become prospective in OA therapeutic revolution.

Dual functional construct containing kartogenin releasing microtissues and curcumin for cartilage regeneration

BACKGROUND

Regeneration of articular cartilage poses a tremendous challenge due to its limited self-repair capability and inflammation at the damaged site. To generate the desired structures that mimic the structure of native tissue, microtissues with repeated functional units such as cell aggregates have been developed. Multicellular aggregates of mesenchymal stem cells (MSCs) can be used as microscale building blocks of cartilage due to their potential for cell-cell contact, cell proliferation, and differentiation.

METHODS

Chondrogenic microtissues were developed through incorporation of kartogenin-releasing poly (lactic-co-glycolic acid) (PLGA) microparticles (KGN-MP) within the MSC aggregates. The chondrogenic potential of KGN-MP treated MSC aggregates was proven in vitro by studying the chondrogenic markers at the RNA level and histological analysis. In order to address the inflammatory responses at the defect site, the microtissues were delivered in vivo via an injectable, anti-inflammatory hydrogel that contained gelatin methacryloyl (GelMA) loaded with curcumin (Cur).

RESULTS

The KGN-MPs were fabricated to support MSCs during cartilage differentiation. According to real-time RT-PCR analysis, the presence of KGN in the aggregates led to the expression of cartilage markers by the MSCs. Both toluidine blue (TB) and safranin O (SO) staining demonstrated homogeneous glycosaminoglycan production throughout the KGN-MP incorporated MSC aggregates. The curcumin treatment efficiently reduced the expressions of hypertrophy markers by MSCs in vitro. The in vivo results showed that implantation of chondrogenic microtissues (KGN-MP incorporated MSC aggregates) using the curcumin loaded GelMA hydrogel resulted in cartilage tissue regeneration that had characteristic features close to the natural hyaline cartilage according to observational and histological results.

CONCLUSIONS

The use of this novel construct that contained chondrogenic cell blocks and curcumin is highly desired for cartilage regeneration.

Tougu Xiaotong capsules may inhibit p38 MAPK pathway-mediated inflammation: In vivo and in vitro verification

ETHNOPHARMACOLOGICAL RELEVANCE

Tougu Xiaotong capsules (TXC) are an herbal compound commonly used to treat osteoarthritis (OA) in China.

AIM OF THE STUDY

We attempted to verify TXC's therapeutic effects and mechanisms related to the p38 mitogen-activated protein kinase (MAPK) pathway in vivo and in vitro.

MATERIALS AND METHODS

TXC's therapeutic effects were assessed by observing cartilage degeneration and inflammatory factors in a modified Hulth's model (in vivo) and a lipopolysaccharides (LPS)-exposed cellular model (in vitro). The expression of biomarkers related to p38 MAPK pathway-mediated inflammation was also investigated.

RESULTS

TXC treatment reversed cartilage degeneration related biomarkers (ADAMTS 4, ADAMTS 5, Col I, Col V, MMP 3, MMP 9, and MMP 13) and inflammation factors (IL-1β, TNF-α, and IL-6) in both the animal and cellular OA models. Expression of p-p38 MAPK was downregulated following TXC administration, and changes to microRNAs in the cellular models were recovered. These results indicated that the p38 MAPK pathway-related mechanism may involve therapeutic effects of TXC.

CONCLUSIONS

This study verified TXC's efficacy to treat OA in vivo and in vitro and suggests that p38 MAPK pathway-related mechanisms may be involved in TXC's therapeutic effects.

Cartilage Extracellular Matrix Scaffold With Kartogenin-Encapsulated PLGA Microspheres for Cartilage Regeneration

Repair of articular cartilage defects is a challenging aspect of clinical treatment. Kartogenin (KGN), a small molecular compound, can induce the differentiation of bone marrow-derived mesenchymal stem cells (BMSCs) into chondrocytes. Here, we constructed a scaffold based on chondrocyte extracellular matrix (CECM) and poly(lactic-co-glycolic acid) (PLGA) microspheres (MP), which can slowly release KGN, thus enhancing its efficiency. Cell adhesion, live/dead staining, and CCK-8 results indicated that the PLGA(KGN)/CECM scaffold exhibited good biocompatibility. Histological staining and quantitative analysis demonstrated the ability of the PLGA(KGN)/CECM composite scaffold to promote the differentiation of BMSCs. Macroscopic observations, histological tests, and specific marker analysis showed that the regenerated tissues possessed characteristics similar to those of normal hyaline cartilage in a rabbit model. Use of the PLGA(KGN)/CECM scaffold may mimic the regenerative microenvironment, thereby promoting chondrogenic differentiation of BMSCs in vitro and in vivo. Therefore, this innovative composite scaffold may represent a promising approach for acellular cartilage tissue engineering.

DAla2GIP antagonizes H2O2-induced chondrocyte apoptosis and inflammatory factor secretion

OBJECTIVE

To investigate the protective effects of DAla2GIP against the apoptosis and inflammatory factor secretion in H₂O₂-induced chondrocyte, and explore the possible mechanisms of DAla2GIP underlying its protection.

METHODS

The chondrocytes were divided into the following four groups: Control, 300 μM H₂O₂, 100 pM DAla2GIP and 300 μM H₂O₂ + 100 pM DAla2GIP. The apoptosis of chondrocyte was measured by using mitochondrial membrane potential assay kit (JC-1) and TUNEL assay, the inflammatory factor secretion were assessed by ELISA assay, and the cellular and molecular mechanisms of DAla2GIP protection were investigated by using Real time-PCR, flow cytometry, Non- invasive calcium detection and western blotting techniques.

RESULTS

(1) DAPla2GIP prevents apoptosis of chondrocyte induced by H₂O₂. (2) DAla2GIP alleviated the inflammation of chondrocyte induced by H₂O₂. (3) DAla2GIP prevents chondrocyte apoptosis by inhibiting calcium influx of chondrocyte and regulating expression of Bcl-2 and Caspase-3induced by H₂O₂. (4) DAla2GIP inhibited the H₂O₂ mediated inflammation by up- regulating the expressions of Sox9 and Col2a1 and inhibiting PI3K/Akt/NF-κB pathway.

CONCLUSION

Our experimental results revealed that DAla2GIP prevents chondrocyte apoptosis by inhibiting calcium influx of chondrocyte and induced regulating expression of Bcl-2 and Casp ase-3by H₂O₂. Further, molecular biology experiments confirmed that DAla2GIP inhibited the H₂O₂ mediated inflammation vis up-regulating the expressions of Sox9 and Col2a1 and inhibiting PI3K/Akt/NF-κB pathway. The results demonstrate that DAla2GIP has protective properties in H₂O₂-induced chondrocyte injury, this finding shows that novel GIP analogues have the potential as a novel therapeutic for osteoarthritis patients.

Levels of matrix metalloproteinase-2 in committed differentiation of bone marrow mesenchymal stem cells induced by kartogenin

Objective

To measure the inductive effect of kartogenin on matrix metalloproteinase-2 levels during the differentiation of human bone marrow mesenchymal stem cells (hMSCs) into chondrocytes in vitro.

Methods

In vitro cultured bone marrow hMSCs were grown to the logarithmic phase and then divided into three groups: control group (0 µM kartogenin), 1 µM kartogenin group and 10 µM kartogenin group. After 72 h of culture, cell proliferation and differentiation were observed microscopically. Matrix metalloproteinase-2 (MMP-2) in the cell supernatant and type II collagen levels in the cells were detected by enzyme linked immunosorbent assay and immunofluorescence staining, respectively.

Results

Kartogenin induced the proliferation and differentiation of hMSCs. With the increase of kartogenin concentration, the level of type II collagen was increased, while the level of MMP-2 decreased.

Conclusion

These findings indicate that kartogenin can induce hMSCs to differentiate into chondrocytes, and with the increase of kartogenin concentration, degeneration of the cartilage extracellular matrix may be inhibited.

[Expression of KCNA2 in the dorsal root ganglia of rats with osteoarthritis pain induced by monoiodoacetate]

OBJECTIVE

To investigate the changes in the expression of voltage-gated potassium channel subunit KCNA2 in the dorsal root ganglion (DRG) neurons of rats with osteoarthritis (OA) pain induced by sodium monoiodoacetate and explore the mechanism.

METHODS

A total of 156 adult male Sprague-Dawley rats were randomly divided into blank control group, saline group and intra-articular monoiodoacetate injection-induced OA group. The paw withdrawal mechanical threshold (PWMT) was measured before and at 1, 2, 4, and 6 weeks after monoiodoacetate injection. At 4 weeks after the injection, the pathological changes in the knee joints were analyzed using HE staining and Safranin O-Fast Green staining, and the expression of activating transcription factor 3 (ATF-3) and inducible nitric oxide synthase (iNOS) in the DRG neurons were detected by immunofluorescence staining. The expression of Kcna2 mRNA in the DRG neurons was detected by RT-qPCR at 1, 2, 4 and 6 weeks after the injection. The expression of KCNA2 in the DRG was measured by Western blotting, and the methylation level of Kcna2 promoter region was measured by MSPCR at 4 weeks after the injection.

RESULTS

The PWMT of the rats in OA group was significantly decreased at 2, 4, and 6 weeks after the injection as compared with the baseline (P &lt; 0.05 or P &lt; 0.001) as well as the control group (P &lt; 0.05 or P &lt; 0.001). Four weeks after the intra-articular injection, fractures and defects on the surface of the articular cartilage, bone hyperplasia, and blurred tidal line were observed in the rats in OA group, but no obvious pathological changes were detected in the control or saline groups. Compared with those in the control group, the expressions of ATF-3 and iNOS were significantly increased (P &lt; 0.01) at 4 weeks after injection; the expression of Kcna2 mRNA at 2, 4 and 6 weeks and the expression of KCNA2 protein at 4 weeks were all significantly decreased (P &lt; 0.05 or P &lt; 0.01), and the methylation level of Kcna2 gene was significantly increased at 4 weeks after the injection in OA group (P &lt; 0.01).

CONCLUSIONS

The expression of KCNA2 is decreased in the DRG neurons of rats with OA pain likely as a result of enhanced methylation of Kcna2 promoter region.