Chondroitin sulfate microspheres anchored with drug-loaded liposomes play a dual antioxidant role in the treatment of osteoarthritis

Gel@CAT-L hydrogel mediates mitochondrial unfolded protein response to regulate reactive oxygen species and mitochondrial homeostasis in osteoarthritis

OBJECTIVE

This study investigates the role of Gelatin-Catalase (Gel@CAT)-L hydrogel in mediating reactive oxygen species (ROS) production and maintaining mitochondrial homeostasis through SIRT3-mediated unfolded protein response (UPRmt), while exploring its involvement in the molecular mechanism of osteoarthritis (OA).

METHODS

Self-assembled Gel@CAT-L hydrogels were fabricated and characterized using transmission electron microscopy, mechanical testing, external release property evaluation, and oxygen production measurement. Biocompatibility was assessed via live/dead cell staining and CCK8 assays. An OA mouse model was established using destabilization of the medial meniscus (DMM) surgery. X-ray and micro-CT imaging were employed to evaluate the structural integrity of the mouse knee joints, while histological staining was used to assess cartilage degeneration. Immunohistochemistry was performed to analyze the expression of proteins including Col2a1, Aggrecan, MMP13, ADAMTS5, SIRT3, PINK1, and Parkin. Multi-omics analyses-encompassing high-throughput sequencing, proteomics, and metabolomics-were conducted to identify key genes and metabolic pathways targeted by Gel@CAT-L hydrogel intervention in OA. Immunofluorescence techniques were utilized to measure ROS levels, mitochondrial membrane potential, and the expression of SIRT3, PINK1, Parkin, LYSO, LC3B, Col2a1, and MMP13 in primary mouse chondrocytes and mouse knee joints. Flow cytometry was applied to quantify ROS-positive cells. RT-qPCR analysis was conducted to determine mRNA levels of Aggrecan, Col2a1, ADAMTS5, MMP13, SIRT3, mtDNA, HSP60, LONP1, CLPP, and Atf5 in primary mouse chondrocytes, mouse knee joints, and human knee joints. Western blotting was performed to measure protein expression levels of SIRT3, HSP60, LONP1, CLPP, and Atf5 in both primary mouse chondrocytes and mouse knee joints. Additionally, 20 samples each from the control (CON) and OA groups were collected for analysis. Hematoxylin and eosin staining was used to evaluate cartilage degeneration in human knee joints. The Mankin histological scoring system quantified the degree of cartilage degradation, while immunofluorescence analyzed SIRT3 protein expression in human knee joints.

RESULTS

In vitro experiments demonstrated that self-assembled Gel@CAT-L hydrogels exhibited excellent biodegradability and oxygen-releasing capabilities, providing a stable three-dimensional environment conducive to cell viability and proliferation while reducing ROS levels. Multi-omics analysis identified SIRT3 as a key regulatory gene in mitigating OA and revealed its central role in the UPRmt pathway. Furthermore, Gel@CAT-L was confirmed to regulate mitochondrial homeostasis. Both in vitro experiments and in vivo mouse model studies confirmed that Gel@CAT-L significantly reduced ROS levels and regulated mitochondrial autophagy by activating the SIRT3-mediated UPRmt pathway, thereby improving the pathological state of OA. Clinical trials indicated downregulation of SIRT3 and UPRmt-related proteins in OA patients.

CONCLUSION

Gel@CAT-L hydrogel activates SIRT3-mediated UPRmt to regulate ROS and mitochondrial homeostasis, providing potential therapeutic benefits for OA.

Seeds-and-soil inspired hydrogel microspheres: A dual-action antioxidant and cellular therapy for reversing intervertebral disc degeneration

Intervertebral disc degeneration (IVDD) is a globally prevalent disease, yet achieving dual repair of tissue and function presents significant challenges. Considering reactive oxygen species (ROS) is a primary cause of IVDD, and given the decrease of nucleus pulposus cells (NPCs) and extensive degradation of extracellular matrix (ECM) during IVDD development, the present study, inspired by the "seeds-and-soil" strategy, has developed NPCs-loaded TBA@Gel&Chs hydrogel microspheres. These microspheres serve as exogenous supplements of NPCs and ECM analogs, replenishing "seeds" and "soil" for nucleus pulposus repair, and incorporating polyphenol antioxidant components to interrupt the oxidative stress-IVDD cycle, thereby constructing a microsphere system where NPCs and ECM support each other. Experiments proved that TBA@Gel&Chs exhibited significant extracellular ROS-scavenging antioxidant capabilities while effectively upregulating intracellular antioxidant proteins expression (Sirt3 and Sod2). This dual-action antioxidant capability effectively protects the vitality and physiological functions of NPCs. The therapeutic effects of microspheres on IVDD were also confirmed in rat models, which was found significantly restore histological structure and mechanical properties of degenerated discs. Additionally, RNA-seq results have provided evidences of antioxidant mechanism by which TBA@Gel&Chs protected NPCs from oxidative stress. Therefore, the NPCs-loaded TBA@Gel&Chs microspheres developed in this study have achieved excellent therapeutic effects, offering a paradigm using antioxidant biomaterials combined with cellular therapy for IVDD treatment.

Selenium nanozyme-crosslinked composite hydrogel for promoting cartilage regeneration in osteoarthritis via an integrated 'outside-in' and 'inside-out' strategy

Osteoarthritis (OA), a degenerative joint disease, is characterized by chondrocyte senescence, extracellular matrix (ECM) degradation, and chronic inflammation, with limited regenerative capacity. Current therapies primarily provide symptom relief, therefore highlighting the need for more effective strategies to address OA's multifactorial pathology. This study introduces an innovative selenium nanozyme-crosslinked injectable composite hydrogel (Se/PRP-OGel), which combines selenium nanoparticles (SeNPs) with platelet-rich plasma (PRP) in a biocompatible oxidized chondroitin sulfate-gelatin scaffold (OGel), to address OA through an integrated "outside-in" and "inside-out" strategy. The "outside-in" strategy utilizes SeNPs to scavenge reactive oxygen species (ROS), alleviate oxidative stress, and restore redox balance, thereby reducing extracellular damage and modulating inflammation in the OA microenvironment. Concurrently, the "inside-out" strategy utilizes PRP's bioactive growth factors (e.g., TGF-β, IGF, FGF) to rejuvenate senescent chondrocytes, stimulate proliferation, and enhance ECM synthesis, creating a regenerative microenvironment. The results showed that Se/PRP-OGel demonstrated excellent biocompatibility, reduced ROS levels, mitigated chondrocyte senescence, and balanced ECM homeostasis. Moreover, it promoted cartilage repair, pain relief, and functional restoration in an OA rat model. This dual approach interrupts OA's degenerative cycle and fosters cartilage regeneration, providing a groundbreaking solution for effective cartilage regeneration and OA treatment.

Inhibiting synovial inflammation and promoting cartilage repair in rheumatoid arthritis using a matrix metalloproteinase-binding hydrogel

Originating from synovial tissue, matrix metalloproteinase-9 (MMP-9) is a key inflammatory factor that promotes the formation and invasion of synovial pannus, leading to cartilage matrix destruction in rheumatoid arthritis (RA). However, clinical trials of systemic use of MMP-9 inhibitors are not successful due to severe side effects. Thus, locally inhibiting MMP-9 may be an alternative in the treatment of RA. Herein, we developed MMP-9 binding peptide-functionalized copper sulfide nanoparticles (CuS-T NPs) and delivered them with light crosslinking chondroitin sulfate methacrylate (ChSMA) hydrogel. We found that the CuS NP-doped hydrogels could inhibit synovial inflammation. Specifically, the CuS-T/ChSMA hydrogel could rapidly bind to MMP-9, thereby inhibiting not only the invasion of RA fibroblast-like synoviocytes but also the polarization of inflammatory M1-type macrophages. The underlying mechanism involved the inhibition of the MAPK pathway. Moreover, ChSMA hydrogel provided a cartilage matrix-mimic microenvironment and synergistically promoted the generation of collagen-2 and aggrecan with CuS NPs. In an adjuvant-induced arthritis mouse model, the intra-articular injection of ChSMA/CuS-T hydrogel significantly alleviated synovial inflammation and accelerated cartilage repair without causing any side effects, killing two birds with one stone in RA therapy.

Microfluidic-engineering Prussian blue hydrogel microspheres for enhanced osteoarthritis antioxidant therapy

Osteoarthritis (OA), a degenerative joint disorder and leading cause of global disabilty, imposes substantial societal and familial burdens. Current antioxidant therapies for OA are hindered by poor targeting and transient efficacy, failing to address the excessive reactive oxygen species (ROS)-driven pathogenesis. Herein, we innovatively integrate Prussian blue (PB) nanozymes with alginate-hyaluronic acid (HA) hydrogel microspheres through microfluidic engineering, creating the injectable AlgHA@PB platform that synergizes dual therapeutic mechanisms: ROS scavenging and oxygen generation via PB nanozymes, and sustained intra-articular retention and mechanical compatibility enabled by the hydrogel microsphere architecture. In vitro studies demonstrated that AlgHA@PB scavenged all of intracellular ROS while continuously releasing oxygen within. In a rat OA model, AlgHA@PB exhibited prolonged joint retention and reduced cartilage degeneration. Critically, the microspheres demonstrated a stable friction coefficient, enabling smooth intra-articular motion without mechanical irritation. This study establishes AlgHA@PB as a multifunctional OA therapeutic platform that integrates antioxidative defense, anti-inflammatory action, and biomechanical compatibility. The microfluidic-engineered design ensures scalable production, aligning with clinical translation requirements.

Nicotinamide Adenine Dinucleotide-Loaded Lubricated Hydrogel Microspheres with a Three-Pronged Approach Alleviate Age-Related Osteoarthritis

Chondrocyte senescence, synovitis, and decreased level of lubrication play pivotal roles in the pathogenesis of age-related osteoarthritis (AROA). However, there are currently no effective therapeutic interventions capable of altering the progression of OA until it reaches advanced stages, necessitating joint replacement. In this study, lubricious and drug-loaded hydrogel microspheres were designed and fabricated by utilizing microfluidic technology for radical polymerization of chondroitin sulfate methacrylate and incorporating nicotinamide adenine dinucleotide (NAD)-loaded liposomes modified with lactoferrin that are positively charged. Mechanical, tribological, and drug release analyses demonstrated enhanced lubrication properties and an extended drug dissemination time for the NAD@NPs@HM microspheres. In vitro assays unveiled the ability of NAD@NPs@HM to counteract chondrocyte senescence. RNA sequencing analysis, untargeted metabolomics analysis, and in vitro experiments on macrophages revealed that NAD@NPs@HM can regulate the metabolic reprogramming of synovial macrophages, promoting their repolarization from the M1 to M2 phenotype, thereby alleviating synovitis. Intra-articular injection of NAD@NPs@HM in aged mice reduced the mechanisms associated with AROA. These results suggest that NAD@NPs@HM may provide extended drug release, improved joint lubrication leading to better gait, and attenuation of AROA pathogenic processes, indicating its potential as a therapeutic approach for AROA.

A review of polysaccharide-based hydrogels: From structural modification to biomedical applications

Hydrogels prepared from natural polysaccharide possess excellent biocompatibility and adjustable physical properties similar to those of natural extracellular matrices, and have thus been extensively utilized in the biomedical field. However, natural polysaccharide hydrogels have limited applications owing to their performance deficiencies. For instance, poor mechanical properties restrict their application in tissue engineering, while instability hinders their adaptation to complex and dynamic physiological environments. The chemical modification of polysaccharides and their combination with other matrix materials, such as proteins, synthetic polymers, and inorganic materials, to form hybrid hydrogels have been utilized to enhance the properties of polysaccharide-based hydrogels for diverse applications. This paper reviews comprehensively and systematically the methods of natural polysaccharide modification and describes in detail the various types of polysaccharide-based hydrogels. Additionally, the applications of these hydrogels in drug delivery, wound dressings, tissue engineering and biosensing are summarized. Finally, the challenges and future directions for the application of polysaccharide-based hydrogels are envisioned to provide a reference for the design of novel multifunctional hydrogels.

Hyaluronic acid composite hydrogel with enhanced lubrication and controllable drug release for the mitigation of osteoarthritis

Excessive inflammation, overexpressed reactive oxygen species (ROS), degradation of the extracellular matrix, and high friction aggravate osteoarthritis (OA). Intra-articular injection for local drug delivery in the joint cavity enhances drug retention duration for OA treatment. Nevertheless, it remains a challenge to attenuate OA by thoroughly modulating the joint microenvironment, achieving controlled drug release, and enhancing lubrication. This study develops hyaluronic acid (HA) composite hydrogels, infused with gelatin microspheres containing a drug, utilizing dynamic interactions between phenylboronic acid and catechol to modulate the microenvironment by scavenging ROS, facilitating controlled drug release, and improving lubrication to mitigate OA. The composite hydrogels can be injected by intra-articular injection due to the shear-thinning properties, demonstrating broad ROS scavenging capacity and matrix metalloproteinase-9 responsive drug release. Both the in vitro and in vivo experiments prove the protective efficacy of the composite hydrogels against the degradation of cartilage matrix. Additionally, the hydrogels can offer efficient lubrication and effectively attenuate OA. Thus, the injectable HA composite hydrogels demonstrated potential in the management of OA.

Reduce electrical overload via threaded Chinese acupuncture in nerve electrical therapy

Bioelectrical stimulation is a powerful technique used to promote tissue regeneration, but it can be hindered by an "electrical overload" phenomenon in the core region of stimulation. We develop a threaded microneedle electrode system that protects against "electrical overload" by delivering medicinal hydrogel microspheres into the core regions. The threaded needle body is coated with polydopamine and chitosan to enhance the adhesion of microspheres, which are loaded into the threaded grooves, allowing for their stereoscopic release in the core regions. After the electrode is inserted, the microspheres can be delivered three-dimensionally through physical swelling and the shear-thinning effect of chitosan, mitigating the electrical damage. Microspheres are designed to release alkylated vitamin B12 and vitamin E, providing antioxidant and cell protection effects upon in-situ activation, reducing reactive oxygen species (ROS) by 72.8 % and cell death by 59.5 %. In the model of peripheral nerve injury, the electrode system improves the overall antioxidant capacity by 78.5 % and protects the surrounding cells. Additionally, it leads to an improved nerve conduction velocity ratio of 41.9 % and sciatic nerve function index of 12.1 %, indicating enhanced neuroregeneration. The threaded microneedle electrode system offers a promising approach for nerve repair by inhibiting "electrical overload", potentially improving outcomes for tissue regeneration.

Liposome-Based Interventions in Knee Osteoarthritis

Osteoarthritis (OA) is the most common degenerative disease of the joints, causing significant disability and socio-economic burden in the aging population. Simultaneously, however, it is a common occurrence in younger individuals, initiated by joint injuries or obesity alongside other factors. Intravenous and oral pharmaceutical OA management have both been associated with systemic adverse effects, thereby resulting in a growing interest in intra-articular (IA) treatment. IA-administered drugs circumvent the requirement for high dosage, offering immediate access to the site of interest while minimizing any unfavorable effects. Nonetheless, IA-injected drugs, administered in their free form, present low retention time in the knee joint raising the need for multiple injection dosage regimens, while their capability to target the cartilage or specific cell populations is limited. Liposomes, due to their unique characteristics and tunable nature, have proven to be excellent candidates for the management of knee OA. This review explores the last decade's research on the efficacy of various IA liposomal formulations, investigating their multifaceted properties as pharmaceutical carriers, lubricating agents, and a basis for combinatorial approaches paving the way to novel treatment solutions for OA.

Preparation of hydrogel microsphere and its application in articular cartilage injury

In recent years, hydrogel microspheres have garnered significant attention due to their unique structure and functionality, demonstrating substantial potential in articular cartilage injury repair. This paper provides a comprehensive overview of current strategies for cartilage injury repair and summarizes the materials and preparation methods of hydrogel microspheres. Furthermore, it highlights the multiple roles of hydrogel microspheres in cartilage repair, including inflammation control, regulation of chondrocyte metabolism, drug and cell delivery, lubrication improvement, and recruitment of endogenous stem cells. Finally, the paper discusses the application prospects of hydrogel microspheres, identifies current limitations and challenges, and offers insights to guide future research and practical applications in cartilage injury repair.

Reprogramming Macrophage Phenotype Using a Reactive Oxygen Species-Responsive Liposome Delivery System for Inflammation Microenvironment Remodeling and Osteoarthritis Treatment

The progression of osteoarthritis (OA) is closely linked to synovial inflammation caused by an imbalance between M1 and M2 macrophages. To tackle this problem, we developed a liposome responsive to reactive oxygen species (ROS), modified with folic acid ligands to target M1-polarized macrophages, and loaded with the anti-inflammatory agent dimethyl fumarate (DMF). This liposome-based drug delivery system was designed to reprogram macrophage phenotype to remodel the inflammatory microenvironment in the joint cavity and alleviate OA degeneration. The liposome we prepared had a suitable size and negative zeta potential, with uniform size, good stability in aqueous solution, and excellent biocompatibility. Laboratory tests showed that these DMF-filled liposomes notably decreased high levels of ROS in M1-type macrophages and shifted macrophage polarization via the Nrf2/HO-1 pathway, which in turn lessened inflammation in chondrocytes and averted their apoptosis. Additionally, animal studies demonstrated that liposomes containing DMF exhibited notable anti-inflammatory properties, significantly reduced synovial inflammation, safeguarded injured cartilage, reversed changes in subchondral bone, and effectively slowed the progression of osteoarthritis in a mouse model induced by anterior cruciate ligament transection (ACLT). Therefore, ROS-responsive liposomes targeting M1-polarized macrophages represent a promising and valuable approach for OA treatment.

A shear-responsive and lubricating hyaluronic acid-chondroitin sulfate-decellularized matrix hydrogel for articular cartilage regeneration

The high-dynamic, high-loading environment in the joint cavity puts urgent demands on the cartilage regenerative materials with shear responsiveness and lubrication. Here, a new type of injectable hydrogel composed of oxidized hyaluronic acid (OHA), adipic dihydrazide-grafted hyaluronic acid (HA-ADH), oxidized chondroitin sulfate (OChs), and decellularized extracellular matrix methacrylate (dECMMA) was fabricated. The aldehyde groups in OHA and OChs reacted with the amino groups in HA-ADH to form a dynamic hydrogel, which was then covalently crosslinked with dECMMA to create a dual-crosslinked hydrogel with sufficient mechanical strength. This hydrogel possesses injectability and self-healing capabilities, making it suitable for use in the dynamic and high-frequency loading environment of joint cartilage. dECMMA fibers in this hydrogel could be oriented and aligned under certain shear forces, together with the biopolymers, giving the hydrogel lubricity and low strain-liquid transition properties that do not interfere with the daily mobility of the joint. In vitro and in vivo experiments showed that the hydrogel has sufficient tissue adhesion and excellent biocompatibility, promotes chondrocyte migration, and induces stem cell differentiation. The animal experiments demonstrated that the hydrogel promoted cartilage repair, and the lubricating effect of the newborn cartilage was close to that of normal cartilage.

Free radical synthesis of succinic anhydride grafted poly(lactic acid) porous templates for sustained drug delivery in the buffer media

Poly(lactic) (PLA) is a biodegradable material obtained from renewable resources and is recognized as a safe biopolymer by the Food and Drug Administration. PLA expresses excellent mechanical and moldability attributes nonetheless poor elasticity/functionality limits its widespread utilization. One approach to compensate for this is chemical surface modification through free radical grafting with small organic molecules like maleic anhydride (MA). The study undertakes the synthesis of succinic anhydride (SA)-grafted PLA [SA-g-PLA] films for sustained drug delivery applications. The entrapped porogen was leached out under alkaline treatment to make the PLA film porous by creating channels/cavities for drug inclusion. The success of the surface treatment of PLA-based films was investigated using specific chemical analyses. The results demonstrated the hydrophilic nature (water contact angle of 31°) of the SA-g-PLA films for the prevalence of MA (1780 cm-1) and methylamine (340-640 cm-1) congeners as expressed under FTIR analysis. The SA-g-PLA film expressed a crystallinity of 72.41 % and a melting temperature of 201.9 °C. The SA-g-PLA film exhibited pH-responsive streptomycin sulfate uptake (pH 6.5) and release (pH 7.4) profiles and obeyed first-order kinetics. The SA-g-PLA porous films with potential modification would be a sustainable and biocompatible candidate for drug delivery applications.

Injectable Chondroitin Sulfate Microspheres with Gallic Acid-Magnesium MOF for Anti-Inflammatory and Cartilage Degeneration Alleviation in Osteoarthritis Treatment

Inflammation and cartilage degeneration are critical challenges in osteoarthritis (OA) treatment. Achieving sustained drug efficacy while mitigating the adverse effects of inflammation and reactive oxygen species remains a significant challenge. This study synthesizes a gallic acid-magnesium (GA-Mg) metal-organic framework (MOF) as a drug carrier for puerarin (PA). The PA-loaded GA-Mg MOF (pGM) is encapsulated within chondroitin sulfate methacrylate, forming monodisperse hybrid microspheres (CM@pGM) under ultraviolet light using microfluidic technology. The pGM is physically confined within the microspheres through a network of structural obstructions and noncovalent interactions. During degradation, GA and Mg2+ ions release from pGM, improving the inflammatory microenvironment of the articular cavity and mitigating oxidative stress. The sustained release of Mg2+ and PA supports chondrocyte anabolism and facilitates cartilage repair. In vitro studies confirm that injectable microspheres extend the drug release period to over 2 weeks. In vivo experiments demonstrate that CM@pGM significantly reduces osteophyte formation, alleviates degenerative changes in articular cartilage, and delays OA progression. In conclusion, CM@pGM, as a drug delivery platform that ameliorates the inflammatory microenvironment, alleviates oxidative stress, and promotes cartilage repair, holds significant potential for OA treatment.

Lubrication for Osteoarthritis: From Single-Function to Multifunctional Lubricants

Osteoarthritis (OA) is a common degenerative joint disease that progressively destroys articular cartilage, leading to increased joint friction and severe pain. Therefore, OA can be treated by restoring the lubricating properties of cartilage. In this study, recent advances in lubricants for the treatment of OA are reviewed for both single-function and multifunctional lubricants. Single-function lubricants mainly include glycosaminoglycans, lubricin, and phospholipids, whereas multifunctional lubricants are composed of lubricating and anti-inflammatory bifunctional hydrogels, stem cell-loaded lubricating hydrogels, and drug-loaded lubricating nanoparticles. This review emphasizes the importance of restoring joint lubrication capacity for the treatment of OA and explores the structural features, lubrication properties, and role of these lubricants in modulating intracellular inflammatory responses and metabolism. Current challenges and future research directions in this field are also discussed, with the aim of providing a scientific basis and new ideas for the clinical treatment of OA.

Treatment of rheumatoid arthritis using dual-targeted and dual-response intelligent micelles: a "three birds with one stone" strategy

Rheumatoid arthritis (RA) is an autoimmune disease whose pathophysiology is closely related to inflammation-associated cells and the microenvironment of inflamed joints. This study aimed to develop dual-targeted, reactive oxygen species (ROS)/pH dual-responsive, size-shrinkable intelligent micelles targeting M1 macrophages and fibroblast-like synoviocytes (FLSs) to enhance drug efficacy and safety. These micelles were surface-modified with PEG5000 to prolong their circulation time in the bloodstream and hide the targeting molecules. The optimized particle size allowed the micelles to reside in inflamed joints through the extravasation through leaky vasculature and subsequent inflammatory cell-mediated sequestration (ELVIS) effect. The high concentration of ROS in the inflamed joint caused the detachment of the hydration layer of PEG5000, which was then specifically recognized and internalized by M1 macrophages and FLSs via CD44 receptor-mediated endocytosis, ultimately allowing the release of the drug into the acidic environment of the inflamed cells. The in vivo and in vitro evaluation showed that micelles precisely targeted the inflammatory site, thus inhibiting the expression of pro-inflammatory cytokines, reversing the polarization of M1 macrophages, inhibiting the invasion and migration of proliferative FLSs, and, at the same time, regulating the seeds and soils of RA. This "three birds with one stone" approach targeted multiple aspects of RA, opening new horizons for comprehensive treatment of RA.

Therapeutic Controlled Release Strategies for Human Osteoarthritis

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

Facile fabrication of nano-bioactive glass functionalized blended hydrogel with nucleus pulposus-derived MSCs to improve regeneration potential in treatment of disc degeneration by in vivo rat model

Orthopaedic medicine often treats intervertebral disc degeneration (IVDD), which is caused by nucleus pulposus (NP) tissue damage and mechanical stress. Bioactive glasses (BGs), widely used for bone regeneration, can incorporate therapeutic ions into their network. Manganese (Mn) activates human osteoblast integrins, proliferation, and spreading. The CMnBGNPs-NPMSCs are carboxymethyl cellulose hydrogels functionalized with MnBGsNPs and NP-derived mesenchymal stem cells to treat IVDD. To ensure stability and biocompatibility of CMnBGNPs-NPMSCs were characterized for rheological properties like gelation time and swelling ratio. Gene expression analysis of PAX1, FOXF1, CA12, HBB, and OVOS2 via qRT-PCR further assessed the hydrogel's characteristics. Rat models with induced IVDD had hydrogel-MSC composite injected into their intervertebral discs for in vivo studies. Histological examination, immunohistochemical staining for inflammation and disc regeneration markers, and disc height assessments assessed therapeutic efficacy. CMnBGNPs-NPMSCs show promising results for IVDD treatment, offering a novel therapeutic strategy with clinical implications for degenerative disc diseases.

Controlled Stimulus-Responsive Delivery Systems for Osteoarthritis Treatment

Osteoarthritis (OA), a common and disabling degenerative joint disease, affects millions of people worldwide and imposes a considerable burden on patients and society due to its high prevalence and economic costs. The pathogenesis of OA is closely related to the progressive degradation of articular cartilage and the accompany inflammation; however, articular cartilage itself cannot heal and modulate the inflammation due to the lack of nerves, blood vessels, and lymph-vessels. Therefore, reliable and effective methods to treat OA remain highly desired. Local administration of drugs or bioactive materials by intra-articular injection of the delivery system represents a promising approach to treat OA, especially considering the prolonged joint retention, cartilage or chondrocytes targeting, and stimuli-responsive release to achieve precision OA therapy. This article summarizes and discusses the advances in the currently used delivery systems (nanoparticle, hydrogel, liposome, and microsphere) and then focuses on their applications in OA treatment from the perspective of endogenous stimulus (redox reactions, pH, enzymes, and temperature) and exogenous stimulus (near-infrared, magnetic, and ultrasound)-responsive release. Finally, the challenges and potential future directions for the development of nano-delivery systems are summarized.

Recent advancements in microspheres mediated targeted delivery for therapeutic interventions in osteoarthritis

Osteoarthritis (OA), affecting around 240 million people globally is a major threat. Currently, available drugs only treat the symptoms of OA; they cannot reverse the disease's progression. The delivery of drugs to afflicted joints is challenging because of poor vasculature of articular cartilage results in their less bioavailability and quick elimination from the joints. Recently approved drugs such as KGN and IL-1 receptor antagonists also encounter challenges because of inadequate formulations. Therefore, microspheres could be a potential player for the intervention of OA owing to its excellent physicochemical properties. This review primarily focuses on microspheres of distinct biomaterials acting as cargo for drugs and biologicals via different delivery routes in the effective management of OA. Microspheres can improve the efficacy of therapeutics by targeting strategies at specific body locations. This review also highlights clinical trials conducted in the last few decades.

GAPDH-Silence Microsphere via Reprogramming Macrophage Metabolism and eradicating Bacteria for Diabetic infection bone regeneration

Macrophage metabolism dysregulation, which is exacerbated by persistent stimulation in infectious and inflammatory diseases, such as diabetic infectious bone defects (DIBD), eventually leads to the failure of bone repair. Here, we have developed an injectable, macrophage-modulated GAPDH-Silence drug delivery system. This microsphere comprises chondroitin sulfate methacrylate (CM) and methacrylated gelatin (GM), while the dimethyl fumarate (DMF)-loaded liposome (D-lip) is encapsulated within the microsphere (CM@GM), named D-lip/CM@GM. Triggered by the over-expressed collagenase in DIBD, the microspheres degrade and release the encapsulated D-lip. D-lip could modulate metabolism by inhibiting GAPDH, which suppresses the over-activation of glycolysis, thus preventing the inflammatory response of macrophages in vitro. While beneficial for macrophages, D-lip/CM@GM is harmful to bacteria. GAPDH, while crucial for glycolysis of staphylococcal species (S. aureus), can be effectively countered by D-lip/CM@GM. We are utilizing existing drugs in innovative ways to target central metabolism for effective eradication of bacteria. In the DIBD model, our results confirmed that the D-lip/CM@GM enhanced bacteria clearance and reprogrammed dysregulated metabolism, thereby significantly improving bone regeneration. In conclusion, this GAPDH-Silence microsphere system may provide a viable strategy to promote diabetic infection bone regeneration.

Cell-recruited microspheres for OA treatment by dual-modulating inflammatory and chondrocyte metabolism

Osteoarthritis (OA) is a degenerative disease potentially exacerbated due to inflammation, cartilage degeneration, and increased friction. Both mesenchymal stem cells (MSCs) and pro-inflammatory macrophages play important roles in OA. A promising approach to treating OA is to modify multi-functional hydrogel microspheres to target the OA microenvironment and structure. Arginyl-glycyl-aspartic acid (RGD) is a peptide widely used in bioengineering owing to its cell adhesion properties, which can recruit BMSCs and macrophages. We developed TLC-R, a microsphere loaded with TGF-β1-containing liposomes. The recruitment effect of TLC-R on macrophages and BMSCs was verified by in vitro experiments, along with its function of promoting chondrogenic differentiation of BMSCs. And we evaluated the effect of TLC-R in balancing OA metabolism in vitro and in vivo. When TLC-R was co-cultured with BMSCs and lipopolysaccharide (LPS)-treated macrophages, it showed the ability to recruit both cells in substantial numbers. As the microspheres degraded, TGF-β1 and chondroitin sulfate (ChS) were released to promote chondrogenic differentiation of the recruited BMSCs, modulate chondrocyte metabolism and inhibit inflammation induced by the macrophages. Furthermore, in vivo analysis showed that TLC-R restored the narrowed space, reduced osteophyte volume, and improved cartilage metabolic homeostasis in OA rats. Altogether, TLC-R provides a comprehensive and novel solution for OA treatment by dual-modulating inflammatory and chondrocyte metabolism.

Research Progress on Injectable Microspheres as New Strategies for the Treatment of Osteoarthritis Through Promotion of Cartilage Repair

Osteoarthritis (OA) is a degenerative disease caused by a variety of factors with joint pain as the main symptom, including fibrosis, chapping, ulcers, and loss of cartilage. Traditional treatment can only delay the progression of OA, and classical delivery system have many side effects. In recent years, microspheres have shown great application prospects in the field of OA treatment. Microspheres can support cells, reproduce the natural tissue microenvironment in vitro and in vivo, and are an efficient delivery system for the release of drugs or biological agents, which can promote cell proliferation, migration, and differentiation. Thus, they have been widely used in cartilage repair and regeneration. In this review, preparation processes, basic materials, and functional characteristics of various microspheres commonly used in OA treatment are systematically reviewed. Then it is introduced surface modification strategies that can improve the biological properties of microspheres and discussed a series of applications of microsphere functionalized scaffolds in OA treatment. Finally, based on bibliometrics research, the research development, future potential, and possible research hotspots of microspheres in the field of OA therapy is systematically and dynamically evaluated. The comprehensive and systematic review will bring new understanding to the field of microsphere treatment of OA.

A multifunctional injectable, self-healing, and adhesive hydrogel-based wound dressing stimulated diabetic wound healing with combined reactive oxygen species scavenging, hyperglycemia reducing, and bacteria-killing abilities

The proficient handling of diabetic wounds, a rising issue coinciding with the global escalation of diabetes cases, poses significant clinical difficulties. A range of biofunctional dressings have been engineered and produced to expedite the healing process of diabetic wounds. This study proposes a multifunctional hydrogel dressing for diabetic wound healing, which is composed of Polyvinyl Alcohol (PVA) and N1-(4-boronobenzyl)-N3-(4-boronophenyl)-N1, N1, N3, N3-teramethylpropane-1, 3-diaminium (TSPBA), and a dual-drug loaded Gelatin methacryloyl (GM) microgel. The GM microgel is loaded with sodium fusidate (SF) and nanoliposomes (LP) that contain metformin hydrochloride (MH). Notably, adhesive and self-healing properties the hydrogel enhance their therapeutic potential and ease of application. In vitro assessments indicate that SF-infused hydrogel can eliminate more than 98% of bacteria within 24 h and maintain a sustained release over 15 days. Additionally, MH incorporated within the hydrogel has demonstrated effective glucose level regulation for a duration exceeding 15 days. The hydrogel demonstrates a sustained ability to neutralize ROS throughout the entire healing process, predominantly by electron donation and sequestration. This multifunctional hydrogel dressing, which integrated biological functions of efficient bactericidal activity against both MSSA and MRSA strains, blood glucose modulation, and control of active oxygen levels, has successfully promoted the healing of diabetic wounds in rats in 14 days. The hydrogel dressing exhibited significant effectiveness in facilitating the healing process of diabetic wounds, highlighting its considerable promise for clinical translation.

Nano-Micron Combined Hydrogel Microspheres: Novel Answer for Minimal Invasive Biomedical Applications

Hydrogels, key in biomedical research for their hydrophilicity and versatility, have evolved with hydrogel microspheres (HMs) of micron-scale dimensions, enhancing their role in minimally invasive therapeutic delivery, tissue repair, and regeneration. The recent emergence of nanomaterials has ushered in a revolutionary transformation in the biomedical field, which demonstrates tremendous potential in targeted therapies, biological imaging, and disease diagnostics. Consequently, the integration of advanced nanotechnology promises to trigger a new revolution in the realm of hydrogels. HMs loaded with nanomaterials combine the advantages of both hydrogels and nanomaterials, which enables multifaceted functionalities such as efficient drug delivery, sustained release, targeted therapy, biological lubrication, biochemical detection, medical imaging, biosensing monitoring, and micro-robotics. Here, this review comprehensively expounds upon commonly used nanomaterials and their classifications. Then, it provides comprehensive insights into the raw materials and preparation methods of HMs. Besides, the common strategies employed to achieve nano-micron combinations are summarized, and the latest applications of these advanced nano-micron combined HMs in the biomedical field are elucidated. Finally, valuable insights into the future design and development of nano-micron combined HMs are provided.

Cyaonoside A-loaded composite hydrogel microspheres to treat osteoarthritis by relieving chondrocyte inflammation

Cyaonoside A (CyA), derived from the natural Chinese medicine, Cyathula officinalis Kuan, which was for a long time used to treat knee injuries and relieve joint pain in traditional Chinese medicine, showed an unclear mechanism for protecting cartilage. In addition, CyA was poorly hydrosoluble and incapable of being injected directly into the joint cavity, which limited its clinical application. This study reveals that CyA resisted IL-1β-mediated chondrogenic inflammation and apoptosis. Next, transcriptome sequencing is used to explore the potential mechanisms underlying CyA regulation of MSC chondrogenic differentiation. Based on these findings, CyA-loaded composite hydrogel microspheres (HLC) were developed and they possessed satisfactory loading efficiency, a suitable degradation rate and good biocompatibility. HLC increased chondrogenic anabolic gene (Acan, COL2A, and SOX9) expression, while downregulating the expression of the catabolic marker MMP13 in vitro. In the osteoarthritis mouse model, HLC demonstrated promising therapeutic capabilities by protecting the integrity of articular cartilage. In conclusion, this study provides insights into the regulatory mechanisms of CyA for chondrocytes and proposes a composite hydrogel microsphere-based advanced therapeutic strategy for osteoarthritis.

Liquiritin reduces chondrocyte apoptosis through P53/PUMA signaling pathway to alleviate osteoarthritis

AIMS

The main pathological features of osteoarthritis (OA) include the degeneration of articular cartilage and a decrease in matrix synthesis. Chondrocytes, which contribute to matrix synthesis, play a crucial role in the development of OA. Liquiritin, an effective ingredient extracted from Glycyrrhiza uralensis Fisch., has been used for over 1000 years to treat OA. This study aims to investigate the impact of liquiritin on OA and its underlying mechanism.

MATERIALS AND METHODS

Gait and hot plate tests assessed mouse behavior, while Micro-CT and ABH/OG staining observed joint morphological changes. The TUNEL kit detected chondrocyte apoptosis. Western blot and immunofluorescence techniques determined the expression levels of cartilage metabolism markers COL2 and MMP13, as well as apoptosis markers caspase3, bcl2, P53, and PUMA. KEGG analysis and molecular docking technology were used to verify the relationship between liquiritin and P53.

KEY FINDINGS

Liquiritin alleviated pain sensitivity and improved gait impairment in OA mice. Additionally, we found that liquiritin could increase COL2 levels and decrease MMP13 levels both in vivo and in vitro. Importantly, liquiritin reduced chondrocyte apoptosis induced by OA, through decreased expression of caspase3 expression and increased expression of bcl2 expression. Molecular docking revealed a strong binding affinity between liquiritin and P53. Both in vivo and in vitro studies demonstrated that liquiritin suppressed the expression of P53 and PUMA in cartilage.

SIGNIFICANCE

This indicated that liquiritin may alleviate OA progression by inhibiting the P53/PUMA signaling pathway, suggesting that liquiritin is a potential strategy for the treatment of OA.

Injectable hydrogels as promising in situ therapeutic platform for cartilage tissue engineering

Injectable hydrogels are gaining prominence as a biocompatible, minimally invasive, and adaptable platform for cartilage tissue engineering. Commencing with their synthesis, this review accentuates the tailored matrix formulations and cross-linking techniques essential for fostering three-dimensional cell culture and melding with complex tissue structures. Subsequently, it spotlights the hydrogels' enhanced properties, highlighting their augmented functionalities and broadened scope in cartilage tissue repair applications. Furthermore, future perspectives are advocated, urging continuous innovation and exploration to surmount existing challenges and harness the full clinical potential of hydrogels in regenerative medicine. Such advancements are crucial for validating the long-term efficacy and safety of hydrogels, positioning them as a promising direction in regenerative medicine to address cartilage-related ailments.

Microenvironment-responsive bilayer hydrogel microspheres with gelatin-shell for osteoarthritis treatment

Osteoarthritis is a long-term degenerative condition of the joints that is characterized by the breakdown of cartilage and inflammation of the synovial membrane. The presence of an inflammatory microenvironment and the degradation of the extracellular matrix produced by chondrocytes leads to the aggravation of cartilage injury, hindering the treatment of osteoarthritis. A promising approach to address this issue is to apply a combined strategy that is sensitive to the specific conditions in osteoarthritic joints and possesses properties that can reduce inflammation and promote cartilage healing. Here, inspired by the structure of chocolate-covered peanuts, we developed an injectable, environment-responsive bilayer hydrogel microsphere using microfluidics technology. The microsphere applied chondroitin sulfate methacryloyl (ChsMA) as its core and was coated with a methacryloyl gelatin (GelMA) shell that was loaded with celecoxib (CLX) liposomes (ChsMA+CLX@Lipo@GelMA). CLX was released from the liposomes when the GelMA shell rapidly degraded in response to the osteoarthritic microenvironment and suppressed the generation of inflammatory agents, demonstrating a beneficial impact of the outer shell in reducing inflammation. While the inner methacryloyl microsphere core degraded, chondroitin sulfate was released to promote chondrocyte anabolism and facilitate cartilage repair. Thus, the synthesized bilayer hydrogel microspheres hold great potential for treating osteoarthritis.

Intra-articular injection of ascorbic acid enhances microfracture-mediated cartilage repair

Previous studies have confirmed that ascorbic acid (AA) can promote cartilage repair and improve cartilage differentiation in bone marrow mesenchymal stem cells. However, the use of microfracture (MFX) combined with AA to repair cartilage damage has not been studied. This study established a rabbit animal model and treated cartilage injury with different concentrations of AA combined with MFX. Macroscopic observations, histological analysis, immunohistochemical analysis and reverse transcription quantitative polymerase chain reaction analysis of TGF-β, AKT/Nrf2, and VEGF mRNA expression were performed. The results showed that intra-articular injection of AA had a positive effect on cartilage repair mediated by microfractures. Moreover, 10 mg/ml AA was the most effective at promoting cartilage repair mediated by microfractures. Intra-articular injection of AA promoted the synthesis of type II collagen and the formation of glycosaminoglycans by downregulating the mRNA expression of TGF-β and VEGF. In summary, this study confirmed that AA could promote cartilage repair after MFX surgery.

Reprogramming macrophages via immune cell mobilized hydrogel microspheres for osteoarthritis treatments

Regulating macrophage activation precisely is crucial in treating chronic inflammation in osteoarthritis (OA). However, the stable pro-inflammatory state and deep distribution of macrophages in vivo pose a great challenge to treatment. In this study, inspired by the innate immune, immune cell mobilized hydrogel microspheres were constructed by microfluidic methods and load chemokines, macrophage antibodies and engineered cell membrane vesicles (sEVs) via covalent and non-covalent junctions. The immune cell mobilized hydrogel microspheres, based on a mixture of streptavidin grafted hyaluronic acid methacrylate (HAMA-SA) and Chondroitin sulfate methacrylate (ChSMA) microspheres (HCM), can recruit, capture and reprogram proinflammatory macrophages in the joint cavity to improve the joint inflammatory microenvironment. In vitro experiments demonstrated that immune cell mobilized hydrogel microspheres had excellent macrophage recruitment, capture, and reprogramming abilities. Pro-inflammatory macrophages can be transformed into anti-inflammatory macrophages with an efficiency of 88.5 %. Animal experiments also revealed significant reduction in synovial inflammation and cartilage matrix degradation of OA. Therefore, the immune cell mobilized hydrogel microspheres may be an effective treatment of OA inflammation for the future.

Hydrogel-mediated delivery of platelet-derived exosomes: Innovations in tissue engineering

In this scholarly review, we conduct a thorough examination of the significant role played by platelet-derived exosomes (Plt-Exos) and hydrogels in the fields of tissue engineering and regenerative medicine. Our detailed investigation highlights the central involvement of Plt-Exos in various physiological and pathological processes, underscoring their potential contributions to diverse areas such as wound healing, neural rejuvenation, and cancer progression. Despite the promising therapeutic aspects, the notable variability in the isolation and characterization of pEVs underscores the need for a more rigorous and standardized methodology. Shifting our focus to hydrogels, they have emerged as promising biomaterials relevant to tissue engineering and regenerative medicine. Their unique characteristics, especially their chemical and physical adaptability, along with the modifiability of their biochemical properties, make hydrogels a captivating subject. These exceptional features open avenues for numerous tissue engineering applications, facilitating the delivery of essential growth factors, cytokines, and microRNAs. This analysis explores the innovative integration of Plt-Exos with hydrogels, presenting a novel paradigm in tissue engineering. Through the incorporation of Plt-Exos into hydrogels, there exists an opportunity to enhance tissue regeneration endeavors by combining the bioactive features of Plt-Exos with the restorative capabilities of hydrogel frameworks. In conclusion, the cooperative interaction between platelet-derived exosomes and hydrogels indicates a promising path in tissue engineering and regenerative medicine. Nevertheless, the successful execution of this approach requires a deep understanding of molecular dynamics, coupled with a dedication to refining isolation techniques.

Injectable smart stimuli-responsive hydrogels: pioneering advancements in biomedical applications

Hydrogels have established their significance as prominent biomaterials within the realm of biomedical research. However, injectable hydrogels have garnered greater attention compared with their conventional counterparts due to their excellent minimally invasive nature and adaptive behavior post-injection. With the rapid advancement of emerging chemistry and deepened understanding of biological processes, contemporary injectable hydrogels have been endowed with an "intelligent" capacity to respond to various endogenous/exogenous stimuli (such as temperature, pH, light and magnetic field). This innovation has spearheaded revolutionary transformations across fields such as tissue engineering repair, controlled drug delivery, disease-responsive therapies, and beyond. In this review, we comprehensively expound upon the raw materials (including natural and synthetic materials) and injectable principles of these advanced hydrogels, concurrently providing a detailed discussion of the prevalent strategies for conferring stimulus responsiveness. Finally, we elucidate the latest applications of these injectable "smart" stimuli-responsive hydrogels in the biomedical domain, offering insights into their prospects.

Recent advances in polymeric microparticle-based drug delivery systems for knee osteoarthritis treatment

Due to the poor bioavailability and high joint clearance of drugs, sustained delivery of therapeutic agents has proven difficult in the treatment of osteoarthritis (OA). Intra-articular (IA) drug delivery strategy is an attractive option for enhancing OA patients' prognosis, for which various polymer materials have been used as drug carriers due to their attractive delivery properties, to slow or even reverse the progress of OA by prolonging the duration of therapeutic agent residence in the joint. This article focuses on the recent developments in natural and synthetic polymer-based microsphere drug delivery systems for treating knee osteoarthritis. It evaluates the translational potential of some novel formulations for clinical application.

Harnessing the multifunctionality of lipid-based drug delivery systems for the local treatment of osteoarthritis

Osteoarthritis (OA) is a widespread joint condition affecting millions globally, presenting a growing socioeconomic burden thus making the development of more effective therapeutic strategies crucial. This review emphasizes recent advancements in lipid-based drug delivery systems (DDSs) for intra-articular administration of OA therapeutics, encompassing non-steroidal anti-inflammatory drugs, corticosteroids, small molecule disease-modifying OA drugs, and RNA therapeutics. Liposomes, lipid nanoparticles, lipidic mesophases, extracellular vesicles and composite systems exhibit enhanced stability, targeted delivery, and extended joint retention, which contribute to improved therapeutic outcomes and minimized systemic drug exposure. Although active targeting strategies hold promise, further research is needed to assess their targeting efficiency in physiologically relevant conditions. Simultaneously, multifunctional DDSs capable of delivering combinations of distinct therapeutic classes offer synergistic effects and superior OA treatment outcomes. The development of such long-acting systems that resist rapid clearance from the joint space is crucial, where particle size and targeting capabilities emerge as vital factors. Additionally, combining cartilage lubrication properties with sustained drug delivery has demonstrated potential in animal models, meriting further investigation in human clinical trials. This review highlights the crucial need for direct, head-to-head comparisons of novel DDSs with standard treatments, particularly within the same drug class. These comparisons are essential in accurately evaluating their effectiveness, safety, and clinical applicability, and are set to significantly shape the future of OA therapy.

Marine biomaterials in biomedical nano/micro-systems

Marine resources in unique marine environments provide abundant, cost-effective natural biomaterials with distinct structures, compositions, and biological activities compared to terrestrial species. These marine-derived raw materials, including polysaccharides, natural protein components, fatty acids, and marine minerals, etc., have shown great potential in preparing, stabilizing, or modifying multifunctional nano-/micro-systems and are widely applied in drug delivery, theragnostic, tissue engineering, etc. This review provides a comprehensive summary of the most current marine biomaterial-based nano-/micro-systems developed over the past three years, primarily focusing on therapeutic delivery studies and highlighting their potential to cure a variety of diseases. Specifically, we first provided a detailed introduction to the physicochemical characteristics and biological activities of natural marine biocomponents in their raw state. Furthermore, the assembly processes, potential functionalities of each building block, and a thorough evaluation of the pharmacokinetics and pharmacodynamics of advanced marine biomaterial-based systems and their effects on molecular pathophysiological processes were fully elucidated. Finally, a list of unresolved issues and pivotal challenges of marine-derived biomaterials applications, such as standardized distinction of raw materials, long-term biosafety in vivo, the feasibility of scale-up, etc., was presented. This review is expected to serve as a roadmap for fundamental research and facilitate the rational design of marine biomaterials for diverse emerging applications.

Polysaccharide hydrogel platforms as suitable carriers of liposomes and extracellular vesicles for dermal applications

Lipid-based nanocarriers have been extensively investigated for their application in drug delivery. Particularly, liposomes are now clinically established for treating various diseases such as fungal infections. In contrast, extracellular vesicles (EVs) - small cell-derived nanoparticles involved in cellular communication - have just recently sparked interest as drug carriers but their development is still at the preclinical level. To drive this development further, the methods and technologies exploited in the context of liposome research should be applied in the domain of EVs to facilitate and accelerate their clinical translation. One of the crucial steps for EV-based therapeutics is designing them as proper dosage forms for specific applications. This review offers a comprehensive overview of state-of-the-art polysaccharide-based hydrogel platforms designed for artificial and natural vesicles with application in drug delivery to the skin. We discuss their various physicochemical and biological properties and try to create a sound basis for the optimization of EV-embedded hydrogels as versatile therapeutic avenues.

Chondroitin Sulfate Supplements for Osteoarthritis: A Critical Review

Over the years, chondroitin sulfate (CS) has been used as a slow-acting drug for the treatment of osteoarthritis, for the reduction of pain and improvement of function, and for its disease-modifying properties by limiting cartilage volume loss and joint space narrowing progression. However, there have been inconsistencies in published trials regarding clinical efficacy, with reports of a lack of significant effects compared to placebo. The therapeutic effects of chondroitin sulfate may depend on many variables, such as the source of origin, purity, and contamination with by-products. Another source of confusion may be related to the fact that CS is commonly combined with glucosamine, which makes it challenging to isolate the specific contribution of chondroitin to the therapeutic outcome. This is aggravated by the fact that CS supplements, used in many countries, are not regulated, and labels wrongly claim high levels of purity. Many of these inferior CS products may have been used in clinical trials, which may have had limited but significant results. This has led to recent recommendations to opt for higher-purity pharmacologic-grade CS for the treatment of OA. This article aims to provide an up-to-date view of the current literature regarding the biological effects and efficacy of CS and discusses the quality of available chondroitin sulfate supplements and the current direction in CS investigation. This review concludes that pharmacologic-grade CS supplements may have clinically significant benefits when properly standardized; however, high-quality evidence from properly designed clinical trials is still needed to draw definitive conclusions about clinical efficacy in osteoarthritis.

Targeting macrophage polarization as a promising therapeutic strategy for the treatment of osteoarthritis

Osteoarthritis (OA) is a chronic osteoarthropathy characterized by the progressive degeneration of articular cartilage and synovial inflammation. Early OA clinical treatments involve intra-articular injection of glucocorticoids, oral acetaminophen and non-steroidal anti-inflammatory drugs (NSAIDs), which are used for anti-inflammation and pain relief. However, long-term use of these agents will lead to inevitable side effects, even aggravate cartilage loss. At present, there are no disease-modifying OA drugs (DMOADs) yet approved by regulatory agencies. Polarization regulation of synovial macrophages is a new target for OA treatment. Inhibiting M1 polarization and promoting M2 polarization of synovial macrophages can alleviate synovial inflammation, relieve joint pain and inhibit articular cartilage degradation, which is a promising strategy for OA treatment. In this study, we describe the molecular mechanisms of macrophage polarization and its key role in the development of OA. Subsequently, we summarize the latest progress of strategies for OA treatment through macrophage reprogramming, including small molecule compounds (conventional western medicine and synthetic compounds, monomer compounds of traditional Chinese medicine), biomacromolecules, metal/metal oxides, cells, and cell derivatives, and interprets the molecular mechanisms, hoping to provide some information for DMOADs development.

Nanodevices for deep cartilage penetration

Osteoarthritis (OA) is a degenerative joint disease and is the main cause of chronic pain and functional disability in adults. Articular cartilage is a hydrated soft tissue that is composed of normally quiescent chondrocytes at a low density, a dense network of collagen fibrils with a pore size of 60-200 nm, and aggrecan proteoglycans with high-density negative charge. Although certain drugs, nucleic acids, and proteins have the potential to slow the progression of OA and restore the joints, these treatments have not been clinically applied owing to the lack of an effective delivery system capable of breaking through the cartilage barrier. Recently, the development of nanotechnology for delivery systems renders new ideas and treatment methods viable in overcoming the limited penetration. In this review, we focus on current research on such applications of nanotechnology, including exosomes, protein-based cationic nanocarriers, cationic liposomes/solid lipid nanoparticles, amino acid-based nanocarriers, polyamide derivatives-based nanocarriers, manganese dioxide, and carbon nanotubes. Exosomes are the smallest known nanoscale extracellular vesicles, and they can quickly deliver nucleic acids or proteins to the required depth. Through electrostatic interactions, nanocarriers with appropriate balance in cationic property and particle size have a strong ability to penetrate cartilage. Although substantial preclinical evidence has been obtained, further optimization is necessary for clinical transformation. STATEMENT OF SIGNIFICANCE: The dense cartilage matrix with high-negative charge was associated with reduced therapeutic effect in osteoarthritis patients with deep pathological changes. However, a systematic review in nanodevices for deep cartilage penetration is still lacking. Current approaches to assure penetration of nanosystems into the depth of cartilage were reviewed, including nanoscale extracellular vesicles from different cell lines and nanocarriers with appropriate balance in cationic property and size particle. Moreover, nanodevices entering clinical trials and further optimization were also discussed, providing important guiding significance to future research.