Self-Reinforced MOF-Based Nanogel Alleviates Osteoarthritis by Long-Acting Drug Release

MXene-Based Cartilage-Adhesive Microspheres for Photothermal-Controlled Hydrophobic Drug Release and Mesenchymal Stem Cell Delivery in Osteoarthritis

Intra-articular drug injection is an effective treatment for osteoarthritis (OA). However, the rapid clearance of drugs from the joint cavity results in low drug utilization and suboptimal therapeutic outcomes. This study describes MXene-based cartilage-adhesive microspheres for photothermal-controlled hydrophobic drug release and bone marrow mesenchymal stem cell (BMSC) delivery. Nano cationic amylose (NCA) was obtained by modifying amylose with glycidyltrimethylammonium chloride (GTAC), and hydrophobic drug Kartogenin (KGN) was encapsulated in the hydrophobic helical cavity of NCA through ultrasonic treatment, resulting in nano cationic amylose@KGN complexes (NCA@KGN). HAMA/MXene-NCA@KGN (H/M-NCA@KGN) microspheres were prepared using a microfluidic device. These microspheres exhibited excellent biocompatibility, effectively adhered to the cartilage surface, and carried BMSCs. H/M-NCA@KGN microspheres demonstrated photothermal-controlled release of the hydrophobic drug KGN. Notably, KGN promoted the differentiation of BMSCs into chondrocytes, thereby improving the loss of extracellular matrix in joint cartilage. Additionally, appropriate thermal stimulation induced the expression of heat shock protein 70 (HSP70) in OA chondrocytes, providing a protective effect and delaying the progression of OA. H/M-NCA@KGN microspheres enable controlled hydrophobic drug release and stem cell delivery for potential OA treatment applications.

A Nanosystem Alleviates Severe Acute Pancreatitis via Reactive Oxygen Species Scavenging and Enhancing Mitochondrial Autophagy

Severe acute pancreatitis (SAP) is a life-threatening condition characterized by excessive reactive oxygen species (ROS) production and impaired mitochondrial function, resulting from disrupted autophagic flux. Current clinical treatment for SAP fails to address the condition comprehensively, with the treatment targeting only a single pathogenesis. Herein, we report an innovative acid-responsive biomimetic nanozyme. This system features a hollow Prussian blue (PB) core, serving as an ROS scavenger encapsulated within a porous ZIF-8 shell, enabling the efficient delivery of celastrol that activates autophagic flux. Encased in a macrophage membrane, this system selectively targets inflamed pancreatic tissues and is readily internalized by pancreatic acinar cells. This dual-scavenging mechanism effectively attenuates inflammatory cytokine levels and restores mitochondrial homeostasis in three distinct SAP mouse models. Overall, this study presents a promising synergistic strategy for the dual scavenging of damaged mitochondria and ROS, offering a novel therapeutic approach to the treatment of SAP.

Long-Acting Extracellular Vesicle-Based Biologics in Osteoarthritis Immunotherapy

Osteoarthritis (OA) is a chronic degenerative joint disease characterized by low-grade inflammation, cartilage breakdown, and persistent pain. Despite its prevalence, current therapeutic strategies primarily focus on symptom management rather than modifying disease progression. Monoclonal antibodies and cytokine inhibitors targeting inflammatory pathways, including TNF-α and IL-1, have shown promise but remain limited by inconsistent efficacy and safety concerns. Long-acting biologic therapies-ranging from extended-release formulations, such as monoclonal antibodies and cytokine inhibitors, to gene therapy approaches-have emerged as promising strategies to enhance treatment durability and improve patient outcomes. Extracellular vesicles (EVs) have gained particular attention as a novel delivery platform due to their inherent stability, biocompatibility, and ability to transport therapeutic cargo, including biologics and immunomodulatory agents, directly to joint tissues. This review explores the evolving role of EVs in OA treatment, highlighting their ability to extend drug half-life, improve targeting, and modulate inflammatory responses. Additionally, strategies for EV engineering, including endogenous and exogenous cargo loading, genetic modifications, and biomaterial-based delivery systems, are discussed.

Localized Hydrogel Microspheres for Osteoarthritis Treatment: Recruitment and Differentiation of Stem Cells

Osteoarthritis (OA) represents a common degenerative joint disorder marked by progressive cartilage degradation, necessitating innovative therapeutic approaches beyond symptom management. Here, this study introduces a novel strategy leveraging the regenerative capabilities of mesenchymal stem cells (MSCs) by utilizing a bioactive extracellular matrix (ECM) derived from IFN-γ-stimulated MSCs, encapsulated within aldehyde- and methacrylic anhydride-modified hyaluronic acid hydrogel microspheres (AH). This engineered scaffold effectively mimics the native cartilage microenvironment, promoting targeted adhesion and retention at damaged sites via spontaneous Schiff base reactions. Notably, the IFN-γ-ECM@AH microspheres facilitate the localized release of key chemokines, such as CXCL12, enhancing endogenous stem cell recruitment, and bioactive factors (e.g., TGF-βI and TGF-β3) to drive chondrogenic differentiation. Additionally, the scaffold possesses binding sites for cellular integrins, further augmenting the regenerative potential of stem cells. Collectively, the approach presents a dual-action mechanism that supports efficient cartilage repair and regeneration, positioning this engineered microenvironment as a promising therapeutic avenue for OA and potentially other degenerative conditions.

Current Status and Perspectives of Research on Polymer Hydrogels in the Treatment and Protection of Osteoarthritis

Arthritis is a degenerative disease characterized by chronic cartilage degeneration. It affects hundreds of millions of people worldwide and often has serious consequences such as joint pain and swelling, limited mobility, and joint deformity. However, conventional treatments still struggle to achieve satisfactory results. Finding more effective treatments for arthritis remains an important clinical challenge. As hydrogels have a unique 3D spatial mesh structure, significant material interaction ability, adjustable mechanical properties, and good biodegradability, they can provide a suitable cellular or tissue microenvironment, and their potential in scaffolding effect, lubrication, anti-inflammatory effect, or drug or cellular delivery is expected to be a potent therapeutic approach for the treatment of osteoarthritis. In this review, three aspects of hydrogel products for osteoarthritis treatment are comprehensively summarized and discussed, namely, material selection and gel design, exploration of cross-linking mechanisms, and mechanisms of hydrogel therapy for osteoarthritis, and focus on the advantages and limitations of their clinical applications, which point out the direction of the development strategy of innovative products in this field, applied research, and clinical transformation.

Blockade of ZMIZ1-GATA4 Axis Regulation Restores Youthfulness to Aged Cartilage

Susceptibility to cartilage degeneration increases in an age-dependent manner and older cartilage exhibits increased catabolic factor expression leading to osteoarthritis (OA). While inhibition of cellular senescence can prevent age-related diseases, the understanding of the regulators governing cartilage senescence and the potential for senolytic intervention remains limited. Here, in vitro and in vivo results are reported, demonstrating for the first time that the transcriptional regulator, ZMIZ1, is upregulated in aged and OA cartilage, and that it acts through GATA4 to accelerate chondrocyte senescence and trigger cartilage deterioration. Furthermore, it is shown that K-7174 interferes with the ZMIZ1-GATA4 interaction and effectively hampers cartilage senescence and OA. It is proposed that inhibition of the ZMIZ1-GATA4 axis could be a valuable strategy for eliminating senescent chondrocytes and impeding OA development and that the relevant inhibitor, K-7174, could potentially be developed as a senolytic drug for managing cartilage senescence and age-related degeneration.

β-Diketone Functionalized Microspheres Chelate Reactive Iron via Metal Coordination for Cartilage Repair

Excessive intracellular iron accumulation can induce mitochondrial dysfunction, leading to chondrocyte ferroptosis, a key contributor to cartilage damage in osteoarthritis (OA). Here, micelle-microfluidic hydrogel microspheres, featuring keto-enol-thiol bridged nano-sized secondary structures that disintegrate within the intracellular peroxidative environment to reveal β-diketone groups with metal chelation capabilities, are utilized for the in situ removal of reactive iron, thereby facilitating cartilage repair through the restoration of mitochondrial homeostasis. The relevant experiments demonstrate that the microspheres reduce iron influx by downregulating transferrin receptor (TfR1) expression and decrease mitochondrial iron uptake by upregulating mitochondrial outer membrane iron-sulfur cluster protein (CISD1), thus restoring intracellular mitochondrial iron homeostasis. Furthermore, the antioxidant properties of the ketone-thioether segments synergistically mitigate chondrocyte phospholipid peroxidation via Nrf2/SLC7A11/GPX4 axis, inhibiting ferroptosis and slowing OA progression. In summary, this system that in situ sustainably chelates reactive iron via metal coordination exhibits great potential in the minimally invasive treatment of OA and other ferroptosis-mediated diseases.

3D-printed bioceramic scaffolds for bone defect repair: bone aging and immune regulation

The management of bone defects, particularly in aging populations, remains a major clinical challenge. The immune microenvironment plays an important role in the repair of bone defects and a favorable immune environment can effectively promote the repair of bone defects. However, aging is closely associated with chronic low-grade systemic inflammation, which adversely affects bone healing. Persistent low-grade systemic inflammation critically regulates bone repair through all stages. This review explores the potential of 3D-printed bioceramic scaffolds in bone defect repair, focusing on their capacity to modulate the immune microenvironment and counteract the effects of bone aging. The scaffolds not only provide structural support for bone regeneration but also serve as effective carriers for anti-osteoporosis drugs, offering a novel therapeutic strategy for treating osteoporotic bone defects. By regulating inflammation and improving the immune response, 3D-printed bioceramic scaffolds may significantly enhance bone repair, particularly in the context of age-related bone degeneration. This approach underscores the potential of advanced biomaterials in addressing the dual challenges of bone aging and immune dysregulation, offering promising avenues for the development of effective treatments for bone defects in the elderly. We hope the concepts discussed in this review could offer novel therapeutic strategies for bone defect repair, and suggest promising avenues for the future development and optimization of bioceramic scaffolds.

Intelligent Nanomaterials Design for Osteoarthritis Managements

Osteoarthritis (OA) is the most prevalent degenerative joint disorder, characterized by progressive joint degradation, pain, and diminished mobility, all of which collectively impair patients' quality of life and escalate healthcare expenditures. Current treatment options are often inadequate due to limited efficacy, adverse side effects, and temporary symptom relief, underscoring the urgent need for more effective therapeutic strategies. Recent advancements in nanomaterials and nanomedicines offer promising solutions by improving drug bioavailability, reducing side effects and providing targeted therapeutic benefits. This review critically examines the pathogenesis of OA, highlights the limitations of existing treatments, and explores the latest innovations in intelligent nanomaterials design for OA therapy, with an emphasis on their engineered properties, therapeutic mechanisms, and translational potential in clinical application. By compiling recent findings, this work aims to inspire further exploration and innovation in nanomedicine, ultimately advancing the development of more effective and personalized OA therapies.

Tribology in Nature: Inspirations for Advanced Lubrication Materials

Friction-induced energy consumption is a significant global concern, driving researchers to explore advanced lubrication materials. In nature, lubrication is vital for the life cycle of animals, plants, and humans, playing key roles in movement, predation, and decomposition. After billions of years of evolution, natural lubrication exhibits remarkable professionalism, high efficiency, durability, and intelligence, offering valuable insights for designing advanced lubrication materials. This review focuses on the lubrication mechanisms of natural organisms and significant advancements in biomimetic soft matter lubrication materials. It begins by summarizing common biological lubrication behaviors and their underlying mechanisms, followed by current design strategies for biomimetic soft matter lubrication materials. The review then outlines the development and performance of these materials based on different mechanisms and strategies. Finally, it discusses potential research directions and prospects for soft matter lubrication materials. This review will be a valuable resource for advancing research in biomimetic lubrication materials.

Microenvironment-Responsive Hydrogels Comprising Engineering Zeolitic Imidazolate Framework-8-Anchored Parathyroid Hormone-Related Peptide-1 for Osteoarthritis Therapy

Intra-articular drug injections are effective for osteoarthritis (OA), but challenges such as the complex microenvironment and rapid drug diffusion require frequent injections. Herein, we propose a biofunctional hydrogel-based strategy for prolonged drug delivery and microenvironment remodeling. We propose a strategy to functionalize zeolitic imidazolate framework-8 with tannic acid (TA-ZIF), anchor PTH-related peptide-1 (PTHrP-1) within this framework (TA-ZIF@P1) and incorporate a phenylboronic acid-modified gelatin-based hydrogel (GP hydrogel) drug delivery system (GP@TA-ZIF@P1, GPTP hydrogel) with responsive release properties that respond to the pathological microenvironments of OA. The GPTP hydrogel facilitated controlled, sustained release of PTHrP-1 via dynamic boronic esters, with in vitro and in vivo studies showing continuous release for over 28 days. It not only promotes chondrocyte proliferation but also exhibits significant cytoprotective effects under hyperactive ROS and IL-1β-induced conditions. Notably, transcriptome sequencing confirms that the GPTP hydrogel facilitates both chondrocyte proliferation and chondrogenesis under inflammatory conditions by deactivating Wnt/β-Catenin signaling pathways and enhancing the PI3K/AKT signaling pathway. Additionally, the GPTP hydrogel delays the catabolic metabolism of cartilage explants from mice in inflammatory environments. In a surgical model of mouse OA, we show that the intra-articular injection of GPTP hydrogels reduced periarticular bone remodeling and promoted the production of glycosaminoglycans while offering chondroprotection against cartilage degeneration. To sum up, this pioneering research on PTHrP-1 as a treatment for OA, combined with the GPTP hydrogel system, offers valuable insights and a paradigm for the controlled and sustained release of PTHrP-1, representing a significant advancement in OA treatment strategies.

Metal ion-crosslinking multifunctional hydrogel microspheres with inflammatory immune regulation for cartilage regeneration

Introduction

Osteoarthritis (OA) is a degenerative disease of the joints characterized by cartilage degradation and synovial inflammation. Due to the complex pathogenesis of OA, multifaceted therapies that modulate inflammatory and immune microenvironmental disturbances while promoting cartilage regeneration are key to control the progression of OA.

Methods

Herein, a multifunctional nanoparticle (DIC/Mg-PDA NPs) was constructed successfully by the metal chelation effect between Mg2+ and catecholamine bond from dopamine, followed by the amidation with diclofenac (DIC), which was then prepared into an injectable hydrogel microsphere (DIC/Mg-PDA@HM) with immune-regulating and cartilage-repairing abilities through microfluidic technology for the treatment of osteoarthritis.

Results and discussion

The sustained release of Mg2+ from the composite hydrogel microspheres achieved inflammatory immune regulation by converting macrophages from M1 to M2 and promoted cartilage regeneration through the differentiation of BMSCs. Moreover, the enhanced release of DIC and polydopamine (PDA) effectively downregulated inflammatory factors, and finally achieved OA therapy. In addition, in vivo MRI and tissue section staining of OA model proved the significant efficacy of the hydrogel microspheres on OA. In conclusion, these novel hydrogel microspheres demonstrated a promising prospect for multidisciplinary repairing of OA.

3D-Printed In Situ Growth of Bilayer MOF Hydrogels for Accelerated Osteochondral Defect Repair

Repairing osteochondral (OC) defect presents a significant challenge due to the intricate structural requirements and the unpredictable differentiation pathways of bone marrow mesenchymal stem cells (BMSCs). To address this challenge, a novel biomimetic OC hydrogel scaffold is developed that features a structure of soft and hard components. This scaffold incorporates bilayer metal-organic frameworks (MOFs), specifically ZIF-67 in the upper layer and ZIF-8 in the lower layer, achieved through an in situ printing process. This configuration enables the spatial and temporal modulation of BMSC differentiation by controlling the release of Co2⁺ and Zn2⁺. The results demonstrate that the bilayer MOF hydrogels significantly outperform hydrogels that either lack MOFs or contain a single type of MOF in enhancing repair outcomes in rabbit models of knee OC defects. The improved regenerative efficacy is attributed to the distinct chondrogenic and osteogenic differentiation cues provided by the bilayer MOFs, effectively guiding BMSCs toward enhanced tissue regeneration. This customizable biomimetic OC hydrogel scaffold not only opens new avenues for innovative therapeutic strategies but also holds great promise for widespread clinical applications.

Lubricating and Dual-Responsive Injectable Hydrogels Formulated From ZIF-8 Facilitate Osteoarthritis Treatment by Remodeling the Microenvironment

Osteoarthritis (OA) is a progressively developing condition primarily characterized by the deterioration of articular cartilage and the proliferation of bone, along with ongoing inflammation. Although the precise pathogenesis remains somewhat elusive, restoring the homeostatic balance of the intra-articular microenvironment is crucial for the management of OA. Intra-articular injection of medication is one of the most direct and effective treatment methods; however, most injectable drugs used for osteoarthritis treatment, due to their rapid breakdown, quick release, poor biological activity, and frequent injections, leading to increased risk of infection and suboptimal therapeutic outcomes. In this study, a lubricating and dual-responsive injectable hydrogel based on zeolitic imidazolate frameworks-8 (ZIF-8) impregnated with Quercetin (Que) is designed, which can facilitate OA treatment by remodeling the microenvironment. The prepared injectable nanocomposite hydrogel (MH/CCM@ZIF-8@Que) exhibits pH and reactive oxygen species (ROS) responsiveness, alongside a controllable release of bioactive substances to modulate the microenvironment of bone tissue, thereby mitigating synovitis and the degeneration of cartilage matrix, while simultaneously facilitating cartilage repair. This developed thermosensitive injectable hydrogel, which effectively balances lubrication with the controlled release of bioactive substances, represents a highly promising therapeutic approach for osteoarthritis.

MOF-Based Guided Bone Regeneration Membrane for Promoting Osteogenesis by Regulating Bone Microenvironment through Cascade Effects

Regulation of bone microenvironment (BME) including innate pH values and metal ions affects cellular functions and activities of osteoblasts and osteoclasts, thereby significantly influencing the process of bone regeneration. How to achieve multiple effective regulations of the BME through cascade effects via facile material design and fabrication to significantly facilitate osteogenesis remains a challenge. Herein, a facilely-designed resorbable guided bone regeneration membrane (PCL/DEX@Ca-Zol) based on a drug-loaded metal-organic framework is reported. Thereinto, calcium ions, zoledronic acid, and dexamethasone embedded in the membrane can be responsively released specifically inside bone defect in an acid-triggered manner to synergistically regulate BME by neutralization of pH value, enhancement of osteogenic differentiation and mineralization, and inhibition of osteoclasts in one-go. Along with polycaprolactone as a structural support in the membrane for bone regeneration with fully utilized components of the composite membrane material, enhances bone regeneration with minimized side effects is accordingly achieved with the assistance of effective modulation of BME through multiple cascade effects.