Polyacrylonitrile-Reinforced Composite Gel Polymer Electrolytes for Stable Potassium Metal Anodes.

The potassium-ion battery (PIB) is an emerging energy storage technology due to its potential low cost and reasonably high energy density. However, PIB suffers from severe potassium (K) dendrites growth and even short circuiting caused by the high reactivity of K metal. To address these challenges, this work develops a robust composite gel polymer electrolyte (CGPE), named poly(vinylidene fluoride-hexafluoropropylene) potassium bis(fluorosulfonyl)imide polyacrylonitrile (PVDF-HFP-KFSI@PAN). It is found that the introduction of PAN nanofibers not only improves the mechanical properties but also widens the electrochemical stability window of the CGPE. As a result, the CGPE is much more effective in regulating K stripping/plating and enabling stable K metal anode. K metal symmetrical cells with CGPE exhibit a lifetime of over 1200 h at the current density of 0.5 mA cm-2 , in contrast to 22 h for PVDF-HFP-KFSI and 185 h for a conventional glass fiber separator. The main reasons for the excellent performance of K metal cells with CGPE are attributed to the suppressed K dendrite growth, good structural integrity electrochemical stability of the CGPE, and stable KF-rich solid electrolyte interphase layer at the electrode-CGPE interface. It is expected that this facile strategy to stabilize K metal will pave the way for safer and more durable K metal batteries.

Electrospun nanofibrous membrane with antibacterial and antiviral properties decorated with Myoporum bontioides extract and silver-doped carbon nitride nanoparticles for medical masks application.

Public health safety issues have been plaguing the world since the pandemic outbreak of coronavirus disease (COVID-19). However, most personal protective equipments (PPE) do not have antibacterial and anti- toxicity effects. In this work, we designed and prepared a reusable, antibacterial and anti-toxicity Polyacrylonitrile (PAN) based nanofibrous membrane cooperated with Ag/g-C3N4 (Ag-CN), Myoporum.bontioides (M. bontioides) plant extracts and Ag nanoparticles (NPs) by an electrospinning-process. The SEM and TEM characterization revealed the formation of raised, creased or wrinkled areas on the fiber surface caused by the Ag nanoparticles, the rough surface prevented the aerosol particles on the fiber surface from sliding and stagnating, thus providing excellent filtration performance. The PAN/M. bontioides/Ag-CN/Ag nanofibrous membrane could be employed as a photocatalytic bactericidal material, which not only degraded 96.37% of methylene blue within 150 min, but also exhibited the superior bactericidal effect of 98.65 ± 1.49% and 97.8 ± 1.27% against E. coli and S. aureus, respectively, under 3 hs of light exposure. After 3 cycles of sterilization experiments, the PAN/M. bontioides/Ag-CN/Ag nanofibrous membrane maintained an efficient sterilization effect. Molecular docking revealed that the compounds in M. bontioides extracts interacted with neo-coronavirus targets mainly on Mpro and RdRp proteins, and these compounds had the strongest docking energy with Mpro protein, the shortest docking radius, and more binding sites for key amino acids around the viral protein targets, which influenced the replication and transcription process of neo-coronavirus. The PAN/M.bontioides/Ag-CN/Ag nanofibrous membrane also performed significant inhibition of influenza A virus H3N2. The novel nanofiber membrane is expected to be applied to medical masks, which will improve human isolation and protection against viruses.

How faithfully does intramembranous bone regeneration recapitulate embryonic skeletal development?

Postnatal intramembranous bone regeneration plays an important role during a wide variety of musculoskeletal regeneration processes such as fracture healing, joint replacement and dental implant surgery, distraction osteogenesis, stress fracture healing, and repair of skeletal defects caused by trauma or resection of tumors. The molecular basis of intramembranous bone regeneration has been interrogated using rodent models of most of these conditions. These studies reveal that signaling pathways such as Wnt, TGFß/BMP, FGF, VEGF, and Notch are invoked, reminiscent of embryonic development of membranous bone. Discoveries of several skeletal stem cell/progenitor populations using mouse genetic models also reveal the potential sources of postnatal intramembranous bone regeneration. The purpose of this review is to compare the underlying molecular signals and progenitor cells that characterize embryonic development of membranous bone and postnatal intramembranous bone regeneration.

Fabrication and Characterization of Lignin/Dendrimer Electrospun Blended Fiber Mats.

Blending lignin as the second most abundant polymer in Nature with nanostructured compounds such as dendritic polymers can not only add value to lignin, but also increase its application in various fields. In this study, softwood Kraft lignin/polyamidoamine dendritic polymer (PAMAM) blends were fabricated by the solution electrospinning to produce bead-free nanofiber mats for the first time. The mats were characterized through scanning electron microscopy, Fourier transform infrared (FTIR) spectroscopy, zeta potential, and thermogravimetry analyses. The chemical intermolecular interactions between the lignin functional groups and abundant amino groups in the PAMAM were verified by FTIR and viscosity measurements. These interactions proved to enhance the mechanical and thermal characteristics of the lignin/PAMAM mats, suggesting their potential applications e.g. in membranes, filtration, controlled release drug delivery, among others.

CHIP regulates skeletal development and postnatal bone growth.

C terminus of Hsc70-interacting protein (CHIP) is a chaperone-dependent and U-box containing E3 ubiquitin ligase. In previous studies, we found that CHIP regulates the stability of multiple tumor necrosis factor receptor-associated factor proteins in bone cells. In Chip global knockout (KO) mice, nuclear factor-κB signaling is activated, osteoclast formation is increased, osteoblast differentiation is inhibited, and bone mass is decreased in postnatal Chip KO mice. To determine the role of Chip in different cell types at different developmental stages, we created Chipflox/flox mice. We then generated Chip conditional KO mice ChipCMV and ChipOsxER and demonstrated defects in skeletal development and postnatal bone growth in Chip conditional KO mice. Our findings indicate that Chip conditional KO mice could serve as a critical reagent for further investigations of functions of CHIP in bone cells and in other cell types.

Biomechanics of Implant Fixation in Osteoporotic Bone.

PURPOSE OF REVIEW: The purpose of this review is to critically evaluate the current literature regarding implant fixation in osteoporotic bone. RECENT FINDINGS: Clinical studies have not only demonstrated the growing prevalence of osteoporosis in patients undergoing total joint replacement (TJR) but may also indicate a significant gap in screening and treatment of this comorbidity. Osteoporosis negatively impacts bone in multiple ways beyond the mere loss of bone mass, including compromising skeletal regenerative capacity, architectural deterioration, and bone matrix quality, all of which could diminish implant fixation. Recent findings both in preclinical animal models and in clinical studies indicate encouraging results for the use of osteoporosis drugs to promote implant fixation. Implant fixation in osteoporotic bone presents an increasing clinical challenge that may be benefitted by increased screening and usage of osteoporosis drugs.

Molecular Orientation and Organization of Technical Lignin-Based Composite Nanofibers and Films.

Natural materials are highly anisotropic, maximizing performance of the polymeric structures while conserving mass and enhancing function. In synthetic materials, nanoscale fibers produced by electrospinning often contain molecular alignment of polymers along the fiber axis achieving some similarity to natural fibers. In this study, isolated softwood kraft lignin (SKL) was electrospun into aligned fibers utilizing a special collector. The molecular organization of lignin within the aligned nanofibers was investigated by polarized light optical microscopy. Furthermore, the functional groups that had preferred alignment along the fiber axis were identified with polarized Fourier transform infrared (FTIR) spectroscopy based on dichroism measurements. In addition, nanocrystalline cellulose (NCC) was added to the lignin solutions in order to create composite nanofibers. Both the orientation of NCC within the nanoscale fibers and the impact this component had on the degree of orientation of SKL within the aligned nanofibers were revealed by utilizing polarized FTIR. Finally, solvent cast lignin films were analyzed for their anisotropic polarizability, demonstrating birefringence with and without nanocrystalline cellulose. The work provided unique insight into both preferred orientation (fibers) and assembly (films) for technical lignin due to processing.

Loss of Intestinal Alkaline Phosphatase Leads to Distinct Chronic Changes in Bone Phenotype.

BACKGROUND: The gut is becoming increasingly recognized as the source of various systemic diseases, and recently, it has been linked to bone metabolism via the so-called gut-bone axis. The microbiome and gut-derived mediators are thought to impact upon bone metabolism, and administration of probiotics has been shown to have beneficial effects in bone. The gut brush border enzyme intestinal alkaline phosphatase (IAP) plays an important role in controlling calcium absorption, inhibiting lipopolysaccharides, and other inflammatory mediators responsible for endotoxemia and appears to preserve the normal gut microbiota. Interestingly, IAP-deficient mice (AKP3-/-) also display a significant decrease in fecal Lactobacillus, the genus shown to be beneficial to bone. MATERIALS AND METHODS: IAP mRNA levels in mouse bone were measured using quantitative real-time polymerase chain reaction. Femurs of IAP-knockout (KO) and wild-type (WT) mice were analyzed by microcomputed tomography and histopathology. Serum levels of alkaline phosphatase, calcium, and phosphorus were measured. Target cell response upon exposure to serum from IAP-KO and WT mice was quantified using primary bone marrow macrophages. RESULTS: IAP was not significantly expressed in bones of WT or KO animals. IAP (alkaline phosphatase 3) expression in bone was vanishingly low compared to the duodenum (bone versus duodenum, 56.9 ± 17.7 versus 25,430.3 ± 10,884.5 relative expression, P = 0.01). Bone histology of younger IAP-KO and WT animals was indistinguishable, whereas older IAP-deficient mice showed a distinctly altered phenotype on histology and computed tomography scan. Younger KO mice did not display any abnormal levels in blood chemistry. Older IAP-KO animals showed an isolated increase in serum alkaline phosphatase levels reflecting an environment of active bone formation (IAP-WT versus IAP-KO, 80 ± 27.4 U/I versus 453 ± 107.5 U/I, P = 0.004). There was no significant difference in serum calcium or phosphorus levels between KO and WT mice. Serum from IAP-KO mice induced a significantly higher inflammatory target cell response. CONCLUSIONS: Through its multiple functions, IAP seems to play a crucial role in connecting the gut to the bone. IAP deficiency leads to chronic changes in bone formation, most likely through dysbiosis and systemic dissemination of proinflammatory mediators.

Novel Flexible Wearable Sensor Materials and Signal Processing for Vital Sign and Human Activity Monitoring.

Advances in flexible electronic materials and smart textile, along with broad availability of smart phones, cloud and wireless systems have empowered the wearable technologies for significant impact on future of digital and personalized healthcare as well as consumer electronics. However, challenges related to lack of accuracy, reliability, high power consumption, rigid or bulky form factor and difficulty in interpretation of data have limited their wide-scale application in these potential areas. As an important solution to these challenges, we present latest advances in novel flexible electronic materials and sensors that enable comfortable and conformable body interaction and potential for invisible integration within daily apparel. Advances in novel flexible materials and sensors are described for wearable monitoring of human vital signs including, body temperature, respiratory rate and heart rate, muscle movements and activity. We then present advances in signal processing focusing on motion and noise artifact removal, data mining and aspects of sensor fusion relevant to future clinical applications of wearable technology.

Changes in Structural-Mechanical Properties and Degradability of Collagen during Aging-associated Modifications.

During aging, changes occur in the collagen network that contribute to various pathological phenotypes in the skeletal, vascular, and pulmonary systems. The aim of this study was to investigate the consequences of age-related modifications on the mechanical stability and in vitro proteolytic degradation of type I collagen. Analyzing mouse tail and bovine bone collagen, we found that collagen at both fibril and fiber levels varies in rigidity and Young's modulus due to different physiological changes, which correlate with changes in cathepsin K (CatK)-mediated degradation. A decreased susceptibility to CatK-mediated hydrolysis of fibrillar collagen was observed following mineralization and advanced glycation end product-associated modification. However, aging of bone increased CatK-mediated osteoclastic resorption by ∼27%, and negligible resorption was observed when osteoclasts were cultured on mineral-deficient bone. We observed significant differences in the excavations generated by osteoclasts and C-terminal telopeptide release during bone resorption under distinct conditions. Our data indicate that modification of collagen compromises its biomechanical integrity and affects CatK-mediated degradation both in bone and tissue, thus contributing to our understanding of extracellular matrix aging.

Kynurenine Modulates MMP-1 and Type-I Collagen Expression Via Aryl Hydrocarbon Receptor Activation in Dermal Fibroblasts.

Dermal fibrosis is characterized by a high deposition of extracellular matrix (ECM) and tissue cellularity. Unfortunately all means of treating this condition are unsatisfactory. We have previously reported the anti-fibrotic effects of Kynurenine (Kyn), a tryptophan metabolite, in fibrotic rabbit ear model. Here, we report the mechanism by which Kyn modulates the expression of key ECM components in dermal fibroblasts. The results showed that Kyn activates aryl hydrocarbon receptor (AHR) nuclear translocation and up-regulates cytochrome-P450 (CYP1A-1) expression, the AHR target gene. A specific AHR antagonist, 6,2',4'-trimethoxyflavone, inhibited the Kyn-dependent modulation of CYP1A-1, MMP-1, and type-I collagen expression. Establishing the anti-fibrogenic effect of Kyn and its mechanism of action, we then developed nano-fibrous Kyn slow-releasing dressings and examined their anti-fibrotic efficacy in vitro and in a rat model. Our results showed the feasibility of incorporating Kyn into PVA/PLGA nanofibers, prolonging the Kyn release up to 4 days tested. Application of medicated-dressings significantly improved the dermal fibrosis indicated by MMP-1 induction, alpha-smooth muscle actin and type-I collagen suppression, and reduced tissue cellularity, T-cells and myofibroblasts. This study clarifies the mechanism by which Kyn modulates ECM expression and reports the development of a new slow-releasing anti-fibrogenic dressing. J. Cell. Physiol. 231: 2749-2760, 2016. © 2016 Wiley Periodicals, Inc.

In vivo cyclic compression causes cartilage degeneration and subchondral bone changes in mouse tibiae.

OBJECTIVE: Alterations in the mechanical loading environment in joints may have both beneficial and detrimental effects on articular cartilage and subchondral bone, and may subsequently influence the development of osteoarthritis (OA). Using an in vivo tibial loading model, the aim of this study was to investigate the adaptive responses of cartilage and bone to mechanical loading and to assess the influence of load level and duration. METHODS: Cyclic compression at peak loads of 4.5N and 9.0N was applied to the left tibial knee joint of adult (26-week-old) C57BL/6 male mice for 1, 2, and 6 weeks. Only 9.0N loading was utilized in young (10-week-old) mice. Changes in articular cartilage and subchondral bone were analyzed by histology and micro-computed tomography. RESULTS: Mechanical loading promoted cartilage damage in both age groups of mice, and the severity of joint damage increased with longer duration of loading. Metaphyseal bone mass increased with loading in young mice, but not in adult mice, whereas epiphyseal cancellous bone mass decreased with loading in both young and adult mice. In both age groups, articular cartilage thickness decreased, and subchondral cortical bone thickness increased in the posterior tibial plateau. Mice in both age groups developed periarticular osteophytes at the tibial plateau in response to the 9.0N load, but no osteophyte formation occurred in adult mice subjected to 4.5N peak loading. CONCLUSION: This noninvasive loading model permits dissection of temporal and topographic changes in cartilage and bone and will enable investigation of the efficacy of treatment interventions targeting joint biomechanics or biologic events that promote OA onset and progression.

Cells transiently expressing periostin are required for intramedullary intramembranous bone regeneration.

Intramembranous bone regeneration plays an important role in fixation of intramedullary implants used in joint replacement and dental implants used in tooth replacement. Despite widespread recognition of the importance of intramembranous bone regeneration in these clinical procedures, the underlying mechanisms have not been well explored. A previous study that examined transcriptomic profiles of regenerating bone from the marrow space showed that increased periostin gene expression preceded increases in several osteogenic genes. We therefore sought to determine the role of cells transiently expressing periostin in intramedullary intramembranous bone regeneration. We used a genetic mouse model that allows tamoxifen-inducible fluorescent labeling of periostin expressing cells. These mice underwent ablation of the bone marrow cavity through surgical disruption, a well-established intramembranous bone regeneration model. We found that in intact bones, fluorescently labeled cells were largely restricted to the periosteal surface of cortical bone and were absent in bone marrow. However, following surgical disruption of the bone marrow cavity, cells transiently expressing periostin were found within the regenerating tissue of the bone marrow compartment even though the cortical bone remained intact. The source of these cells is likely heterogenous, including cells occupying the periosteal surface as well as pericytes and endothelial cells within the marrow cavity. We also found that diphtheria toxin-mediated depletion of cells transiently expressing periostin at the time of surgery impaired intramembranous bone regeneration in mice. These data suggest a critical role of periostin expressing cells in intramedullary intramembranous bone regeneration and may lead to novel therapeutic interventions to accelerate or enhance implant fixation.

Skeletal consequences of preterm birth in pigs as a model for preterm infants.

Preterm birth affects about 10% of all live births with many resultant health challenges, including metabolic bone disease of prematurity (MBDP) which is characterized by elevated alkaline phosphatase, suppressed phosphate, and deficient skeletal development. Because of the lack of an animal model, very little is known about bone structure, strength, and quality after preterm birth. This study investigated the utility of a pig model to replicate clinical features of preterm birth, including MBDP, and sought to determine if early postnatal administration of insulin-like growth factor (IGF)-1 was an effective treatment. Preterm pigs, born by caesarean section at 90% gestation, were reared in intensive care facilities (respiratory, thermoregulatory and nutritional support) and compared with sow-reared term pigs born vaginally. Preterm pigs were systemically treated with vehicle or IGF-1 (recombinant human IGF-1/BP-3, 2.25 mg/kg/day). Tissues were collected at postnatal days 1, 5, and 19 (the normal weaning period in pigs). Most bone-related outcomes were affected by preterm birth throughout the study period whereas IGF-1 supplementation had almost no effect. By day 19, alkaline phosphatase was elevated, phosphate and calcium were reduced, and the bone resorption marker CTX-1 was elevated in preterm pigs compared to term pigs. Preterm pigs also had decrements in femoral cortical cross-sectional properties, consistent with reduced whole-bone strength. Thus, the preterm pig model replicates many features of preterm bone development in infants, including features of MBDP, and allows for direct interrogation of skeletal tissues, enhancing the field's ability to examine underlying mechanisms.

Premature birth interrupts a critical period of skeletal development as the majority of fetal bone mineral accumulation occurs during the last gestational trimester, leaving preterm infants at increased risk for low bone mineral density and fractures. While there are some data on growth in bone mass in preterm infants, very little is known about bone structural properties, quality, and strength during development after preterm birth. In this study we sought to evaluate the pig as a model for postnatal skeletal development after premature birth. Preterm pigs born after approximately 90% of the full gestation period were compared to full-term control pigs through day 19 of life. Levels of two blood markers used to diagnose osteoporosis of prematurity were replicated in the pig model. Bone properties related to strength were reduced even when accounting for their smaller body size, possibly suggesting elevated fracture risk in preterm infants. Based on the similarities between the preterm pig model and preterm human infants, the pig model may prove to be useful to study factors and interventions affecting postnatal bone development after preterm birth.

Clearing-enabled light sheet microscopy as a novel method for three-dimensional mapping of the sensory innervation of the mouse knee.

A major barrier that hampers our understanding of the precise anatomic distribution of pain sensing nerves in and around the joint is the limited view obtained from traditional two dimensional (D) histological approaches. Therefore, our objective was to develop a workflow that allows examination of the innervation of the intact mouse knee joint in 3D by employing clearing-enabled light sheet microscopy. We first surveyed existing clearing protocols (SUMIC, PEGASOS, and DISCO) to determine their ability to clear the whole mouse knee joint, and discovered that a DISCO protocol provided the most optimal transparency for light sheet microscopy imaging. We then modified the DISCO protocol to enhance binding and penetration of antibodies used for labeling nerves. Using the pan-neuronal PGP9.5 antibody, our protocol allowed 3D visualization of innervation in and around the mouse knee joint. We then implemented the workflow in mice intra-articularly injected with nerve growth factor (NGF) to determine whether changes in the nerve density can be observed. Both 3D and 2D analytical approaches of the light sheet microscopy images demonstrated quantifiable changes in midjoint nerve density following 4 weeks of NGF injection in the medial but not in the lateral joint compartment. We provide, for the first time, a comprehensive workflow that allows detailed and quantifiable examination of mouse knee joint innervation in 3D.

Visualization of CO2 electrolysis using optical coherence tomography.

Electrolysers offer an appealing technology for conversion of CO2 into high-value chemicals. However, there are few tools available to track the reactions that occur within electrolysers. Here we report an electrolysis optical coherence tomography platform to visualize the chemical reactions occurring in a CO2 electrolyser. This platform was designed to capture three-dimensional images and videos at high spatial and temporal resolutions. We recorded 12 h of footage of an electrolyser containing a porous electrode separated by a membrane, converting a continuous feed of liquid KHCO3 to reduce CO2 into CO at applied current densities of 50-800 mA cm-2. This platform visualized reactants, intermediates and products, and captured the strikingly dynamic movement of the cathode and membrane components during electrolysis. It also linked CO production to regions of the electrolyser in which CO2 was in direct contact with both membrane and catalyst layers. These results highlight how this platform can be used to track reactions in continuous flow electrochemical reactors.

Effects of emulsion droplet size on the structure of electrospun ultrafine biocomposite fibers with cellulose nanocrystals.

Electrospinning of cellulose nanocrystals (CNC)/poly(lactic acid) (PLA) emulsions has been demonstrated to be an effective dispersion and alignment method to control assembly of CNC into continuous composite ultrafine fibers. CNC-PLA nanocomposite random-fiber mats and aligned-fiber yarns were prepared by emulsion electrospinning. A dispersed phase of CNC aqueous suspension and an immiscible continuous phase of PLA solution comprised the CNC-PLA water-in-oil (W/O) emulsion system. Under a set of specific conditions, the as-spun composite ultrafine fibers assumed core-shell or hollow structures. In these structures, CNCs were aligned along the core in the core-shell case, or on the wall of the hollow cylinder in the hollow fiber case. CNCs act as nucleating agents influencing PLA crystallinity, and improve the strength and stiffness of electrospun composite fibers. The effects of emulsion droplet size on fiber structural formation and CNC distribution within the electrospun fibers have been carefully examined.

Novel biomimetic hydroxyapatite/alginate nanocomposite fibrous scaffolds for bone tissue regeneration.

Hydroxyapatite/alginate nanocomposite fibrous scaffolds were fabricated via electrospinning and a novel in situ synthesis of hydroxyapatite (HAp) that mimics mineralized collagen fibrils in bone tissue. Poorly crystalline HAp nanocrystals, as confirmed by X-ray diffractometer peak approximately at 2θ = 32° and Fourier transform infrared spectroscopy spectrum with double split bands of PO4(v 4) at 564 and 602 cm(-1), were induced to nucleate and grow at the [-COO(-)]-Ca(2+)-[-COO(-)] linkage sites on electrospun alginate nanofibers impregnated with PO4 (3-) ions. This novel process resulted in a uniform deposition of HAp nanocrystals on the nanofibers, overcoming the severe agglomeration of HAp nanoparticles processed by the conventional mechanical blending/electrospinning method. Preliminary in vitro cell study showed that rat calvarial osteoblasts attached more stably on the surface of the HAp/alginate scaffolds than on the pure alginate scaffold. In general, the osteoblasts were stretched and elongated into a spindle-shape on the HAp/alginate scaffolds, whereas the cells had a round-shaped morphology on the alginate scaffold. The unique nanofibrous topography combined with the hybridization of HAp and alginate can be advantageous in bone tissue regenerative medicine applications.

Roll-to-roll fabrication of silver/silver chloride coated yarns for dry electrodes and applications in biosignal monitoring.

This work presents a continuous roll-to-roll electrochemical coating system for producing silver/silver chloride (Ag/AgCl)-coated yarns, and their application in e-textile electrodes for biosignal monitoring. Ag/AgCl is one of the most preferred electrode materials as an interface between the conductive backbone of an electrode and skin. E-textile Ag/AgCl-coated multi-filament nylon yarns offer stable, flexible, and breathable alternatives to standard rigid or flexible film-based Ag/AgCl electrodes. The developed system allows for highly controlled process parameters to achieve stable and uniform AgCl film deposition on Ag-coated nylon yarns. The electrical, electrochemical properties, and morphology of the coated yarns were characterized. Dry electrodes were fabricated and could measure electrocardiogram (ECG) signals with comparable performance to standard gel electrodes. Ag/AgCl e-textile electrodes demonstrated high stability, with low average polarization potential (1.22 mV/min) compared with Ag-coated electrodes (3.79 mV/min), low impedance (below 2 MΩ, 0.1-150 Hz), and are excellent candidates for heart rate detection and monitoring.

Chemokine Regulation in Temporomandibular Joint Disease: A Comprehensive Review.

Temporomandibular joint disorders (TMDs) are conditions that affect the muscles of mastication and joints that connect the mandible to the base of the skull. Although TMJ disorders are associated with symptoms, the causes are not well proven. Chemokines play an important role in the pathogenesis of TMJ disease by promoting chemotaxis inflammatory cells to destroy the joint synovium, cartilage, subchondral bone, and other structures. Therefore, enhancing our understanding of chemokines is critical for developing appropriate treatment of TMJ. In this review, we discuss chemokines including MCP-1, MIP-1α, MIP-3a, RANTES, IL-8, SDF-1, and fractalkine that are known to be involved in TMJ diseases. In addition, we present novel findings that CCL2 is involved in ß-catenin-mediated TMJ osteoarthritis (OA) and potential molecular targets for the development of effective therapies. The effects of common inflammatory factors, IL-1ß and TNF-α, on chemotaxis are also described. In conclusion, this review aims to provide a theoretical basis for future chemokine-targeted therapies for TMJ OA.