Nitric Oxide Nanosensors for Predicting the Development of Osteoarthritis in Rat Model

Nanostructures in Orthopedics: Advancing Diagnostics, Targeted Therapies, and Tissue Regeneration

Nanotechnology, delving into the realm of nanometric structures, stands as a transformative force in orthopedics, reshaping diagnostics, and numerous regenerative interventions. Commencing with diagnostics, this scientific discipline empowers accurate analyses of various diseases and implant stability, heralding an era of unparalleled precision. Acting as carriers for medications, nanomaterials introduce novel therapeutic possibilities, propelling the field towards more targeted and effective treatments. In arthroplasty, nanostructural modifications to implant surfaces not only enhance mechanical properties but also promote superior osteointegration and durability. Simultaneously, nanotechnology propels tissue regeneration, with nanostructured dressings emerging as pivotal elements in accelerating wound healing. As we navigate the frontiers of nanotechnology, ongoing research illuminates promising avenues for further advancements, assuring a future where orthopedic practices are not only personalized but also highly efficient, promising a captivating journey through groundbreaking innovations and tailored patient care.

Shedding light on the effects of blood on meniscus tissue: the role of mononuclear leukocytes in mediating meniscus catabolism

OBJECTIVE

Traumatic meniscal injuries can cause acute pain, hemarthrosis (bleeding into the joint), joint immobility, and post-traumatic osteoarthritis (PTOA). However, the exact mechanism(s) by which PTOA develops following meniscal injuries is unknown. Since meniscus tears commonly coincide with hemarthrosis, investigating the direct effects of blood and its constituents on meniscus tissue is warranted. The goal of this study was to determine the direct effects of blood and blood components on meniscus tissue catabolism.

METHODS

Porcine meniscus explants or primary meniscus cells were exposed to whole blood or various fractions of blood for 3 days to simulate blood exposure following injury. Explants were then washed and cultured for an additional 3 days prior to collection for biochemical analyses.

RESULTS

Whole blood increased matrix metalloproteinase (MMP) activity. Fractionation experiments revealed blood-derived red blood cells did not affect meniscus catabolism. Conversely, viable mononuclear leukocytes induced MMP activity, nitric oxide (NO) production, and loss of tissue sulfated glycosaminoglycan (sGAG) content, suggesting that these cells are mediating meniscus catabolism.

CONCLUSIONS

These findings highlight the potential challenges of meniscus healing in the presence of hemarthrosis and the need for further research to elucidate the in vivo effects of blood and blood-derived mononuclear leukocytes due to both hemarthrosis and blood-derived therapeutics.

Arginine and its metabolites stimulate proliferation, differentiation, and physiological function of porcine trophoblast cells through β-catenin and mTOR pathways

Arginine, which is metabolized into ornithine, proline, and nitric oxide, plays an important role in embryonic development. The present study was conducted to investigate the molecular mechanism of arginine in proliferation, differentiation, and physiological function of porcine trophoblast cells (pTr2) through metabolic pathways. The results showed that arginine significantly increased cell viability (P < 0.05). The addition of arginine had a quadratic tendency to increase the content of progesterone (P = 0.06) and protein synthesis rate (P = 0.03), in which the maximum protein synthesis rate was observed at 0.4 mM arginine. Arginine quadratically increased (P < 0.05) the intracellular contents of spermine, spermidine and putrescine, as well as linearly increased (P < 0.05) the intracellular content of NO in a dose-dependent manner. Arginine showed a quadratic tendency to increase the content of putrescine (P = 0.07) and a linear tendency to increase NO content (P = 0.09) in cell supernatant. Moreover, increasing arginine activated (P < 0.05) the mRNA expressions for ARG, ODC, iNOS and PCNA. Furthermore, inhibitors of arginine metabolism (L-NMMA and DFMO) both inhibited cell proliferation, while addition of its metabolites (NO and putrescine) promoted the cell proliferation and cell cycle, the mRNA expressions of PCNA, EGF and IGF-1, and increased (P < 0.05) cellular protein synthesis rate, as well as estradiol and hCG secretion (P < 0.05). In conclusion, our results suggested that arginine could promote cell proliferation and physiological function by regulating the metabolic pathway. Further studies showed that arginine and its metabolites modulate cell function mainly through β-catenin and mTOR pathways.

Recent developments in nanomaterials for upgrading treatment of orthopedics diseases

Nanotechnology has changed science in the last three decades. Recent applications of nanotechnology in the disciplines of medicine and biology have enhanced medical diagnostics, manufacturing, and drug delivery. The latest studies have demonstrated this modern technology's potential for developing novel methods of disease detection and treatment, particularly in orthopedics. According to recent developments in bone tissue engineering, implantable substances, diagnostics and treatment, and surface adhesives, nanomedicine has revolutionized orthopedics. Numerous nanomaterials with distinctive chemical, physical, and biological properties have been engineered to generate innovative medication delivery methods for the local, sustained, and targeted delivery of drugs with enhanced therapeutic efficacy and minimal or no toxicity, indicating a very promising strategy for effectively controlling illnesses. Extensive study has been carried out on the applications of nanotechnology, particularly in orthopedics. Nanotechnology can revolutionize orthopedics cure, diagnosis, and research. Drug delivery precision employing nanotechnology using gold and liposome nanoparticles has shown especially encouraging results. Moreover, the delivery of drugs and biologics for osteosarcoma is actively investigated. Different kind of biosensors and nanoparticles has been used in the diagnosis of bone disorders, for example, renal osteodystrophy, Paget's disease, and osteoporosis. The major hurdles to the commercialization of nanotechnology-based composite are eventually examined, thus helping in eliminating the limits in connection to some pre-existing biomaterials for orthopedics, important variables like implant life, quality, cure cost, and pain and relief from pain. The potential for nanotechnology in orthopedics is tremendous, and most of it looks to remain unexplored, but not without challenges. This review aims to highlight the up tp date developments in nanotechnology for boosting the treatment modalities for orthopedic ailments. Moreover, we also highlighted unmet requirements and present barriers to the practical adoption of biomimetic nanotechnology-based orthopedic treatments.

Gold nanoparticle-based two-photon fluorescent nanoprobe for monitoring intracellular nitric oxide levels

Nitric oxide (NO) plays an important role in the regulation of the immune, cardiovascular and nervous systems. Consequently, being able to monitor and quantify intracellular NO levels would provide a greater understanding of the implications of this molecule in the different biological processes, including, for example, in cancer. Here, we report a broadly applicable two-photon excitable fluorescent nanoprobe able to detect and potentially quantify NO levels in an extensive range of cellular environments. The nanoprobe consists of a thiolated photoinduced electron transfer-based two=photon fluorescent probe attached onto the surface of 2.4 ± 0.7 nm gold nanoparticles (DANPY-NO@AuNPs). The nanoprobe, which can be synthesised in a reproducible manner and exhibits great stability when stored at room temperature, is able to selectively detect NO in solution, with a dynamic range up to 150 μM, and at pH values of biological relevance. DANPY-NO@AuNPs were able to selectively detect endogenous NO in RAW264.7γ NO^- macrophages and THP-1 human leukemic cells; and endogenous and exogenous NO in endothelial cells. The nanoprobe accumulated in the acidic organelles of the tested cell lines showing negligible toxicity. Importantly, DANPY-NO@AuNPs showed potential to quantify intracellular NO concentrations in MDA-MB-231 breast cancer cells. The biological evaluation of the nanoprobe was undertaken using confocal laser scanning (images and intracellular emission spectra) and multiphoton microscopies, and flow cytometry. Based on their excellent sensitivity and stability, and outstanding versatility, DANPY-NO@AuNPs can be applied for the spatiotemporal monitoring of in vitro and in vivo NO levels.

A nitric oxide responsive AIE probe for detecting the progression of osteoarthritis

Nitric oxide (NO) is reported to be elevated in osteoarthritis (OA) both in vitro and in vivo and may be adopted to develop fluorescent probes for detecting the progression of OA. Here we report a nitric oxide responsive aggregation induced emission (AIE) probe TPE-2NHCOCH₂CH₂-(PEG)₂₄-NH-Diacerein, which is derived from tetraphenylethene (TPE) modified with the hydrophilic group long poly(ethylene glycol) chain and an anti-inflammatory drug diacerein. o-Phenylenediamine within its structure can react with NO to form benzotriazole and emit fluorescence. The results show that the NO-responsive AIE probe can smartly monitor the progression of OA with the change of fluorescence intensity in vitro and in vivo. This study may provide a new development direction for early OA monitoring in clinics.

New insights in osteoarthritis diagnosis and treatment: Nano-strategies for an improved disease management

Osteoarthritis (OA) is a common chronic joint pathology that has become a predominant cause of disability worldwide. Even though the origin and evolution of OA rely on different factors that are not yet elucidated nor understood, the development of novel strategies to treat OA has emerged in the last years. Cartilage degradation is the main hallmark of the pathology though alterations in bone and synovial inflammation, among other comorbidities, are also involved during OA progression. From a molecular point of view, a vast amount of signaling pathways are implicated in the progression of the disease, opening up a wide plethora of targets to attenuate or even halt OA. The main purpose of this review is to shed light on the recent strategies published based on nanotechnology for the early diagnosis of the disease as well as the most promising nano-enabling therapeutic approaches validated in preclinical models. To address the clinical issue, the key pathways involved in OA initiation and progression are described as the main potential targets for OA prevention and early treatment. Furthermore, an overview of current therapeutic strategies is depicted. Finally, to solve the drawbacks of current treatments, nanobiomedicine has shown demonstrated benefits when using drug delivery systems compared with the administration of the equivalent doses of the free drugs and the potential of disease-modifying OA drugs when using nanosystems. We anticipate that the development of smart and specific bioresponsive and biocompatible nanosystems will provide a solid and promising basis for effective OA early diagnosis and treatment. This article is categorized under: Diagnostic Tools > In Vivo Nanodiagnostics and Imaging Implantable Materials and Surgical Technologies > Nanotechnology in Tissue Repair and Replacement.

Local delivery of gaseous signaling molecules for orthopedic disease therapy

Over the past decade, a proliferation of research has used nanoparticles to deliver gaseous signaling molecules for medical purposes. The discovery and revelation of the role of gaseous signaling molecules have been accompanied by nanoparticle therapies for their local delivery. While most of them have been applied in oncology, recent advances have demonstrated their considerable potential in diagnosing and treating orthopedic diseases. Three of the currently recognized gaseous signaling molecules, nitric oxide (NO), carbon monoxide (CO), and hydrogen sulfide (H2S), are highlighted in this review along with their distinctive biological functions and roles in orthopedic diseases. Moreover, this review summarizes the progress in therapeutic development over the past ten years with a deeper discussion of unresolved issues and potential clinical applications.

Nanomaterial-assisted theranosis of bone diseases

Bone-related diseases refer to a group of skeletal disorders that are characterized by bone and cartilage destruction. Conventional approaches can regulate bone homeostasis to a certain extent. However, these therapies are still associated with some undesirable problems. Fortunately, recent advances in nanomaterials have provided unprecedented opportunities for diagnosis and therapy of bone-related diseases. This review provides a comprehensive and up-to-date overview of current advanced theranostic nanomaterials in bone-related diseases. First, the potential utility of nanomaterials for biological imaging and biomarker detection is illustrated. Second, nanomaterials serve as therapeutic delivery platforms with special functions for bone homeostasis regulation and cellular modulation are highlighted. Finally, perspectives in this field are offered, including current key bottlenecks and future directions, which may be helpful for exploiting nanomaterials with novel properties and unique functions. This review will provide scientific guidance to enhance the development of advanced nanomaterials for the diagnosis and therapy of bone-related diseases.

Applications and prospects of intra-articular drug delivery system in arthritis therapeutics

Arthritis is a kind of chronic disease that affects joints and muscles with the symptoms of joint pain, inflammation and limited movement of joints. Among various clinical therapies, drug therapy has been extensively applied because of its accessibility, safety and effectiveness. In recent years, the intra-articular injection has dramatic therapeutic effects in treating arthritis with high patient compliance and low side effects. In this review, we will introduce pathology of arthritis, along with the accessible treatment and diagnosis methods, then we will summarize major advances of current hopeful intra-articular delivery systems such as microspheres, hydrogels, nanoparticles and liposomes. At last, some safety assessments in the preclinical work and the main challenges for the further development of intra-articular treatment were also discussed.

Bibliometric and visualization analysis of macrophages associated with osteoarthritis from 1991 to 2021

Background

Macrophages significantly contributes to symptomology and structural progression of osteoarthritis (OA) and raise increasing attention in the relative research field. Recent studies have shown that tremendous progress has been made in the research of macrophages associated with osteoarthritis. However, a comprehensive bibliometric analysis is lacking in this research field. This study aimed to introduce the research status as well as hotspots and explore the field of macrophages research in OA from a bibliometric perspective.

Methods

This study collected 1481 records of macrophages associated with osteoarthritis from 1991 to 2021 in the web of science core collection (WoSCC) database. CiteSpace, VOSviewer, and R package “bibliometrix” software were used to analyze regions, institutions, journals, authors, and keywords to predict the latest trends in macrophages associated with osteoarthritis research.

Results

The number of publications related to macrophages associated with osteoarthritis is increasing annually. China and the USA, contributing more than 44% of publications, were the main drivers for research in this field. League of European Research Universities was the most active institution and contributed the most publications. Arthritis and Rheumatism is the most popular journal in this field with the largest publications, while Osteoarthritis and Cartilage is the most co-cited journal. Koch AE was the most prolific writer, while Bondeson J was the most commonly co-cited author. “Rheumatology”, “Orthopedics”, and “Immunology” were the most widely well-represented research areas of OA associated macrophages. “Rheumatoid arthritis research”, “clinical symptoms”, “regeneration research”, “mechanism research”, “pathological features”, and “surgery research” are the primary keywords clusters in this field.

Conclusion

This is the first bibliometric study comprehensively mapped out the knowledge structure and development trends in the research field of macrophages associated with osteoarthritis in recent 30 years. The results comprehensively summarize and identify the research frontiers which will provide a reference for scholars studying macrophages associated with osteoarthritis.

Facile Synthesis of Conductive Metal-Organic Frameworks Nanotubes for Ultrahigh-Performance Flexible NO Sensors

Cu-benzenehexathiol (Cu-BHT) has attracted significant attention due to its record high electrical conductivity and crystal defects Cu_2c . However, the nonporous structure and small specific surface area of Cu-BHT with two-dimensional kagome lattice invariably limit its practical application in sensing and catalysis. In this work, Cu-BHT nanotubes (Cu-BHT-NTs) are designed and prepared via a facile homogeneous reaction to solve these problems. Compared with the traditional nanorod-like structure, the Cu-BHT-NTs not only have a higher specific surface area but also possess a higher proportion of crystal defects (66.6%). The successfully configured DPPTT/Cu-BHT-NTs heterostructure organic field-effect transistor (OFET)-based sensor exhibits excellent sensitivity as high as 13 610%, a minimum detection limits down to 5 ppb, and exceptional selectivity to nitric oxide (NO) toxic gases. Theoretical analysis systematically shows that Cu_2c sites in the Cu-BHT-NTs increase the number of electrons transferred from the heterostructure to NO molecules, confirming that the high sensitivity and selectivity result from the high binding between Cu-BHT-NTs and NO molecules. Furthermore, a fully flexible device based on the heterojunction OFET sensor is prepared to ensure the convenience of wearing and carrying gas sensors, opening up a new avenue for the next generation of wearable intelligent electronics.

A flexible and highly sensitive organic electrochemical transistor-based biosensor for continuous and wireless nitric oxide detection

As nitric oxide (NO) plays significant roles in a variety of physiological processes, the capability for real-time and accurate detection of NO in live organisms is in great demand. Traditional assessments of NO rely on indirect colorimetric techniques or electrochemical sensors that often comprise rigid constituent materials and can hardly satisfy sensitivity and spatial resolution simultaneously. Here, we report a flexible and highly sensitive biosensor based on organic electrochemical transistors (OECTs) capable of continuous and wireless detection of NO in biological systems. By modifying the geometry of the active channel and the gate electrodes of OECTs, devices achieve optimum signal amplification of NO. The sensor exhibits a low response limit, a wide linear range, high sensitivity, and excellent selectivity, with a miniaturized active sensing region compared with a conventional electrochemical sensor. The device demonstrates continuous detection of the nanomolar range of NO in cultured cells for hours without significant signal drift. Real-time and wireless measurement of NO is accomplished for 8 d in the articular cavity of New Zealand White rabbits with anterior cruciate ligament (ACL) rupture injuries. The observed high level of NO is associated with the onset of osteoarthritis (OA) at the later stage. The proposed device platform could provide critical information for the early diagnosis of chronic diseases and timely medical intervention to optimize therapeutic efficacy.

Cartilage-Inspired Hydrogel with Mechanical Adaptability, Controllable Lubrication, and Inflammation Regulation Abilities

Cartilage is a key component in joints because of its load-bearing and lubricating abilities. However, osteoarthritis often leads to afunction of load-bearing/lubrication and occurrence of inflammation with overexpressed reactive oxygen species (ROS) and nitric oxide (NO). To address these issues, we fabricated a novel polyanionic hydrogel with abundant carboxylates/sulfonates ("CS" hydrogel), inspired by normal cartilage rich in anionic hyaluronate/sulfonate glycosaminoglycan/lubricin, and crosslinked it tightly by Fe3+ ("CS-Fe" hydrogel). The "CS-Fe" hydrogel displayed mechanical adaptability and shear resistance. A low coefficient of friction (∼0.02) appeared when a loose hydrogel layer was generated because of the photoreduction of Fe3+ to Fe2+ by UV irradiation. This biocompatible "CS-Fe" hydrogel suppressed the overexpressed hydroxyl radical (·OH) and NO in macrophages and protected chondrocytes/fibroblasts from aggressive inflammation. Moreover, the layered "CS-Fe" hydrogel avoided cell death of chondrocytes in sliding tests. The results demonstrate that this cartilage-inspired hydrogel is a promising candidate material in cartilage tissue engineering to especially address inflammation.

The advances in nanomedicine for bone and cartilage repair

With the gradual demographic shift toward an aging and obese society, an increasing number of patients are suffering from bone and cartilage injuries. However, conventional therapies are hindered by the defects of materials, failing to adequately stimulate the necessary cellular response to promote sufficient cartilage regeneration, bone remodeling and osseointegration. In recent years, the rapid development of nanomedicine has initiated a revolution in orthopedics, especially in tissue engineering and regenerative medicine, due to their capacity to effectively stimulate cellular responses on a nanoscale with enhanced drug loading efficiency, targeted capability, increased mechanical properties and improved uptake rate, resulting in an improved therapeutic effect. Therefore, a comprehensive review of advancements in nanomedicine for bone and cartilage diseases is timely and beneficial. This review firstly summarized the wide range of existing nanotechnology applications in the medical field. The progressive development of nano delivery systems in nanomedicine, including nanoparticles and biomimetic techniques, which are lacking in the current literature, is further described. More importantly, we also highlighted the research advancements of nanomedicine in bone and cartilage repair using the latest preclinical and clinical examples, and further discussed the research directions of nano-therapies in future clinical practice.

Reactive oxygen species (ROS)-responsive nanoprobe for bioimaging and targeting therapy of osteoarthritis

Stimulus-responsive therapy that allows precise imaging-guided therapy is limited for osteoarthritis (OA) therapy due to the selection of proper physiological markers as stimulus. Based on that the over-production of Reactive Oxygen Species (ROS) is associated with the progression in OA, we selected ROS as markers and designed a cartilage targeting and ROS-responsive theranostic nanoprobe that can be used for effective bioimaging and therapy of OA. This nanoprobe was fabricated by using PEG micelles modified with ROS-sensitive thioketal linkers (TK) and cartilage-targeting peptide, termed TKCP, which was then encapsulated with Dexamethasone (DEX) to form TKCP@DEX nanoparticles. Results showed that the nanoprobe can smartly “turn on” in response to excessive ROS and “turn off” in the normal joint. By applying different doses of ROS inducer and ROS inhibitor, this nanoprobe can emit ROS-dependent fluorescence according to the degree of OA severity, helpful to precise disease classification in clinic. Specifically targeting cartilage, TKCP@DEX could effectively respond to ROS and sustained release DEX to remarkably reduce cartilage damage in the OA joints. This smart, sensitive and endogenously activated ROS-responsive nanoprobe is promising for OA theranostics.

Nanosensor Chemical Cytometry for Characterizing the Efflux Heterogeneity of Nitric Oxide from Macrophages

Macrophages are a critical part of the human immune response, and their collective heterogeneity is implicated in disease progression and prevention. A nondestructive, label-free tool does not currently exist for profiling the dynamic, antigenic responses of single macrophages in a collection to correlate with specific molecular expression and correlated biophysical properties at the cellular level, despite the potential for diagnosis and therapeutics. Herein, we develop a nanosensor chemical cytometry (NCC) that can profile the heterogeneity of inducible nitric oxide synthase (iNOS) responses from macrophage populations. By integrating a near-infrared (nIR) fluorescent nanosensor array and collagen layer with microfluidics, the cellular lensing effect of the macrophage was utilized to characterize both nitric oxide (NO) efflux and refractive index (RI) changes at a single-cell level. Using a parallel, multichannel approach, distinct iNOS heterogeneities of macrophages can be monitored at an attomolar (10^-18 mol) sensitivity in a nondestructive and real-time manner with a throughput of exceeding the 200 cells/frame. We demonstrate that estimated mean NO efflux rates of macrophage populations are elevated from 342 (σ = 199) to 464 (σ = 206) attomol/cell·hr with a 3% larger increase in the heterogeneity, and estimated RI of macrophage decrease from 1.366 (σ = 0.015) to 1.359 (σ = 0.009) with trimodal subpopulations under lipopolysaccharide (LPS) activation. These measured values are also in good agreement with Griess assay results and previously reported measurements. This work provides an efficient strategy for single-cell analysis of macrophage populations for cellular manufacturing and biopharmaceutical engineering.

Nanoparticle-Cartilage Interaction: Pathology-Based Intra-articular Drug Delivery for Osteoarthritis Therapy

Osteoarthritis is the most prevalent chronic and debilitating joint disease, resulting in huge medical and socioeconomic burdens. Intra-articular administration of agents is clinically used for pain management. However, the effectiveness is inapparent caused by the rapid clearance of agents. To overcome this issue, nanoparticles as delivery systems hold considerable promise for local control of the pharmacokinetics of therapeutic agents. Given the therapeutic programs are inseparable from pathological progress of osteoarthritis, an ideal delivery system should allow the release of therapeutic agents upon specific features of disorders. In this review, we firstly introduce the pathological features of osteoarthritis and the design concept for accurate localization within cartilage for sustained drug release. Then, we review the interactions of nanoparticles with cartilage microenvironment and the rational design. Furthermore, we highlight advances in the therapeutic schemes according to the pathology signals. Finally, armed with an updated understanding of the pathological mechanisms, we place an emphasis on the development of "smart" bioresponsive and multiple modality nanoparticles on the near horizon to interact with the pathological signals. We anticipate that the exploration of nanoparticles by balancing the efficacy, safety, and complexity will lay down a solid foundation tangible for clinical translation.

Intracellular detection of singlet oxygen using fluorescent nanosensors

Detection of singlet oxygen is of great importance for a range of therapeutic applications, particularly photodynamic therapy, plasma therapy and also during photo-endosomolytic activity. Here we present a novel method of intracellular detection of singlet oxygen using biocompatible polymeric nanosensors, encapsulating the organic fluorescent dye, Singlet Oxygen Sensor Green (SOSG) within its hydrophobic core. The singlet oxygen detection efficiency of the nanosensors was quantified experimentally by treating them with a plasma source and these results were further validated by using Monte Carlo simulations. The change in fluorescence intensity of the nanosensors serves as a metric to detect singlet oxygen in the local micro-environment inside mammalian cancer cells. We used these nanosensors for monitoring singlet oxygen inside endosomes and lysosomes of cancer cells, during cold plasma therapy, using a room-temperature Helium plasma jet.

Recent advances in nanotherapeutic strategies that target nitric oxide pathway for preventing cartilage degeneration

Nitric oxide (NO) is an important inflammatory mediator involved in the development and progression of osteoarthritis (OA). Increased production of NO in the affected joints promote cartilage damage. As NO synthesis is catalysed by the inducible NO synthase (iNOS) enzyme, iNOS inhibition serves as an attractive therapeutic target to prevent NO release. Despite a number of direct and indirect iNOS inhibitor molecules demonstrating chondro-protective effect, none have reached the clinic. Its limited bioavailability and adverse side effects served as a deterrent for pursuing clinical trials in OA patients. With the advent of nanotechnology, interest in targeting NO for preventing cartilage degeneration has revived. In this article, we discuss the limitations of the existing molecules and provide an insight on recent nanotechnology-based strategies that have been explored for the diagnosis and inhibition of NO in OA. These approaches hold promise in reviving the hitherto under explored potential of targeting NO to address OA.

Dopamine/Phosphorylcholine Copolymer as an Efficient Joint Lubricant and ROS Scavenger for the Treatment of Osteoarthritis

Osteoarthritis (OA) is a chronic joint disease and its progression and pathogenesis are highly associated with the significant increase of joint friction and overproduction of reactive oxygen species (ROS) in inflammation. Combination of ROS elimination and lubrication enhancement may provide a novel strategy for the treatment of OA. In the present study, a pure biomaterial and nondrug system P(DMA-co-MPC), synthesized via free radical copolymerization, was designed and developed for the first time using 2-methacryloxyethyl phosphorylcholine (MPC) as a bioinspired lubricant and N-(3,4-dihydroxyphenethyl)methacrylamide (DMA) as an ROS scavenger. Our results showed that the P(DMA-co-MPC) aggregates could efficiently eliminate the ROS radicals and provide good lubrication property by adjusting the molar ratio of DMA and MPC in the copolymer. It is attributed to the antioxidant function of the hydroquinone moiety in DMA and the hydration lubrication effect of the zwitterionic phosphocholine group in MPC. Furthermore, the in vitro experiments demonstrated that the P(DMA-co-MPC) showed good biocompatibility with MC3T3-E1 cells and intracellular anti-inflammatory property by inhibiting the production of ROS and regulating the expression levels of pro-inflammatory cytokines, pain-related gene, anabolic genes, and catabolic genes. In conclusion, the drug-free P(DMA-co-MPC) aggregates developed herein can achieve dual functions of lubrication enhancement and anti-inflammatory effect and thus they may be representative as promising candidates for the treatment of OA.

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

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

Gold Nanorod-Based Nanoplatform Catalyzes Constant NO Generation and Protects from Cardiovascular Injury

Cardiovascular disease is a leading cause of death, and one of the effective therapeutic strategies for cardiovascular disease is to provide a controlled, constant supply of nitric oxide (NO) in a mild manner; however, this has proved challenging in the clinic. To address this problem, we built a nitric oxide synthase (NOS)-like nanoplatform (NanoNOS) that consists of a noble metal nanoparticle core and a mesoporous silica shell and demonstrated the ability of NanoNOS to catalyze production of NO in vitro. Mechanistic studies show that the catalysis consists of a three-step reaction: the oxidation of NADPH to produce O₂^-via oxidase-like activity and the subsequent dismutation of O₂^- to H₂O₂via SOD-like activity, followed by H₂O₂-mediated oxidation of l-arginine to produce NO via a nonenzymatic pathway. The generation of NO is precisely regulated by both the content of the NanoNOS species and the plasmon excitation. We found that NanoNOS greatly suppressed injury-driven monocyte-endothelial cell adhesion, suggesting the NanoNOS treatment could help prevent cardiovascular disease. With such a design as well as plasmon excitation that allows for controlled and constant catalytic activity, NanoNOS technology could have a variety of biomedical applications.

MMP-13 enzyme and pH responsive theranostic nanoplatform for osteoarthritis

Stimulus-responsive therapy permits precise control of therapeutic effect only at lesion of interest, which determines it a promising method for diagnosis and imaging-guided precision therapy. The acid environment and overexpressed matrix metalloproteinases-13 (MMP-13) are typical markers in osteoarthritis (OA), which enables the development of stimulus-responsive drug delivery system with high specificity for OA. We herein demonstrate a nano-micelle based stimuli-responsive theranostic strategy with reporting and drug release controlled by acidic pH and MMP-13 for OA therapy. Such nanoplatform is incorporated with a motif specifically targeting on cartilage, a motif responsive to matrix metalloproteinases-13 to specifically report OA condition and biodynamics of nano-micelles, an anti-inflammatory drug (e.g., psoralidin (PSO)) from traditional Chinese medicine, and a biocompatible polymeric skeleton for sustainable drug release in response to the acidic OA condition. The high effectiveness of this targeted precision therapy is demonstrated comprehensively by both in vitro and vivo evidences.

Perfluorooctane sulfonate enhances mRNA expression of PPARγ and ap2 in human mesenchymal stem cells monitored by long-retained intracellular nanosensor

Perfluorooctane sulfonate (PFOS) has been widely used as a surface coating for household products. It still exists in living environments despite being restricted, due to its bioaccumulation and long half-life. Studies have shown that PFOS has the ability to induce adipogenic differentiation of human cells. Human mesenchymal stem cells (hMSCs) distributed within the adipose tissue might be a potential target of accumulated PFOS. However, traditional end-point toxicity assays failed to examine the subtle changes of cellular function exposed to low-dose persistent organic pollutants in real time. In the present work, highly sensitive and long-retained (more than 30 days) fluorescence based polymeric nanosensors were developed and employed for real-time assessment of cellular functions. hMSCs were engineered with sensor molecules encapsulated poly (lactic-co-glycolic acid) (PLGA) particles. Once internalized by hMSCs, PLGA particles continuously release and replenish sensor molecules to cytoplasm, resulting in prolonged fluorescence signal against photo bleaching and dilution by exocytosis. With this method, the dynamic changes of viability, ROS induction, and adipogenic differentiation related mRNA expression of hMSCs were monitored. PFOS with the concentration as low as 0.1 μM can induce cellular ROS and enhance the PPARγ and ap2 mRNA expression, suggesting the effect on promoting adipogenic differentiation of hMSCs.

Andrographolide mitigates cartilage damage via miR-27-3p-modulated matrix metalloproteinase13 repression

BACKGROUND

As a potential anti-arthritic agent, Andrographolide (And) is capable of promoting chondrocyte proliferation and preventing apoptosis in pathologic condition. The present study aimed to explore the roles of And in in vivo and in vitro models of osteoarthritis (OA), as well as its underlying molecular mechanisms.

METHODS

An OA mouse model was established using anterior cruciate ligament transection operation on the left knee joint. The pathological changes of articular cartilage were assessed using safranin O staining. Chondrocyte proliferation and apoptosis were measured using cell a counting kit-8 assay and flow cytometry. Bioinformatics algorithms and a luciferase reporter assay were used to evaluate matrix metalloproteinase13 (MMP13) as a direct target of miR-27-3p.

RESULTS

And had the ability to prevent catabolism and facilitate anabolism of articular cartilage in an experimental OA model in mice. In addition, And alleviated chondrocyte apoptosis in in vitro and in vivo models of OA. We also found that both up-regulation of MMP13 and down-regulation of miR-27-3p in the proximal tibia of OA mice and interleukin (IL)-1β-stimulated chondrocytes were reversed by And administration simultaneously. MMP13 was validated as direct target of miR-27-3p and could be suppressed by overexpression of miR-27-3p in mouse chondrocyte. Furthermore, overexpression of miR-27-3p or MMP13 loss-of-function in chondrocytes could alleviate IL-1β-induced apoptosis.

CONCLUSIONS

These results indicated that miR-27-3p/MMP13 signaling axis might be a potential therapeutic target of And for preventing the progression of OA.

A flexible and physically transient electrochemical sensor for real-time wireless nitric oxide monitoring

Real-time sensing of nitric oxide (NO) in physiological environments is critically important in monitoring neurotransmission, inflammatory responses, cardiovascular systems, etc. Conventional approaches for NO detection relying on indirect colorimetric measurement or built with rigid and permanent materials cannot provide continuous monitoring and/or require additional surgical retrieval of the implants, which comes with increased risks and hospital cost. Herein, we report a flexible, biologically degradable and wirelessly operated electrochemical sensor for real-time NO detection with a low detection limit (3.97 nmol), a wide sensing range (0.01-100 μM), and desirable anti-interference characteristics. The device successfully captures NO evolution in cultured cells and organs, with results comparable to those obtained from the standard Griess assay. Incorporated with a wireless circuit, the sensor platform achieves continuous sensing of NO levels in living mammals for several days. The work may provide essential diagnostic and therapeutic information for health assessment, treatment optimization and postsurgical monitoring.

A novel view of the problem of Osteoarthritis in experimental rat model

Introduction: The article presents the results of the functional tests to improve the assessment of MIA-induced osteoarthritis development and the effectiveness of NSAID therapy.

Materials and methods: In the study, 26 male SD rats were used. MIA-induced osteoarthritis was simulated in the right knee joint. After an intra-articular injection of MIA, the animals were treated with ibuprofen and meloxicam. Pain assessment was studied in the following functional tests: incapacitance (hind limb weight bearing) test, von Frey test (mechanical allodynia), grip strength test, and knee diameter measurement. At the end of the study, a histological analysis of the knee joint was performed.

Results and discussion: An intra-articular MIA injection reduced 1.5 times the paw withdrawal threshold. In the rats that suffered MIA-induced osteoarthritis, the difference between the diameters of the intact and injected joints was 1.05 mm, compared to 0.03 mm difference in the control group. Hind limb weight bearing asymmetry was 89.5% when simulating MIA-induced osteoarthritis. The muscular hind limb grip strength in rats with MIA-induced osteoarthritis was significantly reduced on 3rd and 7th days after simulating osteoarthritis. Ibuprofen and meloxicam showed significant efficacy in all the above tests, although ibuprofen effectiveness was more pronounced than that of meloxicam.

Conclusion: The following functional tests were identified as the most significant and sufficient to assess the development of MIA-induced osteoarthritis and analgesic efficacy of NSAIDs: incapacitance test, allodynia test (von Frey filaments), measurement of hind limb grip strength and measurement of the diameter of the inflamed knee joint. The histological analysis made it possible to confirm the correspondence of the physiological response and pathological changes in the knee joint.

A Nitric Oxide (NO) Nanoreporter for Noninvasive Real-Time Imaging of Macrophage Immunotherapy

Macrophage-centered therapeutic approaches that rely on immune modulation of tumor associated macrophages (TAMs) from a pro-tumorigenic phenotype (M2) to an anti-tumorigenic phenotype (M1) have facilitated a paradigm shift in macrophage immunotherapy. However, limited clinical success has been achieved due to the low response rates observed in different types of cancers. The ability to measure immune response in real time is critical in order to differentiate responders from non-responders; however, there are currently no platforms to monitor real-time macrophage immunotherapy response. Hence, there is an immediate need to develop imaging techniques that can longitudinally monitor macrophage immunotherapy response. Nitric oxide (NO) produced as a result of activation of macrophages to an anti-tumorigenic state is considered as a hallmark of M1 and can be a direct indication of response. In this study, a NO nanoreporter (NO-NR) is reported that enables real-time monitoring of macrophage immunotherapy drugs in vitro and in vivo. Furthermore, it is observed that sustained inhibition of colony stimulating factor 1 receptor (CSF1R) using a CSF1R inhibitor-NO-NR system leads to enhanced efficacy and better imaging signal. In conclusion, a first-of-its-kind NO nanoreporter tool is reported that can be used as an activatable imaging agent to monitor macrophage immunotherapy response in real time.

Nanotechnological Strategies for Osteoarthritis Diagnosis, Monitoring, Clinical Management, and Regenerative Medicine: Recent Advances and Future Opportunities

PURPOSE OF REVIEW

In this review article, we discuss the potential for employing nanotechnological strategies for the diagnosis, monitoring, and clinical management of osteoarthritis (OA) and explore how nanotechnology is being integrated rapidly into regenerative medicine for OA and related osteoarticular disorders.

RECENT FINDINGS

We review recent advances in this rapidly emerging field and discuss future opportunities for innovations in enhanced diagnosis, prognosis, and treatment of OA and other osteoarticular disorders, the smart delivery of drugs and biological agents, and the development of biomimetic regenerative platforms to support cell and gene therapies for arresting OA and promoting cartilage and bone repair. Nanotubes, magnetic nanoparticles, and other nanotechnology-based drug and gene delivery systems may be used for targeting molecular pathways and pathogenic mechanisms involved in OA development. Nanocomposites are also being explored as potential tools for promoting cartilage repair. Nanotechnology platforms may be combined with cell, gene, and biological therapies for the development of a new generation of future OA therapeutics. Graphical Abstract.

Biomaterial-engineered intra-articular drug delivery systems for osteoarthritis therapy

Osteoarthritis (OA) is a progressive and degenerative disease, which is no longer confined to the elderly. So far, current treatments are limited to symptom relief, and no valid OA disease-modifying drugs are available. Additionally, OA relative joint is challenging for drug delivery, since the drugs experience rapid clearance in joint, showing a poor bioavailability. Existing therapeutic drugs, like non-steroidal anti-inflammatory drugs (NSAIDs) and corticosteroids, are not conducive for long-term use due to adverse effects. Though supplementations, including chondroitin sulfate and glucosamine, have shown beneficial effects on joint tissues in OA, their therapeutic use is still debatable. New emerging agents, like Kartogenin (KGN) and Interleukin-1 receptor antagonist (IL-1 ra), without a proper formulation, still will not work. Therefore, it is urgent to establish a suitable and efficient drug delivery system for OA therapy. In this review, we pay attention to various types of drug delivery systems and potential therapeutic drugs that may escalate OA treatments.

Cartilage-targeting and dual MMP-13/pH responsive theranostic nanoprobes for osteoarthritis imaging and precision therapy

Osteoarthritis (OA) microenvironment is marked by matrix metalloproteinases-13 (MMP-13) overexpression and weak acidity, making it possible to develop dual-stimuli responsive theranostic nanoprobes for OA diagnosis and therapy. However, current MMP/pH-responsive systems are not suitable for OA because of their poor biocompatibility, poor degradation and non-cartilage-targeting of the responsive probes. Here we designed a novel biocompatible cartilage-targeting and MMP-13/pH-responsive ferritin nanocages (CMFn) loaded with an anti-inflammatory drug (Hydroxychloroquine, HCQ), termed CMFn@HCQ, for OA imaging and therapy. We found that CMFn could be smartly "turned on" to emit light for OA imaging in response to the level of overexpressed MMP-13 in OA microenvironment, corresponding to the degree of OA severity. Thus the light intensity detected reflected the degree of OA severity, enabling the precise disease classification by our CMFn. CMFn could be "turned off" to stop emitting light in the normal joint. CMFn@HCQ nanocages could target the cartilage and release HCQ in the OA joint specifically under acidic pH conditions in a sustained manner, prolonging the drug retention time to 14 days to remarkably reduce synovial inflammation in the OA joints. The CMFn@HCQ nanocages represent a smart dual-stimuli responsive and cartilage-targeting nanoprobes, and hold promise for imaging-guided precision therapy for OA.

A double-blind, randomized, placebo-controlled study to assess the efficacy of Andrographis paniculata standardized extract (ParActin®) on pain reduction in subjects with knee osteoarthritis

Andrographis paniculata Wall (Acanthaceae) is becoming more recognized for its anti-inflammatory and antioxidant properties. A randomized, double-blind, placebo-controlled study was conducted to assess the efficacy of an andrographolide-containing supplement, ParActin® (300 and 600 mg daily), on Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) pain reduction in patients with knee osteoarthritis. Joint stiffness, physical function, changes in the SF-36 quality of life questionnaire, a fatigue scale, and safety were also evaluated. A total of 103 male and female patients with I-II osteoarthritis of the knee joint were assessed. Patients treated with 300 or 600 mg/day of ParActin® showed a significant reduction in pain at days 28, 56, and 84 compared with a placebo group. WOMAC stiffness scores, physical function score, and the fatigue score showed a significant improvement in both ParActin®-treated groups compared with the placebo group. At the end of the study, the quality of life (SF-36 questionnaire) and Functional Assessment of Chronic Illness Therapy (FACIT) scores showed significant improvements in both ParActin®-treated groups compared with the placebo group. Overall, it can be concluded that ParActin® in 300 and 600 mg/day dosages were found to be effective and safe in reducing pain in individuals suffering from mild to moderate knee osteoarthritis.

A photothermal-triggered nitric oxide nanogenerator combined with siRNA for precise therapy of osteoarthritis by suppressing macrophage inflammation

Although nitric oxide (NO) can be used to treat osteoarthritis (OA) by inhibiting inflammation, a method for the accurately controlled release of NO in inflammatory cells is still elusive. Herein, photothermal-triggered NO nanogenerators NO-Hb@siRNA@PLGA-PEG (NHsPP) were constructed by assembling photothermal-agents and NO molecules within nanoparticles. In the NHsPP nanoparticles the hemoglobin (Hb) nanoparticles can act as a NO carrier which can absorb near-infrared light at 650 nm (0.5 W cm-2) and convert it into heat to trigger the release of NO. Moreover, after loading Notch1-siRNA, precise treatment can be achieved. Furthermore, using the synergistic effect of photothermal therapy, the NHsPP nanoparticles achieved simultaneous treatment with NO, siRNA and PTT. Through this combination therapy, the therapeutic effect of the NHsPP nanoparticles was significantly enhanced compared to the treatment groups using only NO, siRNA or PTT. This combination therapy inhibits the inflammatory response effectively by reducing the level of pro-inflammatory cytokines and the macrophage response. Subsequently, guided by dual-modal imaging, the NHsPP nanoparticles can not only accumulate effectively in OA mice, but can also reduce the inflammatory response and efficiently prevent cartilage erosion, without causing toxic side effects in the major organs. Therefore, this novel photothermal nanoparticle-based NO-releasing system is expected to be a potential alternative for clinical inflammatory disease therapy and may provide image guidance when combined with other nanotherapy systems.

Clinical Applications of Carbon Nanomaterials in Diagnostics and Therapy

Nanomaterials have the potential to improve how patients are clinically treated and diagnosed. While there are a number of nanomaterials that can be used toward improved drug delivery and imaging, how these nanomaterials confer an advantage over other nanomaterials, as well as current clinical approaches is often application or disease specific. How the unique properties of carbon nanomaterials, such as nanodiamonds, carbon nanotubes, carbon nanofibers, graphene, and graphene oxides, make them promising nanomaterials for a wide range of clinical applications are discussed herein, including treating chemoresistant cancer, enhancing magnetic resonance imaging, and improving tissue regeneration and stem cell banking, among others. Additionally, the strategies for further improving drug delivery and imaging by carbon nanomaterials are reviewed, such as inducing endothelial leakiness as well as applying artificial intelligence toward designing optimal nanoparticle-based drug combination delivery. While the clinical application of carbon nanomaterials is still an emerging field of research, there is substantial preclinical evidence of the translational potential of carbon nanomaterials. Early clinically trial studies are highlighted, further supporting the use of carbon nanomaterials in clinical applications for both drug delivery and imaging.