Charge based intra-cartilage delivery of single dose dexamethasone using Avidin nano-carriers suppresses cytokine-induced catabolism long term

Screening of poly-beta amino ester coated emulsion of ketorolac for cartilage delivery

Osteoarthritis (OA) is a prevalent chronic health condition necessitating effective treatment strategies. Globally, there were 86 million people with incident knee osteoarthritis in 2020. Pain management remains the primary approach to OA as the nature of cartilage poses challenges for drug delivery. An emulsion-based delivery system, using a class of positively charged and hydrolysable polymers (poly-beta-amino-esters) to coat oil droplets containing drugs, has been shown to enhance and prolong drug localization in ex vivo cartilage models. As the properties of the polymers used in this technology strongly depend on the monomers used in the synthesis, this study presents the screening of a wide range of PBAEs as droplet coating agents and using ketorolac as a model of nonsteroidal anti-inflammatory drugs. The emulsions prepared with this PBAE library were characterized, and drug localisation and retention were evaluated in both native and glycosaminoglycan (GAG) depleted cartilage ex vivo models. Optimal candidates were identified and tested in an ex vivo model showing the ability to protect chondrocyte cell viability and increase both GAG and collagen contents in cartilage exposed to cytokine (IL-1α) simulating acute cartilage damage. This work demonstrates the potential of PBAE coated emulsion as a delivery system for effective drug delivery in OA treatment.

Zwitterionic polymer-dexamethasone conjugates penetrate and protect cartilage from inflammation

Improving the pharmacokinetics of intra-articularly injected therapeutics is a major challenge in treating joint disease. Small molecules and biologics are often cleared from the joint within hours, which greatly reduces their therapeutic efficacy. Furthermore, they are often injected at high doses, which can lead to local cytotoxicity and systemic side effects. In this study, we present modular polymer-drug conjugates of zwitterionic poly(carboxybetaine acrylamide) (pCBAA) and the anti-inflammatory glucocorticoid dexamethasone (DEX) to create cartilage-targeted carriers with slow-release kinetics. pCBAA polymers showed excellent cartilage penetration (full thickness in 1 h) and retention (>50 % after 2 weeks of washing). DEX was loaded onto the pCBAA polymer by employing two different DEX-bearing comonomers to produce pCBAA-co-DEX conjugates with different release kinetics. The slow-releasing conjugate showed zero-order release kinetics in PBS over 70 days. The conjugates elicited no oxidative stress on chondrocytes compared to dose-matched free DEX and protected bovine cartilage explants from the inflammatory response after treatment with IL-1β. By combining cartilage targeting and sustained drug release properties, the pCBAA-co-DEX conjugates solve many issues of today's intra-articular therapeutics, which could ultimately enable better long-term clinical outcomes with fewer side effects.

Branched poly-l-lysine for cartilage penetrating carriers

Joint diseases, such as osteoarthritis, often require delivery of drugs to chondrocytes residing within the cartilage. However, intra-articular delivery of drugs to cartilage remains a challenge due to their rapid clearance within the joint. This problem is further exacerbated by the dense and negatively charged cartilage extracellular matrix (ECM). Cationic nanocarriers that form reversible electrostatic interactions with the anionic ECM can be an effective approach to overcome the electrostatic barrier presented by cartilage tissue. For an effective therapeutic outcome, the nanocarriers need to penetrate, accumulate, and be retained within the cartilage tissue. Nanocarriers that adhere quickly to cartilage tissue after intra-articular administration, transport through cartilage, and remain within its full thickness are crucial to the therapeutic outcome. To this end, we used ring-opening polymerization to synthesize branched poly(l-lysine) (BPL) cationic nanocarriers with varying numbers of poly(lysine) branches, surface charge, and functional groups, while maintaining similar hydrodynamic diameters. Our results show that the multivalent BPL molecules, including those that are highly branched (i.e., generation two), can readily adhere and transport through the full thickness of cartilage, healthy and degenerated, with prolonged intra-cartilage retention. Intra-articular injection of the BPL molecules in mouse knee joint explants and rat knee joints showed their localization and retention. In summary, this study describes an approach to design nanocarriers with varying charge and abundant functional groups while maintaining similar hydrodynamic diameters to aid the delivery of macromolecules to negatively charged tissues.

Poly-beta-amino-ester licofelone conjugates development for osteoarthritis treatment

Disease-modifying osteoarthritis drugs (DMOADs) are a new therapeutic class for osteoarthritis (OA) prevention or inhibition of the disease development. Unfortunately, none of the DMOADs have been clinically approved due to their poor therapeutic performances in clinical trials. The joint environment has played a role in this process by limiting the amount of drug effectively delivered as well as the time that the drug stays within the joint space. The current study aimed to improve the delivery of the DMOADs into cartilage tissue by increasing uptake and retention time of the DMOADs within the tissue. Licofelone was used a model DMOAD due to its significant therapeutic effect against OA progression as shown in the recent phase III clinical trial. For this purpose licofelone was covalently conjugated to the two different A16 and A87 poly-beta-amino-ester (PBAEs) polymers taking advantage of their hydrolysable, cytocompatible, and cationic nature. We have shown cartilage uptake of the licofelone-PBAE conjugates increased 18 times and retention in tissues was prolonged by 37 times compared to the equivalent dose of the free licofelone. Additionally, these licofelone conjugates showed no detrimental effect on the chondrocyte viability. In conclusion, the cationic A87 and A16 PBAE polymers increased the amount of licofelone within the cartilage, which could potentially enhance the therapeutic effect and pharmacokinetic performance of this drug and other DMOADs clinically.

Sustained intra-cartilage delivery of interleukin-1 receptor antagonist using cationic peptide and protein-based carriers

OBJECTIVE

Blocking the interleukin-1 (IL-1) catabolic cascade following joint trauma can be achieved using its receptor antagonist, IL-1Ra. However, its clinical translation for osteoarthritis therapy has been unsuccessful due to its rapid joint clearance and lack of targeting and penetration into deep cartilage layers at therapeutic concentrations. Here, we target the high negative charge of cartilage aggrecan-glycosaminoglycans (GAGs) by attaching cationic carriers to IL-1Ra. IL-1Ra was conjugated to the cartilage targeting glycoprotein, Avidin, and a short length optimally charged cationic peptide carrier (CPC+14). It is hypothesized that electro-diffusive transport and binding properties of IL-1Ra-Avidin and IL-1Ra-CPC+14 will create intra-cartilage depots of IL-1Ra, resulting in long-term suppression of IL-1 catabolism with only a single administration.

DESIGN

IL-1Ra was conjugated to Avidin or CPC+14 using site specific maleimide linkers, and confirmed using gel electrophoresis, high-performance liquid chromatography (HPLC), and mass spectrometry. Intra-cartilage transport and retention of conjugates was compared with native IL-1Ra. Attenuation of IL-1 catabolic signaling with one-time dose of IL-1Ra-CPC+14 and IL-1Ra-Avidin was assessed over 16 days using IL-1α challenged bovine cartilage and compared with unmodified IL-1Ra.

RESULTS

Positively charged IL-1Ra penetrated through the full-thickness of cartilage, creating a drug depot. A single dose of unmodified IL-1Ra was not sufficient to attenuate IL-1-induced cartilage deterioration over 16 days. However, when delivered using Avidin, and to a greater extent CPC+14, IL-1Ra significantly suppressed cytokine induced GAG loss and nitrite release while improving cell metabolism and viability.

CONCLUSION

Charge-based cartilage targeting drug delivery systems hold promise as they can enable long-term therapeutic benefit with only a single dose.

Intra-articular kinetics of a cartilage targeting cationic PEGylated protein for applications in drug delivery

OBJECTIVES

Cartilage targeting cationic glycoprotein Avidin was PEGylated to synthesize a multi-arm Avidin (mAv) nano-construct with high drug loading content. Here we investigate mAv biodistribution and kinetics over a 7-day period following intra-articular (IA) administration in rat knee joints.

METHODS

Labeled mAv was injected into healthy rat knees, and joint tissues (articular cartilage, menisci, ligaments, tendons, fat pad) were harvested following sacrifice at 6 h, 1, 4 and 7 days. Its IA biodistribution and retention were measured using fluorescence microscopy. Tissue localization was compared in young vs old rats by immunohistochemistry. mAv chondrotoxicity and immune response were evaluated to determine safe carrier dose limits.

RESULTS

mAv penetrated through the full thickness of rat cartilage and other joint tissues within 6 h, remaining detectable within most joint tissues over 7 days. Intra-tissue uptake correlated strongly with tissue GAG concentration, confirming the dominant role of electrostatic interactions between positively charged mAv and the negatively charged aggrecan proteoglycans. mAv was uptaken by chondrocytes and also penetrated the osteocyte lacuno-canalicular system of peri-articular bone in both young and old rats. mAv did not cause cytotoxicity at concentrations up to 300 μM but elicited a dose dependent immunogenic response.

CONCLUSIONS

mAv's ability to target a variety of joint tissues, chondrocytes, and peri-articular osteocytes without sequestration in synovial fluid makes it a versatile carrier for delivering a wide range of drugs for treating a broad class of musculoskeletal diseases. Drugs can be conjugated using simple aqueous based avidin-biotin reaction, supporting its clinical prospects.

Cell morphology as a biological fingerprint of chondrocyte phenotype in control and inflammatory conditions

Introduction

Little is known how inflammatory processes quantitatively affect chondrocyte morphology and how single cell morphometric data could be used as a biological fingerprint of phenotype.

Methods

We investigated whether trainable high-throughput quantitative single cell morphology profiling combined with population-based gene expression analysis can be used to identify biological fingerprints that are discriminatory of control vs. inflammatory phenotypes. The shape of a large number of chondrocytes isolated from bovine healthy and human osteoarthritic (OA) cartilages was quantified under control and inflammatory (IL-1β) conditions using a trainable image analysis technique measuring a panel of cell shape descriptors (area, length, width, circularity, aspect ratio, roundness, solidity). The expression profiles of phenotypically relevant markers were quantified by ddPCR. Statistical analysis, multivariate data exploration, and projection-based modelling were used for identifying specific morphological fingerprints indicative of phenotype.

Results

Cell morphology was sensitive to both cell density and IL-1β. In both cell types, all shape descriptors correlated with expression of extracellular matrix (ECM)- and inflammatory-regulating genes. A hierarchical clustered image map revealed that individual samples sometimes responded differently in control or IL-1β conditions than the overall population. Despite these variances, discriminative projection-based modeling revealed distinct morphological fingerprints that discriminated between control and inflammatory chondrocyte phenotypes: the most essential morphological characteristics attributable to non-treated control cells was a higher cell aspect ratio in healthy bovine chondrocytes and roundness in OA human chondrocytes. In contrast, a higher circularity and width in healthy bovine chondrocytes and length and area in OA human chondrocytes indicated an inflammatory (IL-1β) phenotype. When comparing the two species/health conditions, bovine healthy and human OA chondrocytes exhibited comparable IL-1β-induced morphologies in roundness, a widely recognized marker of chondrocyte phenotype, and aspect ratio.

Discussion

Overall, cell morphology can be used as a biological fingerprint for describing chondrocyte phenotype. Quantitative single cell morphometry in conjunction with advanced methods for multivariate data analysis allows identifying morphological fingerprints that can discriminate between control and inflammatory chondrocyte phenotypes. This approach could be used to assess how culture conditions, inflammatory mediators, and therapeutic modulators regulate cell phenotype and function.

Mechanical Articular Cartilage Injury Models and Their Relevance in Advancing Therapeutic Strategies

This chapter details how Alan Grodzinsky and his team unraveled the complex electromechanobiological structure-function relationships of articular cartilage and used these insights to develop an impressively versatile shear and compression model. In this context, this chapter focuses (i) on the effects of mechanical compressive injury on multiple articular cartilage properties for (ii) better understanding the molecular concept of mechanical injury, by studying gene expression, signal transduction and the release of potential injury biomarkers. Furthermore, we detail how (iii) this was used to combine mechanical injury with cytokine exposure or co-culture systems for generating a more realistic trauma model to (iv) investigate the therapeutic modulation of the injurious response of articular cartilage. Impressively, Alan Grodzinsky's research has been and will remain to be instrumental in understanding the proinflammatory response to injury and in developing effective therapies that are based on an in-depth understanding of complex structure-function relationships that underlay articular cartilage function and degeneration.

In Vitro Models and Proteomics in Osteoarthritis Research

This review summarizes and exemplifies the current understanding of osteoarthritis in vitro models and describes their relevance for new insights in the future of osteoarthritis research. Our friend and highly appreciated colleague, Prof. Alan Grodzinsky has contributed greatly to the understanding of joint tissue biology and cartilage biomechanics. He frequently utilizes in vitro models and cartilage explant cultures, and recent work also includes proteomics studies. This review is dedicated to honor his 75-year birthday and will focus on recent proteomic in vitro studies related to osteoarthritis, and within this topic highlight some of his contributions to the field.

The Current Role of Disease-modifying Osteoarthritis Drugs

Contemporary treatments for osteoarthritis (OA) pursue only to alleviate the pain caused by the illness. Discovering disease-modifying osteoarthritis drugs (DMOADs) that can induce the repair and regeneration of articular tissues would be of substantial usefulness. The purpose of this manuscript is to review the contemporary role of DMOADs in managing OA. A narrative literature review on the subject, exploring the Cochrane Library and PubMed (MEDLINE) was performed. It was encountered that many publications have analyzed the impact of several DMOAD methods, including anti-cytokine therapy (tanezumab, AMG 108, adalimumab, etanercept, anakinra), enzyme inhibitors (M6495, doxycycline, cindunistat, PG-116800), growth factors (bone morphogenetic protein-7, sprifermin), gene therapy (micro ribonucleic acids, antisense oligonucleotides), peptides (calcitonin) and others (SM04690, senolitic, transient receptor potential vanilloid 4, neural EGFL-like 1, TPCA-1, tofacitinib, lorecivivint and quercitrin). Tanezumab has been demonstrated to alleviate hip and knee pain in individuals with OA but can cause major adverse events (osteonecrosis of the knee, rapid illness progression, augmented prevalence of total joint arthroplasty of involved joints, particularly when tanezumab is combined with nonsteroidal anti-inflammatory drugs. SM04690 (a Wnt inhibitor) has been demonstrated to be safe and efficacious in alleviating pain and ameliorating function as measured by the Western Ontario and McMaster Universities Arthritis Index. The intraarticular injection of lorecivivint is deemed safe and well tolerated, with no important reported systemic complications. In conclusion, even though DMOADs seem promising, their clinical effectiveness has not yet been demonstrated for managing OA. Until forthcoming studies can proved the medications' capacity to repair and regenerate tissues affected by OA, physicians should keep using treatments that only intend to alleviate pain.

Nanodevices for deep cartilage penetration

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

Charge-based drug delivery to cartilage: Hydrophobic and not electrostatic interactions are the dominant cause of competitive binding of cationic carriers in synovial fluid

Charge-based drug delivery has proven to be effective for targeting negatively charged cartilage for the treatment of osteoarthritis. Cartilage is surrounded by synovial fluid (SF), which is comprised of negatively charged hyaluronic acid and hydrophobic proteins that can competitively bind cationic carriers and prevent their transport into cartilage. Here we investigate the relative contributions of charge and hydrophobic effects on the binding of cationic carriers within healthy and arthritic SF by comparing the transport of arginine-rich cartilage targeting cationic peptide carriers with hydrophilic (CPC +14N) or hydrophobic property (CPC +14A). CPC +14N had significantly greater intra-cartilage uptake in presence of SF compared to CPC +14A in-vitro and in vivo. In presence of individual anionic SF constituents, both CPCs maintained similar high intra-cartilage uptake while in presence of hydrophobic constituents, CPC +14N had greater uptake confirming that hydrophobic and not charge interactions are the dominant cause of competitive binding within SF. Results also demonstrate that short-range effects can synergistically stabilize intra-cartilage charge-based binding - a property that can be utilized for enhancing drug-carrier residence time in arthritic cartilage with diminished negative fixed charge density. The work provides a framework for the rational design of cationic carriers for developing targeted therapies for another complex negatively charged environments. STATEMENT OF SIGNIFICANCE: This work demonstrates that hydrophobic and not charge interactions are the dominant cause of the binding of cationic carriers in synovial fluid. Therefore, cationic carriers can be effectively used for cartilage targeting if they are made hydrophilic. This can facilitate clinical translation of various osteoarthritis drugs for cartilage repair that have failed due to a lack of effective cartilage targeting methods. It also demonstrates that short-range hydrogen bonds can synergistically stabilize electrostatic binding in cartilage offering a method for enhancing the targeting and residence time of cationic carriers within arthritic cartilage with reduced charge density. Finally, the cartilage-synovial fluid unit provides an excellent model of a complex negatively charged environment and allows us to generalize these findings and develop targeted therapies for other charged tissue-systems.

Effects of polycationic drug carriers on the electromechanical and swelling properties of cartilage

Cationic nanocarriers offer a promising solution to challenges in delivering drugs to negatively charged connective tissues, such as to articular cartilage for the treatment of osteoarthritis (OA). However, little is known about the effects that cationic macromolecules may have on the mechanical properties of cartilage at high interstitial concentrations. We utilized arginine-rich cationic peptide carriers (CPCs) with varying net charge (from +8 to +20) to investigate the biophysical mechanisms of nanocarrier-induced alterations to cartilage biomechanical properties. We observed that CPCs increased the compressive modulus of healthy bovine cartilage explants by up to 70% and decreased the stiffness of glycosaminoglycan-depleted tissues (modeling OA) by 69%; in both cases, the magnitude of the change in stiffness correlated with the uptake of CPC charge variants. Next, we directly measured CPC-induced osmotic deswelling in cartilage tissue due to shielding of charge repulsions between anionic extracellular matrix constituents, with magnitudes of reductions between 36 and 64 kPa. We then demonstrated that electrostatic interactions were required for CPC-induced stiffening to occur, evidenced by no observed increase in tissue stiffness when measured in hypertonic bathing salinity. We applied a non-ideal Donnan osmotic model (under triphasic theory) to separate bulk modulus measurements into Donnan and non-Donnan components, which further demonstrated the conflicting charge-shielding and matrix-stiffening effects of CPCs. These results show that cationic drug carriers can alter tissue mechanical properties via multiple mechanisms, including the expected charge shielding as well as a novel stiffening phenomenon mediated by physical linkages. We introduce a model for how the magnitudes of these mechanical changes depend on tunable physical properties of the drug carrier, including net charge, size, and spatial charge distribution. We envision that the results and theory presented herein will inform the design of future cationic drug-delivery systems intended to treat diseases in a wide range of connective tissues.

Inflammatory cytokines and mechanical injury induce post-traumatic osteoarthritis-like changes in a human cartilage-bone-synovium microphysiological system

Background

Traumatic knee injuries in humans trigger an immediate increase in synovial fluid levels of inflammatory cytokines that accompany impact damage to joint tissues. We developed a human in vitro cartilage-bone-synovium (CBS) coculture model to study the role of mechanical injury and inflammation in the initiation of post-traumatic osteoarthritis (PTOA)-like disease.

Methods

Osteochondral plugs (cartilage-bone, CB) along with joint capsule synovium explants (S) were harvested from 25 cadaveric distal femurs from 16 human donors (Collin’s grade 0–2, 23–83years). Two-week monocultures (cartilage (C), bone (B), synovium (S)) and cocultures (CB, CBS) were established. A PTOA-like disease group was initiated via coculture of synovium explants with mechanically impacted osteochondral plugs (CBS+INJ, peak stress 5MPa) with non-impacted CB as controls. Disease-like progression was assessed through analyses of changes in cell viability, inflammatory cytokines released to media (10-plex ELISA), tissue matrix degradation, and metabolomics profile.

Results

Immediate increases in concentrations of a panel of inflammatory cytokines occurred in CBS+INJ and CBS cocultures and cultures with S alone (IL-1, IL-6, IL-8, and TNF-α among others). CBS+INJ and CBS also showed increased chondrocyte death compared to uninjured CB. The release of sulfated glycosaminoglycans (sGAG) and associated ARGS-aggrecan neoepitope fragments to the medium was significantly increased in CBS and CBS+INJ groups. Distinct metabolomics profiles were observed for C, B, and S monocultures, and metabolites related to inflammatory response in CBS versus CB (e.g., kynurenine, 1-methylnicotinamide, and hypoxanthine) were identified.

Conclusion

CBS and CBS+INJ models showed distinct cellular, inflammatory, and matrix-related alterations relevant to PTOA-like initiation/progression. The use of human knee tissues from donors that had no prior history of OA disease suggests the relevance of this model in highlighting the role of injury and inflammation in earliest stages of PTOA progression.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13075-022-02881-z.

Nanobiosensor Based on Sugar Code-AuNPs Aggregation: A Key to Opening New Gates in Rapid Diagnosis of Streptococcal Pharyngitis

Streptococcal pharyngitis is mainly caused by Streptococcus pyogenes (GAS), which if left untreated can lead to rheumatic heart disease. The accurate diagnosis of streptococcal pharyngitis is a challenge for clinicians because several symptoms of streptococcal pharyngitis are similar to viral pharyngitis. There are some commercially available biosensors for the rapid diagnosis of streptococcal pharyngitis. Nevertheless, they are not widely used by physicians, mainly because of their high price and dependence on the instrument. Serotype M1 GAS is the most prevalent cause of streptococcal pharyngitis and binds to H-1 antigen, a sugar code found on oral epithelial cells. Here, we present a nanobiosensor based on aggregation of H-1 antigen-conjugated gold nanoparticles for the rapid, qualitative, and quantitative detection of M1 GAS, which is inspired by the sugar code-lectin interaction. It is noteworthy that M1 GAS was detected in a wide concentration range (1 × 103–1×106 CFU/ml) with a linear response and a short detection time of 20 min. Good reproducibility, easy-to-use, and relatively low production cost are among other attractive features of this nanobiosensor. This work provides a strategic roadmap for developing a new generation of biosensors via targeting the sugar code-lectin interaction in future studies.

Cationic peptide carriers enable long-term delivery of insulin-like growth factor-1 to suppress osteoarthritis-induced matrix degradation

Background

Insulin-like growth factor-1 (IGF-1) has the potential to be used for osteoarthritis (OA) treatment but has not been evaluated in clinics yet owing to toxicity concerns. It suffers from short intra-joint residence time and a lack of cartilage targeting following its intra-articular administration. Here, we synthesize an electrically charged cationic formulation of IGF-1 by using a short-length arginine-rich, hydrophilic cationic peptide carrier (CPC) with a net charge of +14, designed for rapid and high uptake and retention in both healthy and arthritic cartilage.

Methods

IGF-1 was conjugated to CPC by using a site-specific sulfhydryl reaction via a bifunctional linker. Intra-cartilage depth of penetration and retention of CPC-IGF-1 was compared with the unmodified IGF-1. The therapeutic effectiveness of a single dose of CPC-IGF-1 was compared with free IGF-1 in an IL-1α-challenged cartilage explant culture post-traumatic OA model.

Results

CPC-IGF-1 rapidly penetrated through the full thickness of cartilage creating a drug depot owing to electrostatic interactions with negatively charged aggrecan-glycosaminoglycans (GAGs). CPC-IGF-1 remained bound within the tissue while unmodified IGF-1 cleared out. Treatment with a single dose of CPC-IGF-1 effectively suppressed IL-1α-induced GAG loss and nitrite release and rescued cell metabolism and viability throughout the 16-day culture period, while free IGF at the equivalent dose was not effective.

Conclusions

CPC-mediated depot delivery of IGF-1 protected cartilage by suppressing cytokine-induced catabolism with only a single dose. CPC is a versatile cationic motif that can be used for intra-cartilage delivery of other similar-sized drugs.

[Research progress of nanomaterials for intra-articular targeted drug delivery in treatment of osteoarthritis]

OBJECTIVE

To review the research progress of intra-articular targeted delivery of nanomaterials in the treatment of osteoarthritis (OA).

METHODS

The domestic and foreign related literature on intra-articular targeted delivery of nanomaterials for the treatment of OA was extensively reviewed, and their targeting strategies were discussed and summarized.

RESULTS

Rapid drug clearance from the joint remains a critical limitation in drug efficacy. Nanocarriers can not only significantly improve the residence profiles of drugs in the joint, but also achieve targeted delivery of drugs to specific joint tissues through active or passive targeting strategies.

CONCLUSION

With the continuous development of various emerging tissue- or cell-specific drugs, the targeted delivery of drugs with nanomaterials promise to realize the clinical translation of these drugs in the treatment of OA.

Recent Advances in Nano-Therapeutic Strategies for Osteoarthritis

Osteoarthritis (OA) is the most common type of arthritis and the leading cause of disability globally. It tends to occur in middle age or due to an injury or obesity. OA occurs with the onset of symptoms, including joint swelling, joint effusion, and limited movement at a late stage of the disease, which leads to teratogenesis and loss of joint function. During the pathogenesis of this degenerative joint lesion, several local inflammatory responses are activated, resulting in synovial proliferation and pannus formation that facilitates the destruction of the bone and the articular cartilage. The commonly used drugs for the clinical diagnosis and treatment of OA have limitations such as low bioavailability, short half-life, poor targeting, and high systemic toxicity. With the application of nanomaterials and intelligent nanomedicines, novel nanotherapeutic strategies have shown more specific targeting, prolonged half-life, refined bioavailability, and reduced systemic toxicity, compared to the existing medications. In this review, we summarized the recent advancements in new nanotherapeutic strategies for OA and provided suggestions for improving the treatment of OA.

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

OBJECTIVE

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

DESIGN

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

RESULTS

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

CONCLUSION

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

Intra-articular drug delivery systems for osteoarthritis therapy: shifting from sustained release to enhancing penetration into cartilage

Osteoarthritis (OA) is a progressive chronic inflammation that leads to cartilage degeneration. OA Patients are commonly given pharmacological treatment, but the available treatments are not sufficiently effective. The development of sustained-release drug delivery systems (DDSs) for OA may be an attractive strategy to prevent rapid drug clearance and improve the half-life of a drug at the joint cavity. Such delivery systems will improve the therapeutic effects of anti-inflammatory effects in the joint cavity. Whereas, for disease-modifying OA drugs (DMOADs) which target chondrocytes or act on mesenchymal stem cells (MSCs), the cartilage-permeable DDSs are required to maximize their efficacy. This review provides an overview of joint structure in healthy and pathological conditions, introduces the advances of the sustained-release DDSs and the permeable DDSs, and discusses the rational design of the permeable DDSs for OA treatment. We hope that the ideas generated in this review will promote the development of effective OA drugs in the future.

Cationic Contrast Agents for Computed Tomography of Cartilage for Early Diagnosis of Osteoarthritis

Here we describe methods for synthesizing cationic contrast agents for computed tomography (CT) of cartilage for early diagnosis of tissue degeneration. CT imaging of soft tissues like cartilage is possible only if radio-opaque contrast agents (e.g., ioxaglate) can penetrate through the full thickness of tissue in sufficient concentrations. Ioxaglate (IOX), however, is anionic and is repelled by the negatively charged cartilage matrix resulting in poor CT attenuation. Here we demonstrate cartilage penetrating cationic contrast agents using multi-arm Avidin (mAv) conjugated to ioxaglate (mAv-IOX). mAv-IOX rapidly penetrates through the full thickness of cartilage in high concentrations owing to weak-reversible nature of electrostatic interactions resulting in high CT attenuation even with low doses unlike IOX. The technology has the potential for enabling clinical CT of cartilage and other negatively charged soft tissues.

Charge-Based Multiarm Avidin Nanoconstruct as a Platform Technology for Applications in Drug Delivery

Here we describe methods for synthesizing cationic multiarm Avidin (mAv) nanoconstruct that has a wide range of applications in drug delivery and imaging for a variety of negatively charged tissues. The multiarm structure provides multiple sites for covalent conjugation of drugs. We use avidin-biotin reaction that gives the flexibility for conjugating any desired biotinylated drug to mAv by simple mixing at room temperature. We also describe methods to control hydrolysis rates of ester linkers to enable sustained (and tunable) drug release rates in therapeutic doses.

Intra-Articular Drug Delivery for Osteoarthritis Treatment

Osteoarthritis (OA) is the most prevalent degenerative joint disease affecting millions of people worldwide. Currently, clinical nonsurgical treatments of OA are only limited to pain relief, anti-inflammation, and viscosupplementation. Developing disease-modifying OA drugs (DMOADs) is highly demanded for the efficient treatment of OA. As OA is a local disease, intra-articular (IA) injection directly delivers drugs to synovial joints, resulting in high-concentration drugs in the joint and reduced side effects, accompanied with traditional oral or topical administrations. However, the injected drugs are rapidly cleaved. By properly designing the drug delivery systems, prolonged retention time and targeting could be obtained. In this review, we summarize the drugs investigated for OA treatment and recent advances in the IA drug delivery systems, including micro- and nano-particles, liposomes, and hydrogels, hoping to provide some information for designing the IA injected formulations.

Resveratrol and Curcumin Attenuate Ex Vivo Sugar-Induced Cartilage Glycation, Stiffening, Senescence, and Degeneration

OBJECTIVE

Advanced glycation end-product (AGE) accumulation is implicated in osteoarthritis (OA) pathogenesis in aging and diabetic populations. Here, we develop a representative nonenzymatic glycation-induced OA cartilage explant culture model and investigate the effectiveness of resveratrol, curcumin, and eugenol in inhibiting AGEs and the structural and biological hallmarks of cartilage degeneration.

DESIGN

Bovine cartilage explants were treated with AGE-bovine serum albumin, threose, and ribose to determine the optimal conditions that induce physiological levels of AGEs while maintaining chondrocyte viability. AGE crosslinks, tissue stiffness, cell viability, metabolism and senescence, nitrite release and loss of glycosaminoglycans were assessed. Explants were cotreated with resveratrol, curcumin, or eugenol to evaluate their anti-AGE properties. Blind docking analysis was conducted to estimate binding energies of drugs with collagen II.

RESULTS

Treatment with 100 mM ribose significantly increased AGE crosslink formation and tissue stiffness, resulting in reduced chondrocyte metabolism and enhanced senescence. Blind docking analysis revealed stronger binding energies of both resveratrol and curcumin than ribose, with glycation sites along a human collagen II fragment, indicating their increased likelihood of competitively inhibiting ribose activity. Resveratrol and curcumin, but not eugenol, successfully inhibited AGE crosslink formation and its associated downstream biological response.

CONCLUSIONS

We establish a cartilage explant model of OA that recapitulates several aspects of aged human cartilage. We find that resveratrol and curcumin are effective anti-AGE therapeutics with the potential to decelerate age-related and diabetes-induced OA. This in vitro nonenzymatic glycation-induced model provides a tool for screening OA drugs, to simultaneously evaluate AGE-induced biological and mechanical changes.

Non-invasive monitoring of arthritis treatment response via targeting of tyrosine-phosphorylated annexin A2 in chondrocytes

BACKGROUND

The development and optimization of therapies for rheumatoid arthritis (RA) is currently hindered by a lack of methods for early non-invasive monitoring of treatment response. Annexin A2, an inflammation-associated protein whose presence and phosphorylation levels are upregulated in RA, represents a potential molecular target for tracking RA treatment response.

METHODS

LS301, a near-infrared dye-peptide conjugate that selectively targets tyrosine 23-phosphorylated annexin A2 (pANXA2), was evaluated for its utility in monitoring disease progression, remission, and early response to drug treatment in mouse models of RA by fluorescence imaging. The intraarticular distribution and localization of LS301 relative to pANXA2 was determined by histological and immunohistochemical methods.

RESULTS

In mouse models of spontaneous and serum transfer-induced inflammatory arthritis, intravenously administered LS301 showed selective accumulation in regions of joint pathology including paws, ankles, and knees with positive correlation between fluorescent signal and disease severity by clinical scoring. Whole-body near-infrared imaging with LS301 allowed tracking of spontaneous disease remission and the therapeutic response after dexamethasone treatment. Histological analysis showed preferential accumulation of LS301 within the chondrocytes and articular cartilage in arthritic mice, and colocalization was observed between LS301 and pANXA2 in the joint tissue.

CONCLUSIONS

We demonstrate that fluorescence imaging with LS301 can be used to monitor the progression, remission, and early response to drug treatment in mouse models of RA. Given the ease of detecting LS301 with portable optical imaging devices, the agent may become a useful early treatment response reporter for arthritis diagnosis and drug evaluation.

Encapsulation of polyprodrugs enables an efficient and controlled release of dexamethasone

Water-soluble low molecular weight drugs, such as the synthetic glucocorticoid dexamethasone (DXM), can easily leak out of nanocarriers after encapsulation due to their hydrophilic nature and small size. This can lead to a reduced therapeutic efficacy and therefore to unwanted adverse effects on healthy tissue. Targeting DXM to inflammatory cells of the liver like Kupffer cells or macrophages is a promising approach to minimize typical side effects. Therefore, a controlled transport to the cells of interest and selective on-site release is crucial. Aim of this study was the development of a DXM-phosphate-based polyprodrug and the encapsulation in silica nanocontainers (SiO₂ NCs) for the reduction of inflammatory responses in liver cells. DXM was copolymerized with a linker molecule introducing pH-cleavable hydrazone bonds in the backbone and obtaining polyprodrugs (PDXM). Encapsulation of PDXMs into SiO₂ NCs provided a stable confinement avoiding uncontrolled leakage. PDXMs were degraded under acidic conditions and subsequently released out of SiO₂ NCs. Biological studies showed significantly enhanced anti-inflammatory capacity of the polyprodrug nanoformulations over non-encapsulated DXM or soluble polyprodrugs. These results demonstrate the advantage of combining the polyprodrug strategy with nanocarrier-mediated delivery for enhanced control of the delivery of water-soluble low molecular weight drugs.

Targeted treatment for osteoarthritis: drugs and delivery system

The management of osteoarthritis (OA) is a clinical challenge due to the particular avascular, dense, and occluded tissue structure. Despite numerous clinical reports and animal studies, the pathogenesis and progression of OA are still not fully understood. On the basis of traditional drugs, a large number of new drugs have been continuously developed. Intra-articular (IA) administration for OA hastens the development of targeted drug delivery systems (DDS). OA drugs modification and the synthesis of bioadaptive carriers contribute to a qualitative leap in the efficacy of IA treatment. Nanoparticles (NPs) are demonstrated credible improvement of drug penetration and retention in OA. Targeted nanomaterial delivery systems show the prominent biocompatibility and drug loading-release ability. This article reviews different drugs and nanomaterial delivery systems for IA treatment of OA, in an attempt to resolve the inconsonance between in vitro and in vivo release, and explore more interactions between drugs and nanocarriers, so as to open up new horizons for the treatment of OA.

Poly beta amino ester coated emulsions of NSAIDs for cartilage treatment

Delivering drugs directly into cartilage is still the major challenge in the management and treatment of osteoarthritis (OA) resulting from the aneural, avascular and alymphatic nature of an articular cartilage structure. Progress has been made in the design of drug delivery systems that enhance corticosteroid uptake and retention in cartilage; however also non-steroidal anti-inflammatory drugs (NSAIDs) are prescribed for patients affected by OA and a drug delivery system specifically designed for this drug category is currently unavailable. We developed an approach based on the preparation of NSAID oil-in-water emulsions coated with poly-beta-amino-esters (PBAEs) to exploit the cartilage penetrating ability of such polymers and the high solubility of drugs in oil. These emulsions containing different NSAIDs (indomethacin, ketorolac, diclofenac and naproxen) exhibited enhanced and prolonged drug localisation not only in healthy cartilage tissues but also in early-stage OA samples. The critical role of the PBAE layer on oil droplets was established along with the retained biological activity of the drug as glycosaminoglycan (GAG) and collagen degradation induced by interleukin-1 (IL-1) was prevented by the novel technology. Oil-in-water coated emulsions are very flexible and cost-effective drug delivery systems and such an approach presented here could provide a substantial improvement in the therapeutic treatments of OA and thus patients' outcomes.

Anti-Inflammatory Therapeutic Approaches to Prevent or Delay Post-Traumatic Osteoarthritis (PTOA) of the Knee Joint with a Focus on Sustained Delivery Approaches

Inflammation plays a central role in the pathogenesis of knee PTOA after knee trauma. While a comprehensive therapy capable of preventing or delaying post-traumatic osteoarthritis (PTOA) progression after knee joint injury does not yet clinically exist, current literature suggests that certain aspects of early post-traumatic pathology of the knee joint may be prevented or delayed by anti-inflammatory therapeutic interventions. We discuss multifaceted therapeutic approaches that may be capable of effectively reducing the continuous cycle of inflammation and concomitant processes that lead to cartilage degradation as well as those that can simultaneously promote intrinsic repair processes. Within this context, we focus on early disease prevention, the optimal timeframe of treatment and possible long-lasting sustained delivery local modes of treatments that could prevent knee joint-associated PTOA symptoms. Specifically, we identify anti-inflammatory candidates that are not only anti-inflammatory but also anti-degenerative, anti-apoptotic and pro-regenerative.

A potent peptide-steroid conjugate accumulates in cartilage and reverses arthritis without evidence of systemic corticosteroid exposure

On-target, off-tissue toxicity limits the systemic use of drugs that would otherwise reduce symptoms or reverse the damage of arthritic diseases, leaving millions of patients in pain and with limited physical mobility. We identified cystine-dense peptides (CDPs) that rapidly accumulate in cartilage of the knees, ankles, hips, shoulders, and intervertebral discs after systemic administration. These CDPs could be used to concentrate arthritis drugs in joints. A cartilage-accumulating peptide, CDP-11R, reached peak concentration in cartilage within 30 min after administration and remained detectable for more than 4 days. Structural analysis of the peptides by crystallography revealed that the distribution of positive charge may be a distinguishing feature of joint-accumulating CDPs. In addition, quantitative whole-body autoradiography showed that the disulfide-bonded tertiary structure is critical for cartilage accumulation and retention. CDP-11R distributed to joints while carrying a fluorophore imaging agent or one of two different steroid payloads, dexamethasone (dex) and triamcinolone acetonide (TAA). Of the two payloads, the dex conjugate did not advance because the free drug released into circulation was sufficient to cause on-target toxicity. In contrast, the CDP-11R-TAA conjugate alleviated joint inflammation in the rat collagen-induced model of rheumatoid arthritis while avoiding toxicities that occurred with nontargeted steroid treatment at the same molar dose. This conjugate shows promise for clinical development and establishes proof of concept for multijoint targeting of disease-modifying therapeutic payloads.

Nanoghosts: Mesenchymal Stem cells derived nanoparticles as a unique approach for cartilage regeneration

Osteoarthritis (OA) is a chronic degenerative disease, which affects the joints and is characterized by inflammation, cartilage loss and bone changes. Nowadays, there are no treatments for OA, and current therapies are focused on relieving the symptoms. As a new therapy approach, micro and nanoparticles have been extensively explored and among all the studied particles, the use of cell-membrane-based particles is expanding. Another promising approach studied to treat OA, is the use of mesenchymal stem cells (MSCs) which play an important role modulating inflammation. We developed a novel kind of MSCs' cytoplasmic-membrane-based nanoparticles, termed nano-ghosts (NGs). Retaining MSCs' surface properties and lacking cells' internal machinery allow the NGs to have immunomodulatory capacity and to be immune-evasive while not susceptible to host-induced changes. In this study, we demonstrate NGs' ability to target cartilage tissues, in vitro and in vivo, while modulating the inflammatory process. In vivo studies demonstrated NGs ability to act as an immunomodulatory drug slowing down cartilage degeneration process. Our proof-of-concept experiments show that NGs system is a versatile nano-carrier system, capable of therapeutics loading, with targeting capabilities towards healthy and inflamed cartilage cells. Our results, along with previously published data, clearly reveal the NGs system as a promising nano-carrier platform and as a potential immunomodulatory drug for several inflammation-related diseases.

Dexamethasone Conjugates: Synthetic Approaches and Medical Prospects

Dexamethasone (DEX) is the most commonly prescribed glucocorticoid (GC) and has a wide spectrum of pharmacological activity. However, steroid drugs like DEX can have severe side effects on non-target organs. One strategy to reduce these side effects is to develop targeted systems with the controlled release by conjugation to polymeric carriers. This review describes the methods available for the synthesis of DEX conjugates (carbodiimide chemistry, solid-phase synthesis, reversible addition fragmentation-chain transfer [RAFT] polymerization, click reactions, and 2-iminothiolane chemistry) and perspectives for their medical application as GC drug or gene delivery systems for anti-tumor therapy. Additionally, the review focuses on the development of DEX conjugates with different physical-chemical properties as successful delivery systems in the target organs such as eye, joint, kidney, and others. Finally, polymer conjugates with improved transfection activity in which DEX is used as a vector for gene delivery in the cell nucleus have been described.

Recent developments in natural and synthetic polymeric drug delivery systems used for the treatment of osteoarthritis

Osteoarthritis (OA), is a common musculoskeletal disorder that will progressively increase in older populations and is expected to be the most dominant cause of disability in the world population by 2030. The progression of OA is controlled by a multi-factorial pathway that has not been completely elucidated and understood yet. However, over the years, research efforts have provided a significant understanding of some of the processes contributing to the progression of OA. Both cartilage and bone degradation processes induce articular cells to produce inflammatory mediators that produce proinflammatory cytokines that block the synthesis of collagen type II and aggrecan, the major components of cartilage. Systemic administration and intraarticular injection of anti-inflammatory agents are the first-line treatments of OA. However, small anti-inflammatory molecules are rapidly cleared from the joint cavity which limits their therapeutic efficacy. To palliate this strong technological drawback, different types of polymeric materials such as microparticles, nanoparticles, and hydrogels, have been examined as drug carriers for the delivery of therapeutic agents to articular joints. The main purpose of this review is to provide a summary of recent developments in natural and synthetic polymeric drug delivery systems for the delivery of anti-inflammatory agents to arthritic joints. Furthermore, this review provides an overview of the design rules that have been proposed so far for the development of drug carriers used in OA therapy. Overall it is difficult to state clearly which polymeric platform is the most efficient one because many advantages and disadvantages could be pointed to both natural and synthetic formulations. That requires further research in the near future.

Optimisation and feature selection of poly-beta-amino-ester as a drug delivery system for cartilage

Drug localisation is one of the main challenges in treating cartilage; poly-beta-amino-esters (PBAEs) drug conjugates are a possible solution; their efficacy depends on the polymer structure hence the full potential of this system is still unknown.

Drug localisation is still one of the main challenges in treating pathologies affecting cartilage; poly-beta-amino-esters (PBAEs) drug conjugates are a possible solution; however, their efficacy highly depends on the polymer structure hence the full potential of this delivery system is still unknown. For the purpose of optimising the delivery system design, a large library of PBAEs was synthesised and dexamethasone (DEX) uptake in cartilage was determined. All three components of PBAE (amine, acrylate and end-capping) impacted the outcome. The most effective PBAE identified enhanced DEX uptake by 8 folds compared to an equivalent dose of the commercial formulation and also prevented, through delivery of DEX, the cartilage degradation caused by IL-1α (interleukine1α). A chemometrics based predictive model was constructed and PBAEs properties most affecting the performance of the drug delivery systems were identified. This model will allow further computer based PBAEs optimisation and fast track the bench to market process for this delivery system.

Modulation of Inflammatory Mediators by Polymeric Nanoparticles Loaded with Anti-Inflammatory Drugs

The first-line treatment of osteoarthritis is based on anti-inflammatory drugs, the most currently used being nonsteroidal anti-inflammatory drugs, selective cyclooxygenase 2 (COX-2) inhibitors and corticoids. Most of them present cytotoxicity and low bioavailability in physiological conditions, making necessary the administration of high drug concentrations causing several side effects. The goal of this work was to encapsulate three hydrophobic anti-inflammatory drugs of different natures (celecoxib, tenoxicam and dexamethasone) into core-shell terpolymer nanoparticles with potential applications in osteoarthritis. Nanoparticles presented hydrodynamic diameters between 110 and 130 nm and almost neutral surface charges (between −1 and −5 mV). Encapsulation efficiencies were highly dependent on the loaded drug and its water solubility, having higher values for celecoxib (39–72%) followed by tenoxicam (20–24%) and dexamethasone (14–26%). Nanoencapsulation reduced celecoxib and dexamethasone cytotoxicity in human articular chondrocytes and murine RAW264.7 macrophages. Moreover, the three loaded systems did not show cytotoxic effects in a wide range of concentrations. Celecoxib and dexamethasone-loaded nanoparticles reduced the release of different inflammatory mediators (NO, TNF-α, IL-1β, IL-6, PGE₂ and IL-10) by lipopolysaccharide (LPS)-stimulated RAW264.7. Tenoxicam-loaded nanoparticles reduced NO and PGE₂ production, although an overexpression of IL-1β, IL-6 and IL-10 was observed. Finally, all nanoparticles proved to be biocompatible in a subcutaneous injection model in rats. These findings suggest that these loaded nanoparticles could be suitable candidates for the treatment of inflammatory processes associated with osteoarthritis due to their demonstrated in vitro activity as regulators of inflammatory mediator production.

Non-surgical osteoarthritis therapy, intra-articular drug delivery towards clinical applications

Osteoarthritis (OA）is a common orthopaedic disease in middle-aged and aged people. To date, no disease-modifying drug is available to prevent the progression of OA. Surgical treatment of OA has complications such as pain and high costs with increased risk of post-operative infections. An intra-articular drug delivery is a conservative treatment method to apply therapeutic composites directly into the OA joint cavity. This method has an advantage to improve the bioavailability of therapeutics and hence is a widely preferred choice to test novel disease-modifying drug targets for OA. Herein, we summarised and discussed the current status of intra-articular therapy for OA treatment as well as outlined drug delivery of small molecular, protein and gene delivery for OA therapy. Currently, new targeted nano-based drug delivery systems, including nanoparticles, exosomes and hydrogel formulations under investigation for OA treatment via intra-articular injection are also addressed. The emerging trend demonstrates that intra-articular drug delivery has vast prospects for the clinical selective treatment of OA. The rational application of intra-articular injection of drugs and biological agents will be of great significance for alleviating the patients with OA, improving their quality of life, delaying surgery, and reducing the disease burden of OA.

An Evidence-Based Systematic Review of Human Knee Post-Traumatic Osteoarthritis (PTOA): Timeline of Clinical Presentation and Disease Markers, Comparison of Knee Joint PTOA Models and Early Disease Implications

Understanding the causality of the post-traumatic osteoarthritis (PTOA) disease process of the knee joint is important for diagnosing early disease and developing new and effective preventions or treatments. The aim of this review was to provide detailed clinical data on inflammatory and other biomarkers obtained from patients after acute knee trauma in order to (i) present a timeline of events that occur in the acute, subacute, and chronic post-traumatic phases and in PTOA, and (ii) to identify key factors present in the synovial fluid, serum/plasma and urine, leading to PTOA of the knee in 23-50% of individuals who had acute knee trauma. In this context, we additionally discuss methods of simulating knee trauma and inflammation in in vivo, ex vivo articular cartilage explant and in vitro chondrocyte models, and answer whether these models are representative of the clinical inflammatory stages following knee trauma. Moreover, we compare the pro-inflammatory cytokine concentrations used in such models and demonstrate that, compared to concentrations in the synovial fluid after knee trauma, they are exceedingly high. We then used the Bradford Hill Framework to present evidence that TNF-α and IL-6 cytokines are causal factors, while IL-1β and IL-17 are credible factors in inducing knee PTOA disease progresssion. Lastly, we discuss beneficial infrastructure for future studies to dissect the role of local vs. systemic inflammation in PTOA progression with an emphasis on early disease.

Targeting Cartilage Degradation in Osteoarthritis

Osteoarthritis is a common, degenerative joint disease with significant socio-economic impact worldwide. There are currently no disease-modifying drugs available to treat the disease, making this an important area of pharmaceutical research. In this review, we assessed approaches being explored to directly inhibit metalloproteinase-mediated cartilage degradation and to counteract cartilage damage by promoting growth factor-driven repair. Metalloproteinase-blocking antibodies are discussed, along with recent clinical trials on FGF18 and Wnt pathway inhibitors. We also considered dendrimer-based approaches being developed to deliver and retain such therapeutics in the joint environment. These may reduce systemic side effects while improving local half-life and concentration. Development of such targeted anabolic therapies would be of great benefit in the osteoarthritis field.

Hyaluronic Acid-Based Shape-Memory Cryogel Scaffolds for Focal Cartilage Defect Repair

Traumatic joint injuries can result in significant cartilage defects, which can greatly increase the risk of osteoarthritis development. Due to the limited self-healing capacity of avascular cartilage, tissue engineering approaches are required for filling defects and promoting cartilage regeneration. Current approaches utilize invasive surgical procedures for extraction and implantation of autologous chondrocytes; therefore, injectable biomaterials have gained interest to minimize the risk of infection as well as patient pain and discomfort. In this study, we engineered biomimetic, hyaluronic acid (HA)-based cryogel scaffolds that possess shape-memory properties as they contract and regain their shape after syringe injection to noninvasively fill cartilage defects. The cryogels, fabricated with HA and glycidyl methacrylate at -20°C, resulted in an elastic, macroporous, and highly interconnected network that provided a conducive microenvironment for chondrocytes to remain viable and metabolically active after injection through a syringe needle. Chondrocytes seeded within cryogels and cultured for 15 days exhibited enhanced cell proliferation, metabolism, and production of cartilage extracellular matrix glycosaminoglycans compared with HA-based hydrogels. Furthermore, immunohistochemical staining revealed production of collagen type II from chondrocyte-seeded cryogels, indicating the maintenance of cell phenotype. These results demonstrate the potential of chondrocyte-seeded, HA-based, injectable cryogel scaffolds to promote regeneration of cartilage tissue for nonsurgically invasive defect repair. Impact statement Hyaluronic acid-based shape-memory cryogels provide a conducive microenvironment for chondrocyte adhesion, proliferation, and matrix biosynthesis for use in repair of cartilage defects. Due to their sponge-like elastic properties, cryogels can fully recover their original shape back after injection while not impacting metabolism or viability of encapsulated cells. Clinically, they provide an opportunity for filling focal cartilage defects by using a single, minimally invasive injection of a cell encapsulating biocompatible three-dimensional scaffold that can return to its original structure to fit the defect geometry and enable matrix regeneration.

Osteoarthritis In Vitro Models: Applications and Implications in Development of Intra-Articular Drug Delivery Systems

Osteoarthritis (OA) is a complex multi-target disease with an unmet medical need for the development of therapies that slow and potentially revert disease progression. Intra-articular (IA) delivery has seen a surge in osteoarthritis research in recent years. As local administration of molecules, this represents a way to circumvent systemic drug delivery struggles. When developing intra-articular formulations, the main goals are a sustained and controlled release of therapeutic drug doses, taking into account carrier choice, drug molecule, and articular joint tissue target. Therefore, the selection of models is critical when developing local administration formulation in terms of accurate outcome assessment, target and off-target effects and relevant translation to in vivo. The current review highlights the applications of OA in vitro models in the development of IA formulation by means of exploring their advantages and disadvantages. In vitro models are essential in studies of OA molecular pathways, understanding drug and target interactions, assessing cytotoxicity of carriers and drug molecules, and predicting in vivo behaviors. However, further understanding of molecular and tissue-specific intricacies of cellular models for 2D and 3D needs improvement to accurately portray in vivo conditions.

Recent Advances in Clinical Translation of Intra-Articular Osteoarthritis Drug Delivery Systems

Osteoarthritis (OA) is a degenerative disease of the joints and a leading cause of physical disability in adults. Intra-articular (IA) therapy is a popular treatment strategy for localized, single-joint OA; however, small-molecule drugs such as corticosteroids do not provide prolonged relief. One possible reason for their lack of efficacy is high clearance rates from the joint through constant lymphatic drainage of the synovial tissues and synovial fluid and also by their exchange via the synovial vasculature. Advanced drug delivery strategies for extended release of therapeutic agents in the joint space is a promising approach to improve outcomes for OA patients. Broadly, the basic principle behind this strategy is to encapsulate therapeutic agents in a polymeric drug delivery system (DDS) for diffusion- and/or degradation-controlled release, whereby degradation can occur by hydrolysis or tied to relevant microenvironmental cues such as pH, reactive oxygen species (ROS), and protease activity. In this review, we highlight the development of clinically tested IA therapies for OA and highlight recent systems which have been investigated preclinically. DDS strategies including hydrogels, liposomes, polymeric microparticles (MPs) and nanoparticles (NPs), drug conjugates, and combination systems are introduced and evaluated for clinical translational potential.

Cartilage-targeting ultrasmall lipid-polymer hybrid nanoparticles for the prevention of cartilage degradation

Current drug delivery approaches for the treatment of cartilage disorders such as osteoarthritis (OA) remain inadequate to achieve sufficient drug penetration and retention in the dense cartilage matrix. Herein, we synthesize sub-30 nm lipid-polymer hybrid nanoparticles functionalized with collagen-targeting peptides for targeted drug delivery to the cartilage. The nanoparticles consist of a polymeric core for drug encapsulation and a lipid shell modified with a collagen-binding peptide. By combining these design features, the nanoparticles can penetrate deep and accumulate preferentially in the cartilage. Using MK-8722, an activator of 5'-adenosine monophosphate-activated protein kinase (AMPK), as a model drug, the nanoparticles can encapsulate the drug molecules in high capacity and release them in a sustained and controllable manner. When injected into the knee joints of the mice with collagenase-induced OA, the drug-loaded nanoparticles can effectively reduce cartilage damage and alleviate the disease severity. Overall, the ultrasmall targeted nanoparticles represent a promising delivery platform to overcome barriers of dense tissues for the treatment of various indications, including cartilage disorders.

Recent advances in targeted drug delivery for treatment of osteoarthritis

PURPOSE OF REVIEW

Osteoarthritis is associated with severe joint pain, inflammation, and cartilage degeneration. Drugs injected directly into intra-articular joint space clear out rapidly providing only short-term benefit. Their transport into cartilage to reach cellular targets is hindered by the tissue's dense, negatively charged extracellular matrix. This has limited, despite strong preclinical data, the clinical translation of osteoarthritis drugs. Recent work has focused on developing intra-joint and intra-cartilage targeting drug delivery systems (DDS) to enable long-term therapeutic response, which is presented here.

RECENT FINDINGS

Synovial joint targeting hybrid systems utilizing combinations of hydrogels, liposomes, and particle-based carriers are in consideration for pain-inflammation relief. Cartilage penetrating DDS target intra-cartilage constituents like aggrecans, collagen II, and chondrocytes such that drugs can reach their cellular and intra-cellular targets, which can enable clinical translation of disease-modifying osteoarthritis drugs including gene therapy.

SUMMARY

Recent years have witnessed significant increase in both fundamental and clinical studies evaluating DDS for osteoarthritis. Steroid encapsulating polymeric microparticles for longer lasting pain relief were recently approved for clinical use. Electrically charged biomaterials for intra-cartilage targeting have shown promising disease-modifying response in preclinical models. Clinical trials evaluating safety of viral vectors are ongoing whose success can pave the way for gene therapy as osteoarthritis treatment.

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.

Polymer colloids as drug delivery systems for the treatment of arthritis

The most common types of arthritis are osteoarthritis (OA) and rheumatoid arthritis (RA) which are themain causes of disability and pain among older people. Current treatment of arthritis mainly consists of oral and intra-articular medications. Despite the efficacy of the intraarticular injections over the oral treatment, it is still limited by the rapid clearance of the injected drug. Therefore, a rational design of drug delivery systems (DDSs) able to delivery drugs in controlled manner and for required period of time to the arthritis joint is a key in developing safe and effective formulations for OA and RA. In this paper various colloidal systems like nanoparticles, liposomes, cationic carriers, hydrogels, and emulsion-based carriers were presented and discussed in light of their use and efficacy as delivery systems to transport therapeutics for arthritis treatment. Factors influencing the delivery efficacy such as size, charge, structure, drug uptake, retention and its release profile alongside with cytocompatibility and safety were addressed. Moreover, the advantages and disadvantages of the different colloidal systems were emphasised.

Acacetin Suppresses IL-1β-Induced Expression of Matrix Metalloproteinases in Chondrocytes and Protects against Osteoarthritis in a Mouse Model by Inhibiting NF-κB Signaling Pathways

Osteoarthritis (OA) is a very common chronic joint dysfunction, and there is currently a poor understanding of its etiology and pathogenesis. Therefore, there are no active disease-modifying drugs currently available for clinical treatment. Several natural compounds have been shown to play a role in inhibiting OA progression. The present study is aimed at investigating the curative effects of acacetin, a natural flavonoid compound, against OA. Our results demonstrated that MMP-1, MMP-3, and MMP-13 were highly expressed in OA specimens. Acacetin inhibited the interleukin-1β- (IL-1β-) induced expression of MMP-1, MMP-3, and MMP-13in chondrocytes by blocking nuclear factor-κB (NF-κB) signaling pathways. Furthermore, we found that acacetin suppressed OA progression and inhibited the expression of MMP-1, MMP-3, and MMP-13 in ACLT-induced OA mice. Taken together, our study revealed that acacetin may serve as a potential drug for treating OA.

Overcoming negatively charged tissue barriers: Drug delivery using cationic peptides and proteins

Negatively charged tissues are ubiquitous in the human body and are associated with a number of common diseases yet remain an outstanding challenge for targeted drug delivery. While the anionic proteoglycans are critical for tissue structure and function, they make tissue matrix dense, conferring a high negative fixed charge density (FCD) that makes drug penetration through the tissue deep zones and drug delivery to resident cells extremely challenging. The high negative FCD of these tissues is now being utilized by taking advantage of electrostatic interactions to create positively charged multi-stage delivery methods that can sequentially penetrate through the full thickness of tissues, create a drug depot and target cells. After decades of work on attempting delivery using strong binding interactions, significant advances have recently been made using weak and reversible electrostatic interactions, a characteristic now considered essential to drug penetration and retention in negatively charged tissues. Here we discuss these advances using examples of negatively charged tissues (cartilage, meniscus, tendons and ligaments, nucleus pulposus, vitreous of eye, mucin, skin), and delve into how each of their structures, tissue matrix compositions and high negative FCDs create barriers to drug entry and explore how charge interactions are being used to overcome these barriers. We review work on tissue targeting cationic peptide and protein-based drug delivery, compare and contrast drug delivery designs, and also present examples of technologies that are entering clinical trials. We also present strategies on further enhancing drug retention within diseased tissues of lower FCD by using synergistic effects of short-range binding interactions like hydrophobic and H-bonds that stabilize long-range charge interactions. As electrostatic interactions are incorporated into design of drug delivery materials and used as a strategy to create properties that are reversible, tunable and dynamic, bio-electroceuticals are becoming an exciting new direction of research and clinical work.

Drug delivery in intervertebral disc degeneration and osteoarthritis: Selecting the optimal platform for the delivery of disease-modifying agents

Osteoarthritis (OA) and intervertebral disc degeneration (IVDD) as major cause of chronic low back pain represent the most common degenerative joint pathologies and are leading causes of pain and disability in adults. Articular cartilage (AC) and intervertebral discs are cartilaginous tissues with a similar biochemical composition and pathophysiological aspects of degeneration. Although treatments directed at reversing these conditions are yet to be developed, many promising disease-modifying drug candidates are currently under investigation. Given the localized nature of these chronic diseases, drug delivery systems have the potential to enhance therapeutic outcomes by providing controlled and targeted release of bioactives, minimizing the number of injections needed and increasing drug concentration in the affected areas. This review provides a comprehensive overview of the currently most promising disease-modifying drugs as well as potential drug delivery systems for OA and IVDD therapy.