Local Delivery of Indomethacin to Arthritis-Bearing Rats through Polymeric Micelles Based on Amphiphilic Polyphosphazenes

Intra-Articular Injectable Biomaterials for Cartilage Repair and Regeneration

Osteoarthritis is a degenerative joint disease characterized by cartilage deterioration and subsequent inflammatory changes in the underlying bone. Injectable hydrogels have emerged as a promising approach for controlled drug delivery in cartilage therapies. This review focuses on the latest developments in utilizing injectable hydrogels as vehicles for targeted drug delivery to promote cartilage repair and regeneration. The pathogenesis of osteoarthritis is discussed to provide a comprehensive understanding of the disease progression. Subsequently, the various types of injectable hydrogels used for intra-articular delivery are discussed. Specifically, physically and chemically crosslinked injectable hydrogels are critically analyzed, with an emphasis on their fabrication strategies and their capacity to encapsulate and release therapeutic agents in a controlled manner. Furthermore, the potential of incorporating growth factors, anti-inflammatory drugs, and cells within these injectable hydrogels are discussed. Overall, this review offers a comprehensive guide to navigating the landscape of hydrogel-based therapeutics in osteoarthritis.

A Mechanically Resilient Soft Hydrogel Improves Drug Delivery for Treating Post-Traumatic Osteoarthritis in Physically Active Joints

Intra-articular delivery of disease-modifying osteoarthritis drugs (DMOADs) is likely to be most effective in early post-traumatic osteoarthritis (PTOA) when symptoms are minimal and patients are physically active. DMOAD delivery systems therefore must withstand repeated mechanical loading without affecting the drug release kinetics. Although soft materials are preferred for DMOAD delivery, mechanical loading can compromise their structural integrity and disrupt drug release. Here, we report a mechanically resilient soft hydrogel that rapidly self-heals under conditions resembling human running while maintaining sustained release of the cathepsin-K inhibitor L-006235 used as a proof-of-concept DMOAD. Notably, this hydrogel outperformed a previously reported hydrogel designed for intra-articular drug delivery, used as a control in our study, which neither recovered nor maintained drug release under mechanical loading. Upon injection into mouse knee joints, the hydrogel showed consistent release kinetics of the encapsulated agent in both treadmill-running and non-running mice. In a mouse model of aggressive PTOA exacerbated by treadmill running, L-006235 hydrogel markedly reduced cartilage degeneration. To our knowledge, this is the first hydrogel proven to withstand human running conditions and enable sustained DMOAD delivery in physically active joints, and the first study demonstrating reduced disease progression in a severe PTOA model under rigorous physical activity, highlighting the hydrogel's potential for PTOA treatment in active patients.

Pathophysiology to advanced intra-articular drug delivery strategies: Unravelling rheumatoid arthritis

Rheumatoid arthritis (RA) is one of the most prevalent life-long autoimmune diseases with an unknown genesis. It primarily causes chronic inflammation, pain, and synovial joint-associated cartilage and bone degradation. Unfortunately, limited information is available regarding the etiology and pathogenesis of this chronic joint disorder. In the last few decades, an improved understanding of RA pathophysiology about key immune cells, antibodies, and cytokines has inspired the development of several anti-rheumatic drugs and biopharmaceuticals to act on RA-affected joints. However, life-long frequent systemic high doses of commercially available drugs are currently a limiting factor in the efficient management of RA. To address this issue, various single and double-barrier intra-articular drug delivery systems (IA-DDSs) such as nanocarriers, microparticles, hydrogels, and particles-hybrid hydrogel composite have been developed which can exclusively target the RA-affected joint cavity and release the precisely controlled therapeutic drug concentration for prolonged time whilst avoiding the systemic toxicity. This review provides a comprehensive overview of the pathogenesis of RA and discusses the rational design and development of biomaterials-based novel IA-DDs, ranging from conventional to advanced systems, for improved treatment of RA. Therefore, this review aims to unravel the pathophysiology of rheumatoid arthritis and explore cutting-edge IA-DD strategies exploiting biomaterials. It offers researchers a consolidated and up-to-date resource platform to analyze existing knowledge, identify research gaps, and contribute to the scientific literature.

Reduction of systemic exposure and side effects by intra-articular injection of anti-inflammatory agents for osteoarthritis: what is the safer strategy?

Osteoarthritis (OA) is a chronic degenerative joint disease associated with pain, inflammation, and cartilage degradation. However, no current treatment can effectively halt the progression of the disease. Therefore, the use of NSAIDs and intra-articular corticosteroids is usually recommended as the primary treatment for OA-associated pain and inflammation. However, there is accumulating evidence that the long-term use of oral NSAIDs and intra-articular corticosteroids can lead to a myriad of negative side effects. Although numerous efforts have been made to develop intra-articular formulations for NSAIDs, the systemic exposure of intra-articular injection of NSAIDs and its potential side effects have not been explicitly investigated. To ascertain the evident and potential side effects of intra-articular injection of anti-inflammatory agents, we have summarised in this review the systemic exposure, local side effects, and systemic side effects of intra-articular injections of anti-inflammatory agents, including NSAIDs and corticosteroids. For developing a safer treatment to fulfil the unmet long-term use needs of patients, a new therapy, which combines the locally active drug and a sustained-release formulation, has been proposed in this review.

Matrix metalloproteinase-responsive collagen-oxidized hyaluronic acid injectable hydrogels for osteoarthritic therapy

Drug delivery system and intra-articular injection have been clinically applied to prolong drug residence time and reduce side effects in the treatment of osteoarthrosis. Herein, injectable hydrogels with sustained-dexamethasone sodium phosphate (DSP) release behavior in response to matrix metalloproteinase (MMP) were developed for osteoarthritic therapy. Hyaluronic acid undergoes specific oxidation in the present of sodium periodate to prepare oxidized hyaluronic acid (OHA). Then the DSP-loaded collagen-based hydrogels (Col-OHA) were developed by the Schiff's base crosslinking between OHA and Type I collagen besides the self-assembly of collagen induced by OHA. The results indicate that the collagen self-assembly into collagen fibrils makes great contribution for shortening gelation time of Col-OHA hydrogels. Col-OHA hydrogels possess interconnected porous microstructure, good injectability, excellent self-healing performance, strong mechanical property, low swelling ability, good blood compatibility and no cytotoxicity. Significantly, Col-OHA hydrogels show highly sensitive and significantly substantially sustained release of DSP in response to MMP. DSP-loaded Col-OHA hydrogel possesses significant inhibition for the production of inflammatory cytokines in the joint synovium, which can effectively relieve the symptoms of osteoarthritis continuously. Col-OHA hydrogel has no obvious effect on liver and kidney functions. Overall, the Col-OHA hydrogels with excellent biocompatibility are the promising drug-loading system for the intra-articular injection therapy of osteoarthrosis.

Potential Privilege of Maltodextrin-α-Tocopherol Nano-Micelles in Seizing Tacrolimus Renal Toxicity, Managing Rheumatoid Arthritis and Accelerating Bone Regeneration

Background

Tacrolimus (TAC) is a powerful immunosuppressive agent whose therapeutic applicability is confined owing to its systemic side effects.

Objective

Herein, we harnessed a natural polymer based bioconjugate composed of maltodextrin and α-tocopherol (MD-α-TOC) to encapsulate TAC as an attempt to overcome its biological limitations while enhancing its therapeutic anti-rheumatic efficacy.

Methods

The designed TAC loaded maltodextrin-α-tocopherol nano-micelles (TAC@MD-α-TOC) were assessed for their physical properties, safety, toxicological behavior, their ability to combat arthritis and assist bone/cartilage formation.

Results

In vitro cell viability assay revealed enhanced safety profile of optimized TAC@MD-α-TOC with 1.6- to 2-fold increase in Vero cells viability compared with free TAC. Subacute toxicity study demonstrated a diminished nephro- and hepato-toxicity accompanied with optimized TAC@MD-α-TOC. TAC@MD-α-TOC also showed significantly enhanced anti-arthritic activity compared with free TAC, as reflected by improved clinical scores and decreased IL-6 and TNF-α levels in serum and synovial fluids. Unique bone formation criteria were proved with TAC@MD-α-TOC by elevated serum and synovial fluid levels of osteocalcin and osteopontin mRNA and proteins expression. Chondrogenic differentiation abilities of TAC@MD-α-TOC were proved by increased serum and synovial fluid levels of SOX9 mRNA and protein expression.

Conclusion

Overall, our designed bioconjugate micelles offered an excellent approach for improved TAC safety profile with enhanced anti-arthritic activity and unique bone formation characteristics.

Matrix Metalloproteinase Inspired Therapeutic Strategies for Bone Diseases

Matrix Metalloproteinases (MMPs), as a family of zinc-containing enzymes, show the function of decomposing Extracellular Matrix (ECM) and participate in the physiological processes of cell migration, growth, inflammation, and metabolism. Clinical and experimental studies have indicated that MMPs play an essential role in tissue injury and repair as well as tumor diagnosis, metastasis, and prognosis. An increasing number of researchers have paid attention to their functions and mechanisms in bone health and diseases. The present review focuses on MMPs-inspired therapeutic strategies for the treatment of bone-related diseases. We introduce the role of MMPs in bone diseases, highlight the MMPs-inspired therapeutic options, and posit MMPs as a trigger for smart cell/drug delivery.

Nanotechnology and Osteoarthritis. Part 2: Opportunities for advanced devices and therapeutics

Osteoarthritis (OA) is a multifactorial disease of the entire joint which afflicts 140 million individuals worldwide regardless of economic or social status. Current clinical treatments for OA primarily center on reducing pain and increasing mobility, and there are limited therapeutic interventions to restore degraded cartilage or slow disease pathogenesis. This second installment of a two-part review on nanotechnology and OA focuses on novel treatment strategies. Specifically, Part 2 first discusses current surgical and nonsurgical treatments for OA and then summarizes recent advancements in nanotechnology-based treatments, while Part 1 (10.1002/jor.24817) described advances in imaging and diagnostics. We review nano delivery systems for small molecule drugs, nucleic acids, and proteins followed by nano-based scaffolds for neocartilage formation and osteochondral regeneration, and lastly nanoparticle lubricants. We conclude by identifying opportunities for nanomedicine advances, and prospects for OA treatments.

Nitrite-Responsive Hydrogel: Smart Drug Release Depending on the Severity of the Nitric Oxide-Related Disease

Nitric oxide (NO) is known as one of the most important biomarkers of many diseases. However, the development of NO-triggered drug releasing platforms is challenging due to the low concentration and short lifetime of NO in vivo. In this work, a novel nitrite (NO₂^-)-responsive hydrogel (DHPL-GEL), which can be used for smart drug release depending on the severity of the NO-related disease, is demonstrated. A dihydropyridine cross-linking agent is designed to construct DHPL-GEL to enable the responsive degradation of the hydrogel triggered by NO₂^-. On-demand release of the drug loaded in DHPL-GEL was observed under the stimulation of various concentrations of NO₂^- at the physiological level both in vitro and in vivo. In the inflammatory arthritis rat model, the DHPL-GEL drug delivery system showed a better therapeutic effect and less side effects than the traditional therapy and nonresponsive hydrogel drug delivery system, demonstrating the promising application of the NO₂^--responsive hydrogel for the treatment of NO-related diseases.

Indomethacin loaded dextran stearate polymeric micelles improve adjuvant-induced arthritis in rats: design and in vivo evaluation

BACKGROUND

Indomethacin is a non-steroidal anti-inflammatory drug (NSAID) that can effectively control the pain and inflammation caused by rheumatoid arthritis (RA), but its usage is limited due to severe adverse effects. For this reason, making more specific formulations of this drug can be considered. The aim of the present study was designing a novel nano-sized indomethacin delivery system.

MATERIALS AND METHODS

Indomethacin-loaded dextran stearate polymeric micelles were prepared by dialysis method. Particle size and zeta potential of micelles were measured by a zeta sizer instrument. Drug release from micelles was investigated in phosphate buffer medium pH 7.4 and then the best formulation regarding physical properties and drug release was selected for animal studies. Arthritis was induced by complete Freund's adjuvant injection in rats. Then, the animals were randomly assigned into the model, the indomethacin solution and the polymeric micelles groups. The clinical effects of polymeric micelle formulation were assessed by measuring arthritis index, animal paw edema and measuring biochemical parameters including myeloperoxidase (MPO) activity, lipid peroxidation (LPO), glutathione (GSH), total antioxidant capacity (TAC), TNF-α, IL-17 and IL-1β.

RESULTS

Paw edema was attenuated following the administration of indomethacin-loaded polymeric micelles. Based on the findings of the present study, the use of indomethacin-loaded polymeric micelles could improve inflammatory symptoms, decrease arthritis index and decrease the diameter of the paw in arthritic rats in a significant manner (p ≤ 0.05). In addition, the use of polymeric micelles like indomethacin solution significantly reduced (p ≤ 0.05) the activity of MPO, LPO, TNF-α, IL-17 and IL-1β, and made a significant increase (p ≤ 0.05) in glutathione and TAC content and ameliorated structural changes in the paw tissue compared to the control group.

CONCLUSION

Our findings demonstrated that indomethacin-loaded dextran stearate polymeric micelles can provide more effective therapeutic effects in control of inflammation in arthritis in rat.

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.

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.

Novel nano therapeutic materials for the effective treatment of rheumatoid arthritis-recent insights

Rheumatoid arthritis (RA) is the most common complex multifactorial joint related autoimmune inflammatory disease with unknown etiology accomplished with increased cardiovascular risks. RA is characterized by the clinical findings of synovial inflammation, autoantibody production, and cartilage/bone destruction, cardiovascular, pulmonary and skeletal disorders. Pro-inflammatory cytokines such as IL-1, IL-6, IL-8, and IL-10 were responsible for the induction of inflammation in RA patients. Drawbacks such as poor efficacy, higher doses, frequent administration, low responsiveness, and higher cost and serious side effects were associated with the conventional dosage forms for RA treatment. Nanomedicines were recently gaining more interest towards the treatment of RA, and researchers were also focusing towards the development of various anti-inflammatory drug loaded nanoformulations with an aid to both actively/passively targeting the inflamed site to afford an effective treatment regimen for RA. Alterations in the surface area and nanoscale size of the nanoformulations elicit beneficial physical and chemical properties for better pharmacological activities. These drug loaded nanoformulations may enhances the solubility of poorly water soluble drugs, improves the bioavailability, affords targetability and may improve the therapeutic activity. In this regimen, the present review focus towards the novel nanoparticulate formulations (nanoparticles, nanoemulsions, solid lipid nanoparticles, nanomicelles, and nanocapsules) utilized for the treatment of RA. The recent advancements such as siRNA, peptide and targeted based nanoparticulate systems for RA treatment were also discussed. Special emphasis was provided regarding the pathophysiology, prevalence and symptoms towards the development of RA.

Recent approaches for targeted drug delivery in rheumatoid arthritis diagnosis and treatment

Rheumatoid arthritis (RA) is a chronic inflammatory disease with complex pathology characterized by inflammation of joints, devastation of the synovium, pannus formation, bones and cartilage destruction and often is associated with persistent arthritic pain, swelling, stiffness and work disability. In conventional RA therapy, because of short biological half-life, poor bioavailability, high and frequent dosing is required. Thereby, these anti-RA medications, which unable to selectively target affected zone, may cause severe side effects in extra-articular tissues. Today, nanotechnology has emerged as promising tool in the development of novel drug delivery systems for the treatment and diagnosis of intractable diseases such as RA. Active targeting in RA nanomedicine has also been introduced a successful way for facilitating specific uptake of therapeutic agents by the disease cells. In this review, it is attempted to describe various targeted drug delivery systems (localized and receptor-based) used for RA diagnosis and therapy. Then, we highlight recent developments related to various non-viral gene delivery systems for RA gene therapy.

Towards an arthritis flare-responsive drug delivery system

Local delivery of therapeutics for the treatment of inflammatory arthritis (IA) is limited by short intra-articular half-lives. Since IA severity often fluctuates over time, a local drug delivery method that titrates drug release to arthritis activity would represent an attractive paradigm in IA therapy. Here we report the development of a hydrogel platform that exhibits disassembly and drug release controlled by the concentration of enzymes expressed during arthritis flares. In vitro, hydrogel loaded with triamcinolone acetonide (TA) releases drug on-demand upon exposure to enzymes or synovial fluid from patients with rheumatoid arthritis. In arthritic mice, hydrogel loaded with a fluorescent dye demonstrates flare-dependent disassembly measured as loss of fluorescence. Moreover, a single dose of TA-loaded hydrogel but not the equivalent dose of locally injected free TA reduces arthritis activity in the injected paw. Together, our data suggest flare-responsive hydrogel as a promising next-generation drug delivery approach for the treatment of IA.

Renewable poly(δ-decalactone) based block copolymer micelles as drug delivery vehicle: in vitro and in vivo evaluation

Polymers from natural resources are attracting much attention in various fields including drug delivery as green alternatives to fossil fuel based polymers. In this quest, novel block copolymers based on renewable poly(δ-decalactone) (PDL) were evaluated for their drug delivery capabilities and compared with a fossil fuel based polymer i.e. methoxy-poly(ethylene glycol)-b-poly(ε-caprolactone) (mPEG-b-PCL). Using curcumin as a hydrophobic drug model, micelles of PDL block copolymers with different orientation i.e. AB (mPEG-b-PDL), ABA (PDL-b-PEG-b-PDL), ABC (mPEG-b-PDL-b-poly(pentadecalactone) and (mPEG-b-PCL) were prepared by nanoprecipitation method. The size, drug loading and curcumin stability studies results indicated that mPEG-b-PDL micelles was comparable to its counterpart mPEG-b-PCL micelles towards improved delivery of curcumin. Therefore, mixed micelles using these two copolymers were also evaluated to see any change in size, loading and drug release. Drug release studies proposed that sustained release can be obtained using poly(pentadecalactone) as crystalline core whereas rapid release can be achieved using amorphous PDL core. Further, mPEG-b-PDL micelles were found to be non-haemolytic, up to the concentration of 40 mg/mL. In vivo toxicity studies on rats advised low-toxic behaviour of these micelles up to 400 mg/kg dose, as evident by histopathological and biochemical analysis. In summary, it is anticipated that mPEG-b-PDL block copolymer micelles could serve as a renewable alternative for mPEG-b-PCL copolymers in drug delivery applications.

Novel apigenin-loaded sodium hyaluronate nano-assemblies for targeting tumor cells

We aimed to construct a novel nano-assembly carrying apigenin (APG), a hydrophobic drug, and to evaluate its in vitro targeting ability for A549 cells overexpressing CD44 receptors. The apigenin-loaded sodium hyaluronate nano-assemblies (APG/SH-NAs) were assembled by multiple non-covalent interactions between sodium hyaluronate (SH) and APG. The prepared APG/SH-NAs exhibited a small average size and narrow particle size distribution. In addition, satisfactory encapsulation efficiency and drug loading were obtained. The drug release curves indicated that APG/SH-NAs achieved a sustainable drug-release effect due to the presence of hydrophilic materials. The in vitro cytotoxicity of APG/SH-NAs against A549 cells and HepG2 cells was evaluated, and the results indicated that the prepared APG/SH-NA showed higher cytotoxicity compared to apigenin suspensions. When CD44 receptors on the surface of A549 cells were blocked by the addition of excess SH, the cytotoxicity of APG/SH-NA was significantly reduced. However, similar phenomena were not observed in HepG2 cells with relatively low CD44 receptor expression. The resulting APG/SH-NAs could efficiently facilitate the internalization of APG into A549 cells, which might be due to their high affinity for CD44 receptors. Moreover, the apoptotic rate of APG/SH-NAs through receptor-mediated endocytosis mechanism was higher than that of the other groups in A549 cells. Thus, such nano-assemblies were considered to be an effective transport system with excellent affinity for CD44 receptors to allow the SH-mediated targeted delivery of APG.

Synthesis of polyphosphazenes with different side groups and various tactics for drug delivery

Polyphosphazenes (PPZs) are hybrid polymers comprising a main chain containing nitrogen and phosphorous linked through interchanging single and double bonds, and side chains.

Design, preparation and characterization of pH-responsive prodrug micelles with hydrolyzable anhydride linkages for controlled drug delivery

We report a new prodrug micelle-based approach in which a model hydrophobic non-steroidal anti-inflammatory drug (NSAID), ibuprofen (Ibu), is tethered to amphiphilic methoxy polyethylene glycol-polypropylene fumarate (mPEG-PPF) diblock copolymer via hydrolytic anhydride linkages for potential controlled release applications of NSAIDs. Synthesized mPEG-PPF-Ibu polymer drug conjugates (PDCs) demonstrated high drug conjugation efficiency (∼90%) and self-assembled to form micellar nanostructures in aqueous medium with critical micelle concentrations ranging between 16 and 30μg/mL. The entrapment efficiency of Ibu in prepared PDC micelles was as high as 18% (w/w). Crosslinking of prodrug micelles with N,N'-dimethylaminoethyl methacrylate conferred pH-responsive characteristics. pH-responsive PDC micelles averaged 100nm in size at pH 7.4 and exhibited concomitant changes in size upon incubation in physiologically relevant mildly acidic conditions. Ibu release was observed to increase with increasing acidic conditions and could be controlled by varying the amount of crosslinker used. Furthermore, the prepared mPEG-PPF-based micelles demonstrated excellent cytocompatibility and cellular internalization in vitro. More importantly, PDC micelles exerted anti-inflammatory effects by significantly decreasing monosodium urate crystal-induced prostaglandin E2 levels in rabbit synoviocyte cultures in vitro. Cumulatively, our results indicate that this new prodrug micelle approach is promising for NSAID-based therapies in the treatment of arthritis and cancer.

Novel self-assembled tacrolimus nanoparticles cross-linking thermosensitive hydrogels for local rheumatoid arthritis therapy

The aim was to explore the potential application of novel self-assembled nanoparticles cross-linking thermosensitive hydrogels composed of polyvinyl caprolactam-polyvinyl acetate-polyethylene glycol (Soluplus) and tacrolimus (FK-506) for local therapy of rheumatoid arthritis (RA). The sol-gel transition temperature (T_sol-gel), gelation time, rheological behaviors, in vitro release, in vivo gelation and retention, and therapeutic efficacy against adjuvant-induced arthritis (AIA) rats were compared between the Soluplus hydrogels and widely studied poloxamer 407 (P407) delivery systems. In sol, the spherical and uniform FK506 loaded Soluplus nanoparticles (Soluplus-SNPs) were self-assembled with encapsulation efficiency of 99.5±1.5% and particle size of 73.9±2.9nm. The decreased T_sol-gel of Soluplus-SNPs hydrogels was associated with the addition of salts, elevation of pH and ionic strength. The optimal T_sol-gel of Soluplus-SNPs with concentrations of 10%-30% in phosphate buffer (50mM, pH 7.4) was from 37.4±0.1°C to 32.8±0.3°C and the gelation time was not greater than 2min. Soluplus-SNPs gelling systems showed lower viscosity and wider range concentrations in sol state at 25°C and stronger gel strength at 37°C than P407, which resulting in longer sustained release of FK506 but without burst-release in vitro, and longer retention time in the local injection site in vivo. The therapeutic efficacy to treat AIA rats was significantly enhanced from d10 to d17 after a single dose of FK506 loaded in 10% and 20% Soluplus-SNPs hydrogels. In conclusion, Soluplus-SNPs hydrogel is a potential sustainable delivery system for FK506 to treat RA locally.

Particle-based technologies for osteoarthritis detection and therapy

Osteoarthritis (OA) is a disease characterized by degradation of joints with the development of painful osteophytes in the surrounding tissues. Currently, there are a limited number of treatments for this disease, and many of these only provide temporary, palliative relief. In this review, we discuss particle-based drug delivery systems that can provide targeted and sustained delivery of imaging and therapeutic agents to OA-affected sites. We focus on technologies such as polymeric micelles and nano-/microparticles, liposomes, and dendrimers for their potential treatment and/or diagnosis of OA. Several promising studies are highlighted, motivating the continued development of delivery technologies to improve treatments for OA.

Zwitterionic chitosan-polyamidoamine dendrimer complex nanoparticles as a pH-sensitive drug carrier

Polyamidoamine (PAMAM) dendrimers have been widely explored as carriers of therapeutics and imaging agents. However, amine-terminated PAMAM dendrimers are rarely utilized in systemic applications due to their cytotoxicity and risk of opsonization, caused by their cationic charges. Such undesirable effects may be mitigated by shielding the PAMAM dendrimer surface with polymers that reduce the charges. However, this shielding may also interfere with the PAMAM dendrimers' ability to interact with target cells, thus reducing the cellular uptake and overall efficacy of the delivery system. Therefore, we propose to use zwitterionic chitosan (ZWC), a new chitosan derivative, which has a unique pH-sensitive charge profile, as an alternative biomaterial to modify the cationic surface of PAMAM dendrimers. A stable electrostatic complex of ZWC and PAMAM dendrimers was formed at pH 7.4, where the PAMAM dendrimer surface was covered with ZWC, as demonstrated by fluorescence spectroscopy and transmission electron microscopy. The presence of ZWC coating protected red blood cells and fibroblast cells from hemolytic and cytotoxic activities of PAMAM dendrimers, respectively. Confocal microscopy showed that the protective effect of ZWC disappeared at low pH as the complex dissociated due to the charge conversion of ZWC, allowing PAMAM dendrimers to enter cells. These results demonstrate that ZWC is able to provide a surface coverage of PAMAM dendrimers in a pH-dependent manner and, thus, enhance the utility of PAMAM dendrimers as a drug carrier to solid tumors with acidifying microenvironments.

S/O-nanodispersion electrospun fiber mesh effective for sustained release of healthy plasmid DNA with the structural and functional integrity

Localized and sustained delivery of the therapeutic genes using a solid carrier matrix is a potential approach to develop highly curative treatments. Electrospun nanofiber mesh of biodegradable polymer has been applied extensively as a carrier for localized and sustained delivery of drugs, proteins, and DNA, but it remains difficult to release sufficient amounts of DNA while maintaining structural and functional integrity. To realize the stable sustained release of the healthy plasmid DNA (pDNA) from electrospun fiber mesh, a novel method was examined for loading pDNA into the fibers based on solid-in-oil (S/O) nanodispersion of pDNA in organic solvent for electrospinning polymer solution: S/O nanodispersion electrospinning. A prepared pDNA-loaded fiber mesh made of biodegradable polymer showed sustained release of pDNA without burst release. From luciferase activity-based in vitro transcription-translation assay, pDNA released from meshes of the S/O nanodispersion retained about 60% luciferase activity of control pDNA, whereas pDNA released from the meshes of simple mixing showed only about 5% activity, indicating that S/O nanodispersion electrospinning is effective for loading pDNA into electrospun fiber meshes while maintaining their healthy functions. Effectiveness of S/O nanodispersion electrospinning was verified for fabricating a sustained release carrier matrix for high molecular weight bioactives, including therapeutic genes.

Highly efficient nanomedicines assembled via polymer-drug multiple interactions: Tissue-selective delivery carriers

This study presents the construction and evaluation of highly efficient nanomedicines via self-assembly directed by multiple non-covalent interactions between carrier polymer and cargo molecules, including hydrophobic, host-guest recognition, hydrogen bonding and electrostatic forces. β-Cyclodextrin conjugated polyethyleneimine (PEI-CD) was employed as the model carrier material, while indomethacin (IND), a nonsteroidal anti-inflammatory drug, was used as the drug model. Spontaneous assembly of PEI-CD and IND led to core-shell structured nanoparticles with a positive surface and pH-triggering behavior as well as high drug loading capacity. These nano-assemblies can function as gastro-OFF/intestinal-ON delivery systems to selectively transport payload to enteric sites, thereby dramatically increasing the oral bioavailability of the loaded therapeutic, which can also serve as multifunctional nano-platforms for multiple delivery of various therapeutics. In addition, the strategy employed herein may provide new insights into the design of novel nanocarriers by self-assembling.

Nanomicellar formulations for sustained drug delivery: strategies and underlying principles

Micellar delivery systems smaller than 100 nm can be readily prepared. While micelles allow a great depth of tissue penetration for targeted drug delivery, they usually disintegrate rapidly in the body. Thus, sustained drug delivery from micellar nanocarriers is a challenge. This article summarizes various key strategies and underlying principles for sustained drug delivery using micellar nanocarriers. Comparisons are made with other competing delivery systems such as polymeric microparticles and nanoparticles. Amphiphilic molecules self-assemble in appropriate liquid media to form nanoscale micelles. Strategies for sustained release nanomicellar carriers include use of prodrugs, drug polymer conjugates, novel polymers with low critical micellar concentration or of a reverse thermoresponsive nature, reverse micelles, multi-layer micelles with layer by layer assembly, polymeric films capable of forming micelles in vivo and micelle coats on a solid support. These new micellar systems are promising for sustained drug delivery.

Effects of indomethacin-loaded nanocapsules in experimental models of inflammation in rats

BACKGROUND AND PURPOSE

The effects of systemic treatment with indomethacin-loaded nanocapsules (IndOH-NC) were compared with those of free indomethacin (IndOH) in rat models of acute and chronic oedema.

EXPERIMENTAL APPROACH

The following models of inflammation were employed: carrageenan-induced acute oedema (measured between 30 min and 4 h), sub-chronic oedema induced by complete Freund's adjuvant (CFA) (determined between 2 h and 72 h), and CFA-induced arthritis (oedema measured between 14 and 21 days).

KEY RESULTS

IndOH or IndOH-NC produced equal inhibition of carrageenan-elicited oedema. However, IndOH-NC was more effective in both the sub-chronic (33 +/- 4% inhibition) and the arthritis (35 +/- 2% inhibition) model of oedema evoked by CFA, when compared with IndOH (21 +/- 2% and 14 +/- 3% inhibition respectively) (P < 0.01). In the CFA arthritis model, treatment with IndOH-NC markedly inhibited the serum levels of the pro-inflammatory cytokines tumour necrosis factor alpha and IL-6 (by 83 +/- 8% and 84 +/- 11% respectively), while the levels of the anti-inflammatory cytokine IL-10 were significantly increased (196 +/- 55%). The indices of gastrointestinal damage in IndOH-NC-treated animals were significantly less that those after IndOH treatment (58 +/- 16%, 72 +/- 6% and 69 +/- 2%, for duodenum, jejunum and ileum respectively).

CONCLUSIONS AND IMPLICATIONS

IndOH-NC produced an increased anti-inflammatory efficacy in long-term models of inflammation, allied to an improved gastrointestinal safety. This formulation might represent a promising alternative for treating chronic inflammatory diseases, with reduced undesirable effects.

Constructing doxorubicin-loaded polymeric micelles through amphiphilic graft polyphosphazenes containing ethyl tryptophan and PEG segments

By changing the molar ratio of hydrophilic and hydrophobic segments, a series of novel amphiphilic graft polyphosphazenes (PEG/EtTrp-PPPs) was synthesized via thermal ring-opening polymerization and a subsequent two-step substitution reaction of hydrophilic methoxyl polyethylene glycol (MPEG) and hydrophobic ethyl tryptophan (EtTrp). (1)H-Nuclear magnetic resonance and Fourier transform infrared studies validated the expected synthesis of copolymers. The copolymer composition was also confirmed by UV-visible spectrophotometry. The molar ratio of the segment PEG to group EtTrp was 1.33:0.67, 1.01:0.99 and 0.78:1.22, respectively. Micellization behavior of PEG/EtTrp-PPPs in an aqueous phase was characterized by fluorescence technique, dynamic light scattering and transmission electron microscopy. The critical micelle concentration (CMC) of the graft copolymer in aqueous solution was 0.158, 0.033 and 0.020gl(-1), which decreased as the hydrophobic content in amphiphilic copolymers increased. Doxorubicin (DOX) was physically loaded into micelles prepared by an O/W emulsion method with a drug loading content increasing with DOX feeding. In vitro release of DOX from micelles can be accelerated in weak acidic solution. The results of cytotoxicity study using an MTT assay method with HeLa cell showed that amphiphilic graft polyphosphazenes were biocompatible while DOX-loaded micelles achieved comparable cytotoxicity with that of free DOX. In summary, these novel amphiphilic copolymers exhibited potential to be used as injectable drug carriers for tumor treatment.

Intra-articular drug delivery systems: Overcoming the shortcomings of joint disease therapy

BACKGROUND

Intra-articular drug delivery is very useful for treating local disease flare-ups, synovitis and pain in joints. However, the effectiveness of drugs following intra-articular administration is limited by drug delivery issues.

AIM

This review addresses critical drug delivery parameters that influence the biocompatibility, tolerability and efficacy of intra-articular administrations and offers an opinion on aspects of formulation design.

METHODS

The relevant literature was reviewed, focusing on factors influencing tissue targeting, safety and effectiveness of particulate formulations.

RESULTS/CONCLUSION

Therapeutic applications of novel drug delivery systems for the localized treatment of joints have lagged significantly. Future innovations in the field will require the discovery of new therapeutic agents for regional delivery, combination regimens, novel biomaterials as drug carriers and targeting carriers to specific molecules.

Emerging intra-articular drug delivery systems for the temporomandibular joint

Temporomandibular joint (TMJ) disorders are a heterogeneous group of diseases that cause progressive joint degeneration leading to chronic pain and reduced quality of life. Both effective pain reduction and restoration of TMJ function remain unmet challenges. Intra-articular injections of corticosteroids and hyaluronic acid are currently used to treat chronic pain, but these methods require multiple injections that increase the risk of iatrogenic joint damage and other complications. The small and emerging field of TMJ tissue engineering aims to reduce pain and disability through novel strategies that induce joint tissue regeneration. Development of methods for sustained, intra-articular release of growth factors and other pro-regenerative signals will be critical for the success of TMJ tissue engineering strategies. This review discusses methods of intra-articular drug delivery to the TMJ, as well as emerging injectable controlled release systems with potential to improve TMJ drug delivery, to encourage further research in the development of sustained release systems for both long-term pain management and to enhance tissue engineering strategies for TMJ regeneration.