Nanocrystals of a potent p38 MAPK inhibitor embedded in microparticles: Therapeutic effects in inflammatory and mechanistic murine models of osteoarthritis

Nanocrystals and nanosuspensions: an exploration from classic formulations to advanced drug delivery systems

Nanocrystals and nanosuspensions have become realistic approaches to overcome the formulation challenges of poorly water-soluble drugs. They also represent a less-known but versatile platform for multiple therapeutic applications. They can be integrated into a broad spectrum of drug delivery systems including tablets, hydrogels, microneedles, microparticles, or even functionalized liposomes. The recent progresses, challenges, and opportunities in this field are gathered originally together with an informative case study concerning an itraconazole nanosuspension-in-hydrogel formulation. The translational aspects, historical and current clinical perspectives are also critically reviewed here to shed light on the incoming generation of nanocrystal formulations.

Natural products in osteoarthritis treatment: bridging basic research to clinical applications

Osteoarthritis (OA) is the most prevalent degenerative musculoskeletal disease, severely impacting the function of patients and potentially leading to disability, especially among the elderly population. Natural products (NPs), obtained from components or metabolites of plants, animals, microorganisms etc., have gained significant attention as important conservative treatments for various diseases. Recently, NPs have been well studied in preclinical and clinical researches, showing promising potential in the treatment of OA. In this review, we summed up the main signaling pathways affected by NPs in OA treatment, including NF-κB, MAPKs, PI3K/AKT, SIRT1, and other pathways, which are related to inflammation, anabolism and catabolism, and cell death. In addition, we described the therapeutic effects of NPs in different OA animal models and the current clinical studies in OA patients. At last, we discussed the potential research directions including in-depth analysis of the mechanisms and new application strategies of NPs for the OA treatment, so as to promote the basic research and clinical transformation in the future. We hope that this review may allow us to get a better understanding about the potential bioeffects and mechanisms of NPs in OA therapy, and ultimately improve the effectiveness of NPs-based clinical conservative treatment for OA patients.

Impact of the crystal size of crystalline active pharmaceutical compounds on loading into microneedles

Microneedle (MN) technology offers a promising platform for the delivery of a wide variety of active pharmaceutical compounds into and/or through the skin. Yet, the low loading capacity of MNs limits their clinical translation. The solid state of loaded compounds, crystallinity versus amorphousness and crystal size of the former, could greatly affect their loading. Here, we investigated the effect of the crystal size of crystalline compounds on their loading into dissolving MNs, prepared using the solvent-casting technique. A model crystalline compound was subjected to crystal size reduction via wet bead milling and loaded into dissolving MNs. A range of crystal sizes, from micro to nano, was obtained via different milling periods. The obtained crystals were characterized for their size, morphology, and sedimentation behavior. Besides, their content, solid state inside the MNs, and impact on the MN mechanical strength were assessed. The crystals exhibited size-dependent sedimentation, which dramatically affected their loading inside the MNs. However, crystal size and sedimentation demonstrated a negligible effect on the mechanical strength and sharpness of the needles, hence no anticipated impact on the MNs' drug delivery efficiency. The elucidation of the correlation between the crystal size and MN loading opens new potentials to address a major drawback in MN technology.

Spray-dried nanocrystal-loaded polymer microparticles for long-term release local therapies: an opportunity for poorly soluble drugs

Nano- and micro-technologies can salvage drugs with very low solubility that were doomed to pre-clinical and clinical failure. A unique design approach to develop drug nanocrystals (NCs) loaded in extended release polymeric microparticles (MPs) for local treatments is presented here through the case of a potential osteoarthritis (OA) drug candidate for intra-articular (IA) administration. Optimizing a low-shear wet milling process allowed the production of NCs that can be subsequently freeze-dried (FD) and redispersed in a hydrophobic polymer-organic solvent solution to form spray-dried MPs. Results demonstrated a successful development of a ready-to-upscale formulation containing PLGA MPs with high drug NC encapsulation rates that showed a continuous and controlled drug release profile over four months. The screenings and procedures described allowed for identifying and overcoming common difficulties and challenges raised along the drug reduction to nano-size and spray-drying process. Above all, the technical knowledge acquired is intended for formulation scientists aiming to improve the therapeutic perspectives of poorly soluble drugs.

Clofazimine nanoclusters show high efficacy in experimental TB with amelioration in paradoxical lung inflammation

The rise of tuberculosis (TB) superbugs has impeded efforts to control this infectious ailment, and new treatment options are few. Paradoxical Inflammation (PI) is another major problem associated with current anti-TB therapy, which can complicate the treatment and leads to clinical worsening of disease despite a decrease in bacterial burden in the lungs. TB infection is generally accompanied by an intense local inflammatory response which may be critical to TB pathogenesis. Clofazimine (CLF), a second-line anti-TB drug, delineated potential anti-mycobacterial effects in-vitro and in-vivo and also demonstrated anti-inflammatory potential in in-vitro experiments. However, clinical implications may be restricted owing to poor solubility and low bioavailability rendering a suboptimal drug concentration in the target organ. To unravel these issues, nanocrystals of CLF (CLF-NC) were prepared using a microfluidizer® technology, which was further processed into micro-sized CLF nano-clusters (CLF-NCLs) by spray drying technique. This particle engineering offers combined advantages of micron- and nano-scale particles where micron-size (∼5 μm) promise optimum aerodynamic parameters for the finest lung deposition, and nano-scale dimensions (∼600 nm) improve the dissolution profile of apparently insoluble clofazimine. An inhalable formulation was evaluated against virulent mycobacterium tuberculosis in in-vitro studies and in mice infected with aerosol TB infection. CLF-NCLs resulted in the significant killing of virulent TB bacteria with a MIC value of ∼0.62 μg/mL, as demonstrated by Resazurin microtiter assay (REMA). In TB-infected mice, inhaled doses of CLF-NCLs equivalent to ∼300 μg and ∼ 600 μg of CLF administered on every alternate day over 30 days significantly reduced the number of bacteria in the lung. With an inhaled dose of ∼600 μg/mice, reduction of mycobacterial colony forming units (CFU) was achieved by ∼1.95 Log10CFU times compared to CLF administered via oral gavage (∼1.18 Log10CFU). Lung histology scoring showed improved pathogenesis and inflammation in infected animals after 30 days of inhalation dosing of CLF-NCLs. The levels of pro-inflammatory mediators, including cytokines, TNF-α & IL-6, and MMP-2 in bronchoalveolar lavage fluid (BAL-F) and lung tissue homogenates, were attenuated after inhalation treatment. These pre-clinical data suggest inhalable CLF-NCLs are well tolerated, show significant anti-TB activity and apparently able to tackle the challenge of paradoxical chronic lung inflammation in murine TB model.

Alginate/acemannan-based beads loaded with a biocompatible ionic liquid as a bioactive delivery system

Combining biomacromolecules with green chemistry principles and clean technologies has proven to be an effective approach for drug delivery, providing a prolonged and sustained release of the encapsulated material. The current study investigates the potential of cholinium caffeate (Ch[Caffeate]), a phenolic-based biocompatible ionic liquid (Bio-IL) entrapped in alginate/acemannan beads, as a drug delivery system able to reduce local joint inflammation on osteoarthritis (OA) treatment. The synthesized Bio-IL has antioxidant and anti-inflammatory actions that, combined with biopolymers as 3D architectures, promote the entrapment and sustainable release of the bioactive molecules over time. The physicochemical and morphological characterization of the beads (ALC, ALAC0,5, ALAC1, and ALAC3, containing 0, 0.5, 1, and 3 %(w/v) of Ch[Caffeate], respectively) revealed a porous and interconnected structure, with medium pore sizes ranging from 209.16 to 221.30 μm, with a high swelling ability (up 2400 %). Ch[Caffeate] significantly improved the antioxidant activities of the constructs by 95 % and 97 % for ALAC1 and ALAC3, respectively, when compared to ALA (56 %). Besides, the structures provided the environment for ATDC5 cell proliferation, and cartilage-like ECM formation, supported by the increased GAGs in ALAC1 and ALAC3 formulations after 21 days. Further, the ability to block the secretion of pro-inflammatory cytokines (TNF-α and IL-6), from differentiated THP-1 was evidenced by ChAL-Ch[Caffeate] beads. These outcomes suggest that the established strategy based on using natural and bioactive macromolecules to develop 3D constructs has great potential to be used as therapeutic tools for patients with OA.

Nanomaterial-assisted theranosis of bone diseases

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

Selumetinib - a potential small molecule inhibitor for osteoarthritis treatment

Objectives: Osteoarthritis (OA) is a common disease that mainly manifests as inflammation and destruction of cartilage and subchondral bone. Recently, necroptosis has been reported to play an important role in the development of OA. Selumetinib displays a contrasting expression pattern to necroptosis-related proteins. The present study aimed to investigate the potential therapeutic effects of selumetinib in OA process.

Methods:In vitro experiments, interleukin-1β (IL-1β) was used to induce necroptosis of chondrocytes. We used high-density cell culture, Western Blot and PT-PCR to observe the effect of different concentrations of selumetinib on the extracellular matrix of cartilage. Afterwards, we visualized the effect of selumetinib on osteoclast formation by TRAP staining and F-actin rings. In vivo experiment, we induced experimental osteoarthritis in mice by surgically destabilizing the medial meniscus (DMM) while administering different concentrations of selumetinib intraperitoneally.

Results: Selumetinib promoted cartilage matrix synthesis and inhibited matrix decomposition. We found that selumetinib exerted a protective function by inhibiting the activation of RIP1/RIP3/MLKL signaling pathways in chondrocytes. Selumetinib also inhibited the activation of RANKL-induced NF-κB and MAPK signaling pathways in BMMs, thereby interfering with the expression of osteoclast marker genes. In the DMM-induced OA model, a postsurgical injection of selumetinib inhibited cartilage destruction and lessened the formation of TRAP-positive osteoclasts in subchondral bone.

Conclusion: Selumetinib can protect chondrocytes by regulating necroptosis to prevent the progression of OA and reduce osteoclast formation. In summary, our findings suggest that selumetinib has potential as a therapeutic agent for OA.

Nanocrystals for controlled delivery: State of the art and approved drug products

INTRODUCTION

Controlled/extended-release formulations offer numerous benefits over conventional especially reduced side effects, improved therapeutic outcomes and high patient compliance. Controlled release nanocrystal is extremely versatile technology with several advantages such as very high drug loading, ease of manufacturing, avoidance of dose dumping, reproducible drug release. Usually, nanonization of drug is performed to improve dissolution rate, intrinsic solubility and thereby bioavailability. Most of the times, this is done for immediate release dosage forms where objective is quick onset of action. However, nanocrystals can also provide a sustained, reproducible plasma concentration profile for weeks to months based on tissue microenvironment, surface coating administration route.

AREAS COVERED

This review briefly describes the methods for producing nanocrystals, summarizes preclinical research and commercial products demonstrating tremendous potential of controlled release nanocrystals.

EXPERT OPINION

Lipophilic drugs are attractive candidates for the development of nanocrystal based controlled release formulations. However, constraint should be practiced while generalizing the technology for the controlled release purpose. Not all drugs fit in the requirement from the perspectives of physicochemical properties or pharmacokinetic requirements. Additionally, technologies should be explored which can convert the nanocrystal into its final dosage form for administration yet preserves the benefits of small particle size and controlled release.

Obesity, Inflammation, and Immune System in Osteoarthritis

Obesity remains the most important risk factor for the incidence and progression of osteoarthritis (OA). The leading cause of OA was believed to be overloading the joints due to excess weight which in turn leads to the destruction of articular cartilage. However, recent studies have proved otherwise, various other factors like adipose deposition, insulin resistance, and especially the improper coordination of innate and adaptive immune responses may lead to the initiation and progression of obesity-associated OA. It is becoming increasingly evident that multiple inflammatory cells are recruited into the synovial joint that serves an important role in pathological changes in the synovial joint. Polarization of macrophages and macrophage-produced mediators are extensively studied and linked to the inflammatory and destructive responses in the OA synovium and cartilage. However, the role of other major innate immune cells such as neutrophils, eosinophils, and dendritic cells in the pathogenesis of OA has not been fully evaluated. Although cells of the adaptive immune system contribute to the pathogenesis of obesity-induced OA is still under exploration, a quantity of literature indicates OA synovium has an enriched population of T cells and B cells compared with healthy control. The interplay between a variety of immune cells and other cells that reside in the articular joints may constitute a vicious cycle, leading to pathological changes of the articular joint in obese individuals. This review addresses obesity and the role of all the immune cells that are involved in OA and summarised animal studies and human trials and knowledge gaps between the studies have been highlighted. The review also touches base on the interventions currently in clinical trials, different stages of the testing, and their shortcomings are also discussed to understand the future direction which could help in understanding the multifactorial aspects of OA where inflammation has a significant function.

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.

Knee Osteoarthritis Therapy: Recent Advances in Intra-Articular Drug Delivery Systems

Drug delivery for osteoarthritis (OA) treatment is a continuous challenge because of their poor bioavailability and rapid clearance in joints. Intra-articular (IA) drug delivery is a common strategy and its therapeutic effects depend mainly on the efficacy of the drug-delivery system used for OA therapy. Different types of IA drug-delivery systems, such as microspheres, nanoparticles, and hydrogels, have been rapidly developed over the past decade to improve their therapeutic effects. With the continuous advancement in OA mechanism research, new drugs targeting specific cell/signaling pathways in OA are rapidly evolving and effective drug delivery is critical for treating OA. In this review, recent advances in various IA drug-delivery systems for OA treatment, OA targeted strategies, and related signaling pathways in OA treatment are summarized and analyzed based on current publications.

Micro- and nanotechnology in biomedical engineering for cartilage tissue regeneration in osteoarthritis

Osteoarthritis, which typically arises from aging, traumatic injury, or obesity, is the most common form of arthritis, which usually leads to malfunction of the joints and requires medical interventions due to the poor self-healing capacity of articular cartilage. However, currently used medical treatment modalities have reported, at least in part, disappointing and frustrating results for patients with osteoarthritis. Recent progress in the design and fabrication of tissue-engineered microscale/nanoscale platforms, which arises from the convergence of stem cell research and nanotechnology methods, has shown promising results in the administration of new and efficient options for treating osteochondral lesions. This paper presents an overview of the recent advances in osteochondral tissue engineering resulting from the application of micro- and nanotechnology approaches in the structure of biomaterials, including biological and microscale/nanoscale topographical cues, microspheres, nanoparticles, nanofibers, and nanotubes.

All-stage targeted therapy for glioblastoma based on lipid membrane coated cabazitaxel nanocrystals

Glioblastoma (GBM) is the most aggressive brain tumor with poor prognosis and frequent recurrence. The blood-brain barrier (BBB), blood-brain tumor barrier (BBTB) hinder the entry of therapeutics into the glioma region. Vasculogenic mimicry (VM) formed by invasive glioma cells is also related to recurrence of GBM. VAP is a D-peptide ligand of GRP78 protein overexpressed on BBTB, VM, and glioma cells but not on normal tissues. Besides, p-hydroxybenzoic acid (pHA) can effectively traverse the BBB. Herein we developed an all-stage glioma-targeted cabazitaxel (CBZ) nanocrystal loaded liposome modified with a "Y" shaped targeting ligand composed of pHA and VAP (pV-Lip/cNC). The pure drug nanocrystal core provided high drug loading, while lipid membrane promoted the stability and circulation time. pV-Lip/cNC exhibited excellent glioma homing, barriers crossing, and tumor spheroid penetrating capability in vitro. Treatment of pV-Lip/cNC displayed enhanced CBZ accumulation in glioma and anti-glioma effect with a median survival time (53 days) significantly longer than that of cNC loaded liposomes modified with either single ligand (42 days for VAP and 45 days for pHA) in the murine orthotopic GBM model. These results indicated pV-Lip/cNC could traverse the BBB and BBTB, destruct VM, and finally kill glioma cells to realize all-stage glioma therapy.

High drug-loaded microspheres enabled by controlled in-droplet precipitation promote functional recovery after spinal cord injury

Drug delivery systems with high content of drug can minimize excipients administration, reduce side effects, improve therapeutic efficacy and/or promote patient compliance. However, engineering such systems is extremely challenging, as their loading capacity is inherently limited by the compatibility between drug molecules and carrier materials. To mitigate the drug-carrier compatibility limitation towards therapeutics encapsulation, we developed a sequential solidification strategy. In this strategy, the precisely controlled diffusion of solvents from droplets ensures the fast in-droplet precipitation of drug molecules prior to the solidification of polymer materials. After polymer solidification, a mass of drug nanoparticles is embedded in the polymer matrix, forming a nano-in-micro structured microsphere. All the obtained microspheres exhibit long-term storage stability, controlled release of drug molecules, and most importantly, high mass fraction of therapeutics (21.8–63.1 wt%). Benefiting from their high drug loading degree, the nano-in-micro structured acetalated dextran microspheres deliver a high dose of methylprednisolone (400 μg) within the limited administration volume (10 μL) by one single intrathecal injection. The amount of acetalated dextran used was 1/433 of that of low drug-loaded microspheres. Moreover, the controlled release of methylprednisolone from high drug-loaded microspheres contributes to improved therapeutic efficacy and reduced side effects than low drug-loaded microspheres and free drug in spinal cord injury therapy.

High drug loading improves therapeutic efficacy and reduces side effects in drug delivery. Here, the authors use controlled diffusion of solvents to precipitate drug nanoparticles in polymer particles while the polymer is solidifying and demonstrate the particles for drug delivery in a spinal cord injury model.

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.

Injectable hyaluronic acid hydrogels encapsulating drug nanocrystals for long-term treatment of inflammatory arthritis

Antiproliferative chemotherapeutic agents offer a potential effective treatment for inflammatory arthritis. However, their clinical application is limited by high systemic toxicity, low joint bioavailability as well as formulation challenges. Here, we report an intra-articular drug delivery system combining hyaluronic acid hydrogels and drug nanocrystals to achieve localized and sustained delivery of an antiproliferative chemotherapeutic agent camptothecin for long-term treatment of inflammatory arthritis. We synthesized a biocompatible, in situ-forming injectable hyaluronic acid hydrogel using a naturally occurring click chemistry: cyanobenzothiazole/cysteine reaction, which is the last step reaction in synthesizing D-luciferin in fireflies. This hydrogel was used to encapsulate camptothecin nanocrystals (size of 160-560 nm) which released free camptothecin in a sustained manner for 4 weeks. In vivo studies confirmed that the hydrogel remained in the joint over 4 weeks. By using the collagen-induced arthritis rat model, we demonstrate that the hydrogel-camptothecin formulation could alleviate arthritis severity as indicated by the joint size and interleukin-1β level in the harvested joints, as well as from histological and microcomputed tomography evaluation of joints. The hydrogel-nanocrystal formulation strategy described here offers a potential solution for intra-articular therapy for inflammatory arthritis.

In Situ-Activated Phospholipid-Mimic Artemisinin Prodrug via Injectable Hydrogel Nano/Microsphere for Rheumatoid Arthritis Therapy

In situ-activated therapy is a decent option for localized diseases with improved efficacies and reduced side effects, which is heavily dependent on the local conversion or activation of bioinert components. In this work, we applied a phospholipid-mimic artemisinin prodrug (ARP) for preparing an injectable nano/microsphere to first realize an in situ-activated therapy of the typical systemically administrated artemisinin-based medicines for a localized rheumatoid arthritis (RA) lesion. ARP is simultaneously an alternative of phospholipids and an enzyme-independent activable prodrug, which can formulate “drug-in-drug” co-delivery liposomes with cargo of partner drugs (e.g., methotrexate). To further stabilize ARP/methotrexate “drug-in-drug” liposomes (MTX/ARPL) for a long-term intra-articular retention, a liposome-embedded hydrogel nano/microsphere (MTX/ARPL@MS) was prepared. After the local injection, the MTX/ARPL could be slowly released because of imine hydrolysis and targeted to RA synovial macrophages and fibroblasts simultaneously. ARP assembly is relatively stable before cellular internalization but disassembled ARP after lysosomal escape and converted into dihydroartemisinin rapidly to realize the effective in situ activation. Taken together, phospholipid-mimic ARP was applied for the firstly localized in situ-activated RA therapy of artemisinin-based drugs, which also provided a brand-new phospholipid-mimic strategy for other systemically administrated prodrugs to realize a remodeling therapeutic schedule for localized diseases.

Top-Down Fabricated microPlates for Prolonged, Intra-articular Matrix Metalloproteinase 13 siRNA Nanocarrier Delivery to Reduce Post-traumatic Osteoarthritis

Post-traumatic osteoarthritis (PTOA) associated with joint injury triggers a degenerative cycle of matrix destruction and inflammatory signaling, leading to pain and loss of function. Here, prolonged RNA interference (RNAi) of matrix metalloproteinase 13 (MMP13) is tested as a PTOA disease modifying therapy. MMP13 is upregulated in PTOA and degrades the key cartilage structural protein type II collagen. Short interfering RNA (siRNA) loaded nanoparticles (siNPs) were encapsulated in shape-defined poly(lactic-co-glycolic acid) (PLGA) based microPlates (μPLs) to formulate siNP-μPLs that maintained siNPs in the joint significantly longer than delivery of free siNPs. Treatment with siNP-μPLs against MMP13 (siMMP13-μPLs) in a mechanical load-induced mouse model of PTOA maintained potent (65-75%) MMP13 gene expression knockdown and reduced MMP13 protein production in joint tissues throughout a 28-day study. MMP13 silencing reduced PTOA articular cartilage degradation/fibrillation, meniscal deterioration, synovial hyperplasia, osteophytes, and pro-inflammatory gene expression, supporting the therapeutic potential of long-lasting siMMP13-μPL therapy for PTOA.

Preparation and Characterization of Anti-Cancer Crystal Drugs Based on Erythrocyte Membrane Nanoplatform

The simple and functional modification of the nanoparticle’s surface is used to efficiently deliver chemotherapeutic drugs for anti-cancer treatment. Here, we construct a nanocrystalline drug delivery system with doxorubicin wrapped in red blood cell membranes for the treatment of mouse breast cancer models. Compared with traditional free drug treatments, the biodegradable natural red blood cell membrane is combined with pure crystalline drugs. The nanoparticles obtained by the preparation method have superior properties, such as good stability, significantly delaying the release of drugs and enhancing the inhibitory effect on tumor cells. This study shows that the design of RBC as an outsourced drug delivery system provides a promising foundation for the continued development, clinical trials, and nanomedicine research of anti-cancer drug nanocarriers in the future.

Drug Delivery Systems for the Treatment of Knee Osteoarthritis: A Systematic Review of In Vivo Studies

Many efforts have been made in the field of nanotechnology to improve the local and sustained release of drugs, which may be helpful to overcome the present limitations in the treatment of knee OA. Nano-/microparticles and/or hydrogels can be now engineered to improve the administration and intra-articular delivery of specific drugs, targeting molecular pathways and pathogenic mechanisms involved in OA progression and remission. In order to summarize the current state of this field, a systematic review of the literature was performed and 45 relevant studies were identified involving both animal models and humans. We found that polymeric nanoparticles loaded with anti-inflammatory drugs (i.e., dexamethasone or celecoxib) are the most frequently investigated drug delivery systems, followed by microparticles and hydrogels. In particular, the nanosystem most frequently used in preclinical research consists of PLGA-nanoparticles loaded with corticosteroids and non-steroidal anti-inflammatory drugs. Overall, improvement in histological features, reduction in joint inflammation, and improvement in clinical scores in patients were observed. The last advances in the field of nanotechnology could offer new opportunities to treat patients affected by knee OA, including those with previous meniscectomy. New smart drug delivery approaches, based on nanoparticles, microparticles, and hydrogels, may enhance the therapeutic potential of intra-articular agents by increasing the permanence of selected drugs inside the joint and better targeting specific receptors and tissues.

Identification of Potential Antiseizure Agents in Boswellia sacra using In Vivo Zebrafish and Mouse Epilepsy Models

The resin of the tree Boswellia sacra Flueck. (synonym: B. carterii; Burseraceae), also known as "frankincense", is a traditional remedy used for central nervous system disorders in East Africa. Here we report the evaluation of its antiseizure activity in zebrafish and mouse epilepsy models to identify novel antiseizure compounds. The resin was extracted by solvents of increasing polarity. The hexane extract demonstrated the strongest antiseizure activity and was therefore subjected to bioactivity-guided isolation, which leaded to the isolation of eight terpene derivatives. A new prenylbicyclogermacrene derivative (2) was isolated along with seven other compounds (1, 3-8). Among them, the triterpene β-boswellic acid (5) showed the strongest activity and reduced 90% of pentylenetetrazole (PTZ)-induced seizures at 100 μg/mL. In parallel to B. sacra, a commercial extract of Boswellia serrata was also evaluated and showed moderate bioactivity (45% reduction at 30 μg/mL). The extract of B. serrata was subjected to targeted isolation of other boswellic acid derivatives (9-13), which were evaluated for antiseizure activity in comparison with 5. In the whole series, β-boswellic acid (5) was the most active (60% reduction at 200 μM), and its potency was also confirmed with its purchased standard (S5). Pure nanoparticles of S5 and a commercially formulated extract of B. serrata were tested in a PTZ-kindling mouse seizure model. This notably revealed that the S5 administration reduced seizures by 50% in this mouse model, which was consistent with its detection and quantification in plasma and brain samples. This study and the preclinical evaluation performed indicate that β-boswellic acid, common to various species of Boswellia, has some potential as an antiseizure agent.

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.

Polymer particles for the intra-articular delivery of drugs to treat osteoarthritis

Osteoarthritis (OA) is a leading cause of chronic disability. It is a progressive disease, involving pathological changes to the entire joint, resulting in joint pain, stiffness, swelling, and loss of mobility. There is currently no disease-modifying pharmaceutical treatment for OA, and the treatments that do exist suffer from significant side effects. An increasing understanding of the molecular pathways involved in OA is leading to many potential drug targets. However, both current and new therapies can benefit from a targeted approach that delivers drugs selectively to joints at therapeutic concentrations, while limiting systemic exposure to the drugs. Delivery systems including hydrogels, liposomes, and various types of particles have been explored for intra-articular drug delivery. This review will describe progress over the past several years in the development of polymer-based particles for OA treatment, as well as their in vitro, in vivo, and clinical evaluation. Systems based on biopolymers such as polysaccharides and polypeptides, as well as synthetic polyesters, poly(ester amide)s, thermoresponsive polymers, poly(vinyl alcohol), amphiphilic polymers, and dendrimers will be described. We will discuss the role of particle size, biodegradability, and mechanical properties in the behavior of the particles in the joint, and the challenges to be addressed in future research.

Screening and verification of hub genes involved in osteoarthritis using bioinformatics

Osteoarthritis (OA) is one of the most common causes of disability and its development is associated with numerous factors. A major challenge in the treatment of OA is the lack of early diagnosis. In the present study, a bioinformatics method was employed to filter key genes that may be responsible for the pathogenesis of OA. From the Gene Expression Omnibus database, the datasets GSE55457, GSE12021 and GSE55325 were downloaded, which comprised 59 samples. Of these, 30 samples were from patients diagnosed with osteoarthritis and 29 were normal. Differentially expressed genes (DEGs) were obtained by downloading and analyzing the original data using bioinformatics. The Gene Ontology enrichment and Kyoto Encyclopedia of Genes and Genomes pathways were analyzed using the Database for Annotation, Visualization and Integrated Discovery online database. Protein-protein interaction network analysis was performed using the Search Tool for the Retrieval of Interacting Genes/proteins online database. BSCL2 lipid droplet biogenesis associated, seipin, FOS-like 2, activator protein-1 transcription factor subunit (FOSL2), cyclin-dependent kinase inhibitor 1A (CDKN1A) and kinectin 1 (KTN1) genes were identified as key genes by using Cytoscape software. Functional enrichment revealed that the DEGs were mainly accumulated in the ErbB, MAPK and PI3K-Akt pathways. Reverse transcription-quantitative PCR analysis confirmed a significant reduction in the expression levels of FOSL2, CDKN1A and KTN1 in OA samples. These genes have the potential to become novel diagnostic and therapeutic targets for OA.

Molecular mechanisms of mechanical load-induced osteoarthritis

INTRODUCTION

Mechanical loading enhances the progression of osteoarthritis. However, its molecular mechanisms have not been established.

OBJECTIVE

The aim of this review was to summarize the probable mechanisms of mechanical load-induced osteoarthritis.

METHODS

A comprehensive search strategy was used to search PubMed and EMBASE databases (from the 15th of January 2015 to the 20th of October 2020). Search terms included "osteoarthritis", "mechanical load", and "mechanism".

RESULTS

Abnormal mechanical loading activates the interleukin-1β, tumour necrosis factor-α, nuclear factor kappa-B, Wnt, transforming growth factor-β, microRNAs pathways, and the oxidative stress pathway. These pathways induce the pathological progression of osteoarthritis. Mechanical stress signal receptors such as integrin, ion channel receptors, hydrogen peroxide-inducible clone-5, Gremlin-1, and transient receptor potential channel 4 are present in the articular cartilages.

CONCLUSION

This review highlights the molecular mechanisms of mechanical loading in inducing chondrocyte apoptosis and extracellular matrix degradation. These mechanisms provide potential targets for osteoarthritis prevention and treatment.

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.

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.

Nano wet milled celecoxib extended release microparticles for local management of chronic inflammation

Osteoarthritis (OA), the most common form of arthritis, is characterized by chronic inflammation, degeneration of articular cartilage and whole joints. Local delivery by intra-articular (IA) injection of small molecules is an established treatment to relieve pain and improve joint motion, requiring month-lasting release of therapeutic drug doses. We incorporated anti-inflammatory drug celecoxib in poly (D, L-lactic acid) microparticles using two spray-drying approaches - either as a solid drug solution or embedded as milled nano drug. Differential scanning calorimetry, X-ray powder diffraction, electron microscopy and in vitro drug release allowed comparison of the microparticles. Both types resulted in spherical particles ranging from 20 to 40 μm mean size, with high drug loadings (10% to 50% w/w) and entrapment efficiencies > 80%. However, after 90 days, in vitro celecoxib release from nano drug embedded microparticles presented a significantly slower release in comparison to drug in solution microparticles, attributed to the presence of stabilized amorphous drug. No cytotoxicity was observed in human articular synoviocytes and PGE₂ release was fully suppressed at low doses of both microparticulate systems. This study provides techniques to release high drug loads over months in a tunable manner, providing valuable options for the IA management of osteoarthritis.

Intra-Articular injection of acid-sensitive stearoxyl-ketal-dexamethasone microcrystals for long-acting arthritis therapy

Despite advances in treatment of chronic arthritis, there is still a strong need for the development of long-acting formulations that can enable local and sustained drug release at the inflamed tissues. In this work, we fabricated microcrystals of an acid-sensitive stearoxyl-ketal-dexamethasone prodrug for treatment of arthritis. Microcrystals of the prodrug with two sizes were successfully engineered and showed pH-dependent hydrolysis kinetics in vitro. In a collagen-induced arthritis rat model, we evaluated the influence of particle size and injection dose on anti-inflammatory effect after intra-articular injection. Such prodrug demonstrated long-acting anti-arthritis effects with good safety. Our results indicate ketal-based prodrugs are promising for the development of long-acting injectables and may stimulate the development of new treatments for chronic diseases.

Yeast Cell wall Particle mediated Nanotube-RNA delivery system loaded with miR365 Antagomir for Post-traumatic Osteoarthritis Therapy via Oral Route

Post-traumatic osteoarthritis (PTOA) is an acute injury-induced joint inflammation followed by a gradual degradation of articular cartilage. However, there is no FDA-approved Disease-Modifying Osteoarthritis Drug currently. Although gene therapy with microRNA can improve PTOA progression, there is no effective gene delivery vehicle for orally deliver therapeutics due to the harsh environment of the gastrointestinal tract. In this study, we investigated the effect of yeast cell wall particle (YCWP) mediated nanotube-RNA delivery system on PTOA therapy via oral route. Methods: Nontoxic and degradable AAT and miRNA365 antagomir was self-assembled into miR365 antagomir/AAT (NPs). Then NPs-YCWP oral drug delivery system was constructed by using NPs and non-pathogenic YCWP which can be specifically recognized by macrophages. Moreover, surgical destabilization of the medial meniscus induced PTOA mice model was established to evaluate the therapeutic effect of NPs-YCWP via oral route. Results: Compared with control group, NPs showed higher gene inhibition efficiency both in chondrogenic cell line and primary chondrocytes in vitro. Treatment of macrophages with fluorescently labeled NPs-YCWP, the results showed that NPs-YCWP was successfully engulfed by macrophages and participated in the regulation of gene expression in vitro. Under the protection of YCWP, miR365 antagomir/AAT passes through the gastrointestinal tract without degradation after oral administration. After NPs-YCWP therapy, the results of histological staining, gene and protein expression showed that miR365 antagomir/NPs-YCWP improved the symptom of PTOA. Conclusion: Here, we constructed a biodegradable drug delivery system based on non-pathogenic YCWP and nanotubes, which can be used for PTOA therapy via the oral route. It suggests a new gene therapy strategy with YCWP mediated oral nano drug delivery system may serve as a platform for joint degeneration treatment.

Recent advances in the treatment of osteoarthritis

Osteoarthritis (OA) is one of the most debilitating diseases and is associated with a high personal and socioeconomic burden. So far, there is no therapy available that effectively arrests structural deterioration of cartilage and bone or is able to successfully reverse any of the existing structural defects. Efforts to identify more tailored treatment options led to the development of strategies that enabled the classification of patient subgroups from the pool of heterogeneous phenotypes that display distinct common characteristics. To this end, the classification differentiates the structural endotypes into cartilage and bone subtypes, which are predominantly driven by structure-related degenerative events. In addition, further classifications have highlighted individuals with an increased inflammatory contribution (inflammatory phenotype) and pain-driven phenotypes as well as senescence and metabolic syndrome phenotypes. Most probably, it will not be possible to classify individuals by a single definite subtype, but it might help to identify groups of patients with a predominant pathology that would more likely benefit from a specific drug or cell-based therapy. Current clinical trials addressed mainly regeneration/repair of cartilage and bone defects or targeted pro-inflammatory mediators by intra-articular injections of drugs and antibodies. Pain was treated mostly by antagonizing nerve growth factor (NGF) activity and its receptor tropomyosin-related kinase A (TrkA). Therapies targeting metabolic disorders such as diabetes mellitus and senescence/aging-related pathologies are not specifically addressing OA. However, none of these therapies has been proven to modify disease progression significantly or successfully prevent final joint replacement in the advanced disease stage. Within this review, we discuss the recent advances in phenotype-specific treatment options and evaluate their applicability for use in personalized OA therapy.

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

PURPOSE OF REVIEW

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

RECENT FINDINGS

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

Specific Modification with TPGS and Drug Loading of Cyclodextrin Polyrotaxanes and the Enhanced Antitumor Activity Study in Vitro and in Vivo

A kind of specific cyclodextrin polyrotaxanes (PRs) drug delivery system was developed for an effective drug delivery and enhancing antitumor effect. In this work, we prepared the PR by using α-CD derivatives and dicarboxyl-PEG (M_n = 4200) self-assembling and end-capping with β-CD derivatives. Then, we chose d-a-Tocopheryl polyethylene glycol 1000 succinate (TPGS) with an antitumor effect to modify the PR. The modified PRs have a certain anticancer effect and can assist the anticancer drug to treat cancer. The 10-hydroxycamptothecin (HCPT) was combined to the specific PRs by covalent bonds to prepare drug-loaded specificity PRs (PR-TPGS-HCPT). The enhanced antitumor activities of PR-TPGS-HCPT were studied by in vitro and in vivo experiments, and the experiment results proved that the TPGS could effectively assist the drug to treat cancer and prolong the lifetime of the tumor-bearing mice. Therefore, this research provides a promising drug-loaded material for the cancer treatment and the specific water-soluble PRs will have potential applications in the biomedical field.

Development of a validated UPLC-MS/MS method for quantification of p38 MAPK inhibitor PH-797804: Application to a pharmacokinetic study in rat plasma

PH-797804 is a selective p38 MAPK inhibitor currently evaluated in clinical trials. This study described a validated UPLC-MS/MS combined with one-step protein precipitation extraction method for determination of PH-797804 in rat plasma. After protein precipitation with acetonitrile, the plasma sample was analyzed by a Waters Acquity UPLC BEH C₁₈ column, with acetonitrile/0.1% formic acid (70:30) as the mobile phase. Mass spectrometric detection was conducted with a Waters TQ-S mass spectrometer via electrospray, positive-mode ionization, with target quantitative ion pairs of m/z 476.895 → 126.860 for PH-797804, and 482.726 → 269.707 for regorafenib (internal standard). The assay showed a good linearity over the range of 1.0-1600 ng/mL, with acceptable accuracy (RE from -7.8% to 8.5%) and precision (RSD within 8.4%) values. Recovery from plasma was 81.4-90.2% and matrix effect was negligible (93.3-95.4%). The validated method presented a quantification method of PH-797804 in detail for the first time and utilized for a pharmacokinetic study at three dose concentrations after oral administration in Wistar rats. The pharmacokinetic profiles of PH-797804 showed a linear relationship between drug concentration and dose, which provided dosage and safety information on further clinical studies.

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.

Activation of the P38/CREB/MMP13 axis is associated with osteoarthritis

Purposes

Osteoarthritis (OA) is a common joint disease characterized by the degradation of articular cartilage and joint inflammation. Interleukin-1ß induces P38/cAMP response element binding protein (CREB) pathway activation, resulting in increased expression of matrix metallopeptidase-13 (MMP13) in chondrocytes. However, the role of the P38/CREB/MMP13 axis is unclear in the progression of OA. In this study, we aimed to answer the following questions: (1) how does the P38/CREB/MMP13 axis in cartilage from patients with OA compare with control specimens? (2) Can the P38 agonist anisomycin (ANS) induce mouse OA?

Materials and methods

Surgical specimens of human cartilage were divided into OA and control groups. Surgical specimens of mouse cartilage were divided into control and ANS-induced groups. Safranin O staining of the cartilage tissues was performed to evaluate the extracellular matrix. Reverse transcription-polymerase chain reaction was performed using these tissues to investigate messenger RNA expressions of type II collagen, aggrecan, MMP13, and ADAM metallopeptidase with thrombospondin type 1 motif 5. Phosphorylated (p)-P38, p-CREB, and MMP13 were evaluated by Western blot analysis. Anisomycin was used to activate P38, and p-P38, p-CREB, and MMP13 were evaluated by immunofluorescence and Western blot analysis.

Results

Safranin O staining showed that the extracellular matrix degraded in humans with OA and ANS-induced mouse cartilage samples. The expressions of p-P38, p-CREB, and MMP13 were all upregulated in osteoarthritic cartilage or anisomycin-induced chondrocytes, suggesting that the P38/CREB/MMP13 axis may play a role in the progression of OA.

Conclusions

The P38/CREB/MMP13 axis is active in osteoarthritic chondrocytes and may cause the degeneration of cartilage. Effective new therapy directed against this pathway could be developed.

Ligand-Modified Cell Membrane Enables the Targeted Delivery of Drug Nanocrystals to Glioma

The safe and efficient delivery of chemotherapeutic agents remains critical to anticancer therapy. Herein, we report on a targeted drug delivery system based upon a modified cell membrane coating technique and drug nanocrystals (NCs). Specifically, red blood cell (RBC) membrane was modified with targeting peptides through a facile insertion method involving avidin-biotin interactions. The RBC membrane-coated drug NCs (RBC-NCs) exhibited high drug loading, long-term stability, excellent biocompatibility, and prolonged retention time, all of which make them suitable for effective drug delivery. When modified with the tumor-targeting peptide c(RGDyK), the resulting RGD-RBC-NCs showed superior tumor accumulation and therapeutic efficacy both in mice bearing a subcutaneous tumor as well as orthotropic glioma. RBC-NC therapeutics can be readily generalized to the delivery of various drugs and for the treatment of a wide range of cancers.

Targeting chronic innate inflammatory pathways, the main road to prevention of osteoarthritis progression

Osteoarthritis (OA) is a chronic joint disease characterized by cartilage degradation, osteophyte formation, subchondral bone sclerosis, and synovitis. Systemic factors such as obesity and the components of the metabolic syndrome seem to contribute to its progression. Breakdown of cartilage ensues from an altered balance between mechanical overload and its absorption by this tissue. There is in this context a status of persistent local inflammation by means of the chronic activation of innate immunity. A broad variety of danger-associated molecular patterns inside OA joint are able to activate pattern recognition receptors, mainly TLR (toll-like receptor) 2 and 4, which are overexpressed in the OA cartilage. Chronic activation of innate immune responses in chondrocytes results in a robust production of pro-inflammatory cytokines and chemokines, as well as of tissue-destructive enzymes, downstream of NF-κB and MAPK (mitogen activated protein kinase) dependent pathways. Besides, the toxic effects of an excess of glucose and/or fatty acids, which share the same pro-inflammatory intracellular signalling pathways, may add fuel to the fire. Not only high concentrations of glucose can render cells prone to inflammation, but also AGEs (advanced glycation end products) are integrated into the TLR signalling network through their own innate immune receptors. Considering these mechanisms, we argue for the control of both primary inflammation and proteolytic catabolism as a preventive strategy in OA, instead of focusing treatment on the enhancement of anabolic responses. Even though this approach would not return to normal already degraded cartilage, it nonetheless might avoid damage extension to the surrounding tissue.

Nanocrystals: A perspective on translational research and clinical studies

Poorly soluble small molecules typically pose translational hurdles owing to their low solubility, low bioavailability, and formulation challenges. Nanocrystallization is a versatile method for salvaging poorly soluble drugs with the added benefit of a carrier-free delivery system. In this review, we provide a comprehensive analysis of nanocrystals with emphasis on their clinical translation. Additionally, the review sheds light on clinically approved nanocrystal drug products as well as those in development.

Icariin Activates Autophagy via Down-Regulation of the NF-κB Signaling-Mediated Apoptosis in Chondrocytes

Osteoarthritis (OA) is a common chronic and degenerative joint condition that is mainly characterized by cartilage degradation, osteophyte formation, and joint stiffness. The NF-κB signaling pathway in inflammation, autophagy, and apoptosis plays a prominent role in the progression of OA. Icariin, a prenylated flavonol glycoside extracted from Epimedium, have been proven to exert anti-osteoporotic and anti-inflammatory effects in OA. However, the action mechanisms of its effect on chondrocytes have yet to be elucidated. In the present study, we demonstrated that the in vitro therapeutic effects of icariin on rat chondrocytes in a dose-dependent manner. We found that TNF-α induced the production of IL-1, IL-6, IL-12, reactive oxygen species (ROS), nitric oxide (NO), Caspase-3, and Caspase-9 in chondrocytes. We also provided evidence that TNF-α inhibited autophagy markers (Atg 5, Atg 7) and prevented LC3 I translate to LC3 II. Furthermore, TNF-α induced matrix metalloproteinase (MMP)3 and MMP9 expression. The negative effects of TNF-α on chondrocytes can be partially blocked by treating with icariin or ammonium pyrrolidinedithiocarbamate (PDTC, an NF-κB inhibitor). The present study data also suggested that icariin suppressed both TNF-α-stimulated p65 nuclear translocation and IκBα protein degradation. These results indicated that icariin protected against OA by suppressing inflammatory cytokines and apoptosis, through activation of autophagy via NF-κB inhibition. In conclusion, icariin appears to favorably modulate autophagy and apoptosis in chondrocytes making it a promising compound for cartilage tissue engineering in the treatment of OA.