Synthetic nanoscale electrostatic particles as growth factor carriers for cartilage repair

Achieving Precision Healthcare through Nanomedicine and Enhanced Model Systems

The ability to customize medical choices according to an individual's genetic makeup and biomarker patterns marks a significant advancement toward overall improved healthcare for both individuals and society at large. By transitioning from the conventional one-size-fits-all approach to tailored treatments that can account for predispositions of different patient populations, nanomedicines can be customized to target the specific molecular underpinnings of a patient's disease, thus mitigating the risk of collateral damage. However, for these systems to reach their full potential, our understanding of how nano-based therapeutics behave within the intricate human body is necessary. Effective drug administration to the targeted organ or pathological niche is dictated by properties such as nanocarrier (NC) size, shape, and targeting abilities, where understanding how NCs change their properties when they encounter biomolecules and phenomena such as shear stress in flow remains a major challenge. This Review specifically focuses on vessel-on-a-chip technology that can provide increased understanding of NC behavior in blood and summarizes the specialized environment of the joint to showcase advanced tissue models as approaches to address translational challenges. Compared to conventional cell studies or animal models, these advanced models can integrate patient material for full customization. Combining such models with nanomedicine can contribute to making personalized medicine achievable.

Elastic porous microspheres/extracellular matrix hydrogel injectable composites releasing dual bio-factors enable tissue regeneration

Injectable biomaterials have garnered increasing attention for their potential and beneficial applications in minimally invasive surgical procedures and tissue regeneration. Extracellular matrix (ECM) hydrogels and porous synthetic polymer microspheres can be prepared for injectable administration to achieve in situ tissue regeneration. However, the rapid degradation of ECM hydrogels and the poor injectability and biological inertness of most polymeric microspheres limit their pro-regenerative capabilities. Here, we develop a biomaterial system consisting of elastic porous poly(l-lactide-co-ε-caprolactone) (PLCL) microspheres mixed with ECM hydrogels as injectable composites with interleukin-4 (IL-4) and insulin-like growth factor-1 (IGF-1) dual-release functionality. The developed multifunctional composites have favorable injectability and biocompatibility, and regulate the behavior of macrophages and myogenic cells following injection into muscle tissue. The elicited promotive effects on tissue regeneration are evidenced by enhanced neomusle formation, vascularization, and neuralization at 2-months post-implantation in a male rat model of volumetric muscle loss. Our developed system provides a promising strategy for engineering bioactive injectable composites that demonstrates desirable properties for clinical use and holds translational potential for application as a minimally invasive and pro-regenerative implant material in multiple types of surgical procedures.

Subcutaneous angiogenesis induced by transdermal delivery of gel-in-oil nanogel dispersion

Subcutaneous transplantation aims to enhance the growth and functionality of transplanted cells for therapeutic outcomes in tissue engineering. However, the limited subcutaneous vascular network poses a challenge. Conventional methods involve co-transplantation with endothelial cells or angiogenic scaffold implantation, but they have drawbacks like tissue inflammation, compromised endothelial cell functionality, and the risk of repeated scaffold transplantation. Effective techniques are needed to overcome these challenges. This study explores the potential of G/O-NGD, a gel-in-oil nanogel dispersion, as a transdermal carrier of proliferative factors to promote angiogenesis in subcutaneous graft beds before cell transplantation. We observed robust subcutaneous angiogenesis by delivering varying amounts of bFGF using the G/O-NGD emulsion. Quantitative analysis of several parameters confirmed the efficacy of this method for building a subcutaneous vascular network. G/O-NGD is a biodegradable material that facilitates localized transdermal delivery of bFGF while maintaining its activity. The findings of this study have significant implications in both medical and industrial fields.

Designing polymers for cartilage uptake: effects of architecture and molar mass

Osteoarthritis (OA) is a progressive disease, involving the progressive breakdown of cartilage, as well as changes to the synovium and bone. There are currently no disease-modifying treatments available clinically. An increasing understanding of the disease pathophysiology is leading to new potential therapeutics, but improved approaches are needed to deliver these drugs, particularly to cartilage tissue, which is avascular and contains a dense matrix of collagens and negatively charged aggrecan proteoglycans. Cationic delivery vehicles have been shown to effectively penetrate cartilage, but these studies have thus far largely focused on proteins or nanoparticles, and the effects of macromolecular architectures have not yet been explored. Described here is the synthesis of a small library of polycations composed of N-(2-hydroxypropyl)methacrylamide (HPMA) and N-(3-aminopropyl)methacrylamide (APMA) with linear, 4-arm, or 8-arm structures and varying degrees of polymerization (DP) by reversible addition fragmentation chain-transfer (RAFT) polymerization. Uptake and retention of the polycations in bovine articular cartilage was assessed. While all polycations penetrated cartilage, uptake and retention generally increased with DP before decreasing for the highest DP. In addition, uptake and retention were higher for the linear polycations compared to the 4-arm and 8-arm polycations. In general, the polycations were well tolerated by bovine chondrocytes, but the highest DP polycations imparted greater cytotoxicity. Overall, this study reveals that linear polymer architectures may be more favorable for binding to the cartilage matrix and that the DP can be tuned to maximize uptake while minimizing cytotoxicity.

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

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

Assessment of joint pharmacokinetics and consequences for the intraarticular delivery of biologics

Intraarticular (IA) injections provide the opportunity to deliver biologics directly to their site of action for a local and efficient treatment of osteoarthritis. However, the synovial joint is a challenging site of administration since the drug is rapidly eliminated across the synovial membrane and has limited distribution into cartilage, resulting in unsatisfactory therapeutic efficacy. In order to rationally develop appropriate drug delivery systems, it is essential to thoroughly understand the unique biopharmaceutical environments and kinetics in the joint to adequately simulate them in relevant experimental models. This review presents a detailed view on articular kinetics and drug-tissue interplay of IA administered drugs and summarizes how these can be translated into reasonable formulation strategies by identification of key factors through which the joint residence time can be prolonged and specific structures can be targeted. In this way, pros and cons of the delivery approaches for biologics will be evaluated and the extent to which biorelevant models are applicable to gain mechanistic insights and ameliorate formulation design is discussed.

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.

Curcumin primed ADMSCs derived small extracellular vesicle exert enhanced protective effects on osteoarthritis by inhibiting oxidative stress and chondrocyte apoptosis

Osteoarthritis (OA) is a common joint disease caused by progressive articular cartilage degeneration and destruction. Currently, there are no disease-modifying agents officially approved for OA patients. In this study, curcumin was loaded into adipose tissue-derived mesenchymal stem cells (ADMSCs)-derived small extracellular vesicle (ADMSCs-sEV) to synergistically exert chondro-protective effects in vitro and in vivo. We found curcumin primed ADMSCs derived sEV (sEV-CUR) exhibited an enhanced protective effect compared with free curcumin and ADMSCs-sEV in TBHP-induced chondrocytes. Moreover, our study demonstrated sEV-CUR more effectively down-regulated TBHP-induced oxidative stress and chondrocyte apoptosis in vitro. In OA mice model, our results indicated that sEV-CUR showed an improved cartilage protection, as biweekly intra-articular injection of sEV-CUR more efficaciously alleviated oxidative stress and chondrocyte apoptosis in OA cartilage. Overall, our findings showed sEV-CUR exhibited enhanced chondro-protective effects and holds great potential on the recovery of articular cartilage loss and destruction in OA patients.

Intra-articular injections of platelet-rich plasma vs. hyaluronic acid in patients with knee osteoarthritis: Preliminary follow-up results at 6-months

The aim of the present study was to compare the clinical and economic benefits of intra-articular injections of platelet-rich plasma (PRP) and hyaluronic acid (HA) in Chinese patients with knee osteoarthritis (OA). A total of 86 patients (42 treated with PRP and 44 with HA) were treated with three weekly intra-articular injections. The inclusion criteria included patients between 18 and 75 years of age, with chronic knee pain or swelling lasting >3 months and X-ray findings of degenerative joint alterations according to the Kellgren-Lawrence score grade I-III. Clinical examinations were performed before treatment, at 1- and 6-month post-injection intervals. International Knee Documentation Committee subjective, Western Ontario and McMaster Universities and visual analogue scale scores were determined at each examination. Adverse reactions, average cost, treatment time and patient satisfaction were also recorded. Compared with patients injected with HA, PRP was found to be associated with increased and more severe post-injection pain and swelling, where the duration of adverse reactions was greater in the PRP group (P=0.02). During the follow-up evaluations, both groups showed statistically significant improvements in all clinical scores from pre-injection to 1- and 6-month assessments (P<0.05). However, no significant inter-group (PRP vs. HA) differences were observed in the clinical scores between the two follow-up time points. There were also no significant differences in clinical score between the groups with regards to the Kellgren-Lawrence grade I, II or III. The average cost of PRP injections was 22.8X that of HA administration and the average treatment time was 5X that of HA, but there was no significant difference in patient satisfaction. These preliminary results indicate that although PRP injections can significantly improve clinical outcome in patients with knee OA, PRP is not any more effective compared with HA. Furthermore, PRP injections are associated with higher costs and treatment times. Therefore, additional clinical studies are required before PRP injections can be considered as a first-line treatment option for knee OA.

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.

Studies of nanoparticle delivery with in vitro bio-engineered microtissues

A variety of engineered nanoparticles, including lipid nanoparticles, polymer nanoparticles, gold nanoparticles, and biomimetic nanoparticles, have been studied as delivery vehicles for biomedical applications. When assessing the efficacy of a nanoparticle-based delivery system, in vitro testing with a model delivery system is crucial because it allows for real-time, in situ quantitative transport analysis, which is often difficult with in vivo animal models. The advent of tissue engineering has offered methods to create experimental models that can closely mimic the 3D microenvironment in the human body. This review paper overviews the types of nanoparticle vehicles, their application areas, and the design strategies to improve delivery efficiency, followed by the uses of engineered microtissues and methods of analysis. In particular, this review highlights studies on multicellular spheroids and other 3D tissue engineering approaches for cancer drug development. The use of bio-engineered tissues can potentially provide low-cost, high-throughput, and quantitative experimental platforms for the development of nanoparticle-based delivery systems.

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

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

Cyclodextrin Cationic Polymer-Based Nanoassemblies to Manage Inflammation by Intra-Articular Delivery Strategies

Injectable nanobioplatforms capable of locally fighting the inflammation in osteoarticular diseases, by reducing the number of administrations and prolonging the therapeutic effect is highly challenging. β-Cyclodextrin cationic polymers are promising cartilage-penetrating candidates by intra-articular injection due to the high biocompatibility and ability to entrap multiple therapeutic and diagnostic agents, thus monitoring and mitigating inflammation. In this study, nanoassemblies based on poly-β-amino-cyclodextrin (PolyCD) loaded with the non-steroidal anti-inflammatory drug diclofenac (DCF) and linked by supramolecular interactions with a fluorescent probe (adamantanyl-Rhodamine conjugate, Ada-Rhod) were developed to manage inflammation in osteoarticular diseases. PolyCD@Ada-Rhod/DCF supramolecular nanoassemblies were characterized by complementary spectroscopic techniques including UV-Vis, steady-state and time-resolved fluorescence, DLS and ζ-potential measurement. Stability and DCF release kinetics were investigated in medium mimicking the physiological conditions to ensure control over time and efficacy. Biological experiments evidenced the efficient cellular internalization of PolyCD@Ada-Rhod/DCF (within two hours) without significant cytotoxicity in primary human bone marrow-derived mesenchymal stromal cells (hMSCs). Finally, polyCD@Ada-Rhod/DCF significantly suppressed IL-1β production in hMSCs, revealing the anti-inflammatory properties of these nanoassemblies. With these premises, this study might open novel routes to exploit original CD-based nanobiomaterials for the treatment of osteoarticular diseases.

Leveraging Electrostatic Interactions for Drug Delivery to the Joint

Arthritis is a debilitating joint disease with a high economic burden and prevalence. There are many challenges delivering therapeutics to the joint, including low bioavailability when administered systemically and low joint retention after intra-articular injection. Therefore, drug delivery systems such as nanoparticles, liposomes, dendrimers, and carrier proteins have been utilized to overcome some of these limitations. To enhance joint tissue localization and retention, there are opportunities to leverage electrostatic interactions between drug carriers and various tissues and cells. These opportunities, as they pertain to specific joint tissues, are explored in this review. Further, the impact that electrostatic interactions has on various drug delivery parameters, such as the formation of a protein corona, the uptake and cytotoxicity, and the biodistribution of the drug delivery systems, is discussed. Lastly, this review summarizes key findings from studies that have investigated the use of electrostatic interactions to increase targeting of specific joint tissues and limitations in preclinical investigations are identified. As more novel targets are discovered in treating arthritis, there will be a continued need to localize therapeutics to specific tissues for greater therapeutic outcomes and hence attention must be paid in designing the drug delivery systems.

Cartilage-penetrating nanocarriers improve delivery and efficacy of growth factor treatment of osteoarthritis

Osteoarthritis is a debilitating joint disease affecting nearly 30 million people for which there are no disease-modifying therapies. Several drugs that have failed clinical trials have shown inefficient and inadequate delivery to target cells. Anabolic growth factors are one class of such drugs that could be disease-modifying if delivered directly to chondrocytes, which reside deep within dense, anionic cartilage tissue. To overcome this biological barrier, we conjugated a growth factor to a cationic nanocarrier for targeted delivery to chondrocytes and retention within joint cartilage after direct intra-articular injection. The nanocarrier uses reversible electrostatic interactions with anionic cartilage tissue to improve tissue binding, penetration, and residence time. Amine terminal polyamidoamine (PAMAM) dendrimers were end functionalized with variable molar ratios of poly(ethylene glycol) (PEG) to control surface charge. From this small family of variably PEGylated dendrimers, an optimal formulation showing 70% uptake into cartilage tissue and 100% cell viability was selected. When conjugated to insulin-like growth factor 1 (IGF-1), the dendrimer penetrated bovine cartilage of human thickness within 2 days and enhanced therapeutic IGF-1 joint residence time in rat knees by 10-fold for up to 30 days. In a surgical model of rat osteoarthritis, a single injection of dendrimer-IGF-1 rescued cartilage and bone more effectively than free IGF-1. Dendrimer-IGF-1 reduced width of cartilage degeneration by 60% and volumetric osteophyte burden by 80% relative to untreated rats at 4 weeks after surgery. These results suggest that PEGylated PAMAM dendrimer nanocarriers could improve pharmacokinetics and efficacy of disease-modifying osteoarthritis drugs in the clinic.

Targeting the extracellular matrix for delivery of bioactive molecules to sites of arthritis

Modifications to the extracellular matrix (ECM) can be either causal or consequential of disease processes including arthritis and cancer. In arthritis, the cartilage ECM is adversely affected by the aberrant behaviours of inflammatory cells, synoviocytes and chondrocytes, which secrete a plethora of cytokines and degradative proteases. In cancer, the ECM and stromal cells are linked to disease severity, and metalloproteinases are implicated in metastasis. There have been some successes in the field of targeted therapies, but efficacy depends upon the type and stage of disease. ECM targets are becoming increasingly attractive for drug delivery, owing to changes in ECM structure and composition in the diseased state, and the long in vivo half-life of its components. This review will highlight various strategies for targeting therapeutics to arthritic joints, including antibody and peptide-mediated drug delivery platforms to aid delivery to the ECM and retention at disease sites. LINKED ARTICLES: This article is part of a themed section on Translating the Matrix. To view the other articles in this section visit http://onlinelibrary.wiley.com/doi/10.1111/bph.v176.1/issuetoc.

Conductive Shape Memory Microfiber Membranes with Core-Shell Structures and Electroactive Performance

Conductive shape memory polymers as a class of functional materials play a significant role in sensors and actuators. A high conductivity and a high response speed are needed in practical applications. In this work, a conductive shape memory polylactic acid (PLA) microfiber membrane was synthesized by combining electrospinning with chemical vapor polymerization. The shape memory PLA was electrospun into microfibers with different diameters, and a conductive polypyrrole (PPy) coating was applied to the PLA microfiber membranes using vapor polymerization. The conductivity of the microfiber membrane was investigated as a function of different experimental parameters: FeCl₃ concentration, PPy evaporation time, and PPy temperature. The maximum conductivity of the membrane prepared in a sub-zero environment is 0.5 S/cm, which can sustain a heat-generating electric current sufficient to trigger the electro-actuated behaviors of the membrane within 2 s at 30 V. Thermographic imaging was used to assess the uniformity of the temperature distribution during the shape recovery process. The low surface temperature is compatible with potential applications in many fields.

Diagnostic utility of fluorogenic peptide-conjugated Au nanoparticle probe corroborated by rabbit model of mild cartilage injury and panel of osteoarthritic patients

Using a rabbit model of early-stage osteoarthritis (OA) and a sampling patients with OA, we evaluated the diagnostic utility of a fluorogenic peptide-conjugated gold nanoparticle (AuNP) probe in detecting mild cartilage injury, based on the a disintegrin and metalloproteinase with thrombospondin motifs 4 (ADAMTS-4) enzyme. Synthesis of this fluorescent turn-on probe (or AU-probe) required conjugation of AuNPs with a fluorescein isothiocyanate (FITC)-modified ADAMTS-4-specific peptide (DVQEFRGVTAVIR). Synovial fluid samples were then collected from 48 adult rabbits and 100 patients for comparative testing (ADAMTS-4 ELISA and AU-probe). Rabbit and patient MRI images were also evaluated and scored. Receiver operating characteristic (ROC) curve analysis was applied to various diagnostic methods (MRI, ELISA, AU-probe, and arthroscopy), performing comparisons via logistic regression. In rabbits, the AU-probe proved nonsuperior to MRI T2 mapping and ELISA (fluorescence cutpoint > 864.965 au). In patient groups, logistic regression analysis indicated that combined AU-probe/MRI testing outperformed MRI alone, thus offsetting low MRI sensitivity and low AU-probe specificity for improved detection of mild cartilage injury (sensitivity, 82.5%; specificity, 80.0%). We have consequently confirmed the efficacy of this AU-probe, using ADAMTS-4 activity in synovial fluid to diagnose mild cartilage injury. Combining the AU-probe with conventional MRI assessment proved optimal in this setting.