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Controlled Release of Drugs from Extracellular Matrix-Derived Peptide-Based Nanovesicles through Tailored Noncovalent Interactions
Vaccine is the most important way for fighting against infection diseases. However, multiple injections and unsatisfied immune responses are the main obstacles for current vaccine application. Herein, a dynamic covalent hydrogel (DCH) is used as a single‐dose vaccine adjuvant for eliciting robust and sustained humoral immunity. By adjusting the mass ratio of the DCH gel, 10–30 d constant release of the loaded recombinant protein antigens is successfully realized, and it is proved that sustained release of antigens can significantly improve the vaccine efficacy. When loading SARS‐CoV‐2 RBD (Wuhan and Omicron BA.1 strains) antigens into this DCH gel, an over 32 000 times and 8000 times improvement is observed in antigen‐specific antibody titers compared to conventional Aluminum adjuvanted vaccines. The universality of this DCH gel adjuvant is confirmed in a Nipah G antigen test as well as a H1N1 influenza virus antigen test, with much improved protection of C57BL/6 mice against H1N1 virus infection than conventional Aluminum adjuvanted vaccines. This sustainably released, single‐dose DCH gel adjuvant provides a new promising option for designing next‐generation infection vaccines.
Natural originated materials have been well-studied over the past several decades owing to their higher biocompatibility compared to the traditional polymers. Peptides, consisting of amino acids, are among the most popular programable building blocks, which is becoming a growing interest in nanobiotechnology. Structures assembled using those biomimetic peptides allow the exploration of chemical sequences beyond those been routinely used in biology. In this Review, we discussed the most recent experimental discoveries on the peptide-based assembled nanostructures and their potential application at the cellular level such as drug delivery. In particular, we explored the fundamental principles of peptide self-assembly and the most recent development in improving their interactions with biological systems. We believe that as the fundamental knowledge of the peptide assemblies evolves, the more sophisticated and versatile nanostructures can be built, with promising biomedical applications.
To date, the coronavirus disease 2019 (COVID-19) caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has determined 399,600,607 cases and 5,757,562 deaths worldwide. COVID-19 is a serious threat to human health globally. The World Health Organization (WHO) has declared COVID-19 pandemic a major public health emergency. Vaccination is the most effective and economical intervention for controlling the spread of epidemics, and consequently saving lives and protecting the health of the population. Various techniques have been employed in the development of COVID-19 vaccines. Among these, the COVID-19 messenger RNA (mRNA) vaccine has been drawing increasing attention owing to its great application prospects and advantages, which include short development cycle, easy industrialization, simple production process, flexibility to respond to new variants, and the capacity to induce better immune response. This review summarizes current knowledge on the structural characteristics, antigen design strategies, delivery systems, industrialization potential, quality control, latest clinical trials and real-world data of COVID-19 mRNA vaccines as well as mRNA technology. Current challenges and future directions in the development of preventive mRNA vaccines for major infectious diseases are also discussed.
Significant advances in physicochemical properties of polymeric micelles enable optimization of therapeutic drug efficacy, supporting nanomedicine manufacturing and clinical translation. Yet, the effect of micelle morphology on pharmacological efficacy is not adequately addressed. This work addresses this gap by assessing pharmacological efficacy of polymeric micelles with spherical and worm‐like morphologies. It is observed that poly(2‐oxazoline)‐based polymeric micelles can be elongated over time from a spherical structure to worm‐like structure, with elongation influenced by several conditions, including the amount and type of drug loaded into the micelles. The role of different morphologies on pharmacological performance of drug loaded micelles against triple‐negative breast cancer and pancreatic cancer tumor models is further evaluated. Spherical micelles accumulate rapidly in the tumor tissue while retaining large amounts of drug; worm‐like micelles accumulate more slowly and only upon releasing significant amounts of drug. These findings suggest that the dynamic character of the drug–micelle structure and the micelle morphology play a critical role in pharmacological performance, and that spherical micelles are better suited for systemic delivery of anticancer drugs to tumors when drugs are loosely associated with the polymeric micelles.
The intention of this publication is to give an overview on research related to conjugates of polysaccharides and peptides. Dextran, chitosan, and alginate were selected, to cover four of the most often encountered functional groups known to be present in polysaccharides. These groups are the hydroxyl, the amine, the carboxyl, and the acetal functionality. A collection of the commonly used chemical reactions for conjugation is provided. Conjugation, results into distinct properties compared to the parent polysaccharide, and a number of these characteristics are highlighted. This review aims at demonstrating the applicability of said conjugates with a strong emphasis on biomedical applications, drug delivery, biosensing, and tissue engineering. Some suggestions are made for more rigorous chemistries and analytics that could be investigated. Finally, an outlook is given into which direction the field could be developed further. We hope that this survey provides the reader with a comprehensive summary and contributes to the progress of works that aim at synthetically combining two of the main building blocks of life into supramolecular structures with unprecedented biological response.
This study evaluated the cytocompatibility and antimicrobial/antibiofilm effects of epigallocatechin-3-gallate (EGCG) associated with peptide LL-37 and its analogue KR-12-a5 against oral pathogens. The effect of the compounds on metabolism of fibroblasts was evaluated by methyltetrazolium assays. Antimicrobial activity of the compounds was evaluated on Streptococcus mutans, Enterococcus faecalis, Actinomyces israelii, and Fusobacterium nucleatum under planktonic conditions, on single- and dual-species biofilms and E. faecalis biofilms in dentinal tubules and analyzed by bacterial counts and confocal microscopy. Data were statistically analyzed considering p < 0.05. EGCG and peptide combinations were not toxic to fibroblasts. KR-12-a5 showed synergistic or addictive effects with EGCG and LL-37 against all bacteria tested. However, EGCG associated with KR-12-a5 demonstrated the highest bactericidal activity on all bacteria tested, at lower concentrations. In single-species biofilms, EGCG + KR-12-a5 eliminated S. mutans and A. israelii and reduced E. faecalis and F. nucleatum counts around 5 log CFU/mL. EGCG + KR-12-a5 reduced E. faecalis (-3.93 log CFU/mL) and eliminated S. mutans in dual-species biofilms. No growth of E. faecalis and significant reduction in A. israelii (−6.24 log CFU/mL) and F. nucleatum (−4.62 log CFU/mL) counts were detected in dual-species biofilms. The combination of EGCG and KR-12-a5 led to 88% of E. faecalis dead cells inside dentin tubules. The association of EGCG and KR-12-a5 was cytocompatible and promoted synergistic effect against biofilms of bacteria associated with endodontic infections.
Gene therapy offers the possibility to skip, repair, or silence faulty genes or to stimulate the immune system to fight against disease by delivering therapeutic nucleic acids (NAs) to a patient. Compared to other drugs or protein treatments, NA-based therapies have the advantage of being a more universal approach to designing therapies because of the versatility of NA design. NAs (siRNA, pDNA, or mRNA) have great potential for therapeutic applications for an immense number of indications. However, the delivery of these exogenous NAs is still challenging and requires a specific delivery system. In this context, beside other non-viral vectors, cell-penetrating peptides (CPPs) gain more and more interest as delivery systems by forming a variety of nanocomplexes depending on the formulation conditions and the properties of the used CPPs/NAs. In this review, we attempt to cover the most important biophysical and biological aspects of non-viral peptide-based nanoparticles (PBNs) for therapeutic nucleic acid formulations as a delivery system. The most relevant peptides or peptide families forming PBNs in the presence of NAs described since 2015 will be presented. All these PBNs able to deliver NAs in vitro and in vivo have common features, which are characterized by defined formulation conditions in order to obtain PBNs from 60 nm to 150 nm with a homogeneous dispersity (PdI lower than 0.3) and a positive charge between +10 mV and +40 mV.
COVID-19 vaccines have been developed with unprecedented speed which would not have been possible without decades of fundamental research on delivery nanotechnology. Lipid-based nanoparticles have played a pivotal role in the successes of COVID-19 vaccines and many other nanomedicines, such as Doxil ® and Onpattro ® , and have therefore been considered as the frontrunner in nanoscale drug delivery systems. In this review, we aim to highlight the progress in the development of these lipid nanoparticles for various applications, ranging from cancer nano-medicines to COVID-19 vaccines. The lipid-based nanoparticles discussed in this review are lipo-somes, niosomes, transfersomes, solid lipid nanoparticles, and nanostructured lipid carriers. We particularly focus on the innovations that have obtained regulatory approval or that are in clinical trials. We also discuss the physicochemical properties required for specific applications, highlight the differences in requirements for the delivery of different cargos, and introduce current challenges that need further development. This review serves as a useful guideline for designing new lipid nanoparticles for both preventative and therapeutic vaccines including immunotherapies.
The self-assembly of nanostructures from conjugates of elastin-like peptides and collagen-like peptides (ELP-CLP) has been studied as means to produce thermoresponsive, collagen-binding drug delivery vehicles. Motivated by our previous work in which ELP-CLP conjugates successfully self-assembled into vesicles and platelet-like nanostructures, here, we extend our library of ELP-CLP bioconjugates to a series of tryptophan/phenylalanine-containing ELPs and GPO-based CLPs [W2F
x
-b-(GPO)
y
] with various domain lengths to determine the impact of these modifications on the thermoresponsiveness and morphology. The lower transition temperature of the conjugates with longer ELP or CLP domains enables the formation of well-defined nanoparticles near physiological temperature. Moreover, the morphological transition from vesicles to platelet-like nanostructures occurred when the ratio of the lengths of ELP/CLP decreased. Given the previously demonstrated ability of many ELP-CLP bioconjugates to bind to both hydrophobic drugs and collagen-containing materials, our results suggest new opportunities for designing specific thermoresponsive nanostructures for targeted biological applications.
Proteoglycans have emerged as biomacromolecules with important roles in matrix remodeling, homeostasis, and signaling in the past two decades. Due to their negatively charged glycosaminoglycan chains as well as distinct core protein structures, they interact with a variety of molecules, including matrix proteins, growth factors, cytokines and chemokines, pathogens, and enzymes. This led to the dawn of glycan therapies in the 20th century, but this research was quickly overshadowed by readily available DNA and protein-based therapies. The recent development of recombinant technology and advances in our understanding of proteoglycan function have led to a resurgence of these molecules as potential therapeutics. This review focuses on the recent preclinical efforts that are bringing proteoglycan research and therapies back to the forefront. Examples of studies using proteoglycan cores and mimetics have also been included to give the readers a perspective on the wide-ranging and extensive applications of these versatile molecules. Collectively, these advances are opening new avenues for targeting diseases at a molecular level, and providing avenues for the development of new and exciting treatments in regenerative medicine.
Materials that respond to temporally defined exogenous cues continue to be an active pursuit of research toward on‐demand nanoparticle drug delivery applications, and using one or more exogenous temperature stimuli could significantly expand the application of nanoparticle‐based drug delivery formulations under both hyperthermal and hypothermal conditions. Previously we have reported the development of a biocompatible and thermoresponsive elastin‐b‐collagen‐like polypeptide (ELP‐CLP) conjugate that is capable of self‐assembling into vesicles and encapsulating small molecule therapeutics that can be delivered at different rates via a single temperature stimulus. Herein we report the evaluation of multiple ELP‐CLP conjugates, demonstrating that the inverse transition temperature (Tt) of the ELP‐CLPs can be manipulated by modifying the melting temperature (Tm) of the CLP domain, and that the overall hydrophilicity of the ELP‐CLP conjugate also may alter the Tt. Based on these design parameters, we demonstrate that the ELP‐CLP sequence (VPGFG)6‐(GPO)7GG can self‐assemble into stable vesicles at 25°C and dissociate at elevated temperatures by means of the unfolding of the CLP domain above its Tm. We also demonstrate here for the first time the ability of this ELP‐CLP vesicle to dissociate via a hypothermic temperature stimulus by means of exploiting the inverse transition temperature (Tt) phenomena found in ELPs. The development of design rules for manipulating the thermal properties of these bioconjugates will enable future modifications to either the ELP or CLP sequences to more finely tune the transitions of the conjugates for specific biomedical applications.
Adaptive polymersome systems have gained much interest in a wide variety of research fields, ranging from cell mimics to nanomedicine, because of their high stability, tuneable shape and size. Furthermore, polymersomes can be effectively transformed into nanoreactors via the incorporation of catalytic species. By employing polymersomes which are adaptive in structure and function the features of polymersome nanoreactors can be even further extended. In this review, we focus on recent impressive developments of smart polymersomes as functional nanoreactors with an emphasis on the type of adaptivity that is installed, which includes intrinsic permeability, stimuli‐responsiveness and self‐adaptivity. Moreover, particular attention is given to the utility of polymersome nanoreactors in vitro and in vivo, which paves the next step forward towards the engineering of artificial organelles as therapeutic materials.
Rheumatoid arthritis (RA) is a prevalent autoimmune disease characterized by joint inflammation, bone and cartilage erosion. The use of glucocorticoids in the treatment of RA is hampered by significant side effects induced by their unfavorable pharmacokinetics. Delivering glucocorticoids by means of nanotechnologies is promising but the encapsulation of highly crystalline and poorly water-soluble drugs results in poor loading and low stability. We report here the design of 130 nm nanoparticles made of solely dexamethasone palmitate, stabilized by polyethylene glycol-linked phospholipids displaying a negative zeta potential (−55 mV), high entrapment efficiency and stability over 21 days under storage at 4 °C. X ray diffraction showed no crystallization of the drug. When incubated in serum, nanoparticles released free dexamethasone which explains the in vitro anti-inflammatory effect on LPS-activated RAW 264.7 macrophages. Moreover, we demonstrate in a murine collagen-induced arthritis model the improved therapeutic efficacy of these nanoparticles. Their passive accumulation in arthritic joints leads to disease remission and recovery of the joint structure at a dose of 1 mg/kg dexamethasone, without any adverse effects. Dexamethasone palmitate nanoparticles are promising in the treatment of inflammation in rheumatoid arthritis with a very significant difference occurring at the late stage of inflammation allowing to prevent the progression of the disease.
FRET is a powerful approach to study the interactions of fluorescent molecules, and numerous methods have been developed to measure FRET in cells. Here, we present a method based on a donor molecule’s photoswitching properties, which are slower in the presence vs. the absence of an acceptor. The technique, photoswitching FRET (psFRET), is similar to an established but underutilized method called photobleaching FRET (pbFRET), with the major difference being that the molecules are switched “off” rather than photobleached. The psFRET technique has some of the FRET imaging advantages normally attributed to fluorescence lifetime imaging microscopy (FLIM), such as monitoring only donor fluorescence. However, it can be performed on a conventional widefield microscope, requires less illumination light to photoswitch off than photobleaching, and can be photoswitched “on” again to repeat the experiment. We present data testing the validity of the psFRET approach to quantify FRET in cells and demonstrate its use in imaging protein–protein interactions and fluorescent protein-based biosensors.
Rheumatoid arthritis (RA) is a chronic inflammatory systemic autoimmune disease, affecting the joints with varying severity among patients. The risk factors include age, gender, genetics and environmental exposure (cigarette smoking, air pollutants and occupational). Many complications can follow such as permanent joint damage requiring arthroplasty, rheumatoid vasculitis and elty's syndrome requiring splenectomy if it remains unaddressed. As there is no cure for RA, the treatment goals are to reduce the pain and stop/slow further damage. Here we present a brief summary of various past and present treatment modalities to address complications associated with rheumatoid arthritis.
In spite of great significance, few clinically viable nanovehicles possess stable and high anticancer drug loading while fast intracellular drug release. Here, we report that polytyrosine nanoparticles (PTNs) self-assembled from poly(ethylene glycol)-b- poly(L-tyrosine) block copolymer enable ultra-high loading and rapidly enzyme-responsive release of doxorubicin (DOX). Notably, PTNs achieved a remarkably high DOX loading content of 63.1 wt.% likely due to existence of strong π-π stacking between polytyrosine and DOX shown by UV-Vis analysis. PTNs presented also a high loading content of 17.5 wt.% for docetaxel. PTNs exhibited good colloidal stability in 10% FBS but quickly de-stabilized by proteinase K. Interestingly, ca. 90% of DOX was released under 6 U/mL proteinase K in 24 h or in RAW 264.7 cells in 8 h. DOX-loaded PTNs displayed efficient delivery and release of DOX into both RAW 264.7 cells and HCT-116 human colorectal cancer cells, achieving better in vitro antiproliferative effect than the clinically used liposomal DOX formulation. These polytyrosine nanoparticles have appeared to be a potentially viable platform for controlled delivery of anthraquinone anticancer agents.
In this study, we designed a polymersome system for the controlled release of methotrexate (MTX) as an anticancer drug with the objective of improving the loading efficiency of the drug in polymersomes as well as achievement of an efficient control on the release rate of drug from nanocarriers. We synthesized mono methoxy poly (ethylene glycol)-poly (e-caprolactone) (mPEG-PCL) di block copolymers. The structure of the copolymers was characterized by H-NMR, FT-IR and DSC techniques. MTX was encapsulated within nanoparticles through multiple emulsion method. The resulting nanoparticles were characterized further by various techniques such as atomic force microscopy (AFM) and Dynamic light scattering (DLS). Next, the various kinetic equations were fitted to the release data of MTX from MTX-loaded mPEG–PCL polymersomes. The results showed that the zeta potential of MTX-loaded mPEG–PCL polymersomes was about -5.49 mV and the average size was 49.18 nm. MTX was encapsulated into polymersomes loading capacity of 12±0.09% and encapsulation efficiency of 45.5±0.41%. The metabolic activity assays of void of MTX, mPEG–PCL polymersomes and MTX-loaded mPEG–PCL polymersomes were compared to each other by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay of the treated MCF-7 cell lines. It can be concluded that application of nanoparticles is a better and more effective strategy for controlled and slow release of MTX in the treatment of cancer.
Mechanical injury to connective tissue causes changes in collagen structure and material behaviour, but the role and mechanisms of molecular damage have not been established. In the case of mechanical subfailure damage, no apparent macroscale damage can be detected, yet this damage initiates and potentiates in pathological processes. Here, we utilize collagen hybridizing peptide (CHP), which binds unfolded collagen by triple helix formation, to detect molecular level subfailure damage to collagen in mechanically stretched rat tail tendon fascicle. Our results directly reveal that collagen triple helix unfolding occurs during tensile loading of collagenous tissues and thus is an important damage mechanism. Steered molecular dynamics simulations suggest that a likely mechanism for triple helix unfolding is intermolecular shearing of collagen α-chains. Our results elucidate a probable molecular failure mechanism associated with subfailure injuries, and demonstrate the potential of CHP targeting for diagnosis, treatment and monitoring of tissue disease and injury.
Nucleic acid therapeutics are rapidly expanding because of recent advancements in production and purification. This class of therapeutics may change the field of disease treatment and personalized medicine since it can cure diseases. However, drug delivery systems are crucial for these therapeutics to fulfill their potential. Liposomes have long been considered ideal platforms for systemic drugs delivery. Considering the development in cancer therapeutics, this work emphases on the current advancements in liposomes’ Nano-formulations, functionalization, and design and how it has been applied to nucleic acid therapeutics. Accordingly, this review covers the literature that deals with liposomes in nucleic acid therapy.
Despite the great promise of antibiotic therapy in wound infections, antibiotic resistance stemming from frequent dosing diminishes drug efficacy and contributes to recurrent infection. To identify improvements in antibiotic therapies, new antibiotic delivery systems that maximize pharmacological activity and minimize side effects are needed. In this study, we developed elastin-like peptide and collagen-like peptide nanovesicles (ECnVs) tethered to collagen-containing matrices to control vancomycin delivery and provide extended antibacterial effects against methicillin-resistant Staphylococcus aureus (MRSA). We observed that ECnVs showed enhanced entrapment efficacy of vancomycin by 3-fold as compared to liposome formulations. Additionally, ECnVs enabled the controlled release of vancomycin at a constant rate with zero-order kinetics, whereas liposomes exhibited first-order release kinetics. Moreover, ECnVs could be retained on both collagen-fibrin (co-gel) matrices and collagen-only matrices, with differential retention on the two biomaterials resulting in different local concentrations of released vancomycin. Overall, the biphasic release profiles of vancomycin from ECnVs/co-gel and ECnVs/collagen more effectively inhibited the growth of MRSA for 18 and 24 h, respectively, even after repeated bacterial inoculation, as compared to matrices containing free vancomycin, which just delayed the growth of MRSA. Thus, this newly developed antibiotic delivery system exhibited distinct advantages for controlled vancomycin delivery and prolonged antibacterial activity relevant to the treatment of wound infections.
While intra-articular injections continue to be utilized in the remediation of osteoarthritis, the efficacy of such treatment regimens continues to be plagued by the rapid clearance of drug therapeutics from the joint space, independent of whether the therapeutic is a macromolecule or a small-molecule pharmaceutical. Nanoparticle drug delivery vehicles have emerged as potential candidates to enhance the retention of therapeutics within the joint, with a wide variety of formulations that utilize retention strategies such as electrostatic interactions, collagen-type II binding domains, and passive targeting based on the physical size of the particles. However, despite these advances, significant issues regarding carrier and drug retention within the joint remain, so we sought to explore a novel nanoparticle retention scheme based on the integration of collagen peptides. In this work, we demonstrate the successful synthesis and fluorophore labeling of elastin-b-collagen peptide nanovesicles (ECnV). We further demonstrate the matrix/tissue retention and survivability of these ECnVs after novel tissue clearing processes that aid observation and detection of the nanovesicles in vitro. We also demonstrate the retention of these ECnVs in vivo and show successful localization of the ECnVs within murine knee joints. This study represents the first demonstration of the retention of elastin-b-collagen peptide-derived nanovesicles within joints, and suggests their potential for enhancing intra-articular treatment approaches for osteoarthritis.
Antihistamines and glucocorticoids are commonly used to treat allergy symptoms and the inflammatory conditions. In present study, the in-vitro binding interactions a glucocortikoid, dexamethasone/an antihistamine, pheniramine with TSN (TSN) secreted from pancreas to small intestine for protein digestion were investigated by fluorescence emission spectroscopy (FES), UV-Vis spectroscopy, synchronous fluorescence spectroscopy (SFS), CD spectroscopy, FT-IR and molecular modeling methods. Also, the effect of these drugs on the catalytic activity of trypsin (TSN) was determined. The fluorescence quenching experiments indicated that each drugs quenched the intrinsic fluorescence of TSN with their increased concentrations. The results of SFS and UV-Vis spectra proved the interaction of dexamethasone and pheniramine with TSN. CD spectra showed that the secondary structure of enzyme was altered in the presence of the drugs. All these spectroscopy results were validated and explained by molecular docking and molecular dynamic simulation (MD) studies. The IC50 values were determined as 0.0049 mM and 0.0038 mM for dexamethasone and pheniramine, respectively. So, both drugs have inhibition effect on the catalytic activity of TSN. The results of this study can provide valuable information in the field of pharmacokinetics and pharmacodynamics.
Communicated by Ramaswamy H. Sarma
Liposomes are spherical vesicles consisting of one or more concentric phospholipid bilayers enclosing an aqueous core. Being both nontoxic and biodegradable, liposomes represent a powerful delivery system for several drugs. They have improved the therapeutic efficacy of drugs through stabilizing compounds, overcoming obstacles to cellular and tissue uptake and increasing drug biodistribution to target sites in vivo, while minimizing systemic toxicity. This review offers an overview of liposomes, thought the exploration of their key fundamentals. Initially, the main design aspects to obtain a successful liposomal formulation were addressed, following the techniques for liposome production and drug loading. Before application, liposomes required an extensive characterization to assurance in vitro and in vivo performance. Thus, several properties to characterize liposomes were explored, such as size, polydispersity index, zeta potential, shape, lamellarity, phase behavior, encapsulation efficiency, and in vitro drug release. Topics related with liposomal functionalization and effective targeting strategies were also addressed, as well as stability and some limitations of liposomes. Finally, this review intends to explore the current market liposomes used as a drug delivery system in different therapeutic applications.
Delivery of therapeutics to the brain in an efficient, non-invasive manner continues to be a major unmet need in the field of drug delivery. One significant impediment to brain delivery results from the existence of the physical, yet dynamic, blood-brain barrier (BBB). Despite the many, often complex, strategies that currently exist to breach the BBB, adequate delivery of effective therapeutics from the blood stream continues to remain quite low. Nanotechnology has emerged as a promising tool for brain delivery, but little is known about important particle parameters that influence delivery. Here, we synthesized and characterized a library of nanoparticles with distinct properties ranging from size, shape, stiffness, and composition to investigate and identify the key attributes influencing particle uptake and transport for brain delivery. To accomplish this task, an in vitro human BBB model was developed and validated using human cerebral microvascular endothelial cells (hCMEC/D3). Particle uptake and apparent permeability coefficients (Papp) were then determined for each particle group. To elucidate the roles of different parameters on particle uptake and transport across the BBB, the predominant mechanisms of endocytosis were also investigated. Our results show that particle composition yielded the greatest impact on penetration across the BBB model. This work lays the foundation and provides new insights into the role of particle parameters on penetration across the BBB.
Elastin-like polypeptides (ELP) have been widely used in the biomaterials community due to their controllable, thermoresponsive properties and biocompatibility. Motivated by our previous work on the effect of tryptophan (W) substitutions on the LCST-like transitions of short ELPs, we studied a series of short ELPs containing tyrosine (Y) and/or phenylalanine (F) guest residues with only 5 or 6 pentapeptide repeat units. A combination of experiments and molecular dynamics (MD) simulations illustrated that the substitution of F with Y guest residues impacted the transition temperature (Tt) of short ELPs when conjugated to collagen-like-peptides (CLP), with a reduction in the transition temperature observed only after substitution of at least two residues. Placement of the Y residues near the N-terminal end of the ELP, away from the tethering point to the CLP, resulted in a lower Tt than that observed for peptides with the Y residues near the tethering point. Atomistic and coarse-grained MD simulations indicated an increase in intra- and inter-peptide hydrogen bonds in systems containing Y guest residues that are suggested to enhance the ability of the peptides to coacervate, with a concomitantly lower Tt. Simulations also revealed that the placement of Y-containing pentads near the N-terminus (i.e., away from the CLP tethering point) versus C-terminus of the ELP led to more π–π stacking interactions at low temperatures, in agreement with our experimental observations of a lower Tt. Overall, this study provides mechanistic insights into the driving forces for the LCST-like transitions of ELPs and offers additional means for tuning the Tt of short ELPs for biomedical applications such as on-demand drug delivery and tissue engineering.
Rheumatoid arthritis (RA) is an autoimmune disease characterized by chronic inflammation in synovial joints and protease-induced cartilage degradation. Current biologic treatments for RA can effectively reduce symptoms, primarily by neutraliz-ing the proinflammatory cytokine TNFα; however, continued, indiscriminate over-inhibition of inflammatory factors can significantly weaken the host immune system, leading to opportunistic infections and interrupting treatment. We hypothesize that localizing anti-TNFα therapeutics to denatured collagen (dCol) present at arthritic joints, via conjugation with collagen-hybridizing peptides (CHPs), will reduce off-site antigen binding and maintain local immunosuppression. We isolated the antigen-binding fragment of the clinical-ly approved anti-TNFα therapeutic infliximab (iFab) and prepared iFab-CHP conjugates via lysine-based conjugation with an SMCC linker. After successful conjugation, confirmed by LC-MS, the binding affinity of iFab-CHP was characterized by ELISA-like assays, which show comparable antigen binding relative to infliximab, comparable dCol binding relative to CHP, and the hybrid ability to bind both dCol and TNFα simultaneously. We further demonstrated localization of Fab-CHP to areas of high dCol in vivo and promising therapeutic efficacy, assessed by histological staining (Safranin-O and H&E), in a pilot mouse study.
Silver compounds have been used extensively for wound healing due to their antimicrobial properties, but high concentrations of silver are toxic to mammalian cells. We designed a peptide that binds silver and releases only small amounts of this ion over time, therefore overcoming a problem of silver toxicity. Silver binding was achieved through incorporation of an unnatural amino acid, 3’-pyridyl alanine (3’-PyA), into the peptide sequence. Upon addition of silver ions, the peptide adopts a beta-sheet secondary structure and self-assembles into a strong hydrogel as characterized by rheology, circular dichroism, and transmission electron microscopy. We show that the resulting hydrogel kills E. coli and S. aureus but is not toxic to fibroblasts and could be used for wound healing. The amount of Ag(I) released by hydrogels into the solution is less than 4% and this low amount of Ag(I) does not change in the pH range 6-8. These studies provide an initial indication for use of designed hydrogel as injectable, antimicrobial wound dressing.
One of the major hurdles in the development of antimicrobial peptide (AMP)-based materials is their poor capacity in selectively killing bacteria without harming nearby mammalian cells. Namely, they are antimicrobial but cytotoxic. Current methods of nanoparticle-encapsulated AMPs to target bacteria selectively still have not yet overcome this hurdle. Here we demonstrate a simple yet effective method to address this daunting challenge by associating a natural AMP with a β-sheet-forming synthetic peptide. The integrated peptides self-assembled to form a supramolecular nanofiber, resulting in the presentation of the AMP at the nanofiber-solvent interface in a precisely controlled manner. Using melittin as a model natural AMP, we found that the conformation of melittin changed dramatically when presented on the nanofiber surface, which in turn modulated the induced membrane permeability of the bacterial and mammalian cell membranes. Specifically, the presentation of melittin on the nanofiber restricted its hydrophobic residues, leading to a reduction of the hydrophobic interaction with lipids in the cell membranes. Compellingly, the reduced hydrophobic interaction led to a considerably decrease of melittin’s induced permeability of the mammalian cell membrane than that of the bacterial cell membrane. As a result, the AMP-displaying nanofiber preferentially permeabilized and disrupted the membrane of the bacteria without compromising the mammalian cells. Such improved membrane selectivity and cytocompatibility were confirmed in a cell-based membrane localization and live-dead assay. Our new strategy holds great promise for fabricating cytocompatible antimicrobial assemblies that offer safer and more effective administration of therapeutic AMPs. These assemblies, with intrinsic antimicrobial activity and cytocompatibility, can also serve as building blocks for the construction of higher-ordered scaffolds for other biomedical applications such as tissue engineering and regenerative medicine.
Interleukin-1 receptor antagonist (IL-1Ra) is a naturally occurring anti-inflammatory cytokine that inhibits IL-1 activity and has been proposed to treat a wide variety of systemic and local inflammatory pathologies for multiple decades. However, the short half-life and high concentration required to inhibit IL-1 activity has limited its use in clinical applications. Many strategies have been developed with the goal of improving the therapeutic efficacy of IL-1Ra for a variety of pathologies, including fusing IL-1Ra to protein/peptide/polymer partners, releasing IL-1Ra from injectable polymer or mineral particles, and release of IL-1Ra from injectable coacervates and gels. This literature review examines injectable biomaterials engineered to improve IL-1Ra delivery, both locally and systemically, to increase its efficacy and ease of use in clinic.
Statement of Significance
Interleukin-1 receptor antagonist (IL-1Ra) is a therapeutic protein with the potential to treat numerous inflammatory conditions and diseases. However, its short biological half-life and high therapeutic concentration may limit its utility in all but a few clinical scenarios. In this review, we present the biomaterial based delivery strategies which have been explored to deliver IL-1Ra to improve its efficacy and applicability to treat inflammation.
Transamide bonds and fastcis−transisomerization of Xaa-Pro bonds are crucial for the stabilityand folding rate of collagen, the most abundant protein inmammals. Here, we explored the effect of pendanthydrophobic moieties on the folding and stability ofcollagen triple helices. Kinetic studies with a series ofcollagen model peptides showed that a local hydrophobicenvironment acceleratescis−transisomerization to anextent that thermally induced unfolding and folding of thecollagen triple helix take place at the same speed. Thermaldenaturation studies revealed that the hydrophobicappendages provide hyperstable collagen triple helices(Tm=70°C).
Proteins are versatile macromolecules that can perform a variety of functions. In the past three decades, they have been commonly used as building blocks to generate a range of biomaterials. Owing to their flexibility, proteins can either be used alone or in combination with other functional molecules. Advances in synthetic and chemical biology have enabled new protein fusions as well as the integration of new functional groups leading to biomaterials with emergent properties. This review discusses protein‐engineered materials from the perspectives of domain‐based designs as well as physical and chemical approaches for crosslinked materials, with special emphasis on the creation of hydrogels. Engineered proteins that organize or template metal ions, bear noncanonical amino acids (NCAAs), and their potential applications, are also reviewed. This paper provides a comprehensive review of the state‐of‐the‐art protein‐engineered functional materials. The work is divided into five different sections with representative examples: single‐ and multidomain‐based protein materials, crosslinked materials, metal templating protein materials, and noncanonical amino acid (NCAA) bearing protein materials. At the end, insights on the advantages of functional protein‐engineered materials are discussed.
Intra-articular injection has unique advantages in the treatment of osteoarthritis (OA), although it risks rapid clearance of the therapeutic drugs in the joint cavity. Combining therapeutic agents with functionalized nanocarriers may provide an effective solution. Controlling the therapeutic concentration of the drug in the joint cavity through the drug-loading nanosystem can synergistically treat OA. Here, we proposed an intra-articular drug delivery nanosystem MoS2@CS@Dex (MCDs), using the chitosan (CS) modified molybdenum disulfide (MoS2) nanosheets as near-infrared (NIR) photo-responsive carriers, loaed with the anti-inflammatory drug dexamethasone (Dex). The MCDs responded to NIR light both in vitro and in vivo and trigger Dex release through photothermal conversion. This enabled the remote controlled Dex release in the joint cavity by adjusting the radiation behavior of the NIR light. The MCDs prolonged the residence time of Dex in the joint cavity. The intra-articular injection of the MCDs in combination with NIR radiation ensured a significant increase in the therapeutic effect of Dex at low systemic doses, which attenuated the cartilage erosion in the OA caused by the secretion of inflammatory factors including TNF-α and IL-1β. The toxicity and side effects on other internal organs during metabolism were reduced in the body. In addition, the photoacoustic imaging capability of MoS2 nanosheets was used to detect the metabolism of the MCDs in the joint cavity. Our research indicated that MCDs have great potential to treat OA.
The self-assembly of nanostructures from elastin-like (poly)peptide (ELP) containing block copolymers has been a subject of intense investigation over decades. However, short synthetic ELPs have rarely been used due to their high inverse transition temperature; the use of short ELPs has largely been limited to polymer conju-gates. Motivated by our previous work which successful-ly overcame this barrier by simply conjugating short ELPs with a triple helix forming collagen-like peptide, in this study, we further extend the ELP library to a series of ELPs equipped with aromatic residues and having sequences as short as four pentapeptide motifs. The resulting ELP-CLP bioconjugates unexpectedly self-assembled into nanosized platelets likely by forming a bilayer structure. Given the demonstrated ability of CLPs to target collagens and potential strong π-π inter-action for aromatic drug encapsulation, these ELP-CLP nanoplates offer opportunities for targeted delivery ap-plications in biomedical and other arenas.
Elastin-like polypeptides (ELPs) are thermoresponsive biopolymers that undergo an LCST-like phase transition in aqueous solutions. The temperature of this LCST-like transition, Tt , can be tuned by varying the number of repeat units in the ELP, sequence and composition of the repeat units, the solution conditions, and via conjugation to other biomacromolecules. In this study, we show how and why the choice of guest (X) residue in the VPGXG pentad repeat tunes the Tt of short ELPs, (VPGXG)4, in the free state and when conjugated to collagen-like peptides (CLPs). In experiments, the (VPGWG)4 chain (in short, WWWW) has a Tt < 278 K, while (VPGFG)4 or FFFF has a Tt > 353 K in both free ELP and ELP–CLP systems. The Tt for the FWWF ELP sequence decreases from being >353 K for free ELP to <278 K for the corresponding ELP–CLP system. The decrease in Tt upon conjugation to CLP has been shown to be due to the crowding of ELP chains that decreases the entropic loss upon ELP aggregation. Even though the net hydrophobicity of ELP has been reasoned to drive the Tt , the origins of lower Tt of WWWW compared to FFFF are unclear, as there is disagreement in hydrophobicity scales in how phenylalanine (F) compares to tryptophan (W). Motivated by these experimental observations, we use a combination of atomistic and coarse-grained (CG) molecular dynamics simulations. Atomistic simulations of free and tethered ELPs show that WWWW are more prone to acquire β-turn structures than FFFF at lower temperatures. Also, the atomistically informed CG simulations show that the increased local stiffness in W than F due to the bulkier side chain in W compared to F, alone does not cause the shift in the transition of WWWW versus FFFF. The experimentally observed lower Tt of WWWW than FFFF is achieved in CG simulations only when the CG model incorporates both the atomistically informed local stiffness and stronger effective attractions localized at the W position versus the F position. The effective interactions localized at the guest residue in the CG model is guided by our atomistically observed increased propensity for β-turn structure in WWWW versus FFFF and by past experimental work of Urry et al. quantifying hydrophobic differences through enthalpy of association for W versus F.
Articular cartilage is a remarkable tissue whose sophisticated composition and architecture allow it to withstand complex stresses within the joint. Once injured, cartilage lacks the capacity to self-repair, and injuries often progress to joint wide osteoarthritis (OA) resulting in debilitating pain and loss of mobility. Current palliative and surgical management provides short-term symptom relief, but almost always progresses to further deterioration in the long term. A number of bioactive factors, including drugs, corticosteroids, and growth factors, have been utilized in the clinic, in clinical trials, or in emerging research studies to alleviate the inflamed joint environment or to promote new cartilage tissue formation. However, these therapies remain limited in their duration and effectiveness. For this reason, current efforts are focused on improving the localization, retention, and activity of these bioactive factors. The purpose of this review is to highlight recent advances in drug delivery for the treatment of damaged or degenerated cartilage. First, we summarize material and modification techniques to improve the delivery of these factors to damaged tissue and enhance their retention and action within the joint environment. Second, we discuss recent studies using novel methods to promote new cartilage formation via biofactor delivery, that have potential for improving future long-term clinical outcomes. Lastly, we review the emerging field of orthobiologics, using delivered and endogenous cells as drug-delivering “factories” to preserve and restore joint health. Enhancing drug delivery systems can improve both restorative and regenerative treatments for damaged cartilage.
Statement of significance
Articular cartilage is a remarkable and sophisticated tissue that tolerates complex stresses within the joint. When injured, cartilage cannot self-repair, and these injuries often progress to joint-wide osteoarthritis, causing patients debilitating pain and loss of mobility. Current palliative and surgical treatments only provide short-term symptomatic relief and are limited with regards to efficiency and efficacy. Bioactive factors, such as drugs and growth factors, can improve outcomes to either stabilize the degenerated environment or regenerate replacement tissue. This review highlights recent advances and novel techniques to enhance the delivery, localization, retention, and activity of these factors, providing an overview of the cartilage drug delivery field that can guide future research in restorative and regenerative treatments for damaged cartilage.
In this study, amphipathic chitosan derivatives (ACS) and cell-penetrating peptides (CPPs) co-modified colon-specific nanoparticles (CS-CPP NPs) were prepared and evaluated to improve oral bioavailability of protein and peptide drugs. ACS modification was harnessed to protect CPPs from degradation in stomach and small intestine after oral administration and achieve colon-specific drug delivery. After CS-CPP NPs arrived at colon, ACS on the surface of the NPs were gradually degraded and CPPs were exposed to bring into play the penetration efficacy in colon epithelium. Herein, we synthesized four types of ACS (TOCS, TDCS, TPCS and TSCS) and adopted three types of CPPs (Tat, Penetratin and R8) to prepare the NPs (TOCS-Tat NPs, TDCS-Tat NPs, TPCS-Tat NPs, TSCS-Tat NPs, TDCS-Pen NPs and TDCS-R8 NPs). The study of protective effects of ACS upon Tat showed that the modification of ACS exerted favourable protection upon Tat in stomach and small intestine. ACS degradation in colon were indirectly determined in viscosity method, which indicated that ACS could be gradually degraded in colon. Using Caco-2 cell monolayers as cell models, it was found that the cellular uptake amount and transcellular transportation performance of CS-CPP NPs were much enhanced compared with those of TDCS NPs and PVA NPs. With Bama mini-pigs as animal models, the pharmacodynamic study demonstrated that the hypoglycemic effect for insulin-loaded TDCS-Tat NPs was more significant than that for TDCS NPs, lowering the blood glucose by 40%. The pharmacokinetic study indicated that AUC and Cmax for TDCS-Tat NPs were respectively increased by 1.45 times and 1.82 times compared with TDCS NPs. In conclusion, CS-CPP NPs as vehicles for colon-specific drug delivery system may be an efficient approach to improve oral absorption of protein and peptide drugs.
The goal of nanomedicine is to seek strategies that are more efficient to address various limitations and challenges faced by conventional medicines, including lack of target specificity, poor bioavailability, premature degradability, and undesired side effects. Self-assembling drug amphiphiles represent a prospective nanomedicine for cancer therapy owing to their favorable route of administration and therapeutic efficiency compared with pristine drug counterparts. In this work, we report a class of self-deliverable prodrug amphiphiles consisting of the hydrophilic drug methotrexate (MTX) and the hydrophobic anticancer drugs camptothecin (CPT) and doxorubicin (DOX) for targeted and combinational chemotherapy. The disulfide bond and hydrazone bond, which are subject to stimuli-triggered bond cleavage, were introduced to link these therapeutic agents and form two prodrug amphiphiles, named as MTX-CPT and MTX-DOX, respectively, which could self-assemble into stable prodrug nanoaggregates (NAs) in aqueous media. MTX molecules in the prodrug NAs facilitated NA uptake into tumor cells with high expression of folic acid receptors (FRs). This systemic study provided clear evidence of the synergistic therapeutic effect by co-administrating dual prodrug NAs on various tumor cells in vitro and a xenograft tumor model in vivo. The obtained prodrug amphiphiles provide an efficient strategy for the design of multifunctional drug delivery systems and elaborate therapeutic nanoplatforms for cancer chemotherapy.
Statement of significance:
This work presents two kinds of prodrug amphiphiles that are carrier free and integrate targeted drug delivery, stimuli-triggered drug release, synergistic therapy, and theranostic function into a single system. Reduction/acid active prodrug amphiphiles can self-assemble into micellar nanoaggregates (NAs) at a very low critical aggregation concentration. These NAs exhibit superior stability in physiological environment and disassemble in the presence of tumor cells expressing folic acid receptors or the high glutathione or in low pH tumoral endosomal environment. The induced disassembly of prodrug NAs can "switch on" the inherent fluorescence of the internalized camptothecin or doxorubicin for the detection of tumor cells. Compared to a single type of prodrug NA, co-administration of dual prodrug combination can produce an evident synergistic therapeutic effect against various tumor cells in vitro and inhibit xenograft tumor growth in vivo. The methotrexate-based prodrug amphiphiles may provide a potential strategy for developing multifunctional nanoplatforms and delivery of multiple therapeutics in chemotherapy.
Elastin-like peptides (ELP) consist of distinctive repetitive sequences, such as (VPGVG)n, exhibit temperature-dependent reversible self-assembly (coacervation), and have been considered to be useful for the development of thermo-responsive materials. Further fundamental studies evaluating coacervative properties of novel nonlinear ELPs could present design concepts for new thermo-responsive materials. In this study, we prepared novel ELPs, cyclic (FPGVG)n (cyclo[FPGVG]n, n = 1–5), and analyzed its self-assembly properties and structural characteristics. Cyclo[FPGVG]n (n = 3–5) demonstrated stronger coacervation capacity than the corresponding linear peptides. The coacervate of cyclo[FPGVG]5 was able to retain water-soluble dye molecules at 40°C, which implied that cyclo[FPGVG]5 could be employed as a base material of DDS (Drug Delivery System) matrices and other biomaterials. The results of molecular dynamics simulations and circular dichroism measurements suggested that a certain chain length was required for cyclo[FPGVG]n to demonstrate alterations in molecular structure that were critical to the exhibition of coacervation.
It was reported that the shape of nanocarriers played an important role in achieving better therapeutic effect. To optimize the morphology and enhance the antitumor efficacy, in this study based on the amphiphilic PAMAM-b-OEG codendrimer (POD), docetaxel-loaded spherical and flake-like nanoparticles (DTX nanospheres and nanosheets) were prepared via antisolvent precipitation method with the similar particle size, surface charge, stability, and release profiles. The feed weight ratio of DTX/POD and the branched structure of OEG dendron were suggested to influence on the shapes of the self-assembled nanostructures. As expected, DTX nanospheres and nanosheets exhibited strong shape-dependent cellular internalization efficiency and antitumor activity. The clathrin-mediated endocytosis and macropincytosis-dependent endocytosis were proved to be the main uptake mechanism for DTX nanospheres, while it was clathrin-mediated endocytosis for DTX nanosheets. More importantly, DTX nanosheets presented obviously superior antitumor efficacy over nanospheres, the tumor inhibition rate was increased 2-fold in vitro and 1.3-fold in vivo. A approximately 2-fold increase in pharmacokinetic parameter (AUC, MRT, and T1/2) and tumor accumulation were observed in DTX nanosheets group. These results suggested the particle shape played a key role in influencing cellular uptake behaviour, pharmacokinetics, biodistribution, and antitumor activity, the shape of drug-loaded nanoparticles should be considered in the design of new generation of nanoscale drug delivery systems for better therapeutic efficacy of anticancer drug.
Targeted and sustained delivery of drugs to diseased tissues/organs, where body fluid exchange and catabolic activity are substantial, is challenging due to the fast cleansing and degradation of the drugs by these harsh environmental factors. Herein, a multifunctional and bioadhesive polycaprolactone-β-cyclodextrin (PCL-CD) polymersome is developed for localized and sustained co-delivery of hydrophilic and hydrophobic drug molecules. This PCL-CD polymersome affords multivalent crosslinking action via surface CD-mediated host–guest interactions to generate a supramolecular hydrogel that exhibits evident shear thinning and efficient self-healing behavior. The co-delivery of small molecule and proteinaceous agents by the encapsulated PCL-CD polymersomes enhances the differentiation of stem cells seeded in the hydrogel. Furthermore, the PCL-CD polymersomes are capable of in situ grafting to biological tissues via host–guest complexation between surface CD and native guest groups in the tissue matrix both in vitro and in vivo, thereby effectively extending the retention of loaded cargo in the grafted tissue. It is further demonstrated that the co-delivery of small molecule and proteinaceous drugs via PCL-CD polymersomes averts cartilage degeneration in animal osteoarthritic (OA) knee joints, which are known for their biochemically harsh and fluidically dynamic environment.
Over the past few decades, (poly)peptide block copolymers have been widely employed in generating well-defined nanostructures as vehicles for targeted drug delivery applications. We previously reported the assembly of thermoresponsive nanovesicles from an elastin-b-collagen like peptide (ELP-CLP). The nanoparticles were observed to dissociate at elevated temperatures, despite the LCST-like behavior of the tethered ELP domain, which is suggested to be triggered by the unfolding of the CLP domain. Here, the potential of using the nanoparticles as drug delivery vehicles for targeting collagen-containing matrices is evaluated. The sustained release of an encapsulated model drug was achieved over a period of three weeks, with complete release thermally triggered at later timepoints. The ELP-CLP nanoparticles show strong retention on a collagen substrate, presumably through collagen triple helix interactions. Cell viability and proliferation studies using fibroblasts and chondrocytes suggest that the nanoparticles are highly cytocompatible. Additionally, essentially no activation of a macrophage-like cell line is observed, suggesting that the nanoparticles do not initiate an inflammatory response. Endowed with thermally controlled delivery, the ability to bind collagen, and excellent cytocompatibility, these ELP-CLP nanoparticles are suggested to have significant potential in the controlled delivery of drugs to collagen-containing matrices and tissues.
Collagen-like peptides (CLPs), also known as collagen-mimetic peptides (CMPs), are short synthetic peptides that mimic the triple helical conformation of native collagens. Traditionally, CLPs have been widely used in deciphering the chemical basis for collagen triple helix stabilization, mimicking collagen fibril formation and fabricating other higher-order supramolecular self-assembles. While CLPs have been used extensively for elucidation of the assembly of native collagens, less work has been reported on the use of CLP-polymer and CLP-peptide conjugates in the production of responsive assemblies. CLP triple helices have been used as physical cross-links in CLP-polymer hydrogels with predesigned thermoresponsiveness. The more recently reported ability of CLP to target native collagens via triple helix hybridization has further inspired the production of CLP-polymer and CLP-peptide bioconjugates and the employment of these conjugates in generating well defined nanostructures for targeting collagen substrates. This review summarizes the current progress and potential of using CLPs in biomedical arenas and is intended to serve as a general guide for designing CLP-containing biomaterials.
Nanoparticles, such as metals, carbon nanotubes (CNTs), polymers, and dendrimers, are structures having a diameter of 1–100 nm in at least one dimension. Metal nanoparticles include transition metal, paramagnetic, and porous/hollow nanoparticles. Metal nanoparticles are mostly colloids synthesized using a reductive technology, except for silica porous nanoparticles, which are synthesized using a seed-based technology. CNTs are one of the carbon allotropes generated by various physical and chemical (requiring metal catalysts) methods. Linear polymers are the oldest form of nanoparticles that can also be the starting material for synthesis of complex nanoparticles, such as dendrimers. DNA dendrimers are unique nanoparticles used in constructing biological sensors. Nanoparticles, despite their chemical differences, exhibit common size- and shape-dependent physical properties (a large surface area-to-volume ratio and quantum confinement) that are not found in the corresponding bulk materials. Therefore, to understand the physicochemical properties, beneficial effects, and toxicity of nanoparticles, it is important to understand their structure and mode of synthesis.
Injury to the joint provokes a number of local pathophysiological changes, including synthesis of inflammatory cytokines, death of chondrocytes, breakdown of the extra-cellular matrix of cartilage, and reduced synthesis of matrix macromolecules. These processes combine to engender the subsequent development of post-traumatic osteoarthritis (PTOA). To prevent this from happening, it is necessary to inhibit these disparate responses to injury; given their heterogeneity, this is challenging. However, dexamethasone has the necessary pleiotropic properties required of a drug for this purpose. Using in vitro models, we have shown that low doses of dexamethasone sustain the synthesis of cartilage proteoglycans while inhibiting their breakdown after injurious compression in the presence or absence of inflammatory cytokines. Under these conditions, dexamethasone is non-toxic and maintains the viability of chondrocytes exposed chronically to such cytokines as interleukin (IL) -1, IL-6, and tumor necrosis factor-α. Moreover, the anti-inflammatory properties of dexamethasone have been appreciated for decades. In view of this information, we have initiated a pilot clinical study to determine whether a single, intra-articular injection of dexamethasone into the wrist shows promise in preventing PTOA after intra-articular fracture of the distal radius.
Clinical significance:
Suppressing the various etiopathophysiological responses to injury in the joint is an attractive strategy for lowering the clinical burden of PTOA. The intra-articular administration of dexamethasone soon after injury offers a simple and inexpensive means of accomplishing this. © 2017 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 35:406-411, 2017.
Glucocorticoid (GC) is the cornerstone therapy of rheumatoid arthritis, but high doses are associated with serious adverse effects. In an effort to improve the efficacy of low-dose GC therapy, we developed a micelle system for targeted delivery to inflamed joints and validated the approach in a rat model of arthritis. Micelles loaded with dexamethasone (Dex) self-assembled from the amphipathic poly (ethylene glycol)-block-poly (ε-caprolactone) (PCL-PEG) polymer via film dispersion, and they were injected intravenously at a dose of only 0.8mg/kg into rats with adjuvant-induced arthritis. The micelles persisted for a relatively long time in the circulation, and they accumulated preferentially in inflamed joints. Micelle-delivered Dex potently reduced joint swelling, bone erosion, and inflammatory cytokine expression in both joint tissue and serum. PCL-PEG micelles caused only moderate adverse effects on body weight, lymphocyte count and blood glucose concentration, and they weakly activated the host complement system. These results suggest that encapsulating Dex in PCL-PEG micelles may allow for safe and effective low-dose GC therapy targeting inflammatory disorders.
Novel, liposome-crosslinked hybrid hydrogels crosslinked by the Michael-type addition of thiols with maleimides were prepared via the use of maleimide-functionalized liposome crosslinkers and thiolated polyethylene glycol (PEG) polymers. Gelation of the materials was confirmed by oscillatory rheology experiments. These hybrid hydrogels are rendered degradable upon exposure to thiol-containing molecules such as glutathione (GSH), via the incorporation of selected thioether succinimide crosslinks between PEG polymers and liposome nanoparticles. Dynamic light scattering (DLS) characterization confirmed that intact liposomes were released upon network degradation. Owing to the hierarchical structure of the network, multiple cargo molecules relevant for chemotherapies, namely doxorubicin (DOX) and cytochrome c, were encapsulated and simultaneously released from the hybrid hydrogels, with differential release profiles that were driven by degradation-mediated release and Fickian diffusion, respectively. This work introduces a facile approach for the development of advanced, hybrid drug delivery vehicles that exhibit novel chemical degradation.
Stimuli-responsive nanostructures produced with peptide domains from the extracellular matrix offer great opportunities for imaging and drug delivery. Although the individual utility of elastin-like (poly)peptides and collagen-like peptides in such applications has been demonstrated, the synergistic advantages of combining these motifs in short peptide conjugates have surprisingly not been reported. Here, we introduce the conjugation of a thermoresponsive elastin-like peptide (ELP) with a triple-helix-forming collagen-like peptide (CLP) to yield ELP-CLP conjugates that show a remarkable reduction in the inverse transition temperature of the ELP domain upon formation of the CLP triple helix. The lower transition temperature of the conjugate enables the facile formation of well-defined vesicles at physiological temperature and the unexpected resolubilization of the vesicles at elevated temperatures upon unfolding of the CLP domain. Given the demonstrated ability of CLPs to modify collagens, our results not only provide a simple and versatile avenue for controlling the inverse transition behavior of ELPs, but also suggest future opportunities for these thermoresponsive nanostructures in biologically relevant environments.
Elastin-like polypeptides (ELPs) constitute a genetically engineered class of 'protein polymers' derived from human tropoelastin. They exhibit a reversible phase separation whereby samples remain soluble below a transition temperature (Tt) but form amorphous coacervates above Tt. Their phase behavior has many possible applications in purification, sensing, activation, and nanoassembly. As humanized polypeptides, they are non-immunogenic, substrates for proteolytic biodegradation, and can be decorated with pharmacologically active peptides, proteins, and small molecules. Recombinant synthesis additionally allows precise control over ELP architecture and molecular weight, resulting in protein polymers with uniform physicochemical properties suited to the design of multifunctional biologics. As such, ELPs have been employed for various uses including as anti-cancer agents, ocular drug delivery vehicles, and protein trafficking modulators. This review aims to offer the reader a catalogue of ELPs, their various applications, and potential for commercialization across a broad spectrum of fields.
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.