Recent developments in liposomes, microparticles and nanoparticles for protein and peptide drug delivery

Multiple targeting strategies achieve novel protein drug delivery into proapoptosis lung cancer cells by precisely inhibiting survivin

Therapeutic recombinant proteins have numerous advantages and benefits over chemical drugs, particularly high specificity and good biocompatibility. However, the therapeutic potential and clinical application of current anticancer protein drugs are limited as most biomarkers are located within cells, and multiple physiological barriers exist between the point of administration and the intracellular biomarker. Herein, we report a novel strategy to accurately deliver a cell-permeable dominant-negative TATm-Survivin (TmSm) protein (T34A) to intracellular survivin in cancer cells by overcoming multiple barriers in vivo. A poly(d,l-lactide-co-glycolide) (PLGA) inner core, a polyethylene glycol (PEG) modification, and a TATm peptide were simultaneously introduced to mediate tumor tissue targeting and response to pH-triggered TmSm release. Compared to free TmSm, the PEGylated-PLGA nanoparticle platform achieved a significantly higher cellular uptake efficiency (1.79-fold for A549 and 1.77-fold for Capan-2), effectively decreased IC50 (1.22-fold for A549 and 1.17-fold for Capan-2), and largely elevated apoptosis in different cancer cells (1.17-fold for A549 and 1.15-fold for Capan-2). Besides, this newly developed nanoplatform showed increased protein drug accumulation in the tumor site in A549-bearing nude mice and reached a tumor inhibition rate of 55.81% (1.35-fold versus free TmSm) by reducing the expression of intracellular survivin. All these results confirmed that our newly developed delivery strategy is a very promising tool, which helps protein drugs to cross multiple barriers in vivo and achieves precise targeting to intracellular biomarkers. This strategy could also be applied to other types of protein drugs to further improve their clinical anticancer therapeutic efficacy.

Antitumor Effects of N-Butylidenephthalide Encapsulated in Lipopolyplexs in Colorectal Cancer Cells

Colorectal cancer (CRC) is the third most common type of cancer and the second most common cause of cancer-related death in the world. N-Butylidenephthalide (BP), a natural compound, inhibits several cancers, such as hepatoma, brain tumor and colon cancer. However, due to the unstable structure, the activity of BP is quickly lost after dissolution in an aqueous solution. A polycationic liposomal polyethylenimine and polyethylene glycol complex (LPPC), a new drug carrier, encapsulates both hydrophobic and hydrophilic compounds, maintains the activity of the compound, and increases uptake of cancer cells. The purpose of this study is to investigate the antitumor effects and protection of BP encapsulated in LPPC in CRC cells. The LPPC encapsulation protected BP activity, increased the cytotoxicity of BP and enhanced cell uptake through clathrin-mediated endocytosis. Moreover, the BP/LPPC-regulated the expression of the p21 protein and cell cycle-related proteins (CDK4, Cyclin B1 and Cyclin D1), resulting in an increase in the population of cells in the G₀/G₁ and subG₁ phases. BP/LPPC induced cell apoptosis by activating the extrinsic (Fas, Fas-L and Caspase-8) and intrinsic (Bax and Caspase-9) apoptosis pathways. Additionally, BP/LPPC combined with 5-FU synergistically inhibited the growth of HT-29 cells. In conclusion, LPPC enhanced the antitumor activity and cellular uptake of BP, and the BP/LPPC complex induced cell cycle arrest and apoptosis, thereby causing death. These findings suggest the putative use of BP/LPPC as an adjuvant cytotoxic agent for colorectal cancer.

Cartilage Tissue-Mimetic Pellets with Multifunctional Magnetic Hyaluronic Acid-Graft-Amphiphilic Gelatin Microcapsules for Chondrogenic Stimulation

Articular cartilage defect is a common disorder caused by sustained mechanical stress. Owing to its nature of avascular, cartilage had less reconstruction ability so there is always a need for other repair strategies. In this study, we proposed tissue-mimetic pellets composed of chondrocytes and hyaluronic acid-graft-amphiphilic gelatin microcapsules (HA-AGMCs) to serve as biomimetic chondrocyte extracellular matrix (ECM) environments. The multifunctional HA-AGMC with specific targeting on CD44 receptors provides excellent structural stability and demonstrates high cell viability even in the center of pellets after 14 days culture. Furthermore, with superparamagnetic iron oxide nanoparticles (SPIOs) in the microcapsule shell of HA-AGMCs, it not only showed sound cell guiding ability but also induced two physical stimulations of static magnetic field(S) and magnet-derived shear stress (MF) on chondrogenic regeneration. Cartilage tissue-specific gene expressions of Col II and SOX9 were upregulated in the present of HA-AGMC in the early stage, and HA-AGMC+MF+S held the highest chondrogenic commitments throughout the study. Additionally, cartilage tissue-mimetic pellets with magnetic stimulation can stimulate chondrogenesis and sGAG synthesis.

The Role of Bone-Derived Exosomes in Regulating Skeletal Metabolism and Extraosseous Diseases

Bone-derived exosomes are naturally existing nano-sized extracellular vesicles secreted by various cells, such as bone marrow stromal cells, osteoclasts, osteoblasts, and osteocytes, containing multifarious proteins, lipids, and nucleic acids. Accumulating evidence indicates that bone-derived exosomes are involved in the regulation of skeletal metabolism and extraosseous diseases through modulating intercellular communication and the transfer of materials. Following the development of research, we found that exosomes can be considered as a potential candidate as a drug delivery carrier thanks to its ability to transport molecules into targeted cells with high stability, safety, and efficiency. This review aims to discuss the emerging role of bone-derived exosomes in skeletal metabolism and extraosseous diseases as well as their potential role as candidate biomarkers or for developing new therapeutic strategies.

LincRNA-EPS in biomimetic vesicles targeting cerebral infarction promotes inflammatory resolution and neurogenesis

BACKGROUND

Inflammatory damage following stroke aggravates brain damage, resulting in long-term neurological sequelae. The purpose of this study was to identify ways to reduce inflammatory reactions and to accelerate neuron regeneration after cerebral apoplexy.

METHODS

We formulated a biomimetic vesicle, the leukosome, constituted by liposome, artificial long intergenic noncoding RNA (lincRNA)-EPS, and membrane proteins derived from macrophages and their physical-chemical characteristics were evaluated. Migration distance and cytotoxic levels were measured to determine the effect of lncEPS-leukosomes on lipopolysaccharide-activated microglia. An in vivo transient middle cerebral artery occlusion/reperfusion (tMCAO) model was established in mice, which were treated with lncEPS-leukosomes. Vesicle seepage, infiltration of inflammatory cells, cytotoxic levels in the cerebrospinal fluid, and neural stem cell (NSC) density were measured.

RESULTS

Biomimetic vesicles with a homogeneous size increased lincRNA-EPS levels in activated microglia by 77.9%. In vitro studies showed that lincRNA-EPS inhibited the migration and cytotoxic levels of activated microglia by 63.2% and 43.6%, respectively, which promoted NSC proliferation and anti-apoptotic ability. In vivo data showed that leukosomes targeted to inflamed sites and lncEPS-leukosomes decreased the infiltration of inflammatory cells and cytotoxic levels by 81.3% and 48.7%, respectively. In addition, lncEPS-leukosomes improved neuron density in the ischemic core and boundary zone after tMCAO.

CONCLUSIONS

The biomimetic vesicles formulated in this study targeted inflammatory cells and accelerated neuron regeneration by promoting inflammation resolution. This study may provide a promising treatment approach for accelerated neuron regeneration after cerebral apoplexy.

Nanosized Delivery Systems for Therapeutic Proteins: Clinically Validated Technologies and Advanced Development Strategies

The impact of protein therapeutics in healthcare is steadily increasing, due to advancements in the field of biotechnology and a deeper understanding of several pathologies. However, their safety and efficacy are often limited by instability, short half-life and immunogenicity. Nanodelivery systems are currently being investigated for overcoming these limitations and include covalent attachment of biocompatible polymers (PEG and other synthetic or naturally derived macromolecules) as well as protein nanoencapsulation in colloidal systems (liposomes and other lipid or polymeric nanocarriers). Such strategies have the potential to develop next-generation protein therapeutics. Herein, we review recent research progresses on these nanodelivery approaches, as well as future directions and challenges.

Ferritin Nanocages for Protein Delivery to Tumor Cells

The delivery of therapeutic proteins is one of the greatest challenges in the treatment of human diseases. In this frame, ferritins occupy a very special place. Thanks to their hollow spherical structure, they are used as modular nanocages for the delivery of anticancer drugs. More recently, the possibility of encapsulating even small proteins with enzymatic or cytotoxic activity is emerging. Among all ferritins, particular interest is paid to the Archaeoglobus fulgidus one, due to its peculiar ability to associate/dissociate in physiological conditions. This protein has also been engineered to allow recognition of human receptors and used in vitro for the delivery of cytotoxic proteins with extremely promising results.

Myoglobin molecule charging in electrolyte solutions

The compensated charge of myoglobin molecule in electrolyte solution is considerably smaller than the nominal charge.

Inter-protein interactions govern protein loading into porous vaterite CaCO3 crystals

Loading of therapeutic proteins into mesoporous vaterite crystals is driven by inter-protein interactions in bulk solution and inside the crystals.

Liposomes modified with bio-substances for cancer treatment

In recent years, liposomes have been used in the field of biomedicine and have achieved many significant results.

Updates on the use of liposomes for active tumor targeting in cancer therapy

In the development of cancer chemotherapy, besides the discovery of new anticancer drugs, a variety of nanocarrier systems for the delivery of previously developed and new chemotherapeutic drugs have currently been explored. Liposome is one of the most studied nanocarrier systems because of its biodegradability, simple preparation method, high efficacy and low toxicity. To make the best use of this vehicle, a number of multifunctionalized liposomal formulations have been investigated. The objective of this review is to summarize the current development of novel active targeting liposomal formulations, and to give insight into the challenges and future direction of the field. The recent studies in active targeting liposomes suggest the great potential of precise targeted anticancer drug delivery in cancer therapeutics.

Therapeutic efficacy of nanoparticles and routes of administration

In modern-day medicine, nanotechnology and nanoparticles are some of the indispensable tools in disease monitoring and therapy. The term “nanomaterials” describes materials with nanoscale dimensions (< 100 nm) and are broadly classified into natural and synthetic nanomaterials. However, “engineered” nanomaterials have received significant attention due to their versatility. Although enormous strides have been made in research and development in the field of nanotechnology, it is often confusing for beginners to make an informed choice regarding the nanocarrier system and its potential applications. Hence, in this review, we have endeavored to briefly explain the most commonly used nanomaterials, their core properties and how surface functionalization would facilitate competent delivery of drugs or therapeutic molecules. Similarly, the suitability of carbon-based nanomaterials like CNT and QD has been discussed for targeted drug delivery and siRNA therapy. One of the biggest challenges in the formulation of drug delivery systems is fulfilling targeted/specific drug delivery, controlling drug release and preventing opsonization. Thus, a different mechanism of drug targeting, the role of suitable drug-laden nanocarrier fabrication and methods to augment drug solubility and bioavailability are discussed. Additionally, different routes of nanocarrier administration are discussed to provide greater understanding of the biological and other barriers and their impact on drug transport. The overall aim of this article is to facilitate straightforward perception of nanocarrier design, routes of various nanoparticle administration and the challenges associated with each drug delivery method.

Nanotechnology platforms for cancer immunotherapy

Various cancer therapies have advanced remarkably over the past decade. Unlike the direct therapeutic targeting of tumor cells, cancer immunotherapy is a new strategy that boosts the host's immune system to detect specific cancer cells for efficient elimination. Nanoparticles incorporating immunomodulatory agents can activate immune cells and modulate the tumor microenvironment to enhance antitumor immunity. Such nanoparticle-based cancer immunotherapies have received considerable attention and have been extensively studied in recent years. This review thus focuses on nanoparticle-based platforms (especially naturally derived nanoparticles and synthetic nanoparticles) utilized in recent advances; summarizes delivery systems that incorporate various immune-modulating agents, including peptides and nucleic acids, immune checkpoint inhibitors, and other small immunostimulating agents; and introduces combinational cancer immunotherapy with nanoparticles, especially nanoparticle-based photo-immunotherapy and nanoparticle-based chemo-immunotherapy. Undoubtedly, the recent studies introduced in this review prove that nanoparticle-incorporated cancer immunotherapy is a highly promising treatment modality for patients with cancer. Nonetheless further research is needed to solve safety concerns and improve efficacy of nanoplatform-based cancer immunotherapy for future clinical application. This article is categorized under: Therapeutic Approaches and Drug Discovery > Nanomedicine for Oncologic Disease.

Hydrogels For Peptide Hormones Delivery: Therapeutic And Tissue Engineering Applications

Peptides are the most abundant biological compounds in the cells that act as enzymes, hormones, structural element, and antibodies. Mostly, peptides have problems to move across the cells because of their size and poor cellular penetration. Therefore, a carrier that could transfer peptides into cells is ideal and would be effective for disease treatment. Until now, plenty of polymers, e.g., polysaccharides, polypeptides, and lipids were used in drug delivery. Hydrogels made from polysaccharides showed significant development in targeted delivery of peptide hormones because of their natural characteristics such as networks, pore sizes, sustainability, and response to external stimuli. The main aim of the present review was therefore, to gather the important usages of the hydrogels as a carrier in peptide hormone delivery and their application in tissue engineering and regenerative medicine.

Polylactic acid: synthesis and biomedical applications

Social and economic development has driven considerable scientific and engineering efforts on the discovery, development and utilization of polymers. Polylactic acid (PLA) is one of the most promising biopolymers as it can be produced from nontoxic renewable feedstock. PLA has emerged as an important polymeric material for biomedical applications on account of its properties such as biocompatibility, biodegradability, mechanical strength and process ability. Lactic acid (LA) can be obtained by fermentation of sugars derived from renewable resources such as corn and sugarcane. PLA is thus an eco-friendly nontoxic polymer with features that permit use in the human body. Although PLA has a wide spectrum of applications, there are certain limitations such as slow degradation rate, hydrophobicity and low impact toughness associated with its use. Blending PLA with other polymers offers convenient options to improve associated properties or to generate novel PLA polymers/blends for target applications. A variety of PLA blends have been explored for various biomedical applications such as drug delivery, implants, sutures and tissue engineering. PLA and their copolymers are becoming widely used in tissue engineering for function restoration of impaired tissues due to their excellent biocompatibility and mechanical properties. The relationship between PLA material properties, manufacturing processes and development of products with desirable characteristics is described in this article. LA production, PLA synthesis and their applications in the biomedical field are also discussed.

A tetrameric protein scaffold as a nano-carrier of antitumor peptides for cancer therapy

A major pharmacological barrier to peptide therapeutics is their susceptibility to proteolytic degradation and poor membrane permeability, which, in principle, can be overcome by nanoparticle-based delivery technologies. Proteins, by definition, are nano materials and have been clinically proven as an efficient delivery vehicle for small molecule drugs. Here we describe the design of a protein-based peptide drug carrier derived from the tetramerization domain of the chimeric oncogenic protein Bcr/Abl of chronic myeloid leukemia. A dodecameric peptide inhibitor of the p53-MDM2/MDMX interaction, termed PMI, was grafted to the N-terminal helical region of Bcr/Abl tetramer. To antagonize intracellular MDM2/MDMX for p53 activation, we extended this protein, PMIBcr/Abl, by a C-terminal Arg-repeating hexapeptide to facilitate its cellular uptake. The resultant tetrameric protein PMIBcr/Abl-R6 adopted an alpha-helical conformation in solution and bound to MDM2 at an affinity of 32 nM. PMIBcr/Abl-R6 effectively induced apoptosis of HCT116 p53+/+ cells in vitro in a p53-dependent manner and potently inhibited tumor growth in a nude mouse xenograft model by stabilizing p53 in vivo. Our protein-based delivery strategy thus provides a clinically viable solution to p53-inspired anticancer therapy and is likely applicable to the development of many other peptide therapeutics to target a great variety of intracellular protein-protein interactions responsible for disease initiation and progression.

Self-emulsifying drug delivery system: Mucus permeation and innovative quantification technologies

Mucus is a dynamic barrier which covers and protects the underlying mucosal epithelial membrane against bacteria and foreign particles. This protection mechanism extends to include therapeutic macromolecules and nanoparticles (NPs) through trapping of these particles. Mucus is not only a physical barrier that limiting particles movements based on their sizes but it selectively binds with particles through both hydrophilic and lipophilic interactions. Therefore, nano-carriers for mucosal delivery should be designed to eliminate entrapment by the mucus barrier. For this reason, different strategies have been approached for both solid nano-carriers and liquid core nano-carriers to synthesise muco-diffusive nano-carrier. Among these nano-strategies, Self-Emulsifying Drug Delivery System (SEDDS) was recognised as very promising nano-carrier for mucus delivery. The system was introduced to enhance the dissolution and bioavailability of orally administered insoluble drugs. SEDDS has shown high stability against intestinal enzymatic activity and more importantly, relatively rapid permeation characteristics across mucus barrier. The high diffusivity of SEDDS has been tested using various in vitro measurement techniques including both bulk and individual measurement of droplets diffusion within mucus. The selection and processing of an optimum in vitro technique is of great importance to avoid misinterpretation of the diffusivity of SEDDS through mucus barrier. In conclusion, SEDDS is a system with high capacity to diffuse through intestinal mucus even though this system has not been studied to the same extent as solid nano-carriers.

Validation of Size Estimation of Nanoparticle Tracking Analysis on Polydisperse Macromolecule Assembly

As the physicochemical properties of drug delivery systems are governed not only by the material properties which they are compose of but by their size that they conform, it is crucial to determine the size and distribution of such systems with nanometer-scale precision. The standard technique used to measure the size distribution of nanometer-sized particles in suspension is dynamic light scattering (DLS). Recently, nanoparticle tracking analysis (NTA) has been introduced to measure the diffusion coefficient of particles in a sample to determine their size distribution in relation to DLS results. Because DLS and NTA use identical physical characteristics to determine particle size but differ in the weighting of the distribution, NTA can be a good verification tool for DLS and vice versa. In this study, we evaluated two NTA data analysis methods based on maximum-likelihood estimation, namely finite track length adjustment (FTLA) and an iterative method, on monodisperse polystyrene beads and polydisperse vesicles by comparing the results with DLS. The NTA results from both methods agreed well with the mean size and relative variance values from DLS for monodisperse polystyrene standards. However, for the lipid vesicles prepared in various polydispersity conditions, the iterative method resulted in a better match with DLS than the FTLA method. Further, it was found that it is better to compare the native number-weighted NTA distribution with DLS, rather than its converted distribution weighted by intensity, as the variance of the converted NTA distribution deviates significantly from the DLS results.

Topological Aspects of the Design of Nanocarriers for Therapeutic Peptides and Proteins

Supramolecular chemistry holds great potential for the design of versatile and safe carriers for therapeutic proteins and peptides. Nanocarriers can be designed to meet specific criteria for given application (exact drug, administration route, target tissue, etc.). However, alterations in the topology of formulation components can drastically change their activity. This is why the supramolecular topology of therapeutic nanoconstructions has to be considered. Herein, we discuss several topological groups used for the design of nanoformulations for peptide and protein delivery: modification of polypeptide chains by host-guest interactions; packaging of proteins and peptides into liposomes; complexation and conjugation with dendrimers. Each topological type has its own advantages and disadvantages, so careful design of nanoformulations is needed. Ideally, each case where nanomedicine is needed requires a therapeutic construction specially created for that taking into account features of the administration route, target tissue, or organ, properties of a drug, its bioavailability, etc. The wide number of studies in the field of protein delivery by supramolecular and nanocarriers for proteins and peptides evidence their increasing potential for different aspects of the innovative medicine. Although significant progress has been achieved in the field, there are several remaining challenges to be overcome in future.

Lipid Nanoparticles-Encapsulated YF4: A Potential Therapeutic Oral Peptide Delivery System for Hypertension Treatment

Drugs are administered orally in the clinical treatment of hypertension. Antihypertensive peptides have excellent angiotensin converting enzyme inhibitors activity in vitro. However, the poor oral bioavailability and therapeutic effect of antihypertensive peptides were mainly caused by rapid degradation in gastrointestinal and the short circulation time in blood, which remain to be further optimized. Therefore, the novel oral peptide delivery system is urged to improve the oral absorption and efficacy of peptide drugs. In this work, Tyr-Gly-Leu-Phe (YF4)-loaded lipid nanoparticles (YF4-LNPs) combined the advantages of polymer nanoparticles and liposomes were developed, which could greatly enhance the oral bioavailability and ameliorate the sustained release of peptide drug. YF4 loaded nanoparticles (YF4-NPs) were firstly prepared by a double-emulsion internal phase/organic phase/external phase (W1/O/W2) solvent evaporation method. YF4-NPs were further coated by membrane hydration-ultrasonic dispersion method to obtain the YF4-LNPs. The optimal YF4-LNPs showed a small particle size of 227.3 ± 3.8 nm, zeta potential of -7.27 ± 0.85 mV and high entrapment efficiency of 90.28 ± 1.23%. Transmission electronic microscopy analysis showed that the core-shell lipid nanoparticles were spherical shapes with an apparent lipid bilayer on the surface. Differential scanning calorimetry further proved that YF4 was successfully entrapped into YF4-LNPs. The optimal preparation of YF4-LNPs exhibited sustained release of YF4 in vitro and a 5 days long-term antihypertensive effect in vivo. In summary, the lipid nanoparticles for oral antihypertensive peptide delivery were successfully constructed, which might have a promising future for hypertension treatment.

Co-Encapsulation and Co-Delivery of Peptide Drugs via Polymeric Nanoparticles

Combination therapy is a promising form of treatment. In particular, co-treatment of P3 and QBP1 has been shown to enhance therapeutic effect in vivo in treating polyglutamine diseases. These peptide drugs, however, face challenges in clinical administration due to poor stability, inability to reach intracellular targets, and lack of method to co-deliver both drugs. Here we demonstrate two methods of co-encapsulating the peptide drugs via polymer poly(ethylene glycol)-block-polycaprolactone (PEG-b-PCL) based nanoparticles. Nanoparticles made by double emulsion were 100⁻200 nm in diameter, with drug encapsulation efficiency of around 30%. Nanoparticles made by nanoprecipitation with lipid 1-palmitoyl-2-oleoyl-sn-glycero-3-phospho-(1'-rac-glycerol) (POPG) were around 250⁻300 nm in diameter, with encapsulation efficiency of 85⁻100%. Particles made with both formulations showed cellular uptake when decorated with a mixture of peptide ligands that facilitate endocytosis. In vitro assay showed that nanoparticles could deliver bioactive peptides and encapsulation by double emulsion were found to be more effective in rescuing cells from polyglutamine-induced toxicity.

Human cytotoxicity and octanol/water partition coefficients of fluorinated ionic liquids

The use of fluorinated ionic liquids (FILs) as novel materials in biological and pharmaceutical applications is an emerging research field. The knowledge of their cytotoxicity and that of 1-octanol/water partition coefficients are essential to assess their environmental risks, to estimate their toxicity and activity, or the hydrophilic/lipophilic balance, as well as to explore their properties as solvents in extraction processes or for successful drug design. The study of the cytotoxicity in four different human cell lines and the experimental measurement of the partition coefficient between 1-octanol and water (P_o/w), using the slow-stirring method, were carried out for several FILs. In both studies, the effect of the cation ([C₂C₁Im]⁺, [C₂C₁py]⁺, [C₄C₁pyr]⁺, [N_1112(OH)]⁺, or [N₄₄₄₄]⁺), the cationic alkyl side-chain length ([C_nC₁Im]⁺, with n = 2, 6, 8 or 12), and the anionic fluorinated chain length/anionic fluorinated domain size ([C₄F₉SO₃]¯, [C₈F₁₇SO₃]¯, or [N(C₄F₉SO₃)₂]¯) were analysed. The results reveal that both toxicity and partition properties are mainly influenced by the size of the cationic hydrogenated alkyl side-chain and that of the anionic fluorinated domain. The intrinsic tuneability of the FILs allows for their selection according to the lipophilic or hydrophilic character of the target biological system under consideration. The toxicity studies corroborate the biocompatible nature of some FILs tested in this work. Along, for all the FILs under study P_o/w < 1.00. Accordingly, a decadic logarithm of the bioconcentration factor in fish of 0.5 would be estimated, which is below the regulatory endpoint used by regulatory agencies.

Drug-Loaded Biocompatible Nanocarriers Embedded in Poloxamer 407 Hydrogels as Therapeutic Formulations

Hydrogels are three-dimensional networks of hydrophilic polymers able to absorb and retain a considerable amount of water or biological fluid while maintaining their structure. Among these, thermo-sensitive hydrogels, characterized by a temperature-dependent sol–gel transition, have been massively used as drug delivery systems for the controlled release of various bioactives. Poloxamer 407 (P407) is an ABA-type triblock copolymer with a center block of hydrophobic polypropylene oxide (PPO) between two hydrophilic polyethyleneoxide (PEO) lateral chains. Due to its unique thermo-reversible gelation properties, P407 has been widely investigated as a temperature-responsive material. The gelation phenomenon of P407 aqueous solutions is reversible and characterized by a sol–gel transition temperature. The nanoencapsulation of drugs within biocompatible delivery systems dispersed in P407 hydrogels is a strategy used to increase the local residence time of various bioactives at the injection site. In this mini-review, the state of the art of the most important mixed systems made up of colloidal carriers localized within a P407 hydrogel will be provided in order to illustrate the possibility of obtaining a controlled release of the entrapped drugs and an increase in their therapeutic efficacy as a function of the biomaterial used.

Biomaterials for vaccine-based cancer immunotherapy

The development of therapeutic cancer vaccines as a means to generate immune reactivity against tumors has been explored since the early discovery of tumor-specific antigens by Georg Klein in the 1960s. However, challenges including weak immunogenicity, systemic toxicity, and off-target effects of cancer vaccines remain as barriers to their broad clinical translation. Advances in the design and implementation of biomaterials are now enabling enhanced efficacy and reduced toxicity of cancer vaccines by controlling the presentation and release of vaccine components to immune cells and their microenvironment. Here, we discuss the rational design and clinical status of several classes of cancer vaccines (including DNA, mRNA, peptide/protein, and cell-based vaccines) along with novel biomaterial-based delivery technologies that improve their safety and efficacy. Further, strategies for designing new platforms for personalized cancer vaccines are also considered.

Stimuli-Responsive Nano-Architecture Drug-Delivery Systems to Solid Tumor Micromilieu: Past, Present, and Future Perspectives

The microenvironment characteristics of solid tumors, renowned as barriers that harshly impeded many drug-delivery approaches, were precisely studied, investigated, categorized, divided, and subdivided into a complex diverse of barriers. These categories were further studied with a particular perspective, which makes all barriers found in solid-tumor micromilieu turn into different types of stimuli, and were considered triggers that can increase and hasten drug-release targeting efficacy. This review gathers data concerning the nature of solid-tumor micromilieu. Past research focused on the treatment of such tumors, the recent efforts employed for engineering smart nanoarchitectures with the utilization of the specified stimuli categories, the possibility of combining more than one stimuli for much-greater targeting enhancement, examples of the approved nanoarchitectures that already translated clinically as well as the obstacles faced by the use of these nanostructures, and, finally, an overview of the possible future implementations of smart-chemical engineering for the design of more-efficient drug delivery and theranostic systems and for making nanosystems with a much-higher level of specificity and penetrability features.

Protein-Engineered Biomaterials for Cancer Theranostics

Proteins are an important class of biomaterials promising a variety of applications such as drug delivery, and imaging or therapy, owing to their biodegradability, biocompatibility, as well as inherent biological activities acting as enzymes, recognizing molecules, or therapeutics by themselves. Over the few past decades, different types of proteins with desired properties have been widely explored for biomedical applications. Many therapeutic proteins have now entered clinical use. This review therefore summarizes various strategies in the engineering of biomaterials for delivery of therapeutic proteins, as well as the recent development of protein-based biomaterials for cancer theranostics.

Multifarious Biologic Loaded Liposomes that Stimulate the Mammalian Target of Rapamycin Signaling Pathway Show Retina Neuroprotection after Retina Damage

A common event in optic neuropathies is the loss of axons and death of retinal ganglion cells (RGCs) resulting in irreversible blindness. Mammalian target of rapamycin (mTOR) signaling pathway agonists have been shown to foster axon regeneration and RGC survival in animal models of optic nerve damage. However, many challenges remain in developing therapies that exploit cell growth and tissue remodeling including (i) activating/inhibiting cell pathways synergistically, (ii) avoiding tumorigenesis, and (iii) ensuring appropriate physiological tissue function. These challenges are further exacerbated by the need to overcome ocular physiological barriers and clearance mechanisms. Here we present liposomes loaded with multiple mTOR pathway stimulating biologics designed to enhance neuroprotection after retina damage. Liposomes were loaded with ciliary neurotrophic factor, insulin-like growth factor 1, a lipopeptide N-fragment osteopontin mimic, and lipopeptide phosphatase tension homologue inhibitors for either the ATP domain or the c-terminal tail. In a mouse model of N-methyl-d-aspartic acid induced RGC death, a single intravitreal administration of liposomes reduced both RGC death and loss of retina electrophysiological function. Furthermore, combining liposomes with transplantation of induced pluripotent stem cell derived RGCs led to an improved electrophysiological outcome in mice. The results presented here show that liposomes carrying multiple signaling pathway modulators can facilitate neuroprotection and transplant electrophysiological outcome.

Antimicrobial peptide encapsulation and sustained release from polymer network particles prepared in supercritical carbon dioxide

Antimicrobial peptide loaded poly(2-hydroxyethyl methacrylate) particles were synthesized in supercritical carbon dioxide via one-pot free-radical dispersion polymerisation of 2-hydroxyethyl methacrylate and a cross-linker. Discrete particles with a well-defined spherical morphology and a diameter as low as 450 nm have been obtained in mild conditions. The encapsulation and release of the peptide were confirmed by antimicrobial tests that demonstrated for the first time a sustained release of the peptide from poly(2-hydroxyethyl methacrylate) microgels prepared by one-pot dispersion polymerization in supercritical carbon dioxide and then dispersed in water.

Patterning Multi-Nanostructured Poly(l-lactic acid) Fibrous Matrices to Manipulate Biomolecule Distribution and Functions

Precise manipulation of biomolecule distribution and functions via biomolecule-matrix interaction is very important and challenging for tissue engineering and regenerative medicine. As a well-known biomimetic matrix, electrospun fibers often lack the unique spatial complexity compared to their natural counterparts in vivo and thus cannot deliver fully the regulatory cues to biomolecules. In this paper, we report a facile and reliable method to fabricate micro- and nanostructured poly(l-lactic acid) (PLLA) fibrous matrices with spatial complexity by a combination of advanced electrospinning and agarose hydrogel stamp-based micropatterning. Specifically, advanced electrospinning is used to construct multi-nanostructures of fibrous matrices while solvent-loaded agarose hydrogel stamps are used to create microstructures. Compared with other methods, our method shows extreme simplicity and flexibility originated from the mono-/multi-spinneret conversion and limitless micropatterns of agarose hydrogel stamps. Three types of PLLA fibrous matrices including patterned nano-Ag/PLLA hybrid fibers, patterned bicompartment polyethylene terephthalate/PLLA fibers, and patterned hollow PLLA fibers are fabricated and their capability to manipulate biomolecule distribution and functions, that is, bacterial distribution and antibacterial performance, cell patterning and adhesion/spreading behaviors, and protein adsorption and delivery, is demonstrated in detail. The method described in our paper provides a powerful tool to restore spatial complexity in biomimetic matrices and would have promising applications in the field of biomedical engineering.

Therapeutic effect of Aloe vera and silver nanoparticles on acid-induced oral ulcer in gamma-irradiated mice

Radiation combined injury, a life-threatening condition, has higher mortality than simple radiation injury. The aim of the present study was to analyze the efficiency of Aloe vera and silver nanoparticles in improving the healing of ulcerated oral mucosa after irradiation. Thirty male Albino mice were divided into five groups: control, radiation, Aloe vera (AV), silver nanoparticles (NS), and AV+NS. The mice were exposed to whole body 6Gy gamma-radiation. After one hour, 20% acetic acid was injected into the submucosal layer of the lower lip for ulcer induction. The animals received topical treatment with the assigned substances for 5 days. Lip specimens were subjected to hematoxylin and eosin and anti alpha-smooth muscle actin immunohistochemical staining. Results demonstrated occurance of ulcer three days post irradiation in all groups except in the AV+NS group where only epithelial detachment was developed. After seven days, data revealed persistent ulcer in radiation group, and almost normal epithelium in the AV+NS group. A significant reduction of epithelial thickness was detected in all groups at the third day as compared to control. At the seventh day, only the AV+NS group restored the epithelial thickness. Area percent of alpha-smooth muscle actin expression was significantly decreased in radiation group at the third day followed by significant increase at the seventh day. However, all treatment groups showed significant increase in alpha-smooth muscle actin at the third day, which decreased to normal level at the seventh day. Our study demonstrated the efficiency of Aloe vera and silver nanoparticles in enhancing ulcer healing after irradiation.

Stabilization of Human Tyrosine Hydroxylase in Maltodextrin Nanoparticles for Delivery to Neuronal Cells and Tissue

Enzyme replacement therapy (ERT) is a therapeutic approach envisioned decades ago for the correction of genetic disorders, but ERT has been less successful for the correction of disorders with neurological manifestations. In this work, we have tested the functionality of nanoparticles (NP) composed of maltodextrin with a lipid core to bind and stabilize tyrosine hydroxylase (TH). This is a complex and unstable brain enzyme that catalyzes the rate-limiting step in the synthesis of dopamine and other catecholamine neurotransmitters. We have characterized these TH-loaded NPs to evaluate their potential for ERT in diseases associated with TH dysfunction. Our results show that TH can be loaded into the lipid core maltodextrin NPs with high efficiency, and both stability and activity are maintained through loading and are preserved during storage. Binding to NPs also favored the uptake of TH to neuronal cells, both in cell culture and in the brain. The internalized NP-bound TH was active as we measured an increase in intracellular L-Dopa synthesis following NP uptake. Our approach seems promising for the use of catalytically active NPs in ERT to treat neurodegenerative and neuropsychiatric disorders characterized by dopamine deficiency, notably Parkinson's disease.

Liposome‑delivered baicalein induction of myeloid leukemia K562 cell death via reactive oxygen species generation

Baicalein (BL), a potential cancer chemopreventative flavone, has been reported to inhibit cancer cell growth by inducing apoptosis and causing cell cycle arrest in various human cancer cell models. Delivery of BL via nanoliposomes has been shown to improve its oral bioavailability and long-circulating property in vivo. However, the role of BL in the inhibition of human chronic myeloid leukemia (CML) K562 cell growth and its underlying mechanisms has yet to be elucidated. In the present study, BL was formulated into liposomes with different sizes to improve its solubility and stability. The cytotoxic and pro-apoptotic effects of free BL and liposomal BL were also evaluated. The results demonstrated that 100 nm liposomes were the most stable formulation when compared with 200 and 400 nm liposomes. Liposomal BL inhibited K562 cell growth as efficiently as free BL (prepared in DMSO), indicating that the liposome may be a potential vehicle to deliver BL for the treatment of CML. Flow cytometry analysis showed that there was significant (P<0.005) cell cycle arrest in the sub-G1 phase (compared with vehicle control), indicating cell apoptosis following 20 µM liposomal BL or free BL treatment of K562 cells for 48 h. The induction of cell apoptosis by all BL preparations was further confirmed through the staining of treated cells with Annexin V-fluorescein isothiocyanate/propidium iodide. A significant increase in reactive oxygen species (ROS) generation was observed in free BL and liposomal BL treated cells, with a higher level of ROS produced from those treated with free BL. This indicated that cell apoptosis induced by BL may be via ROS generation and liposome delivery may further extend the effect through its long-circulating property.

Effects of TNF receptor blockade on in vitro cell survival and response to negative energy balance in dairy cattle

Background

Associative data and some controlled studies suggest that the inflammatory cytokine tumor necrosis factor (TNF) α can induce fatty liver in dairy cattle. However, research demonstrating that TNFα is a necessary component in the etiology of bovine fatty liver is lacking. The aim of this work was to evaluate whether blocking TNFα signaling with a synthetic cyclic peptide (TNF receptor loop peptide; TRLP) would improve liver metabolic function and reduce triglyceride accumulation during feed restriction.

Results

Capability of TRLP to inhibit TNFα signaling was confirmed on primary bovine hepatocytes treated with recombinant bovine TNFα and 4 doses of TRLP (0, 1, 10, 50 μmol/L) over 24 h. Next, 4 lactating Holstein cows (parity 1.4 ± 0.5, 433 ± 131 d in milk) in an incomplete Latin rectangle design (3 × 2) were subcutaneously administered with different TRLP doses (0, 1.5, 3.0 mg/kg BW) every 4 h for 24 h, followed by an intravenous injection of TNFα (5 μg/kg BW). Before and for 2 h after TNFα injection, TRLP decreased plasma non-esterified fatty acid (NEFA) concentration (P ≤ 0.05), suggesting an altered metabolic response to inflammation. Finally, 10 non-pregnant, non-lactating Holstein cows (3.9 ± 1.1 yr of age) were randomly assigned to treatments: control (carrier: 57% DMSO in PBS) or TRLP (1.75 mg TRLP /kg BW per day). Treatments were administrated every 4 h for 7 d by subcutaneous injection to feed-restricted cows fed 30% of maintenance energy requirements. Daily blood samples were analyzed for glucose, insulin, β-hydroxybutyrate, NEFA, and haptoglobin concentrations, with no treatment effects detected. On d 7, cows completed a glucose tolerance test (GTT) by i.v. administration of a dextrose bolus (300 mg glucose/kg BW). Glucose, insulin, and NEFA responses failed to demonstrate any significant effect of treatment during the GTT. However, plasma and liver analyses were not indicative of dramatic lipolysis or hepatic lipidosis, suggesting that the feed restriction protocol failed to induce the metabolic state of interest. Injection site inflammation, assessed by a scorer blinded to treatment, was enhanced by TRLP compared to control.

Conclusions

Although the TRLP inhibited bovine TNFα signaling and altered responses to i.v. administration of TNFα, repeated use over 7 d caused apparent local allergic responses and it failed to alter metabolism during a feed restriction-induced negative energy balance. Although responses to feed restriction seemed atypical in this study, side effects of TRLP argue against its future use as a tool for investigating the role of inflammation in metabolic impacts of negative energy balance.

Improving the inhibitory effect of CXCR4 peptide antagonist in tumor metastasis with an acetylated PAMAM dendrimer

The metastasis of breast cancer is one of the main factors resulting in the high fatality of patients.

The mechanism of catalase loading into porous vaterite CaCO3 crystals by co-synthesis

The mechanism of catalase loading into vaterite CaCO₃ crystals through co-synthesis is deciphered showing the crucial role of Ca²⁺-induced catalase aggregation.

The Inclusion of Chitosan in Poly-ε-caprolactone Nanoparticles: Impact on the Delivery System Characteristics and on the Adsorbed Ovalbumin Secondary Structure

This report extensively explores the benefits of including chitosan into poly-ε-caprolactone (PCL) nanoparticles (NPs) to obtain an improved protein/antigen delivery system. Blend NPs (PCL/chitosan NPs) showed improved protein adsorption efficacy (84%) in low shear stress and aqueous environment, suggesting that a synergistic effect between PCL hydrophobic nature and the positive charges of chitosan present at the particle surface was responsible for protein interaction. Additionally, thermal analysis suggested the blend NPs were more stable than the isolated polymers and cytotoxicity assays in a primary cell culture revealed chitosan inclusion in PCL NPs reduced the toxicity of the delivery system. A quantitative 6-month stability study showed that the inclusion of chitosan in PCL NPs did not induce a change in adsorbed ovalbumin (OVA) secondary structure characterized by the increase in the unordered conformation (random coil), as it was observed for OVA adsorbed to chitosan NPs. Additionally, the slight conformational changes occurred, are not expected to compromise ovalbumin secondary structure and activity, during a 6-month storage even at high temperatures (45°C). In simulated biological fluids, PCL/chitosan NPs showed an advantageous release profile for oral delivery. Overall, the combination of PCL and chitosan characteristics provide PCL/chitosan NPs valuable features particularly important to the development of vaccines for developing countries, where it is difficult to ensure cold chain transportation and non-parenteral formulations would be preferred.

Improved in vitro corneal delivery of a thrombospondin-1-derived peptide using a liposomal formulation

Peptide delivery to and through ocular sites is a growing field of research interest. However, several barriers restrict the permeation and bioavailability of these molecules to target tissues. The main pharmacological barriers of topical administration are the tear film, rapid drainage of the tear film, and poor corneal permeation. If the administered molecule is a peptide, instability and enzymatic degradation can be significant. Novel approaches such as the design and development of nanocarriers to overcome these drawbacks have been investigated with promising results. Therefore, in continuation of our previous study using a liposome-based (LP) formulation as topical drug delivery system, the aim of this work was to efficiently encapsulate a thrombospondin-1-derived peptide, KRFK, in this formulation and to assess peptide permeability through different ocular surface epithelia. LPs were prepared by the solvent evaporation technique and the labeled peptide FITC-KRFK was incorporated in the aqueous core. Different sonication times were used to optimize encapsulation efficiency. The selected formulation was further analyzed in terms of size, pH, osmolarity, and corneal epithelial cytotoxicity. The permeabilities of the LP-encapsulated and free labeled KRFK peptides were assessed with in vitro models of conjunctival and corneal epithelia. Our results provide a proof of concept that the LP formulation efficiently encapsulates the KRFK peptide and improves corneal permeation. Data reported in this study strongly support that this formulation could be a more effective therapeutic approach than free peptide instillation and warrant further analysis using experimental in vivo models.

Liposomes for the delivery of streptokinase

Streptokinase is an efficient thrombolytic agent used to treat thromboembolic disorders. Conventional streptokinase formulations have limited thrombolytic activity and several shortcomings because of their immunogenicity and dose-related side effects including short half-life, lack of tissue targeting and peripheral bleeding. Different liposomal formulations have been explored by researchers in order to improve thrombolytic activity of streptokinase. Liposomal formulations could improve plasma stability, retain drug for longer periods of time in the circulation and promote selective delivery to the thrombus. Side effects of conventional streptokinase formulations, such as immunogenicity and hemorrhage, can also be reduced by using liposomal carriers. In vivo therapeutic efficacy of the liposomal streptokinase has been demonstrated well in animal models. In the present review, we will discuss the potential of different liposomal carriers to improve thrombolytic efficacy of streptokinase.

Mild synthesis of poly(HEMA)-networks as well-defined nanoparticles in supercritical carbon dioxide

Free-radical dispersion polymerisation of 2-hydroxyethyl methacrylate was carried out in supercritical carbon dioxide (scCO₂) in the presence of stabilisers based on polyethylene oxide (PEO) and poly(heptadecafluorodecyl acrylate) (PFDA). Different architectures of copolymers (random, palm-tree and diblock) were tested for their surface tension, cloud point and as a stabilising agent. The diblock architecture was found to be the best candidate resulting in poly(HEMA) spherical particles with a size of 316 nm. Furthermore, the effect of the CO₂-phobic block (PEO) in the diblock architecture was investigated by using three different chain lengths (1000, 2000, 5000 g mol^-1). By optimizing the stabiliser composition and structure, mild reaction conditions have been identified allowing us to obtain well-defined spherical cross-linked poly(HEMA) particles with a mean diameter of unprecedented low size (216 nm) at a temperature as low as 35 °C.