Nanoprecipitation of polymeric nanoparticle micelles based on 2-methacryloyloxyethyl phosphorylcholine (MPC) with 2-(diisopropylamino)ethyl methacrylate (DPA), for intracellular delivery applications

HSA-nanobinders crafted from bioresponsive prodrugs for combined cancer chemoimmunotherapy-an in vitro exploration

Introduction

Triple-negative breast cancer (TNBC) is an aggressive subtype of breast cancer still lacking effective treatment options. Chemotherapy in combination with immunotherapy can restrict tumor progression and repolarize the tumor microenvironment towards an anti-tumor milieu, improving clinical outcome in TNBC patients. The chemotherapeutic drug paclitaxel has been shown to induce immunogenic cell death (ICD), whereas inhibitors of the indoleamine 2,3- dioxygenase 1 (IDO1) enzyme, whose expression is shared in immune regulatory and tumor cells, have been revealed to enhance the anti-tumor immune response. However, poor bioavailability and pharmacokinetics, off-target effects and hurdles in achieving therapeutic drug concentrations at the target tissue often limit the effectiveness of combination therapies.

Methods

This work describes the development of novel biomimetic and carrier-free nanobinders (NBs) loaded with both paclitaxel and the IDO1 inhibitor NLG919 in the form of bioresponsive and biomimetic prodrugs. A fine tuning of the preparation conditions allowed to identify NB@5 as the most suitable nanoformulation in terms of reproducibility, stability and in vitro effectiveness.

Results and discussion

Our data show that NB@5 effectively binds to HSA in cell-free experiments, demonstrating its protective role in the controlled release of drugs and suggesting the potential to exploit the protein as the endogenous vehicle for targeted delivery to the tumor site. Our study successfully proves that the drugs encapsulated within the NBs are preferentially released under the altered redox conditions commonly found in the tumor microenvironment, thereby inducing cell death, promoting ICD, and inhibiting IDO1.

Self-assembled block copolymer biomaterials for oral delivery of protein therapeutics

Protein therapeutics have guided a transformation in disease treatment for various clinical conditions. They have been successful in numerous applications, but administration of protein therapeutics has been limited to parenteral routes which can decrease patient compliance as they are invasive and painful. In recent years, the synergistic relationship of novel biomaterials with modern protein therapeutics has been crucial in the treatment of diseases that were once thought of as incurable. This has guided the development of a variety of alternative administration routes, but the oral delivery of therapeutics remains one of the most desirable due to its ease of administration. This review addresses important aspects of micellar structures prepared by self-assembled processes with applications for oral delivery. These two characteristics have not been placed together in previous literature within the field. Therefore, we describe the barriers for delivery of protein therapeutics, and we concentrate in the oral/transmucosal pathway where drug carriers must overcome several chemical, physical, and biological barriers to achieve a successful therapeutic effect. We critically discuss recent research on biomaterials systems for delivering such therapeutics with an emphasis on self-assembled synthetic block copolymers. Polymerization methods and nanoparticle preparation techniques are similarly analyzed as well as relevant work in this area. Based on our own and others' research, we analyze the use of block copolymers as therapeutic carriers and their promise in treating a variety of diseases, with emphasis on self-assembled micelles for the next generation of oral protein therapeutic systems.

Bio-Inspired Nanocarriers Derived from Stem Cells and Their Extracellular Vesicles for Targeted Drug Delivery

With their seemingly limitless capacity for self-improvement, stem cells have a wide range of potential uses in the medical field. Stem-cell-secreted extracellular vesicles (EVs), as paracrine components of stem cells, are natural nanoscale particles that transport a variety of biological molecules and facilitate cell-to-cell communication which have been also widely used for targeted drug delivery. These nanocarriers exhibit inherent advantages, such as strong cell or tissue targeting and low immunogenicity, which synthetic nanocarriers lack. However, despite the tremendous therapeutic potential of stem cells and EVs, their further clinical application is still limited by low yield and a lack of standardized isolation and purification protocols. In recent years, inspired by the concept of biomimetics, a new approach to biomimetic nanocarriers for drug delivery has been developed through combining nanotechnology and bioengineering. This article reviews the application of biomimetic nanocarriers derived from stem cells and their EVs in targeted drug delivery and discusses their advantages and challenges in order to stimulate future research.

Redox-Responsive Core-Cross-Linked Micelles of Miktoarm Poly(ethylene oxide)-b-poly(furfuryl methacrylate) for Anticancer Drug Delivery

The physiological instability of nanocarriers, premature drug leakage during blood circulation, and associated severe side effects cause compromised therapeutic efficacy, which have significantly hampered the progress of nanomedicines. The cross-linking of nanocarriers while keeping the effectiveness of their degradation at the targeted site to release the drug has emerged as a potent strategy to overcome these flaws. Herein, we have designed novel (poly(ethylene oxide))₂-b-poly(furfuryl methacrylate) ((PEO_2K)₂-b-PFMA_nk) miktoarm amphiphilic block copolymers by coupling alkyne-functionalized PEO (PEO_2K-C≡H) and diazide-functionalized poly(furfuryl methacrylate) ((N₃)₂-PFMA_nk) via click chemistry. (PEO_2K)₂-b-PFMA_nk self-assembled to form nanosized micelles (mikUCL) with hydrodynamic radii in the range of 25∼33 nm. The hydrophobic core of mikUCL was cross-linked by a disulfide-containing cross-linker using the Diels-Alder reaction to avoid unwanted leakage and burst release of a payload. As expected, the resulting core-cross-linked (PEO_2K)₂-b-PFMA_nk micelles (mikCCL) exhibited superior stability under a normal physiological environment and were de-cross-linked to rapidly release doxorubicin (DOX) upon exposure to a reduction environment. The micelles were compatible with HEK-293 normal cells, while DOX-loaded micelles (mikUCL/DOX and mikCCL/DOX) induced high antitumor activity in HeLa and HT-29 cells. mikCCL/DOX preferentially accumulated at the tumor site and was more efficacious than free DOX and mikUCL/DOX for tumor inhibition in HT-29 tumor-bearing nude mice.

Advances in the Study of Exosomes as Drug Delivery Systems for Bone-Related Diseases

Bone-related diseases are major problems and heavy burdens faced by modern society. Current clinical approaches for the treatment of these pathological conditions often lead to complications and have limited therapeutic efficacy. In this context, the development of nanotherapeutic platforms, such as extracellular vesicles, can improve the relevant therapeutic effects. In particular, exosomes are nano-sized, lipid bilayer extracellular vesicles secreted by many cells in mammals. Due to their innate capacity to transport materials-including proteins, lipids, and genes-among cells, as well as their innate attraction to target cells, they are considered to be a crucial medium for cell communication and are involved in a number of biological processes. Exosomes have been used as drug delivery vehicles in recent bone tissue engineering studies, in order to regulate bone homeostasis. However, the precise workings of the exosome regulatory network in maintaining bone homeostasis and its potential for treating bone injury remain unclear. To provide a fresh perspective for the study of exosomes in drug delivery and bone-related diseases, in this paper, we review recent studies on the roles of exosomes for drug delivery in bone homeostasis and bone-related diseases, as well as the composition and characteristics of exosomes and their regulatory roles in bone homeostasis and bone-related diseases, aiming to provide new ideas for the therapeutic application of exosomes in the treatment of bone-related diseases.

Strategies to deliver RNA by nanoparticles for therapeutic potential

The use of a variety of RNA molecules, including messenger RNA, small interfering RNA, and microRNA, has shown great potential for prevention and therapy of many pathologies. However, this therapeutic promise has historically been limited by short in vivo half-life, lack of targeted delivery, and safety issues. Nanoparticle (NP)-mediated delivery has been a successful platform to overcome these limitations, with multiple formulations already in clinical trials and approved by the FDA. Although there is a diversity of NPs in terms of material formulation, size, shape, and charge that have been proposed for biomedical applications, specific modifications are required to facilitate sufficient RNA delivery and adequate therapeutic effect. This includes optimization of (i) RNA incorporation into NPs, (ii) specific cell targeting, (iii) cellular uptake and (iv) endosomal escape ability. In this review, we summarize the methods by which NPs can be modified for RNA delivery to achieve optimal therapeutic effects.

Development and evaluation of polymeric micelle containing tablet formulation for poorly water-soluble drug: tamoxifen citrate

Poor aqueous solubility is one of the key reasons for slow dissolution rate and poor intestinal absorption and finally that causes low therapeutic efficacy of many existing drugs. Tamoxifen citrate (TMX) (BCS Class II drug) with low water solubility has poor oral bioavailability in the range of 20%-30%, therefore, high doses are required for treatment with TMX. Self-assemblage of amphiphilic polymers leads to the formation of polymeric micelles which makes them unique nano-carriers with excellent biocompatibility, low toxicity, enhanced blood circulation time, and solubilization of poorly water-soluble drugs. In this study poly(ethylene glycol)-block-poly(propylene glycol)-block-poly(ethylene glycol) triblock copolymer, which has been approved by FDA for oral application was used to benefit its micellar solubilization effect. Self-assembled micelles were prepared for the delivery of TMX and this way TMX solubility was increased approximately 60 times. TMX-treated cells showed 38.06 ± 1.5% viability at 50 µM concentration for 24 h; 66.71 ± 11.6% viability at 25 µM concentration for 48 h, at the same conditions TMX-loaded micelles exhibited 24.994 ± 0.25% and 43.36 ± 4.37% cell viability, respectively (p < 0.05). These results showed that the encapsulation of TMX into PEG-PPG-PEG micelles facilitated the cellular uptake, which led to an increased cytotoxicity in MCF-7 cancer cells. Tablet formulation containing lyophilized TMX-loaded micelles was showed an improved dissolution than commercial TMX tablet (Tamoxifen^® TEVA). It can be reasonably expected that the obtained drug dissolution rate and increased cytotoxicity to tumor cells will result in an increase of TMX bioavailability and tolerability associated with an important dose reduction and decreased side effects.

Controlled Dye Aggregation in Sodium Dodecylsulfate-Stabilized Poly(methylmethacrylate) Nanoparticles as Fluorescent Imaging Probes

Polymer nanoparticles are used extensively in biomedical applications. Poly(methylmethacrylate) (PMMA) nanoparticles obtained via nanoprecipitation were unstable and flocculate or precipitate from solution within a few hours. A simple method to improve the stability of the particles using surfactants at low concentrations was carried out to produce PMMA nanoparticles with long-term stability in water (>6 months). The increased stability was attributed to the incorporation of surfactants inside the polymer particles during nanoprecipitation. The same methodology was also adopted to encapsulate a highly fluorescent hydrophobic perylene tetraester inside the polymer nanoparticles with good stability in water. Because of the presence of the anionic sodium dodecyl sulfate, the particles showed a negative zeta potential of -34.7 mV and an average size of 150 nm. Similarly, the dye-encapsulated polymer nanoparticles showed a zeta potential of -35.1 mV and an average particle size of 180 nm. By varying the concentration of encapsulated dyes inside the polymer nanoparticles, dye aggregation could be controlled, and the fluorescence profiles of the nanoparticles were altered. To understand the uptake and toxicity of the polymer nanoparticles, baby hamster kidney cells were chosen as a model system. The polymer nanoparticles were taken up by the cells within 3 h and were nontoxic at concentrations as high as 100 ppm. The confocal micrographs of the cells revealed localized fluorescence from the polymer nanoparticles around the nucleus in the cytoplasm without the penetration of the nuclear envelope.

Nanostructured DPA-MPC-DPA triblock copolymer gel for controlled drug release of ketoprofen and spironolactone

OBJECTIVE

Uncontrolled rapid release of drugs can reduce their therapeutic efficacy and cause undesirable toxicity; however, controlled release from reservoir materials helps overcome this issue. The aims of this study were to determine the release profiles of ketoprofen and spironolactone from a pH-responsive self-assembling DPA-MPC-DPA triblock copolymer gel and elucidate underlying physiochemical properties.

METHODS

Drug release profiles from DPA₅₀ -MPC₂₅₀ -DPA₅₀ gel (pH 7.5), over 32 h (37 °C), were determined using UV-Vis spectroscopy. Nanoparticle size was measured by dynamic light scattering (DLS) and critical micelle concentration (CMC) by pyrene fluorescence. Polymer gel viscosity was examined via rheology, nanoparticle morphology investigated using scanning transmission electron microscopy (STEM) and the gel matrix observed using cryo-scanning electron microscopy (Cryo-SEM).

KEY FINDINGS

DPA₅₀ -MPC₂₅₀ -DPA₅₀ copolymer (15% w/v) formed a free-standing gel (pH 7.5) that controlled drug release relative to free drugs. The copolymer possessed a low CMC, nanoparticle size increased with copolymer concentration, and DLS data were consistent with STEM. The gel displayed thermostable viscosity at physiological temperatures, and the gel matrix was a nanostructured aggregation of smaller nanoparticles.

CONCLUSIONS

The DPA₅₀ -MPC₂₅₀ -DPA₅₀ copolymer gel could be used as a drug delivery system to provide the controlled drug release of ketoprofen and spironolactone.