Polymersomes in Drug Delivery─From Experiment to Computational Modeling

Applications of mRNA Delivery in Cancer Immunotherapy

Cancer treatment is continually advancing, with immunotherapy gaining prominence as a standard modality that has markedly improved the management of various malignancies. Despite these advancements, the efficacy of immunotherapy remains variable, with certain cancers exhibiting limited response and patient outcomes differing considerably. Thus, enhancing the effectiveness of immunotherapy is imperative. A promising avenue is mRNA delivery, employing carriers such as liposomes, peptide nanoparticles, inorganic nanoparticles, and exosomes to introduce mRNA cargos encoding tumor antigens, immune-stimulatory, or immune-modulatory molecules into the tumor immune microenvironment (TIME). This method aims to activate the immune system to target and eradicate tumor cells. In this review, we introduce the characteristics and limitations of these carriers and summarize the application and mechanisms of currently prevalent cargos in mRNA-based tumor treatment. Additionally, given the significant clinical application of immune checkpoint inhibitors (ICIs) and chimeric antigen receptor (CAR)-based cell therapies in solid tumors (including melanoma, non-small-cell lung cancer, head and neck squamous cell carcinoma, triple-negative breast cancer, gastric cancer) and leukemia, which have become first-line treatments, we highlight and discuss recent progress in combining mRNA delivery with ICIs, CAR-T, CAR-NK, and CAR-macrophage therapies. This combination enhances the targeting capabilities and efficacy of ICIs and CAR-cell-based therapies, while also mitigating the long-term off-target toxicities associated with conventional methods. Finally, we analyze the limitations of current mRNA delivery systems, such as nuclease-induced mRNA instability, immunogenicity risks, complex carrier production, and knowledge gaps concerning dosing and safety. Addressing these challenges is crucial for unlocking the potential of mRNA in cancer immunotherapy. Overall, exploring mRNA delivery enriches our comprehension of cancer immunotherapy and holds promise for developing personalized and effective treatment strategies, potentially enhancing the immune responses of cancer patients and extending their survival time.

Hallmarks of Polymersome Characterization

Polymersomes have the potential to become the next generation of vesicular drug delivery systems. Their high chemical versatility and in certain cases higher membrane stability than liposomes raised the high hopes for polymersomes as a drug carrier, but the clinical translation has been slow. To jump-start translation, there is a need for meticulous characterization and reporting of key parameters of polymersome formulations. Regulatory authorities have provided valuable insights on critical quality attributes of liposomes in their guidance document on liposomal nanosimilars. Inspired by this guidance document, this Perspective proposes necessary characterization of polymersomes (hallmarks) regarding their chemical composition, physicochemical properties, drug release profile, stability, stimuli responsiveness, and pharmacokinetics and biodistribution.

Benchmark of Coacervate Formation and Mechanism Exploration Using the Martini Force Field

Peptide-based coacervates are crucial for drug delivery due to their biocompatibility, versatility, high drug loading capacity, and cell penetration rates; however, their stability mechanism and phase behavior are not fully understood. Additionally, although Martini is one of the most famous force fields capable of describing coacervate formation with molecular details, a comprehensive benchmark of its accuracy has not been conducted. This research utilized the Martini 3.0 force field and machine learning algorithms to explore representative peptide-based coacervates, including those composed of polyaspartate (PAsp)/polyarginine (PArg), rmfp-1, sticker-and-spacer small molecules, and HBpep molecules. We identified key coacervate formation driving forces such as Coulomb, cation-π, and π-π interactions and established three criteria for determining coacervate formation in simulations. The results also indicate that while Martini 3.0 accurately captures coacervate formation trends, it tends to underestimate Coulomb interactions and overestimate π-π interactions. What is more, our study on drug encapsulation of HBpep and its derivative coacervates suggested that most loaded drugs were distributed on surfaces of HBpep clusters, awaiting experimental validation. This study employs simulation to enhance understanding of peptide-based coacervate phase behavior and stability mechanisms while also benchmarking Martini 3.0, thereby providing fundamental insights for future experimental and simulation investigations.

Composition Conversion-Induced Disassembly of Amphiphilic ABA Triblock Copolymer Vesicles: A Monte Carlo Study

The composition conversion in block copolymer induced by external stimuli such as light and pH is an effective strategy to trigger the disassembly of vesicles experimentally. Based on this strategy, the disassembly behavior of the A2B12A2 triblock copolymer vesicle induced by the composition conversion from B block to C block was studied using Monte Carlo simulation. In this study, a part of the B block in the A2B12A2 triblock copolymer was converted to the new block C with weaker hydrophobicity, forming the A2B12-nCnA2 tetrablock copolymer. The composition conversion makes the originally stable vesicle unstable, and after sufficiently long simulation time, the system reached a new equilibrium state. The aggregate morphology of the new equilibrium state was highly dependent on the converted chain length (n). A variety of micelles with novel Janus-type phase-separated microstructures in their hydrophobic parts have been observed in the systems with different n. It should be noticed that those Janus-type micelles cannot be obtained via traditional self-assembly processes from homogeneous states of A2B12-nCnA2 tetrablock copolymers under the same conditions. The simulation results further indicated that the morphological transformation from ABA vesicle to ABCA micelles induced by the composition conversion is reversible.

Advances of Stimuli-Responsive Amphiphilic Copolymer Micelles in Tumor Therapy

Amphiphilic copolymers are composed of both hydrophilic and hydrophobic chains, which can self-assemble into polymeric micelles in aqueous solution via the hydrophilic/hydrophobic interactions. Due to their unique properties, polymeric micelles have been widely used as drug carriers. Poorly soluble drugs can be covalently attached to polymer chains or non-covalently incorporated in the micelles, with improved pharmacokinetic profiles and enhanced efficacy. In recent years, stimuli-responsive amphiphilic copolymer micelles have attracted significant attention. These micelles can respond to specific stimuli, including physical triggers (light, temperature, etc). chemical stimuli (pH, redox, etc). and physiological factors (enzymes, ATP, etc). Under these stimuli, the structures or properties of the micelles can change, enabling targeted therapy and controlled drug release in tumors. These stimuli-responsive strategies offer new avenues and approaches to enhance the tumor efficacy and reduce drug side effects. We will review the applications of different types of stimuli-responsive amphiphilic copolymer micelles in tumor therapy, aiming to provide valuable guidance for future research directions and clinical translation.

Dynamics of Amphiphilic Poly(ε-Caprolactone) Micelles with Doxorubicin and Transition Temperature Predictions Using All-Atom Molecular Dynamics Simulation

Despite the advent of novel therapeutics, the efficient delivery of antineoplastic drugs remains a challenge. Biodegradable polymeric micelles represent a promising frontier by offering enhanced drug solubility, tumor targeting, and controlled release profiles. However, the underlying dynamics governing the drug encapsulation and solvation within these micellar structures is still vague and poorly understood. In this study, we used amphiphilic poly(γ-benzyloxy-ε-caprolactone)-b-poly(γ-2-[2-(2-methoxy ethoxy)ethoxy]ethoxy-ε-caprolactone) as a model copolymer with doxorubicin as a model drug and performed all-atom molecular dynamics simulations to understand the regulating mechanism of the encapsulation process. The results are in good agreement with the experimental results. In addition, we interpreted the dynamic behavior of the polymeric micelles and vital intermolecular interactions that play a key role in drug encapsulation. Our study provides a theoretical approach to obtain insights for designing and enhancing novel anticancer drug carriers for therapeutics.

Toward the Integration of Machine Learning and Molecular Modeling for Designing Drug Delivery Nanocarriers

The pioneering work on liposomes in the 1960s and subsequent research in controlled drug release systems significantly advances the development of nanocarriers (NCs) for drug delivery. This field is evolved to include a diverse array of nanocarriers such as liposomes, polymeric nanoparticles, dendrimers, and more, each tailored to specific therapeutic applications. Despite significant achievements, the clinical translation of nanocarriers is limited, primarily due to the low efficiency of drug delivery and an incomplete understanding of nanocarrier interactions with biological systems. Addressing these challenges requires interdisciplinary collaboration and a deep understanding of the nano-bio interface. To enhance nanocarrier design, scientists employ both physics-based and data-driven models. Physics-based models provide detailed insights into chemical reactions and interactions at atomic and molecular scales, while data-driven models leverage machine learning to analyze large datasets and uncover hidden mechanisms. The integration of these models presents challenges such as harmonizing different modeling approaches and ensuring model validation and generalization across biological systems. However, this integration is crucial for developing effective and targeted nanocarrier systems. By integrating these approaches with enhanced data infrastructure, explainable AI, computational advances, and machine learning potentials, researchers can develop innovative nanomedicine solutions, ultimately improving therapeutic outcomes.

Recent Advances in Cyclodextrin-Based Nanoscale Drug Delivery Systems

Cyclodextrins (CDs) belong to a class of cyclic oligosaccharides characterized by their toroidal shape consisting of glucose units linked via α-1,4-glycosidic bonds. This distinctive toroidal shape exhibits a dual nature, comprising a hydrophobic interior and a hydrophilic exterior, making CDs highly versatile in various pharmaceutical products. They serve multiple roles: they act as solubilizers, stabilizers, controlled release promoters, enhancers of drug bioavailability, and effective means of masking undesirable tastes and odors. Taking advantage of these inherent benefits, CDs have been integrated into numerous nanoscale drug delivery systems. The resulting nanomaterials exploit the exceptional properties of CDs, including their ability to solubilize hydrophobic drugs for substantial drug loading, engage in supramolecular complexation for engineered nanomaterials, increase bioavailability for improved therapeutic efficacy, stabilize labile drugs, and exhibit biocompatibility and versatility. This paper compiles recent studies on CD functional nanoscale drug delivery platforms. First, we described the physicochemical and toxicological aspects of CDs, CD/drug inclusion complexation, and their impact on improving drug bioavailability. We then summarized applications for CD-functional nano delivery systems based on polymeric, hybrid, lipid-based nanoparticles, and CD-based nanofibers. Particular interest was in the targeted applications and the function of the CD molecules used. In most applications, CD molecules were used for drug solubilization and loading, while in some studies, CD molecules were employed for supramolecular complexation to construct nanoscale drug delivery systems. Finally, the review concludes with a thoughtful consideration of the current challenges and outlook.

Polymersomes as Innovative, Stimuli-Responsive Platforms for Cancer Therapy

This review addresses the urgent need for more targeted and less toxic cancer treatments by exploring the potential of multi-responsive polymersomes. These advanced nanocarriers are engineered to deliver drugs precisely to tumor sites by responding to specific stimuli such as pH, temperature, light, hypoxia, and redox conditions, thereby minimizing the side effects associated with traditional chemotherapy. We discuss the design, synthesis, and recent applications of polymersomes, emphasizing their ability to improve therapeutic outcomes through controlled drug release and targeted delivery. Moreover, we highlight the critical areas for future research, including the optimization of polymersome-biological interactions and biocompatibility, to facilitate their clinical adoption. Multi-responsive polymersomes emerge as a promising development in nanomedicine, offering a pathway to safer and more effective cancer treatments.

Nanoparticle-Based Immunotherapy for Reversing T-Cell Exhaustion

T-cell exhaustion refers to a state of T-cell dysfunction commonly observed in chronic infections and cancer. Immune checkpoint molecules blockading using PD-1 and TIM-3 antibodies have shown promising results in reversing exhaustion, but this approach has several limitations. The treatment of T-cell exhaustion is still facing great challenges, making it imperative to explore new therapeutic strategies. With the development of nanotechnology, nanoparticles have successfully been applied as drug carriers and delivery systems in the treatment of cancer and infectious diseases. Furthermore, nanoparticle-based immunotherapy has emerged as a crucial approach to reverse exhaustion. Here, we have compiled the latest advances in T-cell exhaustion, with a particular focus on the characteristics of exhaustion that can be targeted. Additionally, the emerging nanoparticle-based delivery systems were also reviewed. Moreover, we have discussed, in detail, nanoparticle-based immunotherapies that aim to reverse exhaustion, including targeting immune checkpoint blockades, remodeling the tumor microenvironment, and targeting the metabolism of exhausted T cells, etc. These data could aid in comprehending the immunopathogenesis of exhaustion and accomplishing the objective of preventing and treating chronic diseases or cancer.