Combinatorial Library of Cyclic Benzylidene Acetal-Containing pH-Responsive Lipidoid Nanoparticles for Intracellular mRNA Delivery

Engineering aspects of lipid-based delivery systems: In vivo gene delivery, safety criteria, and translation strategies

Defects in the genome cause genetic diseases and can be treated with gene therapy. Due to the limitations encountered in gene delivery, lipid-based supramolecular colloidal materials have emerged as promising gene carrier systems. In their non-functionalized form, lipid nanoparticles often demonstrate lower transgene expression efficiency, leading to suboptimal therapeutic outcomes, specifically through reduced percentages of cells expressing the transgene. Due to chemically active substituents, the engineering of delivery systems for genetic drugs with specific chemical ligands steps forward as an innovative strategy to tackle the drawbacks and enhance their therapeutic efficacy. Despite intense investigations into functionalization strategies, the clinical outcome of such therapies still needs to be improved. Here, we highlight and comprehensively review engineering aspects for functionalizing lipid-based delivery systems and their therapeutic efficacy for developing novel genetic cargoes to provide a full snapshot of the translation from the bench to the clinics. We outline existing challenges in the delivery and internalization processes and narrate recent advances in the functionalization of lipid-based delivery systems for nucleic acids to enhance their therapeutic efficacy and safety. Moreover, we address clinical trials using these vectors to expand their clinical use and principal safety concerns.

DNA mechanocapsules for programmable piconewton responsive drug delivery

The mechanical dysregulation of cells is associated with a number of disease states, that spans from fibrosis to tumorigenesis. Hence, it is highly desirable to develop strategies to deliver drugs based on the "mechanical phenotype" of a cell. To achieve this goal, we report the development of DNA mechanocapsules (DMC) comprised of DNA tetrahedrons that are force responsive. Modeling shows the trajectory of force-induced DMC rupture and predicts how applied force spatial position and orientation tunes the force-response threshold. DMCs functionalized with adhesion ligands mechanically denature in vitro as a result of cell receptor forces. DMCs are designed to encapsulate macromolecular cargos such as dextran and oligonucleotide drugs with minimal cargo leakage and high nuclease resistance. Force-induced release and uptake of DMC cargo is validated using flow cytometry. Finally, we demonstrate force-induced mRNA knockdown of HIF-1α in a manner that is dependent on the magnitude of cellular traction forces. These results show that DMCs can be effectively used to target biophysical phenotypes which may find useful applications in immunology and cancer biology.

Stimuli-Responsive Nanotechnology for RNA Delivery

Ribonucleic acid (RNA) drugs have shown promising therapeutic effects for various diseases in clinical and preclinical studies, owing to their capability to regulate the expression of genes of interest or control protein synthesis. Different strategies, such as chemical modification, ligand conjugation, and nanotechnology, have contributed to the successful clinical translation of RNA medicine, including small interfering RNA (siRNA) for gene silencing and messenger RNA (mRNA) for vaccine development. Among these, nanotechnology can protect RNAs from enzymatic degradation, increase cellular uptake and cytosolic transportation, prolong systemic circulation, and improve tissue/cell targeting. Here, a focused overview of stimuli-responsive nanotechnologies for RNA delivery, which have shown unique benefits in promoting RNA bioactivity and cell/organ selectivity, is provided. Many tissue/cell-specific microenvironmental features, such as pH, enzyme, hypoxia, and redox, are utilized in designing internal stimuli-responsive RNA nanoparticles (NPs). In addition, external stimuli, such as light, magnetic field, and ultrasound, have also been used for controlling RNA release and transportation. This review summarizes a wide range of stimuli-responsive NP systems for RNA delivery, which may facilitate the development of next-generation RNA medicines.

Cellular Trafficking of Nanotechnology-Mediated mRNA Delivery

Messenger RNA (mRNA)-based therapy has emerged as a powerful, safe, and rapidly scalable therapeutic approach that involves technologies for both mRNA itself and the delivery vehicle. Although there are some unique challenges for different applications of mRNA therapy, a common challenge for all mRNA therapeutics is the transport of mRNA into the target cell cytoplasm for sufficient protein expression. This review is focused on the behaviors at the cellular level of nanotechnology-mediated mRNA delivery systems, which have not been comprehensively reviewed yet. First, the four main therapeutic applications of mRNA are introduced, including immunotherapy, protein replacement therapy, genome editing, and cellular reprogramming. Second, common types of mRNA cargos and mRNA delivery systems are summarized. Third, strategies to enhance mRNA delivery efficiency during the cellular trafficking process are highlighted, including accumulation to the cell, internalization into the cell, endosomal escape, release of mRNA from the nanocarrier, and translation of mRNA into protein. Finally, the challenges and opportunities for the development of nanotechnology-mediated mRNA delivery systems are presented. This review can provide new insights into the future fabrication of mRNA nanocarriers with desirable cellular trafficking performance.

Novel Vectors and Administrations for mRNA Delivery

mRNA therapy has shown great potential in infectious disease vaccines, cancer immunotherapy, protein replacement therapy, gene editing, and other fields due to its central role in all life processes. However, mRNA is challenging to pass through the cell membrane due to its significant negative charges and degradation from RNase, so the key to mRNA therapy is efficient packaging and delivery of it with appropriate vectors. Presently researchers have developed various vectors such as viruses and liposomes, but these conventional vectors are now difficult to meet the growing requirement like safety, efficiency, and targeting, so many novel delivery vectors with unique advantages have emerged recently. This review mainly introduces two categories of novel vectors: biomacromolecules and inorganic nanoparticles, as well as two novel methods of control and administration based on these novel vectors: controlled-release administration and non-invasive administration. These novel delivery strategies have the advantages of high safety, biocompatibility, versatility, intelligence, and targeting. This paper analyzes the challenges faced by the field of mRNA delivery in depth, and discusses how to use the characteristics of novel vectors and administrations to solve these problems.

Design of Cationic Lipids with Acetal Linkers: Conformational Preferences, Hydrolytic Stability, and High Drug-Loading Abilities

Lipids are key constituents of numerous biomedical drug delivery technologies. Here, we present the design, synthesis and biophysical characterizations of a library of cationic lipids containing an acetal residue in their linker region. These cationic acetal lipids (CALs) were conveniently prepared through a trans-acetalization protocol from commercially available precursors. NMR studies highlighted the conformational rigidity at the acetal residue and the high hydrolytic stability of these CALs. Fluorescence anisotropy studies revealed that the CAL with a pyridinium headgroup (CAL1) formed highly cohesive vesicular aggregates in water. These structural and self-assembly features of the CAL1 allowed up to 196 % w/w loading of curcumin (Cur) as a representative hydrophobic drug. A reconstitutable formulation of Cur was obtained as a result, which could deliver the drug inside mammalian cells with very high efficiency. The hemocompatibility and cytocompatibility of CAL1 was significantly enhanced by creating a coating of polydopamine (PDA) onto its vesicular assemblies to produce hybrid lipid-polymer nanocapsules. This work demonstrates rapid access to the useful synthetic lipid formulations with high potential in drug and gene delivery applications.

Nanomedicine based strategies for oligonucleotide traversion across the blood-brain barrier

Neurological disorders are considered the most prominent cause of disability worldwide. The major hurdle in the management of neurological disorders is the existence of the blood-brain barrier (BBB), which hinders the entry of several therapeutic moieties. In recent years, oligonucleotides have gained tremendous attention for their target specificity, diminished dose and adverse effects, thereby halting disease progression. However, enzymatic degradation, rapid clearance, limited circulation and availability at the bio-active site, etc., limit its clinical translation. Nanomedicine has opened up a breadth of opportunities in the delivery of oligonucleotides across the BBB. This review addresses the pitfalls associated with oligonucleotide delivery in traversing the BBB via nanotherapeutics for the management of brain disorders. Regulatory perspectives pertaining to hastening the clinical translation of oligonucleotide-loaded nanocarriers for brain delivery have been highlighted.

Multifunctional nanoparticle for cancer therapy

Cancer is a complex disease associated with a combination of abnormal physiological process and exhibiting dysfunctions in multiple systems. To provide effective treatment and diagnosis for cancer, current treatment strategies simultaneously focus on various tumor targets. Based on the rapid development of nanotechnology, nanocarriers have been shown to exhibit excellent potential for cancer therapy. Compared with nanoparticles with single functions, multifunctional nanoparticles are believed to be more aggressive and potent in the context of tumor targeting. However, the development of multifunctional nanoparticles is not simply an upgraded version of the original function, but involves a sophisticated system with a proper backbone, optimized modification sites, simple preparation method, and efficient function integration. Despite this, many well-designed multifunctional nanoparticles with promising therapeutic potential have emerged recently. Here, to give a detailed understanding and analyzation of the currently developed multifunctional nanoparticles, their platform structures with organic or inorganic backbones were systemically generalized. We emphasized on the functionalization and modification strategies, which provide additional functions to the nanoparticle. We also discussed the application combination strategies that were involved in the development of nanoformulations with functional crosstalk. This review thus provides an overview of the construction strategies and application advances of multifunctional nanoparticles.

Liposome triggered content release through molecular recognition of inositol trisphosphate

A stimuli-responsive liposomal platform that is selectively activated by inositol 1,4,5-trisphosphate (IP₃) over eleven other phosphorylated metabolites is reported. Dye release assays validated dose-dependent release of both hydrophilic and hydrophobic cargo driven by IP₃, showcasing the potential of this platform for triggered release and sensing applications.

Developing Biodegradable Lipid Nanoparticles for Intracellular mRNA Delivery and Genome Editing

Since the U.S. Food and Drug Administration (FDA) granted emergency use authorization for two mRNA vaccines against SARS-CoV-2, mRNA-based technology has attracted broad attention from the scientific community to investors. When delivered intracellularly, mRNA has the ability to produce various therapeutic proteins, enabling the treatment of a variety of illnesses, including but not limited to infectious diseases, cancers, and genetic diseases. Accordingly, mRNA holds significant therapeutic potential and provides a promising means to target historically hard-to-treat diseases. Current clinical efforts harnessing mRNA-based technology are focused on vaccination, cancer immunotherapy, protein replacement therapy, and genome editing. The clinical translation of mRNA-based technology has been made possible by leveraging nanoparticle delivery methods. However, the application of mRNA for therapeutic purposes is still challenged by the need for specific, efficient, and safe delivery systems.This Account highlights key advances in designing and developing combinatorial synthetic lipid nanoparticles (LNPs) with distinct chemical structures and properties for in vitro and in vivo intracellular mRNA delivery. LNPs represent the most advanced nonviral nanoparticle delivery systems that have been extensively investigated for nucleic acid delivery. The aforementioned COVID-19 mRNA vaccines and one LNP-based small interfering RNA (siRNA) drug (ONPATTRO) have received clinical approval from the FDA, highlighting the success of synthetic ionizable lipids for in vivo nucleic acid delivery. In this Account, we first summarize the research efforts from our group on the development of bioreducible and biodegradable LNPs by leveraging the combinatorial chemistry strategy, such as the Michael addition reaction, which allows us to easily generate a large set of lipidoids with diverse chemical structures. Next, we discuss the utilization of a library screening strategy to identify optimal LNPs for targeted mRNA delivery and showcase the applications of the optimized LNPs in cell engineering and genome editing. Finally, we outline key challenges to the clinical translation of mRNA-based therapies and propose an outlook for future directions of the chemical design and optimization of LNPs to improve the safety and specificity of mRNA drugs. We hope this Account provides insight into the rational design of LNPs for facilitating the development of mRNA therapeutics, a transformative technology that promises to revolutionize future medicine.

High-throughput screening of nanoparticles in drug delivery

The use of pharmacologically active compounds to manage and treat diseases is of utmost relevance in clinical practice. It is well recognized that spatial-temporal control over the delivery of these biomolecules will greatly impact their pharmacokinetic profile and ultimately their therapeutic effect. Nanoparticles (NPs) prepared from different materials have been tested successfully in the clinic for the delivery of several biomolecules including non-coding RNAs (siRNA and miRNA) and mRNAs. Indeed, the recent success of mRNA vaccines is in part due to progress in the delivery systems (NP based) that have been developed for many years. In most cases, the identification of the best formulation was done by testing a small number of novel formulations or by modification of pre-existing ones. Unfortunately, this is a low throughput and time-consuming process that hinders the identification of formulations with the highest potential. Alternatively, high-throughput combinatorial design of NP libraries may allow the rapid identification of formulations with the required release and cell/tissue targeting profile for a given application. Combinatorial approaches offer several advantages over conventional methods since they allow the incorporation of multiple components with varied chemical properties into materials, such as polymers or lipid-like materials, that will subsequently form NPs by self-assembly or chemical conjugation processes. The current review highlights the impact of high-throughput in the development of more efficient drug delivery systems with enhanced targeting and release kinetics. It also describes the current challenges in this research area as well as future directions.