Cationic cholesterol-dependent LNP delivery to lung stem cells, the liver, and heart

Advancing cancer gene therapy: the emerging role of nanoparticle delivery systems

Gene therapy holds immense potential due to its ability to precisely target oncogenes, making it a promising strategy for cancer treatment. Advances in genetic science and bioinformatics have expanded the applications of gene delivery technologies beyond detection and diagnosis to potential therapeutic interventions. However, traditional gene therapy faces significant challenges, including limited therapeutic efficacy and the rapid degradation of genetic materials in vivo. To address these limitations, multifunctional nanoparticles have been engineered to encapsulate and protect genetic materials, enhancing their stability and therapeutic effectiveness. Nanoparticles are being extensively explored for their ability to deliver various genetic payloads-including plasmid DNA, messenger RNA, and small interfering RNA-directly to cancer cells. This review highlights key gene modulation strategies such as RNA interference, gene editing systems, and chimeric antigen receptor (CAR) technologies, alongside a diverse array of nanoscale delivery systems composed of polymers, lipids, and inorganic materials. These nanoparticle-based delivery platforms aim to improve targeted transport of genetic material into cancer cells, ultimately enhancing the efficacy of cancer therapies.

Tailoring Alkyl Side Chains of Ionizable Amino-Polyesters for Enhanced In Vivo mRNA Delivery

Lipid nanoparticles (LNPs) containing ionizable lipids are the most clinically advanced platform for mRNA delivery, but their application beyond the liver remains challenging. Polymer-lipid hybrid nanoparticles offer a promising alternative, combining the synthetic versatility and unique properties of polymers with the biocompatibility of lipid excipients. While the significance of alkyl tail design is well-recognized for ionizable lipids, the impact of the polymer side chain composition on interactions with lipid excipients, mRNA delivery efficacy, and tissue specificity remains poorly understood. Here, we focus on a class of ionizable amino-polyesters (APEs) that exhibit features desired for potential clinical applications, including narrow molecular weight distribution and a good safety profile, and investigate the effect of polymer side chain composition on the formulation of APE lipid nanoparticles (APE-LNPs) for mRNA delivery. A library of 36 APEs was synthesized via ring-opening polymerization of chemically diverse tertiary amino-alcohols and lactone monomers with distinct alkyl side chain compositions, including variations in length and unsaturation. We show that optimal alkyl side chain length is critical for the assembly of stable mRNA nanoparticles and efficient mRNA delivery both in vitro and in vivo. Top-performing APE-LNPs display superior delivery efficacy in vitro and in extrahepatic tissues compared to benchmark LNPs, including DLin-MC3-DMA ionizable lipid. The polymer chain composition affects the tissue selectivity of APE-LNPs, with shorter side chains (4-5 carbons) effectively targeting the spleen and lungs, while longer chains (7-9 carbons) show enhanced liver delivery. We also explored the relevance of lipid excipients in APE-LNPs, demonstrating the essential role of unsaturated phospholipids in enhancing cellular uptake and mRNA delivery, and the limited relevance of cholesterol. These findings provide valuable insights into the design of polymers for use in the LNP context, which could aid the development of polymeric alternatives to ionizable lipids and expand the utility of mRNA LNP technology to nonliver tissues.

More than a delivery system: the evolving role of lipid-based nanoparticles

Lipid-based nanoparticles, including liposomes and lipid nanoparticles (LNPs), make up an important class of drug delivery systems. Their modularity enables encapsulation of a wide range of therapeutic cargoes, their ease of functionalization allows for incorporation of targeting motifs and anti-fouling coatings, and their scalability facilitates rapid translation to the clinic. While the discovery and early understanding of lipid-based nanoparticles is heavily rooted in biology, formulation development has largely focused on materials properties, such as how liposome and lipid nanoparticle composition can be altered to maximize drug loading, stability and circulation. To achieve targeted delivery and enable improved accumulation of therapeutics at target tissues or disease sites, emphasis is typically placed on the use of external modifications, such as peptide, protein, and polymer motifs. However, these approaches can increase the complexity of the nanocarrier and complicate scale up. In this review, we focus on how our understanding of lipid structure and function in biological contexts can be used to design intrinsically functional and targeted nanocarriers. We highlight formulation-based strategies, such as the incorporation of bioactive lipids, that have been used to modulate liposome and lipid nanoparticle properties and improve their functionality while retaining simple nanocarrier designs. We also highlight classes of naturally occurring lipids, their functions, and how they have been incorporated into lipid-based nanoparticles. We will additionally position these approaches into the historical context of both liposome and LNP development.

Effective transcatheter intracoronary delivery of mRNA-lipid nanoparticles targeting the heart

Messenger RNA (mRNA) has great potential to provide innovative medical solutions in the treatment of heart failure. Although lipid nanoparticles (LNPs) are an established mRNA delivery system, effectively delivering LNPs to the heart remains a significant challenge. Here, we evaluated the efficacy of transcatheter intracoronary (IC) administration compared to intravenous (IV) and intramyocardial (IM) administration in normal and ischemia-reperfusion (I/R) model rabbit hearts using LNPs encapsulating Firefly Luciferase (FLuc) mRNA. In the normal model, IVIS spectrum data showed that FLuc expression was widespread throughout the heart in the IC group and was significantly higher than in the IV group, and comparable to the IM group, where it was highly expressed only at the injection sites. Histological analysis revealed that FLuc-expressing cells were observed in cardiomyocytes, endothelial cells, smooth muscle cells, and fibroblasts. In the I/R model, FLuc expression was also significantly higher in the IC group than the IV group, and comparable to the IM group. Although FLuc expression was strongly observed in the infarct area in all three delivery groups, the IC group demonstrated the most widespread FLuc expression in the remote area. Histological analysis revealed significantly higher FLuc-expressing cells in the remote area in the IC group than in the other groups. IC administration effectively delivered mRNA-LNPs not only to the infarct area (damaged area) but also to the remote area (non-damaged area) in the diseased heart. Moreover, VEGF mRNA-LNP administration via the IC method to I/R model rabbit hearts significantly reduced the infarct area and attenuated the impairment of cardiac function caused by I/R injury compared to the other methods. Considering the invasiveness and clinically limited applications of IM administration, our study suggests that less invasive IC administration is a clinically safe and useful method for mRNA-LNP delivery to a wider range of myocardial tissue in the heart.

A Versatile Strategy to Transform Cationic Polymers for Efficient and Organ-Selective mRNA Delivery

The progress of mRNA therapeutics underscores the imperative demand for the development of targeted delivery systems. While cationic polymers hold promise as genetic vectors, their poor in vivo efficacy and numerous variants highlight the urgent need for a universal functionalization strategy to bolster their delivery capabilities. Here, we present a versatile strategy to transform low-cost commercial cationic polymers into phospholipidated and alkylated polymers (PAPs), enabling efficient and organ-selective mRNA delivery in vivo. This straightforward post-functionalization method can be readily broadened to a diverse array of existing cationic polymers, enhancing their cellular uptake, endosomal escape, and mRNA release functionalities. Consequently, PAPs facilitate up to 30,500-fold higher mRNA expression compared to their unmodified counterparts in vivo. Notably, the one-component PAPs enable spleen-specific mRNA delivery, with their vaccine application validated in a mouse melanoma model following intravenous administration. Better still, PAPs can synergize with different helper lipids to formulate four-component lipid nanoparticles (LNPs), achieving respective lung- and liver-specific mRNA delivery. Noteworthy is that these organ-selective mRNA delivery systems significantly outperform previous polymer and LNP benchmarks. This transformation strategy for cationic polymers represents a generalized methodology to give highly effective mRNA carriers, highlighting substantial potential for clinical translation of mRNA therapies with organ-targeting requirements.

Nanoparticle delivery of a prodrug-activating bacterial enzyme leads to anti-tumor responses

Most cancer patients diagnosed with late-stage head and neck squamous cell carcinoma are treated with chemoradiotherapy, which can lead to toxicity. One potential alternative is tumor-limited conversion of a prodrug into its cytotoxic form. We reason this could be achieved by transient and tumor-specific expression of purine nucleoside phosphorylase (PNP), an Escherichia coli enzyme that converts fludarabine into 2-fluoroadenine, a potent cytotoxic drug. To efficiently express bacterial PNP in tumors, we evaluate 44 chemically distinct lipid nanoparticles (LNPs) using species-agnostic DNA barcoding in tumor-bearing mice. Our lead LNP, designated LNP intratumoral (LNPIT), delivers mRNA that leads to PNP expression in vivo. Additionally, in tumor cells transfected with LNPIT, we observe upregulated pathways related to RNA and protein metabolism, providing insight into the tumor cell response to LNPs in vivo. When mice are treated with LNPIT-PNP, then subsequently given fludarabine phosphate, we observe anti-tumor responses. These data are consistent with an approach in which LNP-mRNA expression of a bacterial enzyme activates a prodrug in solid tumors.

Lung-Specific mRNA Delivery by Ionizable Lipids with Defined Structure-Function Relationship and Unique Protein Corona Feature

Targeted delivery of mRNA with lipid nanoparticles (LNPs) holds great potential for treating pulmonary diseases. However, the lack of rational design principles for efficient lung-homing lipids hinders the prevalence of mRNA therapeutics in this organ. Herein, the combinatorial screening with structure-function analysis is applied to rationalize the design strategy for nonpermanently charged lung-targeted ionizable lipids. It is discovered that lipids carrying N-methyl and secondary amine groups in the heads, and three tails originated from epoxyalkanes, exhibiting superior pulmonary selectivity and efficiency. Representative ionizable lipids with systematically variation in chemical structures are selected to study the well-known but still puzzling "protein corona" adsorbed on the surface of LNPs. In addition to the commonly used corona-biomarker vitronectin, other arginine-glycine-aspartic acid (RGD)-rich proteins usually involved in collagen-containing extracellular matrix, such as fibrinogen and fibronectin have also been identified to have a strong correlation with lung tropism. This work provides insight into the rational design of lung-targeting ionizable lipids and reveals a previously unreported potential function of RGD-rich proteins in the protein corona of lung-homing LNPs.

The Interplay of Endosomal Escape and RNA Release from Polymeric Nanoparticles

Ribonucleic acid (RNA) nanocarriers, specifically lipid nanoparticles and polymeric nanoparticles, enable RNA transfection both in vitro and in vivo; however, only a small percentage of RNA endocytosed by a cell is delivered to the cytosolic machinery, minimizing its effect. RNA nanocarriers face two major obstacles after endocytosis: endosomal escape and RNA release. Overcoming both obstacles simultaneously is challenging because endosomal escape is usually achieved by using high positive charge to disrupt the endosomal membrane. However, this high positive charge typically also inhibits RNA release because anionic RNA is strongly bound to the nanocarrier by electrostatic interactions. Many nanocarriers address one over the other despite a growing body of evidence demonstrating that both are crucial for RNA transfection. In this review, we survey the various strategies that have been employed to accomplish both endosomal escape and RNA release with a focus on polymeric nanomaterials. We first consider the various requirements a nanocarrier must achieve for RNA delivery including protection from degradation, cellular internalization, endosomal escape, and RNA release. We then discuss current polymers used for RNA delivery and examine the strategies for achieving both endosomal escape and RNA release. Finally, we review various stimuli-responsive strategies for RNA release. While RNA release continues to be a challenge in achieving efficient RNA transfection, many new innovations in polymeric materials have elucidated promising strategies.

Bioinspired Spatially Ordered Multicellular Lobules for Liver Regeneration

Cell therapy is a promising strategy for acute liver failure (ALF), while its therapeutic efficacy is often limited by cell loss and poor arrangement. Here, inspired by liver microunits, we propose a novel spatially ordered multicellular lobules for the ALF treatment by using a microfluidic continuous spinning technology. The microfluidics with multiple microchannels was constructed by assembling parallel capillaries. Sodium alginate (Alg) solution encapsulating human umbilical vein endothelial cells (HUVECs), hepatocytes, and mesenchymal stem cells (MSCs) are introduced into the middle channel and the 6 parallel outer channels of the microfluidics, respectively. Simultaneously, Ca2+-loaded solutions are pumped through the innermost and outermost channels, forming a hollow microfiber with hepatocytes and MSCs alternately surrounding the HUVECs. These microfibers could highly resemble the cord-like structure of liver lobules, bringing about outstanding liver-like functions. We have demonstrated that in ALF rats, our biomimetic lobules can effectively suppress excessive inflammatory responses, decrease cell necrosis, and promote regenerative pathways, leading to satisfied therapeutic efficacy. These findings underscore the potential of spatially ordered multicellular microfibers in treating related diseases and improving traditional clinical methods.

Why do lipid nanoparticles target the liver? Understanding of biodistribution and liver-specific tropism

Lipid nanoparticles (LNPs) are now highly effective transporters of nucleic acids to the liver. This liver-specificity is largely due to their association with certain serum proteins, most notably apolipoprotein E (ApoE), which directs them to liver cells by binding to the low-density lipoprotein (LDL) receptors on hepatocytes. The liver's distinct anatomy, with its various specialized cell types, also influences how LNPs are taken up from the circulation, cleared, and how effective they are in delivering treatments. In this review, we consider factors that facilitate LNP's effective liver targeting and explore the latest advances in liver-targeted LNP technologies. Understanding how LNPs are targeted to the liver can help for effective design and optimization of nanoparticle-based therapies. Comprehension of the cellular interaction and biodistribution of LNPs not only leads to better treatments for liver diseases but also delivers insight for directing nanoparticles to other tissues, potentially broadening their range of therapeutic applications.

Modular Design of Lipopeptide-Based Organ-Specific Targeting (POST) Lipid Nanoparticles for Highly Efficient RNA Delivery

Lipid nanoparticles (LNPs) with highly efficient and specific extrahepatic targeting abilities are promising in gene delivery, and the lipopeptides (LPs) with excellent designability and functionality are expected to empower the construction of functional LNPs. This study aims to develop highly efficient ionizable components that accurately match different targeting lipid systems through the modular design of LPs. Based on this, a lipopeptide-based organ-specific targeting (POST) LNP screening strategy is constructed, in which lysine-histidine-based lipopeptides (KH-LPs) are designed as highly efficient ionizable components. The optimal KH-LP LNP screened in vitro shows excellent siRNA/mRNA transfecting ability in various hard-to-transfect cell lines. Compared to the classic LNPs, the POST LNPs screened in vivo achieve even higher (or at least comparable) efficiency and specificity in delivering mRNA and siRNA to the lung, liver, and spleen, respectively. The structure-activity relationship (SAR) proves that the modular regulation of LP structures can accurately provide the optimal ionizable components for different targeting lipid systems, demonstrating the potential of this strategy in developing efficient and selective targeting systems, which is expected to open up more possibilities for gene therapy.

Pharmaceutical strategies for optimized mRNA expression

Messenger RNA (mRNA)-based immunotherapies and protein in situ production therapies hold great promise for addressing theoretically all the diseases characterized by aberrant protein levels. The safe, stable, and precise delivery of mRNA to target cells via appropriate pharmaceutical strategies is a prerequisite for its optimal efficacy. In this review, we summarize the structural characteristics, mode of action, development prospects, and limitations of existing mRNA delivery systems from a pharmaceutical perspective, with an emphasis on the impacts from formulation adjustments and preparation techniques of non-viral vectors on mRNA stability, target site accumulation and transfection efficiency. In addition, we introduce strategies for synergistical combination of mRNA and small molecules to augment the potency or mitigate the adverse effects of mRNA therapeutics. Lastly, we delve into the challenges impeding the development of mRNA drugs while exploring promising avenues for future advancements.

Pooled Nanoparticle Screening Using a Chemical Barcoding Approach

We report the development of a small molecule-based barcoding platform for pooled screening of nanoparticle delivery. Using aryl halide-based tags (halocodes), we achieve high-sensitivity detection via gas chromatography coupled with mass spectrometry or electron capture. This enables barcoding and tracking of nanoparticles with minimal halocode concentrations and without altering their physicochemical properties. To demonstrate the utility of our platform for pooled screening, we synthesized a halocoded library of polylactide-co-glycolide (PLGA) nanoparticles and quantified uptake in ovarian cancer cells in a pooled manner. Our findings correlate with conventional fluorescence-based assays. Additionally, we demonstrate the potential of halocodes for spatial mapping of nanoparticles using mass spectrometry imaging (MSI). Halocoding presents an accessible and modular nanoparticle screening platform capable of quantifying delivery of pooled nanocarrier libraries in a range of biological settings.

A Chemoinformatic-Guided Synthesis of a Spleen-Expressing mRNA Lipid Nanoparticle Platform

mRNA lipid nanoparticles (LNPs) are a powerful technology that are actively being investigated for their ability to prevent, treat, and study disease. However, a major limitation remains: achieving extrahepatic mRNA expression. The development of new carriers could enable the expression of mRNA in non-liver targets, thus expanding the utility of mRNA-based medicines. In this study, we use a combination of chemoinformatic-guided material synthesis and design of experiment optimization for the development of a spleen-expressing lipid nanoparticle (SE-LNP). We begin with the synthesis of a novel cholesterol derivative followed by SE-LNP formulation and design of experiment-guided optimization to identify three lead SE-LNPs. We then evaluate their in vitro delivery mechanism, in vivo biodistribution, and protein expression in mice, ultimately achieving spleen-preferential expression. The goal of this paper is thus to create LNPs that preferentially express mRNA in the spleen upon intravenous delivery, demonstrating the potential of LNPs to modulate gene expression in extrahepatic tissues for disease treatment.

Recent Advances in Lipid Nanoparticles and Their Safety Concerns for mRNA Delivery

INTRODUCTION

The advent of lipid nanoparticles (LNPs) as a delivery platform for mRNA therapeutics has revolutionized the biomedical field, particularly in treating infectious diseases, cancer, genetic disorders, and metabolic diseases. Recent Advances in Therapeutic LNPs: LNPs, composed of ionizable lipids, phospholipids, cholesterol, and polyethylene glycol (PEG) lipids, facilitate efficient cellular uptake and cytosolic release of mRNA while mitigating degradation by nucleases. However, as synthetic entities, LNPs face challenges that alter their therapeutic efficacy and safety concerns. Toxicity/Reactogenicity/Immunogenicity: This review provides a comprehensive overview of the latest advancements in LNP research, focusing on preclinical safety assessments encompassing toxicity, reactogenicity, and immunogenicity. Summary and Outlook: Additionally, it outlines potential strategies for addressing these challenges and offers insights into future research directions for enhancing the application of LNPs in mRNA therapeutics.

Lipid nanoparticles-based RNA therapies for breast cancer treatment

Breast cancer (BC) prevails as a major burden on global healthcare, being the most prevalent form of cancer among women. BC is a complex and heterogeneous disease, and current therapies, such as chemotherapy and radiotherapy, frequently fall short in providing effective solutions. These treatments fail to mitigate the risk of cancer recurrence and cause severe side effects that, in turn, compromise therapeutic responses in patients. Over the last decade, several strategies have been proposed to overcome these limitations. Among them, RNA-based technologies have demonstrated their potential across various clinical applications, notably in cancer therapy. However, RNA therapies are still limited by a series of critical issues like off-target effect and poor stability in circulation. Thus, novel approaches have been investigated to improve the targeting and bioavailability of RNA-based formulations to achieve an appropriate therapeutic outcome. Lipid nanoparticles (LNPs) have been largely proven to be an advantageous carrier for nucleic acids and RNA. This perspective explores the most recent advances on RNA-based technology with an emphasis on LNPs' utilization as effective nanocarriers in BC therapy and most recent progresses in their clinical applications.

Pooled nanoparticle screening using a chemical barcoding approach

We report the development of a small molecule-based barcoding platform for pooled screening of nanoparticle delivery. Using aryl halide-based tags (halocodes), we achieve high-sensitivity detection via gas chromatography coupled with mass spectrometry or electron capture. This enables barcoding and tracking of nanoparticles with minimal halocode concentrations and without altering their physicochemical properties. To demonstrate the utility of our platform for pooled screening, we synthesized a halocoded library of polylactide-co-glycolide (PLGA) nanoparticles and quantified uptake in ovarian cancer cells in a pooled manner. Our findings correlate with conventional fluorescence-based assays. Additionally, we demonstrate the potential of halocodes for spatial mapping of nanoparticles using mass spectrometry imaging (MSI). Halocoding presents an accessible and modular nanoparticle screening platform capable of quantifying delivery of pooled nanocarrier libraries in a range of biological settings.

Lipid nanoparticle (LNP) mediated mRNA delivery in cardiovascular diseases: Advances in genome editing and CAR T cell therapy

Cardiovascular diseases (CVDs) are the leading cause of global mortality among non-communicable diseases. Current cardiac regeneration treatments have limitations and may lead to adverse reactions. Hence, innovative technologies are needed to address these shortcomings. Messenger RNA (mRNA) emerges as a promising therapeutic agent due to its versatility in encoding therapeutic proteins and targeting "undruggable" conditions. It offers low toxicity, high transfection efficiency, and controlled protein production without genome insertion or mutagenesis risk. However, mRNA faces challenges such as immunogenicity, instability, and difficulty in cellular entry and endosomal escape, hindering its clinical application. To overcome these hurdles, lipid nanoparticles (LNPs), notably used in COVID-19 vaccines, have a great potential to deliver mRNA therapeutics for CVDs. This review highlights recent progress in mRNA-LNP therapies for CVDs, including Myocardial Infarction (MI), Heart Failure (HF), and hypercholesterolemia. In addition, LNP-mediated mRNA delivery for CAR T-cell therapy and CRISPR/Cas genome editing in CVDs and the related clinical trials are explored. To enhance the efficiency, safety, and clinical translation of mRNA-LNPs, advanced technologies like artificial intelligence (AGILE platform) in RNA structure design, and optimization of LNP formulation could be integrated. We conclude that the strategies to facilitate the extra-hepatic delivery and targeted organ tropism of mRNA-LNPs (SORT, ASSET, SMRT, and barcoded LNPs) hold great prospects to accelerate the development and translation of mRNA-LNPs in CVD treatment.

Exploring the potential of cell-derived vesicles for transient delivery of gene editing payloads

Gene editing technologies have the potential to correct genetic disorders by modifying, inserting, or deleting specific DNA sequences or genes, paving the way for a new class of genetic therapies. While gene editing tools continue to be improved to increase their precision and efficiency, the limited efficacy of in vivo delivery remains a major hurdle for clinical use. An ideal delivery vehicle should be able to target a sufficient number of diseased cells in a transient time window to maximize on-target editing and mitigate off-target events and immunogenicity. Here, we review major advances in novel delivery platforms based on cell-derived vesicles - extracellular vesicles and virus-like particles - for transient delivery of gene editing payloads. We discuss major findings regarding packaging, in vivo biodistribution, therapeutic efficacy, and safety concerns of cell-derived vesicles delivery of gene editing cargos and their potential for clinical translation.

Reformulating lipid nanoparticles for organ-targeted mRNA accumulation and translation

Fully targeted mRNA therapeutics necessitate simultaneous organ-specific accumulation and effective translation. Despite some progress, delivery systems are still unable to fully achieve this. Here, we reformulate lipid nanoparticles (LNPs) through adjustments in lipid material structures and compositions to systematically achieve the pulmonary and hepatic (respectively) targeted mRNA distribution and expression. A combinatorial library of degradable-core based ionizable cationic lipids is designed, following by optimisation of LNP compositions. Contrary to current LNP paradigms, our findings demonstrate that cholesterol and phospholipid are dispensable for LNP functionality. Specifically, cholesterol-removal addresses the persistent challenge of preventing nanoparticle accumulation in hepatic tissues. By modulating and simplifying intrinsic LNP components, concurrent mRNA accumulation and translation is achieved in the lung and liver, respectively. This targeting strategy is applicable to existing LNP systems with potential to expand the progress of precise mRNA therapy for diverse diseases.

Organ- and Cell-Selective Delivery of mRNA In Vivo Using Guanidinylated Serinol Charge-Altering Releasable Transporters

Selective RNA delivery is required for the broad implementation of RNA clinical applications, including prophylactic and therapeutic vaccinations, immunotherapies for cancer, and genome editing. Current polyanion delivery relies heavily on cationic amines, while cationic guanidinium systems have received limited attention due in part to their strong polyanion association, which impedes intracellular polyanion release. Here, we disclose a general solution to this problem in which cationic guanidinium groups are used to form stable RNA complexes upon formulation but at physiological pH undergo a novel charge-neutralization process, resulting in RNA release. This new delivery system consists of guanidinylated serinol moieties incorporated into a charge-altering releasable transporter (GSer-CARTs). Significantly, systematic variations in structure and formulation resulted in GSer-CARTs that exhibit highly selective mRNA delivery to the lung (∼97%) and spleen (∼98%) without targeting ligands. Illustrative of their breadth and translational potential, GSer-CARTs deliver circRNA, providing the basis for a cancer vaccination strategy, which in a murine model resulted in antigen-specific immune responses and effective suppression of established tumors.