Organelle-oriented nanomedicines in tumor therapy: Targeting, escaping, or collaborating?

Precise tumor therapy is essential for improving treatment specificity, enhancing efficacy, and minimizing side effects. Targeting organelles is a key strategy for achieving this goal and is a frontier research area attracting a considerable amount of attention. The concept of organelle targeting has a significant effect on the structural design of the nanodrugs employed. Most notably, the intricate interactions among different organelles in a tumor cell essentially create a unified system. Unfortunately, this aspect might have been somewhat overlooked when existing organelle-targeting nanodrugs were designed. In this review, we underscore the synergistic relationship among the various organelles and advocate for a holistic view of organelle-targeting design. Through the integration of biology and material science, recent advancements in organelle targeting, escaping, and collaborating are consolidated to offer fresh perspectives for the development of antitumor nanomedicines.

DNA nanovaccines derived from ferritin-modified glycogens for targeted delivery to immature dendritic cells and for promotion of Th1 cell differentiation

DNA vaccines have emerged as a powerful approach for advanced cancer therapy. Despite the development of various delivery systems to enhance the immunogenicity of DNA vaccines, many still face challenges such as limited DNA condensation, rapid degradation in vivo and insufficient targeting to lymph nodes (LNs). Synthetic dendrimers with modifiable surfaces exhibit high efficiency in DNA condensation, but their synthesis is extremely complex. This study utilizes cationic glycogen, a natural branched dendrimer-like polymer, as the core structure for efficient DNA condensation and delivery, ensuring good biocompatibility. By connecting ferritin light chain to the glycogen surfaces, active targeting of LNs can be achieved due to its affinity for the SCARA5 receptor on immature dendritic cells (DCs), facilitating vaccine migration to the LNs. In addition, a seperate plasmid encoding adjuvant IL-12 was co-delivered to further boost the immunogenicity of the DNA nanovaccine. In vivo and in vitro experiments confirmed the effective transfection capability of this DNA vaccine, demonstrating promoted DC maturation, increased antigen presentation, and Th1 cell differentiation, resulting in improved anti-tumor efficiency in vivo. This innovative multi-gene co-loaded DNA vaccine offers valuable insights into combined gene therapy and broadens the research horizon on non-viral gene carriers. STATEMENT OF SIGNIFICANCE: The DNA vaccine encounters challenges such as limited DNA condensation, rapid degradation and insufficient targeting to lymph nodes (LNs), resulting in generally weak immunogenicity. In the current study, a novel nanovaccine is developed by connecting ferritin light chain to natural dendrimer glycogen, for simultaneous delivery of dual plasmids. The cationized glycogen provides strong DNA condensation ability, while ensuring excellent stability of the nanovaccine. The presence of ferritin light chain leads to effective targeting of dendritic cells (DCs), facilitating its migration to LNs. Moreover, the plasmid encoding the adjuvant IL-12 is co-incorporated with the antigen plasmid to mitigate the immunosuppression environment. This strategy significantly improves the immunogenicity of DNA vaccines, demonstrating high efficiency in cancer immunotherapy.

Influences of chain length and conformation of guanidinylated linear synthetic polypeptides on nuclear delivery of siRNA with potential application in transcriptional gene silencing

Transcriptional gene silencing (TGS) mediated by siRNA holds promise for long-term silencing efficacy, determined by effective nuclear delivery of siRNA. However, non-viral vectors for this purpose are limited. In this work, we synthesized guanidinylated linear synthetic polypeptides (GLSPs) to explore how chain length and conformation impact siRNA delivery, especially nuclear entry. Results show that helical conformations, particularly right-handed ones, enhance siRNA loading and silencing efficiency compared to unordered structures. Increasing chain length also improves these aspects. The endocytic pathways of carrier/siRNA nanocomplexes (NCs) are mainly determined by conformation, regardless of length. Notably, some NCs derived from right-handed helices can enter cells via direct membrane penetration, like bioactivity of cell penetrating peptides (CPPs). When the peptide chain of GLSPs is long enough, all vectors can rapidly deliver siRNA to the nucleus, similar to bioactivity of nuclear localization signal peptides (NLSPs). Interestingly, helicity of the vectors aids endosomal escape of NCs. Moreover, delivering siRNA to the nucleus via GLSPs induces TGS associated with DNA promoter methylation or histone deacetylation. This study clarifies the structure-activity relationship of GLSPs in siRNA delivery, providing new insights for designing non-viral carriers for TGS.

Intracellular Proteins Targeting with Bi-Functionalized Magnetic Nanoparticles Following their Endosomal Escape

The specific targeting of intracellular proteins or organelles by magnetic nanoparticles (MNPs) is a major challenge in nanomedicine, as most MNPs are internalized by cells through endocytosis and remain trapped inside small intracellular vesicles, limiting their ability to reach intracellular components. Furthermore, this phenomenon limits their heating capacity in magnetic hyperthermia, and therefore their potential for cancer treatment. This study presents a strategy based on an original double functionalization of MNPs, with polyhistidine peptides (PHPs) triggering endosomal escape and antibodies targeting specific cytosolic proteins. Negatively charged γ-Fe2O3@SiO2 MNPs with diameter smaller than 50 nm are functionalized with zwitterionic and thiol groups at their surface. These sulfhydryl groups are used to graft PHPs through a labile link, allowing the peptide to be released from the MNPs' surface once in the cytosolic reductive environment. This severing avoids any interaction between these peptides and intracellular components, which can hinder MNPs' intracellular mobility. The second MNPs' surface functionalization is performed through a non-labile link with antibodies targeting specific cytosolic proteins, namely HSP27 thermosensitive proteins, for this inaugural proof of concept. Bi-functionalized MNPs are able to successfully target the intracellular protein of interest, opening the door to promising biomedical applications of MNPs, in cellular engineering and magnetic hyperthermia.

A promising strategy for ocular noninvasive protein delivery: The case in treating corneal neovascularization

Current clinical treatment of corneal neovascularization (CNV), a leading cause of visual impairment worldwide, by a class of glucocorticoids suffers from the ineffective and numerous adverse effects. Bevacizumab (Beva), an anti-neovascularization protein, is a promising therapeutic option but limited by subconjunctival injection due to its poor penetration across ocular bio-barriers, which significantly reduces patient compliance and increases the risk of infection. Herein, a CmA@Beva nanomedicine was developed, based on the co-assembly of novelly designed peptide, (Cysteine-Histidine-Arginine)3, with Beva in the presence of Zn2+. The conditions for the formation of CmA and encapsulation of Beva in CmA were optimized, and the pH-responsive release of Beva and the protective effects of CmA@Beva on Beva were explored. In vitro and in vivo studies showed CmA@Beva exhibited good biocompatibility and demonstrated notable improvements in Beva retention time in the anterior eye segment. CmA@Beva eye drops could overcome corneal bio-barriers by opening ocular surface tight junctions and the endocytosis-lysosomal escape pathway, which together resulted in a therapeutic outcome on rat CNV superior to subconjunctival injection. The present study contributes to the development of a noninvasive protein drug delivery strategy for the treatment of CNV or other diseases of the eye anterior segment. STATEMENT OF SIGNIFICANCE: Corneal neovascularization (CNV) has been recognized as the leading cause of vision impairment globally, affecting approximately 1.4 million people each year. Protein drugs have shown high specificity and low side effect in disease treatment compared to small molecule drugs. However, limited ability to cross ocular barriers remain a big challenge. Here, a nanomedicine (CmA@Beva) was employed to address this issue through exampling on an anti-neovascularization protein, bevacizumab (Beva). CmA@Beva enhances retention on the ocular surface and effectively delivers Beva across the epithelial barrier, and thus is much more effective than the commonly used subconjunctival injections used for treatment in the clinic. This may be a good strategy for non-invasive delivery of protein drugs for the treatment of anterior segment diseases.

Mapping cellular processes that determine delivery of plasmid DNA to the nucleus: application in Chinese hamster ovary and human embryonic kidney cells to enhance protein production

Delivery of DNA into nucleated eukaryotic cells is known as transfection and has been essential in establishing technologies such as recombinant protein production and gene therapy. Considerable research efforts have led to development of a variety of transfection methods for a multitude of applications and cell types. Many methods are efficient in delivering DNA across the plasma membrane but few focus on subsequent delivery into the nucleus, a necessary step in expression of a recombinant transgene, and the cellular processes governing nuclear import of DNA during transfection have proved elusive. Herein, live confocal microscopy was used to track plasmid DNA during transfection of Chinese hamster ovary (CHO) and human embryonic kidney (HEK) cells to map key cellular processes central to nuclear import of DNA showing that there is a strong relationship between events of cell division, promotion of DNA dispersal from endosomes and subsequent nuclear import leading to gene expression. Furthermore, cationic lipid-mediated transfection is more dependent on events of the cell cycle than electroporation to deliver DNA into the nucleus. These findings have informed the design of a method where both CHO and HEK cells are synchronised at G2 phase of the cell cycle followed by timely release enabling cell cycle progression to maximise the frequency of division events immediately after transfection. This led to a 1.2-1.5 fold increase in transfection efficiency for polyethylenimine (PEI) mediated and electroporation transfection respectively. This process enhanced production yields of a monoclonal antibody 4.5 fold in HEK and 18 fold in CHO cells in the first 24 h post transfection. Overall, this study elucidated key cellular processes fundamental to transfection of CHO and HEK cells providing knowledge which can be applied to DNA delivery technologies in a plethora of fields.

Tailoring Lipid Nanoparticle with Ex Situ Incorporated Conjugated Oligoelectrolyte for Enhanced mRNA Delivery Efficiency

Developing new lipid nanoparticle (LNP) formulations typically involves reconstruction from separate elements followed by rigorous purification steps, contributing to drawn-out drug discovery processes. Membrane-intercalating conjugated oligoelectrolytes (COEs) are water-soluble molecules featuring a conjugated backbone and peripheral ionic groups, specifically designed to spontaneously integrate into lipid bilayers. Herein, an ex situ strategy to "dope" the representative COE-S6 into pre-formed messenger RNA-LNPs (mRNA-LNPs) is presented, exploiting its spontaneous membrane intercalation property through a straightforward add-and-mix procedure. Incorporating 0.2% COE-S6 into mRNA-LNPs relative to lipid content reduced particle size from 84.5 ± 1 to 67.9 ± 0.8 nm, elevated cellular uptake, and improved endosomal escape. These traits culminate in an increase in in cellula transfection from 24.2 ± 1.6% to 98.7 ± 0.6%. When injected intravenously into healthy BALB/c mice, the optimized COE-S6-doped mRNA-LNPs boost in vivo luciferase expression by 1.75-fold. Additionally, COE-S6-doped mRNA-LNPs exhibit fluorogenic properties, enabling intracellular mechanistic studies via confocal microscopy. This simple method enhances the properties of mRNA-LNPs with minimal COE quantities, offering a novel strategy to improve existing LNP formulations and provide optical reporting capabilities, essential for expediting drug discovery and delivery.

pH-Responsive Conformational-Switching Cationic Fusion Protein for Promoted Plasmid DNA Delivery and Transfection

Gene therapy holds great promise for treating various diseases, but challenges such as delivery efficiency, immune response, and long-term effects still remain. Protamine is a frequently used gene delivery vector for its strong nucleic acid binding capacity, but its application is constrained by inadequate nucleic acid release, resulting in low transfection efficiency. Here, we introduce a fusion protein by integrating LAH4 peptides on both ends of protamine's DNA-binding motif. This fusion protein exhibits lower cytotoxicity compared to protamine. At pH 7.4, its uniform charge distribution and α-helical structure enable robust DNA condensation and DNase resistance. Under acidic conditions (pH 5.8), the conformational change of the protein weakens its DNA binding, facilitating controlled release in endosomes/lysosomes. Simultaneously, it interacts with the endosomal membrane to form pores, aiding in the endosomal escape of the nucleic acids, thereby significantly improving transfection efficiency. This fusion protein offers the potential for efficient and safe nucleic acid delivery.

Direct cytosol delivery of mRNA by micron-sized co-assembly with designer oligopeptides

Inefficient endosomal escape has been regarded as the main bottleneck for intracellular nucleic acid delivery. While most research efforts have been spent on designing various nano-sized particles, we took a different path here, investigating micron-sized carriers for direct cytosol entry. Using the spontaneous co-assembly of mRNA and the designer 27 amino acid oligopeptide named pepMAX2, micron-sized co-assemblies were obtained with various sizes by altering the concentration of NaCl salt and time for pre-incubation. Surprisingly, transfection was much more effective using micron-sized than nano-sized co-assemblies, and the efficiency surpasses that of a widely used lipid-based commercial reagent. The study was complemented by computational simulations, inhibitor studies and live-cell confocal imaging to shed light on the role of electrostatic interaction on assembly and the mechanism of uptake and intracellular trafficking. These micron-sized co-assemblies directly enter the cytosol and then release mRNA, bypassing conventional pathways and thus avoiding the lysosomal degradation. This simple approach involving short oligopeptides and salt addition to create optimal micron-sized co-assembly with mRNA should open new avenues to overcome endosomal barriers for intracellular delivery of nucleic acid therapeutics.

Precise intracellular uptake and endosomal release of diverse functional mRNA payloads via glutathione-responsive nanogels

We present a novel, highly customizable glutathione-responsive nanogel (NG) platform for efficient mRNA delivery with precise mRNA payload release control. Optimization of various cationic monomers, including newly synthesized cationic polyarginine, polyhistidine, and acrylated guanidine monomers, allowed fine-tuning of NG properties for mRNA binding. By incorporating a poly(ethylene) glycol-based disulphide crosslinker, we achieved glutathione-triggered mRNA release, enabling targeted intracellular delivery. Our NGs demonstrated superior encapsulation (up to 89.3 %) and loading (10.7 %) efficiencies, with controlled mRNA release kinetics at intracellular glutathione concentrations. NGs outperformed commercial transfection reagents across multiple cell lines, including traditionally difficult-to-transfect lines. We demonstrate the platform's versatility by successfully delivering GFP mRNA, Mango II RNA aptamers, and functionally relevant β2-AMPK mRNA. Furthermore, we used TIRF microscopy to measure exact RNA copy number within the NGs. Notably, mechanistic cellular uptake studies revealed that disulphide-containing NGs exhibit enhanced cellular uptake and endosomal escape, potentially due to interactions with cell surface thiols. This work represents a highly tuneable, efficient, and biocompatible platform for mRNA delivery with relevance for gene therapy and vaccine development.

Optimization of chemical transfection in airway epithelial cell lines

BACKGROUND

Chemical transfection is a widely employed technique in airway epithelium research, enabling the study of gene expression changes and effects. Additionally, it has been explored for its potential application in delivering gene therapies. Here, we characterize the transfection efficiency of EX-EGFP-Lv105, an EGFP-expressing plasmid into three cell lines commonly used to model the airway epithelium (1HAEo-, 16HBE14o-, and NCI-H292).

RESULTS

We used six common and/or commercially available reagents with varying chemical compositions: Lipofectamine 3000 (L3000), FuGENE HD, ViaFect, jetOPTIMUS, EndoFectin, and calcium phosphate. Using L3000, 1HAEo- exhibited the highest transfection efficiency compared to 16HBE14o- and NCI-H292 (1HAEo-: 76.1 ± 3.2%, 16HBE14o-: 35.5 ± 1.2%, NCI-H292: 28.9 ± 2.23%). L3000 yielded the greatest transfection efficiency with the lowest impact on cellular viability, normalized to control, with a 11.3 ± 0.16% reduction in 1HAEo-, 16.3 ± 0.08% reduction in 16HBE14o-, and 17.5 ± 0.09% reduction in NCI-H292 at 48-hour post-transfection. However, jetOPTIMUS had a similar transfection efficiency in 1HAEo- (90.7 ± 4.2%, p = 0.94), but had significantly reduced cellular viability of 37.4 ± 0.11% (p < 0.0001) compared to L3000. In 16HBE14o-, jetOPTIMUS yielded a significantly higher transfection efficiency compared to L3000 (64.6 ± 3.2%, p < 0.0001) but significantly reduced viability of 33.4 ± 0.09% (p < 0.0001) compared to L3000. In NCI-H292, jetOPTIMUS yielded a lower transfection efficiency (22.6 ± 1.2%) with a significant reduction in viability (28.3 ± 0.9%, p < 0.0001). Other reagents varied significantly in their efficiency and impact on cellular viability in other cell lines. Changing the transfection mixture-containing medium at 6-hour post-transfection did not improve transfection efficiency or viability. However, pre-treatment of cell cultures with two rinses of 0.25% trypsin-EDTA improved transfection efficiency in 1HAEo- (85.2 ± 1.1% vs. 71.3 ± 1.0%, p = 0.004) and 16HBE14o- (62.6 ± 4.3 vs. 35.5 ± 1.2, p = 0.003).

CONCLUSIONS

Transfection efficiencies can differ based on airway epithelial cell line, reagents, and optimization techniques used. Consideration and optimization of cell line and transfection conditions may be useful for improving nonviral genetic techniques in vitro.

Multiarm-Assisted Design of Dendron-like Degradable Ionizable Lipids Facilitates Systemic mRNA Delivery to the Spleen

Lipid nanoparticles (LNPs) have emerged as pivotal vehicles for messenger RNA (mRNA) delivery to hepatocytes upon systemic administration and to antigen-presenting cells following intramuscular injection. However, achieving systemic mRNA delivery to non-hepatocytes remains challenging without the incorporation of targeting ligands such as antibodies, peptides, or small molecules. Inspired by comb-like polymeric architecture, here we utilized a multiarm-assisted design to construct a library of 270 dendron-like degradable ionizable lipids by altering the structures of amine heads and multiarmed tails for optimal mRNA delivery. Following in vitro high-throughput screening, a series of top-dendron-like LNPs with high transfection efficacy were identified. These dendron-like ionizable lipids facilitated greater mRNA delivery to the spleen in vivo compared to ionizable lipid analogs lacking dendron-like structure. Proteomic analysis of corona-LNP pellets showed enhancement of key protein clusters, suggesting potential endogenous targeting to the spleen. A lead dendron-like LNP formulation, 18-2-9b2, was further used to encapsulate Cre mRNA and demonstrated excellent genome modification in splenic macrophages, outperforming a spleen-tropic MC3/18PA LNP in the Ai14 mice model. Moreover, 18-2-9b2 LNP encapsulating therapeutic BTB domain and CNC homologue 1 (BACH1) mRNA exhibited proficient BACH1 expression and subsequent Spic downregulation in splenic red pulp macrophages (RPM) in a Spic-GFP transgene model upon intravenous administration. These results underscore the potential of dendron-like LNPs to facilitate mRNA delivery to splenic macrophages, potentially opening avenues for a range of mRNA-LNP therapeutic applications, including regenerative medicine, protein replacement, and gene editing therapies.

The Whole Is Greater than the Sum of Its Parts - Challenges and Perspectives in Polyelectrolytes

Polyelectrolytes offer unique properties for biological applications due to their charged nature and high water solubility. Here, the challenges in their synthesis and characterization techniques are reviewed, emphasizing that their strong interactions with the surrounding media and counterions must be considered when working with this interesting class of materials. Their potential in complexation for gene delivery, their unique stealth and anti-fouling properties, and their more specific interactions with amino acid transporters for cancer therapy are highlighted. The underlying mechanisms responsible for their biological efficacy, including the proton sponge effect for endosomal release and their interactions with cellular membranes, are addressed. For polyelectrolytes with a high level of usage, an overview is given of their historical context. This Perspective outlines the potential of polyelectrolytes for innovative applications in the field of biomedicine. Considering the physicochemical characteristics of this class of materials, this work strives to elucidate the distinctive properties and applications of polyelectrolytes.

Impact of Acetylation, Succinylation, and pH on DNA Packaging in PEI-Based Polyplexes

Polyethylenimine (PEI) is a widely used cationic polymer for nonviral gene delivery, often modified to enhance transfection efficiency and reduce cytotoxicity. This study investigates how acetylation, succinylation (acPEI and zPEI), and pH influence the internal DNA packaging of polyplexes. Both modifications alter physicochemical properties, leading to complexes that decondense more readily with increasing modification. X-ray scattering reveals that high acetylation produces loosely packed DNA, while succinylation unexpectedly tightens DNA packing at higher modification levels. Polyplexes formed at low pH (pH 4) are more stable and tightly packed than those formed at pH 7.5. Acidifying polyplexes initially formed at pH 7.5 induces structural rearrangement to tighter DNA packing accompanied by significant PEI release, providing direct evidence for models where free PEI aids endosomal escape. These findings challenge conventional assumptions about PEI behavior and offer new insights into DNA packaging, emphasizing tailored polymer modifications and pH conditions to optimize gene delivery.

pH-Responsive Peptide Nanoparticles Deliver Macromolecules to Cells via Endosomal Membrane Nanoporation

The synthetically evolved pHD family of peptides is known to self-assemble into macromolecule-sized nanopores of 2-10 nm diameter in synthetic lipid bilayers, but only when the pH is below ∼6. Here, we show that a representative family member, pHD108, has the same pH-responsive nanopore-forming activity in the endosomal membranes of living human cells, which is triggered by endosomal acidification. This enables the cytosolic delivery of endocytosed proteins and other macromolecules. Acylation of either peptide terminus significantly decreases the concentration of peptide required for macromolecule delivery to the cell cytosol while not causing any measurable cytotoxicity. Longer acyl chains are more effective. The N-terminal palmitoylated C16-pHD108 is the most potent of all of the acyl-pHD108 variants and readily delivers a cytotoxic enzyme, fluorescent proteins, and a dye-labeled dextran to the cell cytosol. C16-pHD108 forms stable monodisperse micellar nanoparticles in a buffer at pH 7 with an average diameter of around 120 nm. These nanoparticles are not cytolytic or cytotoxic because the acylated pHD peptide does not partition from the nanoparticles into cell membranes at pH 7. At pH 5, the nanoparticles are unstable, driving acylated pHD108 to bind strongly to membranes. We hypothesize that passive endocytosis of macromolecular cargo and stable peptide nanoparticles, followed by endosomal acidification-dependent destabilization of the nanoparticles, triggers the nanopore-forming activity of acylated pHD peptides in the endosomal membrane, enabling internalized macromolecules to be delivered to the cytosol.

Efficacy of Chitosan-N-Arginine Chitosomes in mRNA Delivery and Cell Viability Enhancement

Cationic lipid-based carriers are recognized for their ability to complex with mRNA and effectively deliver the mRNA for vaccination and therapeutic purposes. However, the significant cytotoxicity of these carriers often restricts their practical application. In the present study, polymer-lipid hybrid nanoparticles, termed chitosomes, incorporating chitosan-N-arginine (CSA) with the DOTAP cationic lipid and the DOPE helper lipid, were synthesized and evaluated. The addition of CSA to the lipid formulations improved their physicochemical stability and enhanced mRNA complexation, resulting in high transfection rates in the HeLa and HEK293T cell lines. However, the transfection efficiency was low in the NIH-3T3 cell line, indicating a cell type-specific response to chitosomes. Importantly, CSA significantly reduced the cytotoxicity typically associated with DOTAP. Overall, the present study indicated that optimizing the ratio of CSA to DOTAP is crucial for developing mRNA nanocarriers to achieve high transfection efficiency and reduce cytotoxicity across different cell lines.

Research Progress on Cyclic-Peptide Functionalized Nanoparticles for Tumor-Penetrating Delivery

A key challenge in cancer treatment is the effective delivery of drugs into deep regions of tumor tissues, which are impermeable due to abnormal vascular network, increased interstitial fluid pressure (IFP), abundant extra cellular matrix (ECM), and heterogeneity of tumor cells. Cyclic peptides have been used for the surface engineering of nanoparticles to enhance the tumor-penetrating efficacy of drugs. Compared with other surface ligands, cyclic peptides are more easily produced by automated chemical synthesis, and they are featured by their higher binding affinity with their targets, tumor selectivity, stability against degradation, and low toxicity. In this review, different types of cyclic peptides, their physicochemical properties and their in vivo pharmacokinetics are introduced. Next, the progress of cyclic peptide-functionalized drug delivery nanodevices is updated, and the mechanism underlying the tumor-penetrating properties of cyclic peptide-functionalized drug delivery nanodevices is discussed.

pH-Responsive Micelles Containing Quinine Functionalities Enhance Intracellular Gene Delivery and Expression

Quinine is a promising building block for creating polymer carriers for intracellular nucleic acid delivery. This is due to its ability to bind to genetic material through intercalation and electrostatic interactions and the balance of hydrophobicity and hydrophilicity dependent on the pH/charge state. Yet, studies utilizing cinchona alkaloid natural products in gene delivery are limited. Herein, we present the incorporation of a quinine functionalized monomer (Q) into block polymer architectures to form self-assembled micelles for highly efficient gene delivery. Q was incorporated into the core and/or the shell of the micelles to introduce the unique advantages of quinine to the system. We found that incorporation of Q into the core of the micelle resulted in acid-induced disassembly of the micelle and a boost in transfection efficiency by promoting endosomal escape. This effect was especially evident in the cancerous cell line, A549, which has a more acidic intracellular environment. Incorporation of Q into the shell of the micelles resulted in intercalative binding to the genetic payload as well as larger micelle-DNA complexes (micelleplexes) from the hydrophobicity of Q in the shell. These factors enable the micelleplexes to be more resistant to serum and have more persistent protein expression post-transfection. Overall, this study is the first to demonstrate the benefits of including quinine functionalities into self-assembled micelles for highly efficient gene delivery and presents a platform for inclusion of other natural products with similar properties into micellar systems.

New insights for the development of efficient DNA vaccines

Despite the great potential of DNA vaccines for a broad range of applications, ranging from prevention of infections, over treatment of autoimmune and allergic diseases to cancer immunotherapies, the implementation of such therapies for clinical treatment is far behind the expectations up to now. The main reason is the poor immunogenicity of DNA vaccines in humans. Consequently, the improvement of the performance of DNA vaccines in vivo is required. This mini-review provides an overview of the current state of DNA vaccines and the various strategies to enhance the immunogenic potential of DNA vaccines, including (i) the optimization of the DNA construct itself regarding size, nuclear transfer and transcriptional regulation; (ii) the use of appropriate adjuvants; and (iii) improved delivery, for example, by careful choice of the administration route, physical methods such as electroporation and nanomaterials that may allow cell type-specific targeting. Moreover, combining nanoformulated DNA vaccines with other immunotherapies and prime-boost strategies may help to enhance success of treatment.

Breaking the final barrier: Evolution of cationic and ionizable lipid structure in lipid nanoparticles to escape the endosome

In the past decade, nucleic acid therapies have seen a boon in development and clinical translation largely due to advances in nanotechnology that have enabled their safe and targeted delivery. Nanoparticles can protect nucleic acids from degradation by serum enzymes and can facilitate entry into cells. Still, achieving endosomal escape to allow nucleic acids to enter the cytoplasm has remained a significant barrier, where less than 5% of nanoparticles within the endo-lysosomal pathway are able to transfer their cargo to the cytosol. Lipid-based drug delivery vehicles, particularly lipid nanoparticles (LNPs), have been optimized to achieve potent endosomal escape, and thus have been the vector of choice in the clinic as demonstrated by their utilization in the COVID-19 mRNA vaccines. The success of LNPs is in large part due to the rational design of lipids that can specifically overcome endosomal barriers. In this review, we chart the evolution of lipid structure from cationic lipids to ionizable lipids, focusing on structure-function relationships, with a focus on how they relate to endosomal escape. Additionally, we examine recent advancements in ionizable lipid structure as well as discuss the future of lipid design.

Enhanced Cellular Immunity for Hepatitis B Virus Vaccine: A Novel Polyinosinic-Polycytidylic Acid-Incorporated Adjuvant Leveraging Cytoplasmic Retinoic Acid-Inducible Gene-Like Receptor Activation and Increased Antigen Uptake

Conventional aluminum adjuvants exhibit limited cellular immunity. Polyinosinic-polycytidylic acid (poly I:C) activates cytoplasmic retinoic acid-inducible gene-like receptor (RLR), triggering strong T cell activation and cellular responses. However, when applied as an adjuvant, its limited endocytosis and restricted cytoplasmic delivery diminish its effectiveness and increase its toxicity. Hybrid polymer-lipid nanoparticle (PLNP) possesses numerous benefits such as good stability, reduced drug leakage, simple fabrication, easy property modulation, and excellent reproducibility compared to the lipid nanoparticle or the polymeric vector. Here, we developed a novel cationic polymer-lipid hybrid adjuvant capable of incorporating poly I:C to enhance cellular immunity. The hepatitis B surface antigen (HBsAg) was immobilized onto poly I:C-incorprated PLNP (PPLNP) via electrostatic interactions, forming the HBsAg/PPLNP vaccine formulation. The PPLNP adjuvant largely enhanced the cellular endocytosis and cytoplasmic transport of poly I:C, activating RLR followed by promoting type I interferon (IFN) secretion. Meanwhile, PPLNP obviously enhanced the antigen uptake, prolonged antigen retention at the site of administration, and facilitated enhanced transport of antigens to lymph nodes. The HBsAg/PPLNP nanovaccine led to amplified concentrations of antigen-specific immunoglobulin G (IgG), IFN-γ, granzyme B, and an enhanced IgG2a/IgG1 ratio, alongside the FasL+/CD8+ T cell activation, favoring a T helper 1 (TH1)-driven immune response. PPLNP, distinguished by its biocompatibility, ease of fabrication, and effectiveness in augmenting cellular immunity, holds significant promise as a new adjuvant.

Synthesis and characterization of chloroquine-modified albumin-binding siRNA-lipid conjugates for improved intracellular delivery and gene silencing in cancer cells

siRNA therapeutics have considerable potential as molecularly-targeted therapeutics in malignant disease, but identification of effective delivery strategies that mediate rapid intracellular delivery while minimizing toxicity has been challenging. Our group recently developed and optimized an siRNA conjugate platform termed "siRNA-L 2 ," which harnesses non-covalent association with endogenous circulating albumin to extend circulation half-life and achieve tumor-selective delivery without the use of traditional cationic lipids or polymers for transfection. To improve intracellular delivery and particularly the endosomal escape properties of siRNA-L 2 towards more efficient gene silencing, we report synthesis of siRNA-CQ-L 2 conjugates, in which chloroquine (CQ), an endosomolytic quinoline alkaloid, is covalently incorporated into the branching lipid tail structure. We accomplished this via synthesis of a novel CQ phosphoramidite, which can be incorporated into a modular siRNA-L 2 backbone using on-column solid-phase synthesis through use of asymmetric branchers with levulinyl-protected hydroxide groups that allow covalent addition of pendant CQ repeats. We demonstrate that siRNA-CQ-L 2 maintains the ability to non-covalently bind albumin, and with multiple copies of CQ, siRNA-CQ-L 2 mediates higher endosomal disruption, cellular uptake/retention, and reporter gene knockdown in cancer cells. Further, in mice, the addition of CQ did not significantly affect circulation kinetics nor organ biodistribution and did not produce hematologic or organ-level toxicity. Thus, controlled, multivalent conjugation of albumin-binding siRNA-L 2 to endosomolytic small molecule compounds holds promise in improving siRNA-L 2 knockdown potency while maintaining albumin-binding properties and overall safety.

Light-Promoted Lysosomal Escape of a Phthalocyanine and Antisense Oligonucleotide-Complexed G-Quadruplex for Dual Photodynamic and Antisense Therapy

Combination therapy has been proven as an effective strategy for cancer treatment. To this end, we report herein a self-assembled nucleic acid-based complex for dual photodynamic and antisense therapy. It contains a nucleolin-targeting As1411-based G-quadruplex platform, a partially hybridized antisense oligonucleotide 4625, which can inhibit the antiapoptotic protein B cell lymphoma-xL inducing apoptotic cell death, and a zinc(II) phthalocyanine (ZnPc)-based photosensitizer held by noncovalent interactions. Through a series of in vitro experiments, we have demonstrated that this DNA complex can be internalized selectively to nucleolin-overexpressed MCF-7 and A549 cells through receptor-mediated endocytosis and is localized in the lysosomes. Upon light irradiation, the photosensitization of ZnPc triggers the formation of reactive oxygen species for cell killing and promotes the lysosomal escape of 4625 for antisense therapy. The combined therapeutic effect can eliminate the cancer cells effectively with a half maximal inhibitory concentration of ca. 0.5 μM.

Therapeutic targeting of siRNA/anti-cancer drug delivery system for non-melanoma skin cancer. Part I: Development and gene silencing of JAK1siRNA/5-FU loaded liposome nanocomplexes

Non-melanoma skin cancer (NMSC) is one of the most prevalent cancers, leading to significant mortality rates due to limited treatment options and a lack of effective therapeutics. Janus kinase (JAK1), a non-receptor tyrosine kinase family member, is involved in various cellular processes, including differentiation, cell proliferation and survival, playing a crucial role in cancer progression. This study aims to provide a more effective treatment for NMSC by concurrently silencing the JAK1 gene and administering 5-Fluorouracil (5-FU) using liposome nanocomplexes as delivery vehicles. Utilizing RNA interference (RNAi) technology, liposome nanocomplexes modified with polyethylene imine (PEI) were conjugated with siRNA molecule targeting JAK1 and loaded with 5-FU. The prepared formulations (NL-PEI) were characterized in terms of their physicochemical properties, morphology, encapsulation efficiency, in vitro drug release, and stability. Cell cytotoxicity, cell uptake and knockdown efficiency were evaluated in human-derived non-melanoma epidermoid carcinoma cells (A-431). High contrast transmission electron microscopy (CTEM) images and dynamic light scattering (DLS) measurements revealed that the nanocomplexes formed spherical morphology with uniform sizes ranging from 80-120 nm. The cationic NL-PEI nanocomplexes successfully internalized within the cytoplasm of A-431, delivering siRNA for specific sequence binding and JAK1 gene silencing. The encapsulation of 5-FU in the nanocomplexes was achieved at 0.2 drug/lipid ratio. Post-treatment with NL-PEI for 24, 48 and 72 h showed cell viability above 80 % at concentrations up to 8.5 × 101 µg/mL. Notably, 5-FU delivery via nanoliposome formulations significantly reduced cell viability at 5-FU concentration of 5 µM and above (p < 0.05) after 24 h of incubation. The NL-PEI nanocomplexes effectively silenced the JAK1 gene in vitro, reducing its expression by 50 %. Correspondingly, JAK1 protein level decreased after transfection with JAK1 siRNA-conjugated liposome nanocomplexes, leading to a 37 % reduction in pERK (phosphor extracellular signal-regulated kinase) protein expression. These findings suggest that the combined delivery of JAK1 siRNA and 5-FU via liposomal formulations offers a promising and novel treatment strategy for targeting genes and other identified targets in NMSC therapy.

Dual-stage Acting Dendrimeric Nanoparticle for Deepened Chemotherapeutic Drug Delivery to Tumor Cells

Purpose

We report on the design of hypoxia-induced dual-stage acting dendrimeric nanoparticles (NPs) for selective delivery of two chemotherapeutic model drugs doxorubicin (DOX) and tirapazamin (TPZ) for deepened drug delivery into hypoxic tumors in vitro.

Methods

PAMAM G5 dendrimers were crosslinked with a hypoxic azo linker, attached to a mPEG to form a detachable corona on the dendrimer surface (PAP NPs). NPs were characterized by Zeta sizer, transmission electron microscope (TEM), Fourier transforms infrared (FTIR) and drug release kinetics. The anti-cancer performance of PAPs was evaluated by numerous tests in 2D and 3D cultured MDA-MB-231 breast cancer cells.

Results

MTT assay showed a significant difference between PAP and PAMAMG5 in terms of biocompatibility, and the effect of PAP@DOX was significantly greater than free DOX in hypoxic conditions. The results of DAPI and Annexin V-FITC/PI cell staining also confirmed uniform drug penetration as validated by induction of 90% cell apoptosis in spheroids and a high level of PAP@DOX-induced ROS generation under hypoxia conditions. Mechanistically, PAP@DOX significantly reduced the expression of mTOR, and Notch1, while the expression of Bax and Caspase3 was considerably unregulated, compared to the controls. Importantly, hypoxia-responsive disintegration and hypoxia-induced activation of HAP drug were synergized to promote deep and homogenous HAP distribution in whole microtumor regions to efficiently eliminate residual tumor cells.

Conclusion

Our results indicate the safety and high therapeutic potential of PAP system for targeted drug delivery of chemotherapeutics in particular HAPs which show maximum anti-cancer activity against hypoxic solid tumors.

Local mRNA Delivery from Nanocomposites Made of Gelatin and Hydroxyapatite Nanoparticles

Local delivery of messenger ribonucleic acid (mRNA) is increasingly being advocated as a promising new strategy to enhance the performance of biomaterials. While extensive research has been dedicated to the complexation of these oligonucleotides into nanoparticles to facilitate systemic delivery, research on developing suitable biomaterial carriers for the local delivery of mRNA is still scarce. So far, mRNA-nanoparticles (mRNA-NPs) are mainly loaded into traditional polymeric hydrogels. Here, we show that calcium phosphate nanoparticles can be used for both reinforcement of nanoparticle-based hydrogels and the complexation of mRNA. mRNA was incorporated into lipid-coated calcium phosphate nanoparticles (LCPs) formulated with a fusogenic ionizable lipid in the outer layer of the lipid coat. Nanocomposites of gelatin and hydroxyapatite nanoparticles were prepared at various ratios. Higher hydroxyapatite nanoparticle content increased the viscoelastic properties of the nanocomposite but did not affect its self-healing ability. Combination of these nanocomposites with peptide, lipid, and the LCP mRNA formulations achieved local mRNA release as demonstrated by protein expression in cells in contact with the biomaterials. The LCP-based formulation was superior to the other formulations by showing less sensitivity to hydroxyapatite and the highest cytocompatibility.

The bench to bedside journey of tricyclo-DNA antisense oligonucleotides for the treatment of Duchenne muscular dystrophy

The development of antisense oligonucleotide (ASO)-based therapeutics has made tremendous progress over the past few years, in particular for the treatment of neuromuscular disorders such as Duchenne muscular dystrophy and spinal muscular atrophy. Several ASO drugs have now reached market approval for these diseases and many more are currently under clinical evaluation. Among them, ASOs made of the tricyclo-DNA originally developed by Christian Leumann have shown particularly interesting properties and demonstrated promise for the treatment of Duchenne muscular dystrophy. In this review, we examine the bench to bedside journey of tricyclo-DNA-ASOs from their early preclinical evaluation as fully phosphorotiated-ASOs to the latest generation of lipid-conjugated-ASOs. Finally we discuss the remaining challenges of ASO-mediated exon-skipping therapy for DMD and future perspectives for this promising chemistry of ASOs.

Inclusion of TAT and NLS sequences in lipopeptide molecules generates homogenous nanoparticles for gene delivery applications

PURPOSES

The objective of this study is to develop a versatile gene carrier based on lipopeptides capable of delivering genetic material into target cells with minimal cytotoxicity.

METHODS

Two lipopeptide molecules, palmitoyl-CKKHH and palmitoyl-CKKHH-YGRKKRRQRRR-PKKKRKV, were synthesized using solid phase peptide synthesis and evaluated as transfection agents. Physicochemical characterization of the lipopeptides included a DNA shift mobility assay, particle size measurement, and transmission electron microscopy (TEM) analysis. Cytotoxicity was assessed in CHO-K1 and HepG2 cells using the MTT assay, while transfection efficiency was determined by evaluating the expression of the green fluorescent protein-encoding gene.

RESULTS

Our findings demonstrate that the lipopeptides can bind, condense, and shield DNA from DNase degradation. The inclusion of the YGRKKRRQRRR sequence, a transcription trans activator, and the PKKKRKV sequence, a nuclear localization signal, imparts desirable properties. Lipopeptide-based TAT-NLS/DNA nanoparticles exhibited stability for up to 20 days when stored at 6-8 °C, displaying uniformity with a compact size of approximately 120 nm. Furthermore, the lipopeptides exhibited lower cytotoxicity compared to the poly-L-lysine. Transfection experiments revealed that protein expression mediated by the lipopeptide occurred at a charge ratio ranging from 4.0 to 8.0.

CONCLUSION

These results indicate that the lipopeptide, composed of a palmitoyl alkyl chain and TAT and NLS sequences, can efficiently condense and protect DNA, form stable and uniform nanoparticles, and exhibit promising characteristics as a potential gene carrier with minimal cytotoxicity.

Determining the Role of Surfactant on the Cytosolic Delivery of DNA Cross-Linked Micelles

Nucleic Acid Nanocapsules (NANs) are nucleic acid nanostructures that radially display oligonucleotides on the surface of cross-linked surfactant micelles. Their chemical makeup affords the stimuli-responsive release of therapeutically active DNA-surfactant conjugates into the cells. While NANs have so far demonstrated the effective cytosolic delivery of their nucleic acid cargo, as seen indirectly by their gene regulation capabilities, there remain gaps in the molecular understanding of how this process happens. Herein, we examine the enzymatic degradation of NANs and confirm the identity of the DNA-surfactant conjugates formed by using mass spectrometry (MS). With surface enhanced (resonance) Raman spectroscopy (SE(R)RS), we also provide evidence that the energy-independent translocation of such DNA-surfactant conjugates is contingent upon their release from the NAN structure, which, when intact, otherwise buries the hydrophobic surfactant tail in its interior. Such information suggests a critical role of the surfactant in the lipid disruption capability of the DNA surfactant conjugates generated from degradation of the NANs. Using NANs made with different tail lengths (C12 and C10), we show that this mechanism likely holds true despite significant differences in the physical properties (i.e., critical micelle concentration (CMC), surfactants per micelle, Nagg) of the resultant particles (C12 and C10 NANs). While the total cellular uptake efficiencies of C12 and C10 NANs are similar, there were differences observed in their cellular distribution and localized trafficking, even after ensuring that the total concentration of DNA was the same for both particles. Ultimately, C10 NANs appeared less diffuse within cells and colocalized less with lysosomes over time, achieving more significant knockdown of the target gene investigated, suggesting more effective endosomal escape. These differences indicate that the surfactant assembly and disassembly properties, including the number of surfactants per particle and the CMC can have important implications for the cellular delivery efficacy of DNA micelles and surfactant conjugates.

Harnessing Guanidinium and Imidazole Functional Groups: A Dual-Charged Polymer Strategy for Enhanced Gene Delivery

Histidine and arginine are two amino acids that exhibit beneficial properties for gene delivery. In particular, the imidazole group of histidine facilitates endosomal release, while the guanidinium group of arginine promotes cellular entry. Consequently, a dual-charged copolymer library based on these amino acids was synthesized via reversible addition-fragmentation chain transfer (RAFT) polymerization. The content of the N-acryloyl-l-histidine (His) monomer was systematically increased, while maintaining consistent levels of methyl N-acryloyl-l-argininate hydrochloride (ArgOMe) or N-(4-guanidinobutyl)acrylamide hydrochloride (GBAm). The resulting polymers formed stable, nanosized polyplexes when complexed with nucleic acids. Remarkably, candidates with increased His content exhibited reduced cytotoxicity profiles and enhanced transfection efficiency, particularly retaining this performance level at lower pDNA concentrations. Furthermore, endosomal release studies revealed that increased His content improved endosomal release, while ArgOMe improved cellular entry. These findings underscore the potential of customized dual-charged copolymers and the synergistic effects of His and ArgOMe/GBAm in enhancing gene delivery.

Optimizing Biocompatibility and Gene Delivery with DMAEA and DMAEAm: A Niacin-Derived Copolymer Approach

Gene therapy is pivotal in nanomedicine, offering a versatile approach to disease treatment. This study aims to achieve an optimal balance between biocompatibility and efficacy, which is a common challenge in the field. A copolymer library is synthesized, incorporating niacin-derived monomers 2-acrylamidoethyl nicotinate (AAEN) or 2-(acryloyloxy)ethyl nicotinate (AEN) with N,N-(dimethylamino)ethyl acrylamide (DMAEAm) or hydrolysis-labile N,N-(dimethylamino)ethyl acrylate (DMAEA). Evaluation of the polymers' cytotoxicity profiles reveals that an increase in AAEN or DMAEA molar ratios correlates with improved biocompatibility. Remarkably, an increase in AAEN in both DMAEA and DMAEAm copolymers demonstrated enhanced transfection efficiencies of plasmid DNA in HEK293T cells. Additionally, the top-performing polymers demonstrate promising gene expression in challenging-to-transfect cells (THP-1 and Jurkat cells) and show no significant effect on modulating immune response induction in ex vivo treated murine monocytes. Overall, the best performing candidates exhibit an optimal balance between biocompatibility and efficacy, showcasing potential advancements in gene therapy.

Advanced biopolymeric materials and nanosystems for RNA/DNA vaccines: a review

The post COVID-19 pandemic era has emerged with more efficient vaccines, all based on genetic materials. However, to expand the use of nucleic components as vaccines, a new generation of nanosystems particularly constructed to increase RNA/DNA stability, half-life and facilitate administration are still required. This review highlights novel developments in mRNA and pDNA vaccines formulated into nanostructures exclusively composed by biopolymeric materials. Recent advances suggest that a new generation of vaccines may arise by adapting the structural features of biopolymers with the effectiveness of nucleic acids. The advantages offered by biopolymers, such as increased stability and targeting ability may cause a revolution in the immunization field for offering promptly adaptable and effective formulations for worldwide distribution.

Beyond Lipids: Exploring Advances in Polymeric Gene Delivery in the Lipid Nanoparticles Era

The recent success of gene therapy during the COVID-19 pandemic has underscored the importance of effective and safe delivery systems. Complementing lipid-based delivery systems, polymers present a promising alternative for gene delivery. Significant advances have been made in the recent past, with multiple clinical trials progressing beyond phase I and several companies actively working on polymeric delivery systems which provides assurance that polymeric carriers can soon achieve clinical translation. The massive advantage of structural tunability and vast chemical space of polymers is being actively leveraged to mitigate shortcomings of traditional polycationic polymers and improve the translatability of delivery systems. Tailored polymeric approaches for diverse nucleic acids and for specific subcellular targets are now being designed to improve therapeutic efficacy. This review describes the recent advances in polymer design for improved gene delivery by polyplexes and covalent polymer-nucleic acid conjugates. The review also offers a brief note on novel computational techniques for improved polymer design. The review concludes with an overview of the current state of polymeric gene therapies in the clinic as well as future directions on their translation to the clinic.

Strategies and mechanisms for endosomal escape of therapeutic nucleic acids

Despite impressive recent establishment of therapeutic nucleic acids as drugs and vaccines, their broader medical use is impaired by modest performance in intracellular delivery. Inefficient endosomal escape presents a major limitation responsible for inadequate cytosolic cargo release. Depending on the carrier, this endosomal barrier can strongly limit or even abolish nucleic acid delivery. Different recent endosomal escape strategies and their hypothesized mechanisms are reviewed.

ROS-Responsive Ferrocenyl Amphiphilic PAMAM Dendrimers for On-Demand Delivery of siRNA Therapeutics to Cancer Cells

Small interfering RNA (siRNA) therapeutics, characterized by high specificity, potency, and durability, hold great promise in the treatment of cancer and other diseases. However, the clinic implementation of siRNA therapeutics critically depends on the safe and on-demand delivery of siRNA to the target cells. Here, we reported a family of ferrocenyl amphiphilic dendrimers (Fc-AmDs) for on-demand delivery of siRNA in response to the high ROS content in cancer cells. These dendrimers bear ROS-sensitive ferrocene moieties in the hydrophobic components and positively chargeable poly(amidoamine) dendrons as the hydrophilic entities, possessing favorable safety profiles and ROS responsive properties. One of these ferrocenyl amphiphilic dendrimers, Fc-C8-AmD 8A, outperforms in siRNA delivery, benefiting from its optimal balance of hydrophobicity and hydrophilicity. Its ROS feature facilitates specific and efficient disassembly of its complex with siRNA in ROS-rich cancer cells for effective siRNA delivery and gene silencing. Moreover, Fc-C8-AmD 8A also integrates the features and beneficial properties of both lipid and dendrimer vectors. Therefore, it represents a novel on-demand delivery system for cancer cell-specific siRNA delivery. This work opens new perspectives for designing self-assembly nanosystems for on-demand drug delivery.

In vivo Fate of Targeted Drug Delivery Carriers

This review aimed to systematically investigate the intracellular and subcellular fate of various types of targeting carriers. Upon entering the body via intravenous injection or other routes, a targeting carrier that can deliver therapeutic agents initiates their journey. If administered intravenously, the carrier initially faces challenges presented by the blood circulation before reaching specific tissues and interacting with cells within the tissue. At the subcellular level, the car2rier undergoes processes, such as drug release, degradation, and metabolism, through specific pathways. While studies on the fate of 13 types of carriers have been relatively conclusive, these studies are incomplete and lack a comprehensive analysis. Furthermore, there are still carriers whose fate remains unclear, underscoring the need for continuous research. This study highlights the importance of comprehending the in vivo and intracellular fate of targeting carriers and provides valuable insights into the operational mechanisms of different carriers within the body. By doing so, researchers can effectively select appropriate carriers and enhance the successful clinical translation of new formulations.

Achieving Endo/Lysosomal Escape Using Smart Nanosystems for Efficient Cellular Delivery

The delivery of therapeutic agents faces significant hurdles posed by the endo-lysosomal pathway, a bottleneck that hampers clinical effectiveness. This comprehensive review addresses the urgent need to enhance cellular delivery mechanisms to overcome these obstacles. It focuses on the potential of smart nanomaterials, delving into their unique characteristics and mechanisms in detail. Special attention is given to their ability to strategically evade endosomal entrapment, thereby enhancing therapeutic efficacy. The manuscript thoroughly examines assays crucial for understanding endosomal escape and cellular uptake dynamics. By analyzing various assessment methods, we offer nuanced insights into these investigative approaches' multifaceted aspects. We meticulously analyze the use of smart nanocarriers, exploring diverse mechanisms such as pore formation, proton sponge effects, membrane destabilization, photochemical disruption, and the strategic use of endosomal escape agents. Each mechanism's effectiveness and potential application in mitigating endosomal entrapment are scrutinized. This paper provides a critical overview of the current landscape, emphasizing the need for advanced delivery systems to navigate the complexities of cellular uptake. Importantly, it underscores the transformative role of smart nanomaterials in revolutionizing cellular delivery strategies, leading to a paradigm shift towards improved therapeutic outcomes.

Dynamic Covalent Boronate Chemistry Accelerates the Screening of Polymeric Gene Delivery Vectors via In Situ Complexation of Nucleic Acids

Gene therapy provides exciting new therapeutic opportunities beyond the reach of traditional treatments. Despite the tremendous progress of viral vectors, their high cost, complex manufacturing, and side effects have encouraged the development of nonviral alternatives, including cationic polymers. However, these are less efficient in overcoming cellular barriers, resulting in lower transfection efficiencies. Although the exquisite structural tunability of polymers might be envisaged as a versatile tool for improving transfection, the need to fine-tune several structural parameters represents a bottleneck in current screening technologies. By taking advantage of the fast-forming and strong boronate ester bond, an archetypal example of dynamic covalent chemistry, a highly adaptable gene delivery platform is presented, in which the polycation synthesis and pDNA complexation occur in situ. The robustness of the strategy entitles the simultaneous evaluation of several structural parameters at will, enabling the accelerated screening and adaptive optimization of lead polymeric vectors using dynamic covalent libraries.

Amino-Acid-Derived Anionic Polyacrylamides with Tailored Hydrophobicity-Physicochemical Properties and Cellular Interactions

Polyanions can internalize into cells via endocytosis without any cell disruption and are therefore interesting materials for biomedical applications. In this study, amino-acid-derived polyanions with different alkyl side-chains are synthesized via postpolymerization modification of poly(pentafluorophenyl acrylate), which is synthesized via reversible addition-fragmentation chain-transfer (RAFT) polymerization, to obtain polyanions with tailored hydrophobicity and alkyl branching. The success of the reaction is verified by size-exclusion chromatography, NMR spectroscopy, and infrared spectroscopy. The hydrophobicity, surface charge, and pH dependence are investigated in detail by titrations, high-performance liquid chromatography, and partition coefficient measurements. Remarkably, the determined pK a-values for all synthesized polyanions are very similar to those of poly(acrylic acid) (pK a = 4.5), despite detectable differences in hydrophobicity. Interactions between amino-acid-derived polyanions with L929 fibroblasts reveal very slow cell association as well as accumulation of polymers in the cell membrane. Notably, the more hydrophobic amino-acid-derived polyanions show higher cell association. Our results emphasize the importance of macromolecular engineering toward ideal charge and hydrophobicity for polymer association with cell membranes and internalization. This study further highlights the potential of amino-acid-derived polymers and the diversity they provide for tailoring properties toward drug delivery applications.

Pathways for macrophage uptake of cell-free circular RNAs

Circular RNAs (circRNAs) are stable RNAs present in cell-free RNA, which may comprise cellular debris and pathogen genomes. Here, we investigate the phenomenon and mechanism of cellular uptake and intracellular fate of exogenous circRNAs. Human myeloid cells and B cells selectively internalize extracellular circRNAs. Macrophage uptake of circRNA is rapid, energy dependent, and saturable. CircRNA uptake can lead to translation of encoded sequences and antigen presentation. The route of internalization influences immune activation after circRNA uptake, with distinct gene expression programs depending on the route of RNA delivery. Genome-scale CRISPR screens and chemical inhibitor studies nominate macrophage scavenger receptor MSR1, Toll-like receptors, and mTOR signaling as key regulators of receptor-mediated phagocytosis of circRNAs, a dominant pathway to internalize circRNAs in parallel to macropinocytosis. These results suggest that cell-free circRNA serves as an "eat me" signal and danger-associated molecular pattern, indicating orderly pathways of recognition and disposal.

Lipo-Xenopeptide Polyplexes for CRISPR/Cas9 based Gene editing at ultra-low dose

Double pH-responsive xenopeptide carriers containing succinoyl tetraethylene pentamine (Stp) and lipo amino fatty acids (LAFs) were evaluated for CRISPR/Cas9 based genome editing. Different carrier topologies, variation of LAF/Stp ratios and LAF types as Cas9 mRNA/sgRNA polyplexes were screened in three different reporter cell lines using three different genomic targets (Pcsk9, eGFP, mdx exon 23). One U-shaped and three bundle (B2)-shaped lipo-xenopeptides exhibiting remarkable efficiencies were identified. Genome editing potency of top carriers were observed at sub-nanomolar EC50 concentrations of 0.4 nM sgRNA and 0.1 nM sgRNA for the top U-shape and top B2 carriers, respectively, even after incubation in full (≥ 90%) serum. Polyplexes co-delivering Cas9 mRNA/sgRNA with a single stranded DNA template for homology directed gene editing resulted in up to 38% conversion of eGFP to BFP in reporter cells. Top carriers were formulated as polyplexes or lipid nanoparticles (LNPs) for subsequent in vivo administration. Formulations displayed long-term physicochemical and functional stability upon storage at 4 °C. Importantly, intravenous administration of polyplexes or LNPs mediated in vivo editing of the dystrophin gene, triggering mRNA exon 23 splicing modulation in dystrophin-expressing cardiac muscle, skeletal muscle and brain tissue.

Supramolecular interaction in the action of drug delivery systems

Complex diseases and diverse clinical needs necessitate drug delivery systems (DDSs), yet the current performance of DDSs is far from ideal. Supramolecular interactions play a pivotal role in various aspects of drug delivery, encompassing biocompatibility, drug loading, stability, crossing biological barriers, targeting, and controlled release. Nevertheless, despite having some understanding of the role of supramolecular interactions in drug delivery, their incorporation is frequently overlooked in the design and development of DDSs. This perspective provides a brief analysis of the involved supramolecular interactions in the action of drug delivery, with a primary emphasis on the DDSs employed in the clinic, mainly liposomes and polymers, and recognized phenomena in research, such as the protein corona. The supramolecular interactions implicated in various aspects of drug delivery systems, including biocompatibility, drug loading, stability, spatiotemporal distribution, and controlled release, were individually analyzed and discussed. This perspective aims to trigger a comprehensive and systematic consideration of supramolecular interactions in the further development of DDSs. Supramolecular interactions embody the true essence of the interplay between the majority of DDSs and biological systems.

Pulmonary siRNA Delivery with Sophisticated Amphiphilic Poly(Spermine Acrylamides) for the Treatment of Lung Fibrosis

RNA interference (RNAi) is an efficient strategy to post-transcriptionally silence gene expression. While all siRNA drugs on the market target the liver, the lung offers a variety of currently undruggable targets, which can potentially be treated with RNA therapeutics. To achieve this goal, the synthesis of poly(spermine acrylamides) (P(SpAA) is reported herein. Polymers are prepared via polymerization of N-acryloxysuccinimide (NAS) and afterward this active ester is converted into spermine-based pendant groups. Copolymerizations with decylacrylamide are employed to increase the hydrophobicity of the polymers. After deprotection, polymers show excellent siRNA encapsulation to obtain perfectly sized polyplexes at very low polymer/RNA ratios. In vitro 2D and 3D cell culture, ex vivo and in vivo experiments reveal superior properties of amphiphilic spermine-copolymers with respect to delivery of siRNA to lung cells in comparison to commonly used lipid-based transfection agents. In line with the in vitro results, siRNA delivery to human lung explants confirm more efficient gene silencing of protease-activated receptor 2 (PAR2), a G protein-coupled receptor involved in fibrosis. This study reveals the importance of the balance between efficient polyplex formation, cellular uptake, gene knockdown, and toxicity for efficient siRNA delivery in vitro, in vivo, and in fibrotic human lung tissue ex vivo.

Between hope and reality: treatment of genetic diseases through nucleic acid-based drugs

Rare diseases (RD) affect a small number of people compared to the general population and are mostly genetic in origin. The first clinical signs often appear at birth or in childhood, and patients endure high levels of pain and progressive loss of autonomy frequently associated with short life expectancy. Until recently, the low prevalence of RD and the gatekeeping delay in their diagnosis have long hampered research. The era of nucleic acid (NA)-based therapies has revolutionized the landscape of RD treatment and new hopes arise with the perspectives of disease-modifying drugs development as some NA-based therapies are now entering the clinical stage. Herein, we review NA-based drugs that were approved and are currently under investigation for the treatment of RD. We also discuss the recent structural improvements of NA-based therapeutics and delivery system, which overcome the main limitations in their market expansion and the current approaches that are developed to address the endosomal escape issue. We finally open the discussion on the ethical and societal issues that raise this new technology in terms of regulatory approval and sustainability of production.

Unlocking the Mitochondria for Nanomedicine-based Treatments: Overcoming Biological Barriers, Improving Designs, and Selecting Verification Techniques

Enhanced targeting approaches will support the treatment of diseases associated with dysfunctional mitochondria, which play critical roles in energy generation and cell survival. Obstacles to mitochondria-specific targeting include the presence of distinct biological barriers and the need to pass through (or avoid) various cell internalization mechanisms. A range of studies have reported the design of mitochondrially-targeted nanomedicines that navigate the complex routes required to influence mitochondrial function; nonetheless, a significant journey lies ahead before mitochondrially-targeted nanomedicines become suitable for clinical use. Moving swiftly forward will require safety studies, in vivo assays confirming effectiveness, and methodologies to validate mitochondria-targeted nanomedicines' subcellular location/activity. From a nanomedicine standpoint, we describe the biological routes involved (from administration to arrival within the mitochondria), the features influencing rational design, and the techniques used to identify/validate successful targeting. Overall, rationally-designed mitochondria-targeted-based nanomedicines hold great promise for precise subcellular therapeutic delivery.

Recent Progress in the Endosomal Escape Mechanism and Chemical Structures of Polycations for Nucleic Acid Delivery

Nucleic acid-based therapies are seeing a spiralling surge. Stimuli-responsive polymers, especially pH-responsive ones, are gaining widespread attention because of their ability to efficiently deliver nucleic acids. These polymers can be synthesized and modified according to target requirements, such as delivery sites and the nature of nucleic acids. In this regard, the endosomal escape mechanism of polymer-nucleic acid complexes (polyplexes) remains a topic of considerable interest owing to various plausible escape mechanisms. This review describes current progress in the endosomal escape mechanism of polyplexes and state-of-the-art chemical designs for pH-responsive polymers. The importance is also discussed of the acid dissociation constant (i.e., pKa) in designing the new generation of pH-responsive polymers, along with assays to monitor and quantify the endosomal escape behavior. Further, the use of machine learning is addressed in pKa prediction and polymer design to find novel chemical structures for pH responsiveness. This review will facilitate the design of new pH-responsive polymers for advanced and efficient nucleic acid delivery.

Liter-scale manufacturing of shelf-stable plasmid DNA/PEI transfection particles for viral vector production

The transfection efficiency and stability of the delivery vehicles of plasmid DNA (pDNA) are critical metrics to ensure high-quality and high-yield production of viral vectors. We previously identified that the optimal size of pDNA/poly(ethylenimine) (PEI) transfection particles is 400-500 nm and developed a bottom-up assembly method to construct stable 400-nm pDNA/PEI particles and benchmarked their transfection efficiency in producing lentiviral vectors (LVVs). Here, we report scale-up production protocols for such transfection particles. Using a two-inlet confined impinging jet (CIJ) mixer with a dual syringe pump set-up, we produced a 1-L batch at a flow rate of 100 mL/min, and further scaled up this process with a larger CIJ mixer and a dual peristaltic pump array, allowing for continuous production at a flow rate of 1 L/min without a lot size limit. We demonstrated the scalability of this process with a 5-L lot and validated the quality of these 400-nm transfection particles against the target product profile, including physical properties, shelf and on-bench stability, transfection efficiency, and LVV production yield in both 15-mL bench culture and 2-L bioreactor runs. These results confirm the potential of this particle assembly process as a scalable manufacturing platform for viral vector production.

Reversible Protection and Targeted Delivery of DNA Origami with a Disulfide-Containing Cationic Polymer

DNA nanostructures have considerable biomedical potential as intracellular delivery vehicles as they are highly homogeneous and can be functionalized with high spatial resolution. However, challenges like instability under physiological conditions, limited cellular uptake, and lysosomal degradation limit their use. This paper presents a bio-reducible, cationic polymer poly(cystaminebisacrylamide-1,6-diaminohexane) (PCD) as a reversible DNA origami protector. PCD displays a stronger DNA affinity than other cationic polymers. DNA nanostructures with PCD protection are shielded from low salt conditions and DNase I degradation and show a 40-fold increase in cell-association when linked to targeting antibodies. Confocal microscopy reveals a potential secondary cell uptake mechanism, directly delivering the nanostructures to the cytoplasm. Additionally, PCD can be removed by cleaving its backbone disulfides using the intracellular reductant, glutathione. Finally, the application of these constructs is demonstrated for targeted delivery of a cytotoxic agent to cancer cells, which efficiently decreases their viability. The PCD protective agent that is reported here is a simple and efficient method for the stabilization of DNA origami structures. With the ability to deprotect the DNA nanostructures upon entry of the intracellular space, the possibility for the use of DNA origami in pharmaceutical applications is enhanced.

Protein-based nanoparticles for therapeutic nucleic acid delivery

To realize the full potential of emerging nucleic acid therapies, there is a need for effective delivery agents to transport cargo to cells of interest. Protein materials exhibit several unique properties, including biodegradability, biocompatibility, ease of functionalization via recombinant and chemical modifications, among other features, which establish a promising basis for therapeutic nucleic acid delivery systems. In this review, we highlight progress made in the use of non-viral protein-based nanoparticles for nucleic acid delivery in vitro and in vivo, while elaborating on key physicochemical properties that have enabled the use of these materials for nanoparticle formulation and drug delivery. To conclude, we comment on the prospects and unresolved challenges associated with the translation of protein-based nucleic acid delivery systems for therapeutic applications.