Dynamic carriers for therapeutic RNA delivery

Investigating the Interactions of Peptide Nucleic Acids with Multicomponent Peptide Hydrogels for the Advancement of Healthcare Technologies

This study reports the development of peptide-based hydrogels for the encapsulation and controlled release of peptide nucleic acids in drug delivery applications. Ultrashort aromatic peptides, such as Fmoc-FF, self-assemble into biocompatible hydrogels with nanostructured architectures. The functionalization of tripeptides (Fmoc-FFK and Fmoc-FFC) with lysine (K) or cysteine (C) enables electrostatic or covalent interactions with model PNAs engineered with glutamic acid or cysteine residues, respectively. Hydrogels were polymerized in situ in the presence of PNAs, and component ratios were systematically varied to optimize mechanical properties, loading efficiency, and release kinetics. The formulations obtained with a 1/10 ratio of Fmoc-FF(K or C)/Fmoc-FF provided an optimal balance between structural integrity and delivery performance. All hydrogel formulations demonstrated high stiffness (G' > 19,000 Pa), excellent water retention, and minimal swelling under physiological conditions (ΔW < 4%). The release studies over 10 days showed that electrostatic loading enabled faster and higher release (up to 90%), while covalent bonding resulted in slower, sustained delivery (~15%). These findings highlight the tunability of the hydrogel system for diverse therapeutic applications.

Ionic Coating of siRNA Polyplexes with cRGD-PEG-Hyaluronic Acid To Modulate Serum Stability and In Vivo Performance

Efficient delivery of siRNA-based polyplexes to tumors remains a major challenge. Nonspecific interactions in the bloodstream, limited circulation time, and nontargeted biodistribution hamper sufficient tumor accumulation. To address these challenges, we developed an ionic hyaluronic acid (HA) coating to shield sequence-defined oligoaminoamide-based polyplexes. This coating should shield the positive polyplex surface charge, thus reducing nonspecific interactions and enhancing serum stability. Additionally, we modified the HA coating with the cyclic RGDfK (cRGD) peptide to specifically target tumor endothelial cells (TECs). Optionally, a polyethylene glycol (PEG) spacer was also introduced to improve ligand presentation on the polyplex surface. The HA-coated polyplexes exhibited favorable physicochemical properties, including a negative zeta potential and effective siRNA retention within the polyplex, which was not adversely affected by PEG or cRGD modification. In vitro analyses revealed that these polyplexes not only enhanced tumor cell association and preserved the high transfection efficiency of plain cationic polyplexes but also exhibited coating-dependent cellular internalization, as evidenced by a competitive inhibition experiment. Even in the presence of serum, the HA-coated polyplexes encapsulated siRNA effectively, exhibited suitable particle sizes, and maintained a high gene silencing efficiency. In vivo studies involving intravenous administration into Neuro2a tumor-bearing mice showed that the HA coating, particularly when modified with PEG and cRGD, significantly increased the tumor accumulation of polyplexes. HA-PEG-cRGD-shielded polyplexes exhibited significantly enhanced in vivo gene silencing in tumors compared with plain polyplexes. Collectively, our results indicate a superior performance of HA-coated polyplexes in terms of stability and cellular uptake, both in vitro and in vivo.

Interactions between PEI and biological polyanions and the ability of glycosaminoglycans in destabilizing PEI/peGFP-C3 polyplexes for genetic material release

The lack of understanding of polyplexes stability and their dissociation mechanisms, allowing the release of DNA, is currently a major limitation in non-viral gene delivery. One proposed mechanism for DNA-based polyplexes dissociation is based on the electrostatic interactions between polycations and biological polyanions, such as glycosaminoglycans (GAGs). This work aimed at investigating whether GAGs such as heparin, chondroitin sulphate and hyaluronic acid promote the dissociation of PEI/DNA polyplexes. We studied the electrostatic complexation between branched poly(ethyleneimine) (b-PEI25) and polyanions (model DNA and GAGs) through conductivity and ζ-potential measurements. The formation of b-PEI25/polyanion polyplexes through electrostatic interactions was analyzed in depth, providing key insights into charge stoichiometry, morphology, thermodynamics and physicochemical characteristics. The stability of polyplexes was tested in the presence of the different GAGs. Heparin was found to be the only polyanion capable of releasing peGFP-C3 plasmid from polyplexes, complexing stoichiometrically with the free b-PEI25 in excess, before releasing the plasmid. The ability of GAGs to disrupt polyplexes and release DNA was correlated with the thermodynamic characteristics of b-PEI25/polyanions complexation. Our findings indicate that heparin's strong interaction with PEI and its high charge density, compared to other GAGs and polyanions, are pivotal in determining complex stability and promoting DNA release.

A novel micelleplex for tumour-targeted delivery of CRISPR-Cas9 against KRAS-mutated lung cancer

CRISPR-Cas9 has emerged as a highly effective and customizable genome editing tool, holding significant promise for the treatment of KRAS mutations in lung cancer. In this study, we introduce a novel micelleplex, named C14-PEI, designed to co-deliver Cas9 mRNA and sgRNA efficiently to excise the mutated KRAS allele in lung cancer cells. C14-PEI is synthesised from 1,2-epoxytetradecane and branched PEI 600 Da via a ring-opening reaction. The resulting C14-PEI has a critical micelle concentration (CMC) of approximately 20.86 ± 0.15 mg L-1, indicating its ability to form stable micelles at low concentrations. C14-PEI efficiently encapsulates mRNA into micelleplexes through electrostatic interactions. When the mass ratio is 8 (w/w 8), the C14-PEI formulation exhibits conducive properties, which showed encapsulation efficiency of eGFP mRNA at 99% and led to a 130-fold increase in eGFP expression in A549 cells compared to untreated cells, demonstrating the robust delivery and expression capability of the micelleplexes. Importantly, toxicity tests using intracellular reduction of a tetrazolium salt revealed no significant cytotoxicity, underscoring the biocompatibility of C14-PEI. C14-PEI also shows high efficiency in co-encapsulating Cas9 mRNA and sgRNA, as confirmed by agarose gel electrophoresis. At an sgRNA to Cas9 mRNA molar ratio of 10, the micelleplexes successfully mediate the cutting of mutated KRAS with an indel efficiency exceeding 60%, as determined by the T7 Endonuclease I (T7EI) assay. Droplet digital polymerase chain reaction (ddPCR) further demonstrates that the gene editing efficiency, measured by edited gene copies, is 48.5% in the w/w 4 group and 37.8% in the w/w 8 group. Treatment with C14-PEI micelleplexes containing Cas9 mRNA and sgRNA targeting the KRAS G12S mutation significantly impairs the migration capability of A549 cells and increases apoptosis rates. These findings suggest that C14-PEI effectively disrupts KRAS signalling pathways, leading to reduced tumor cell proliferation and enhanced cell death.

Clinical applications of oligonucleotides for cancer therapy

Oligonucleotide therapeutics (ONTs) represent a rapidly evolving modality for cancer treatment, capitalizing on their ability to modulate gene expression with high specificity. With more than 20 nucleic acid-based therapies that gained regulatory approval, advances in chemical modifications, sequence optimization, and novel delivery systems have propelled ONTs from research tools to clinical realities. ONTs, including siRNAs, antisense oligonucleotides, saRNA, miRNA, aptamers, and decoys, offer promising solutions for targeting previously "undruggable" molecules, such as transcription factors, and enhancing cancer immunotherapy by overcoming tumor immune evasion. The promise of ONT application in cancer treatment is exemplified by the recent FDA approval of the first oligonucleotide-based treatment to myeloproliferative disease. At the same time, there are challenges in delivering ONTs to specific tissues, mitigating off-target effects, and improving cellular uptake and endosomal release. This review provides a comprehensive overview of ONTs in clinical trials, emerging delivery strategies, and innovative therapeutic approaches, emphasizing the role of ONTs in immunotherapy and addressing hurdles that hinder their clinical translation. By examining advances and remaining challenges, we highlight opportunities for ONTs to revolutionize oncology and enhance patient outcomes.

mRNA delivery with templated dynamic covalent polymers

Messenger RNA is a novel therapeutic modality which was key in curbing the Covid-19 pandemic. However, the delivery of mRNA in cells requires the development of smart vectors. We here report on amphiphilic dynamic covalent polymers formed in situ through RNA templating, and show effective nanoparticle formation and delivery of EGFP mRNA in cells.

Dual pH-responsive CRISPR/Cas9 ribonucleoprotein xenopeptide complexes for genome editing

Clustered regularly interspaced short palindromic repeat (CRISPR)/CRISPR associated (Cas) protein has been proved as a powerful tool for the treatment of genetic diseases. The Cas9 protein, when combined with single-guide RNA (sgRNA), forms a Cas9/sgRNA ribonucleoprotein (RNP) capable of targeting and editing the genome. However, the limited availability of effective carriers has restricted the broader application of CRISPR/Cas9 RNP. In this study, we evaluated dual pH-responsive amphiphilic xenopeptides (XPs) for delivering CRISPR/Cas9 RNP. These artificial lipo-XPs contain apolar cationizable lipoamino fatty acid (LAF) and polar cationizable oligoaminoethylene acid units such as succinoyl-tetraethylenepentamine (Stp) in various ratios and U-shaped topologies. The carriers were screened for functional Cas9/sgRNA RNP delivery in four different reporter cell lines, including a Duchenne muscular dystrophy (DMD) exon skipping reporter cell model. Significantly enhanced cellular uptake into HeLa cells, effective endosomal disruption in HeLa gal8-mRuby3 cells, and potent genome editing by several Cas9/sgRNA RNP complexes was observed in four different cell lines in the 5 nM sgRNA range. Comparing Cas9/sgRNA RNP complexes with Cas9 mRNA/sgRNA polyplexes in the DMD reporter cell model demonstrated similar splice site editing and high exon skipping of the two different molecular Cas9 modalities. Based on these studies, analogues of two potent U1 LAF2-Stp and LAF4-Stp2 structures were deployed, tuning the amphiphilicity of the polar Stp group by replacement with the six oligoamino acids dmGtp, chGtp, dGtp, Htp, Stt, or GEIPA. The most potent LAF2-Stp analogues (containing dGtp, chGtp or GEIPA) demonstrated further enhanced gene editing efficiency with EC50 values of 1 nM in the DMD exon skipping reporter cell line. Notably, the EC50 of LAF2-dGtp reached 0.51 nM even upon serum incubation. Another carrier (LAF4-GEIPA2) complexing Cas9/sgRNA RNP and donor DNA, facilitated up to 43 % of homology-directed repair (HDR) in HeLa eGFPd2 cells visualized by the switch from green fluorescent protein (eGFP) to blue fluorescent protein (BFP). This study presents a delivery system tunable for Cas9 RNP complexes or Cas9 RNP/donor DNA polyplexes, offering an effective and easily applicable strategy for gene editing.

Amphiphilic dynamic covalent polymer vectors of siRNA

Dynamic covalent polymers (DCPs) recently emerged as smart siRNA delivery vectors, which dynamically self-assemble through siRNA templating and depolymerize in a controlled manner. Herein, we report the dynamic combinatorial screening of cationic and amphiphilic peptide-based monomers. We provide experimental evidence, by mass spectrometry analyses, of the siRNA-templated formation of DCPs, and show that amphiphilic DCPs display superior activity in terms of siRNA complexation and delivery in cells. Thus, the work describes a new type of siRNA vector based on dynamic covalent lipopolyplexes, which feature improved activity as well as better nano-structuration compared to previous generations of DCPs.

Anionic polymer coating for enhanced delivery of Cas9 mRNA and sgRNA nanoplexes

Polymeric carriers have long been recognized as some of the most effective and promising systems for nucleic acid delivery. In this study, we utilized an anionic di-block co-polymer, PEG-PLE, to enhance the performance of lipid-modified PEI (C14-PEI) nanoplexes for delivering Cas9 mRNA and sgRNA targeting KRAS G12S mutations in lung cancer cells. Our results demonstrated that PEG-PLE, when combined with C14-PEI at a weight-to-weight ratio of 0.2, produced nanoplexes with a size of approximately 140 nm, a polydispersity index (PDI) of 0.08, and a zeta potential of around -1 mV. The PEG-PLE/C14-PEI nanoplexes at this ratio were observed to be both non-cytotoxic and effective in encapsulating Cas9 mRNA and sgRNA. Confocal microscopy imaging revealed efficient endosomal escape and intracellular distribution of the RNAs. Uptake pathway inhibition studies indicated that the internalization of PEG-PLE/C14-PEI primarily involves scavenger receptors and clathrin-mediated endocytosis. Compared to C14-PEI formulations, PEG-PLE/C14-PEI demonstrated a significant increase in luciferase mRNA expression and gene editing efficiency, as confirmed by T7EI and ddPCR, in A549 cells. Sanger sequencing identified insertions and/or deletions around the PAM sequence, with a total of 69% indels observed. Post-transfection, the KRAS-ERK pathway was downregulated, resulting in significant increases in cell apoptosis and inhibition of cell migration. Taken together, this study reveals a new and promising formulation for CRISPR delivery as potential lung cancer treatment.

Diagnostic and Therapeutic Advances of RNAs in Precision Medicine of Gastrointestinal Tumors

Gastrointestinal tumors present a significant challenge for precision medicine due to their complexity, necessitating the development of more specific diagnostic tools and therapeutic agents. Recent advances have positioned coding and non-coding RNAs as emerging biomarkers for these malignancies, detectable by liquid biopsies, and as innovative therapeutic agents. Many RNA-based therapeutics, such as small interfering RNA (siRNA) and antisense oligonucleotides (ASO), have entered clinical trials or are available on the market. This review provides a narrative examination of the diagnostic and therapeutic potential of RNA in gastrointestinal cancers, with an emphasis on its application in precision medicine. This review discusses the current challenges, such as drug resistance and tumor metastasis, and highlights how RNA molecules can be leveraged for targeted detection and treatment. Additionally, this review categorizes specific diagnostic biomarkers and RNA therapeutic targets based on tissue type, offering a comprehensive analysis of their role in advancing precision medicine for gastrointestinal tumors.

Icariin-Enhanced Osteoclast-Derived Exosomes Promote Repair of Infected Bone Defects by Regulating Osteoclast and Osteoblast Communication

Background

Infected bone defects pose a challenging clinical issue due to an imbalance of osteoclasts (OC) and osteoblasts (OB). Exosomes are crucial for intercellular signaling of OC and OB in bone repair. Icariin, has been shown to regulate the balance between OC and OB. However, the specific mechanisms by which icariin influences exosomes derived from osteoclasts, and subsequently impacts osteoblast activity, remain unclear. This study aims to investigate the effects of icariin-treated osteoclast-derived exosomes (ICA-OC-Exo) on osteoblast function and bone repair in cases of infected bone defects.

Methods

We investigated the exosome profile and localization of multivesicular bodies (MVB) and quantification of intraluminal vesicles (ILVs) in osteoclasts by using transmission electron microscopy. Additionally, the expressions of Rab27A and MITF, which are associated with exosome release, were determined through immunofluorescence staining and Western blot. The profiling of exosomal miRNA expression was conducted via miRNA-sequencing. The effects of ICA-OC-Exo on osteoblast differentiation were determined using RT-qPCR, Western blot, alkaline phosphatase staining. Additionally, ICA-OC-Exo was administered into the localized bone defect of the infected bone rat models, and bone formation was assessed using Micro-CT.

Results

Icariin increased the presence of MVBs in the cytoplasm through modulation of the MITF/Rab27A signaling pathway, resulting in higher number of ICA-OC-Exo compared to OC-Exo. Additionally, miR-331-3p expression in ICA-OC-Exo was found to be elevated compared to OC-Exo. ICA-OC-Exo was observed to stimulate osteoblast function by targeting FGF23, reducing DKK1, and subsequently upregulating ALP. In the in vivo study, ICA-OC-Exo exhibited the capacity to enhance bone healing at the site of a local bone defect following anti-infection treatment.

Conclusion

Icariin enhanced the quantification of OC-Exo and the expression of miRNA-331-3p in OC-Exo, leading to the regulation of osteoblast function via activation of the miRNA-331-3p/FGF23/DKK1 pathway. ICA-OC-Exo demonstrated potential clinical applicability in bone repair of infected bone defects.

Quinine-Based Polymers Are Versatile and Effective Vehicles for Intracellular pDNA, mRNA, and Cas9 Protein Delivery

Quinine-based polymers have previously demonstrated promising performance in delivering pDNA in cells owing to their electrostatic as well as the nonelectrostatic interactions with pDNA. Herein, we evaluate whether quinine-based polymers are versatile for delivery of mRNA and Cas9-sgRNA complexes, especially in a serum-rich environment. Both mRNA and the Cas9-sgRNA complex are potent therapeutics that are structurally, chemically, and functionally very different from pDNA. By exploring a family of 7 quinine-based polymers that vary in monomer structure and polymer composition, we tested numerous formulations (42 with pDNA, 96 with mRNA, and 48 with Cas9-sgRNA) for payload-polymer complexation and delivery to compare payload-dependent structure-activity relationships. Several formulations demonstrated performance comparable to or better than the commercially available transfection agent jetPEI. The results of this study demonstrate the potential of quinine-based as a versatile carrier platform for delivering a wide range of nucleic acid therapeutics and serving the drug delivery needs in the field genetic medicine.

In Vivo Endothelial Cell Gene Silencing by siRNA-LNPs Tuned with Lipoamino Bundle Chemical and Ligand Targeting

Although small-interfering RNAs (siRNAs) are specific silencers for numerous disease-related genes, their clinical applications still require safe and effective means of delivery into target cells. Highly efficient lipid nanoparticles (LNPs) are developed for siRNA delivery, showcasing the advantages of novel pH-responsive lipoamino xenopeptide (XP) carriers. These sequence-defined XPs are assembled by branched lysine linkages between cationizable polar succinoyl tetraethylene pentamine (Stp) units and apolar lipoamino fatty acids (LAFs) at various ratios into bundle or U-shape topologies. Formulation of siRNA-LNPs using LAF4-Stp1 XPs as ionizable compounds led to robust cellular uptake, high endosomal escape, and successful in vitro gene silencing activity at an extremely low (150 picogram) siRNA dose. Of significance is the functional in vivo endothelium tropism of siRNA-LNPs with bundle LAF4-Stp1 XP after intravenous injection into mice, demonstrated by superior knockdown of liver sinusoidal endothelial cell (LSEC)-derived factor VIII (FVIII) and moderate silencing of hepatocyte-derived FVII compared to DLin-MC3-DMA-based LNPs. Optimizing lipid composition following click-modification of siRNA-LNPs with ligand c(RGDfK) efficiently silenced vascular endothelial growth factor receptor-2 (VEGFR-2) in tumor endothelial cells (TECs). The findings shed light on the role of ionizable XPs in the LNP in vivo cell-type functional targeting, laying the groundwork for future therapeutic applications.

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.

Biomimetic Nucleic Acid Drug Delivery Systems for Relieving Tumor Immunosuppressive Microenvironment

Immunotherapy combats tumors by enhancing the body's immune surveillance and clearance of tumor cells. Various nucleic acid drugs can be used in immunotherapy, such as DNA expressing cytokines, mRNA tumor vaccines, small interfering RNAs (siRNA) knocking down immunosuppressive molecules, and oligonucleotides that can be used as immune adjuvants. Nucleic acid drugs, which are prone to nuclease degradation in the circulation and find it difficult to enter the target cells, typically necessitate developing appropriate vectors for effective in vivo delivery. Biomimetic drug delivery systems, derived from viruses, bacteria, and cells, can protect the cargos from degradation and clearance, and deliver them to the target cells to ensure safety. Moreover, they can activate the immune system through their endogenous activities and active components, thereby improving the efficacy of antitumor immunotherapeutic nucleic acid drugs. In this review, biomimetic nucleic acid delivery systems for relieving a tumor immunosuppressive microenvironment are introduced. Their immune activation mechanisms, including upregulating the proinflammatory cytokines, serving as tumor vaccines, inhibiting immune checkpoints, and modulating intratumoral immune cells, are elaborated. The advantages and disadvantages, as well as possible directions for their clinical translation, are summarized at last.

Modulating efficacy and cytotoxicity of lipoamino fatty acid nucleic acid carriers using disulfide or hydrophobic spacers

Double pH-responsive xenopeptides comprising polar ionizable succinoyl tetraethylene pentamine (Stp) motifs and lipophilic ionizable lipoamino fatty acids (LAFs) were recently found to efficiently transfect mRNA and pDNA at low doses. However, potency was often accompanied with cytotoxicity at higher doses. Insertion of bioreducible disulfide building blocks (ssbb) or non-reducible hydrophobic spacers between polar and apolar ionizable domains of LAF-Stp carriers should mitigate toxicity of xenopeptides. Carriers showed stable nucleic acid complexation and endosomal pH-dependent lytic activities, both of which were abolished after reductive cleavage of ssbb-containing carriers. For pDNA, U-shaped carriers with one Stp and two LAF units or bundle carriers with two Stps and four LAFs displayed highest potency. For mRNA, best transfection was achieved with bundle carriers with one Stp and four LAFs. Both the ssbb and hydrophobic spacer containing analogs displayed improved metabolic activity, reduced membrane damage, and improved cell growth. The ssbb carriers were most beneficial regarding living cell count and low apoptosis rates. Mechanistically, inserted spacers decelerated the transfection kinetics and altered the requirement of endosomal protonation. Overall, mRNA and pDNA carriers with improved biocompatibility have been designed, with their high potency illustrated in transfection of various cell lines including low passage number colon carcinoma cells.

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.