siRNA-cell-penetrating peptides complexes as a combinatorial therapy against chronic myeloid leukemia using BV173 cell line as model

Functionalized extracellular nanovesicles as advanced CRISPR delivery systems

The clustered regularly interspaced short palindromic repeat (CRISPR) system, an emerging tool for genome editing, has garnered significant public interest for its potential in treating genetic diseases. Despite the rapid advancements in CRISPR technology, the progress in developing effective delivery strategies lags, impeding its clinical application. Extracellular nanovesicles (EVs), either in their endogenous forms or with engineered modifications, have emerged as a promising solution for CRISPR delivery. These EVs offer several advantages, including high biocompatibility, biological permeability, negligible immunogenicity, and straightforward production. Herein, we first summarize various types of functional EVs for CRISPR delivery, such as unmodified, modified, engineered virus-like particles (VLPs), and exosome-liposome hybrid vesicles, and examine their distinct intracellular pathways. Then, we outline the cutting-edge techniques for functionalizing extracellular vesicles, involving producer cell engineering, vesicle engineering, and virus-like particle engineering, emphasizing the diverse CRISPR delivery capabilities of these nanovesicles. Lastly, we address the current challenges and propose rational design strategies for their clinical translation, offering future perspectives on the development of functionalized EVs.

Nanoplatform-Based In Vivo Gene Delivery Systems for Cancer Therapy

Gene therapy uses modern molecular biology methods to repair disease-causing genes. As a burgeoning therapeutic, it has been widely applied for cancer therapy. Since 1989, there have been numerous clinical gene therapy cases worldwide. However, a few are successful. The main challenge of clinical gene therapy is the lack of efficient and safe vectors. Although viral vectors show high transfection efficiency, their application is still limited by immune rejection and packaging capacity. Therefore, the development of non-viral vectors is overwhelming. Nanoplatform-based non-viral vectors become a hotspot in gene therapy. The reasons are mainly as follows. 1) Non-viral vectors can be engineered to be uptaken by specific types of cells or tissues, providing effective targeting capability. 2) Non-viral vectors can protect goods that need to be delivered from degradation. 3) Nanoparticles can transport large-sized cargo such as CRISPR/Cas9 plasmids and nucleoprotein complexes. 4) Nanoparticles are highly biosafe, and they are not mutagenic in themselves compared to viral vectors. 5) Nanoparticles are easy to scale preparation, which is conducive to clinical conversion and application. Here, an overview of the categories of nanoplatform-based non-viral gene vectors, the limitations on their development, and their applications in cancer therapy.

Advancements and Future Prospects in Molecular Targeted and siRNA Therapies for Chronic Myeloid Leukemia

Chronic myeloid leukemia (CML) is an oncological myeloproliferative disorder that accounts for 15 to 20% of all adult leukemia cases. The molecular basis of this disease lies in the formation of a chimeric oncogene BCR-ABL1. The protein product of this gene, p210 BCR-ABL1, exhibits abnormally high constitutive tyrosine kinase activity. Over recent decades, several targeted tyrosine kinase inhibitors (TKIs) directed against BCR-ABL1 have been developed and introduced into clinical practice. These inhibitors suppress BCR-ABL1 activity through various mechanisms. Furthermore, the advent of RNA interference technology has enabled the highly specific inhibition of BCR-ABL1 transcript expression using small interfering RNA (siRNA). This experimental evidence opens avenues for the development of a novel therapeutic strategy for CML, termed siRNA therapy. The review delves into molecular genetic mechanisms underlying the pathogenesis of CML, challenges in CML therapy, potential molecular targets for drug development, and the latest results from the application of siRNAs in in vitro and in vivo CML models.

Uptake pathways of cell-penetrating peptides in the context of drug delivery, gene therapy, and vaccine development

Cell-penetrating peptides have been extensively utilized for the purpose of facilitating the intracellular delivery of cargo that is impermeable to the cell membrane. The researchers have exhibited proficient delivery capabilities for oligonucleotides, thereby establishing cell-penetrating peptides as a potent instrument in the field of gene therapy. Furthermore, they have demonstrated a high level of efficiency in delivering several additional payloads. Cell penetrating peptides (CPPs) possess the capability to efficiently transport therapeutic molecules to specific cells, hence offering potential remedies for many illnesses. Hence, their utilization is imperative for the improvement of therapeutic vaccines. In contemporary studies, a plethora of cell-penetrating peptides have been unveiled, each characterized by its own distinct structural attributes and associated mechanisms. Although it is widely acknowledged that there are multiple pathways through which particles might be internalized, a comprehensive understanding of the specific mechanisms by which these particles enter cells has to be fully elucidated. The absorption of cell-penetrating peptides can occur through either direct translocation or endocytosis. However, it is worth noting that categories of cell-penetrating peptides are not commonly linked to specific entrance mechanisms. Furthermore, research has demonstrated that cell-penetrating peptides (CPPs) possess the capacity to enhance antigen uptake by cells and facilitate the traversal of various biological barriers. The primary objective of this work is to examine the mechanisms by which cell-penetrating peptides are internalized by cells and their significance in facilitating the administration of drugs, particularly in the context of gene therapy and vaccine development. The current study investigates the immunostimulatory properties of numerous vaccine components administered using different cell-penetrating peptides (CPPs). This study encompassed a comprehensive discussion on various topics, including the uptake pathways and mechanisms of cell-penetrating peptides (CPPs), the utilization of CPPs as innovative vectors for gene therapy, the role of CPPs in vaccine development, and the potential of CPPs for antigen delivery in the context of vaccine development.

Glycopolymer-Cell-Penetrating Peptide (CPP) Conjugates for Efficient Epidermal Growth Factor Receptor (EGFR) Silencing

Overexpression of epidermal growth factor receptor (EGFR) is observed in multiple cancers such as colorectal, lung, and cervical solid tumors. Regulating the EGFR expression is an efficient strategy to manage these malignancies, and it can be achieved by using short interfering RNA (siRNA). Cell-penetrating peptides (CPPs) demonstrated an excellent capability to enhance the cellular uptake of siRNA, but high knockdown efficiencies have not been achieved due to endosomal entrapment. In this work, Schiff's base reaction was used to modify a block {P[LAEMA(2-lactobionamidoethyl methacrylamide)₃₇]-b-P[FPMA(4-formyl phenyl methacrylate)₂-st-DMA(N,N-dimethylacrylamide)₂], P2} and two statistical [P(LAEMA₂₃-st-FPMA₃) (P3) and P(LAEMA₂₅-st-FPMA₂-st-DMA₂) (P4)] aldehyde-based and galactose-based polymers, prepared via reversible addition-fragmentation chain-transfer (RAFT) polymerization. An arginine-rich peptide (ARP, KRRKRRRRRK) was used as a cell-penetrating peptide (CPP) and conjugated to the polymers via a Schiff base reaction. The resulting glycopolymer-peptide conjugates were utilized to condense the siRNA to prepare polyplexes with multivalent CPPs (MCPPs, a nanoparticle with multiple copies of the CPP) to enhance the endosomal escape. The polyplexes have different surface properties as determined by the architecture of polymers and the insertion of dimethyl amide moieties. The enhancement of cellular internalization of ARP was observed by labeling the polyplexes with fluorescein isothiocyanate (FITC)-siRNA showing a localization of polyplexes in the cytoplasm of a HeLa (cervical cancer) cell line. In the in vitro EFGR silencing study, the statistical glycopolymer-peptide (P3-P) polyplexes had superior EGFR silencing efficiency in comparison with the other polymers that were studied. Furthermore, P3-P polyplexes led to less off-targeting silencing than lipofectamine 3000. These encouraging results confirmed the potency of decorating galactose-based polymers with CPP, like ARP for their application in siRNA delivery and management of cervical carcinomas.

Oleyl Conjugated Histidine-Arginine Cell-Penetrating Peptides as Promising Agents for siRNA Delivery

Recent approvals of siRNA-based products motivated the scientific community to explore siRNA as a treatment option for several intractable ailments, especially cancer. The success of approved siRNA therapy requires a suitable and safer drug delivery agent. Herein, we report a series of oleyl conjugated histidine–arginine peptides as a promising nonviral siRNA delivery tool. The conjugated peptides were found to bind with the siRNA at N/P ratio ≥ 2 and demonstrated complete protection for the siRNA from early enzymatic degradation at N/P ratio ≥ 20. Oleyl-conjugated peptide -siRNA complexes were found to be noncytotoxic in breast cancer cells (MCF-7 and MDA-MB-231) and normal breast epithelial cells (MCF 10A) at N/P ratio of ~40. The oleyl-R₃-(HR)₄ and oleyl-R₄-(HR)₄ showed ~80-fold increased cellular uptake in MDA-MB-231 cells at N/P 40. Moreover, the conjugated peptides-siRNA complexes form nanocomplexes (~115 nm in size) and have an appropriate surface charge to interact with the cell membrane and cause cellular internalization. Furthermore, this study provides a proof-of-concept that oleyl-R₅-(HR)₄ can efficiently silence STAT-3 gene (~80% inhibition) in MDA-MB-231 cells with similar effectiveness to Lipofectamine. Further exploration of this approach holds a great promise in discovering a successful in vivo siRNA delivery agent with a favorable pharmacokinetic profile.

Virus-mimetic systems for cancer diagnosis and therapy

Over past decades, various strategies have been developed to enhance the delivery efficiency of therapeutics and imaging agents to tumor tissues. However, the therapeutic outcome of tumors to date have not been significantly improved, which can be partly attributed to the weak targeting ability, fast elimination, and low stability of conventional delivery systems. Viruses are the most efficient agents for gene transfer, serving as a valuable source of inspiration for designing nanoparticle-based delivery systems. Based on the properties of viruses, including well-defined geometry, precise composition, easy modification, stable construction, and specific infection, researchers attempt to design biocompatible delivery vectors by mimicking virus assembly and using the vector system to selectively concentrate drugs or imaging probes in tumors with mitigated toxicity and improved efficacy. In this review, we introduce common viruses features and provide an overview of various virus-mimetic strategies for cancer therapy and diagnosis. The challenges faced by virus-mimetic systems are also discussed. This article is categorized under: Therapeutic Approaches and Drug Discovery > Nanomedicine for Oncologic Disease.

Identification of a novel cell-penetrating peptide derived from the capsid protein of chicken anemia virus and its application in gene delivery

Cell membranes are a great obstacle for entrance of gene therapeutic agents. Cell-penetrating peptides (CPPs) have been proven as a promising gene delivery tool. However, the early TAT peptide derived from the HIV transcription activator protein has been proven that the sequence contains Furin protease cleaved motifs which limited the TAT application in delivery of exogenous active molecules. In the present study, through the bioinformatics and experimental approach, we have identified a novel CPP derived from the N terminus of VP1 protein of chicken anemia virus (CAV), designated as CVP1-N2, which is rich in arginine residues and contains α-helical structure. Then, the ability of CVP1-N2 cell penetrating was detected using confocal imaging and flow cytometry. FITC-labeled CVP1-N2 peptide could rapidly internalize into different types of live cells with dose dependence and without cytotoxic effects by MTT assay. Surprisingly, CVP1-N2 with a pattern of nuclear sub-location has shown the higher uptake efficiency than TAT. At 10, 1, and 0.1 μM, the mean relative internalization of CVP1-N2 was respectively 1.08-, 12-, and 75-fold higher than that of CVP1, as well as 1.6-, 56-, and 75-fold higher than that of TAT. Moreover, using endocytic inhibitors along with low-temperature stress validated that the CVP1-N2 internalization route is direct translocation pathway. Finally, the capacity of CVP1-N2 for delivery of gene into cells was determined, where it was able to carry red fluorescent protein (RFP) and apoptin genes into cells respectively and induce the apoptosis. All these data indicate that CVP1-N2 could be used as a novel gene delivery vehicle for gene therapy in the future. KEY POINTS: • 1CVP1-N2 was identified as a novel more efficient cell-penetrating peptide. • 2. CVP1-N2 localized to the nucleus through the direct transduction pathway. • 3. CVP1-N2 was able to deliver the apoptin gene into HCT116 cells and induce apoptosis.

In Vitro Assays: Friends or Foes of Cell-Penetrating Peptides

The cell membrane is a complex and highly regulated system that is composed of lipid bilayer and proteins. One of the main functions of the cell membrane is the regulation of cell entry. Cell-penetrating peptides (CPPs) are defined as peptides that can cross the plasma membrane and deliver their cargo inside the cell. The uptake of a peptide is determined by its sequence and biophysicochemical properties. At the same time, the uptake mechanism and efficiency are shown to be dependent on local peptide concentration, cell membrane lipid composition, characteristics of the cargo, and experimental methodology, suggesting that a highly efficient CPP in one system might not be as productive in another. To better understand the dependence of CPPs on the experimental system, we present a review of the in vitro assays that have been employed in the literature to evaluate CPPs and CPP-cargos. Our comprehensive review suggests that utilization of orthogonal assays will be more effective for deciphering the true ability of CPPs to translocate through the membrane and enter the cell cytoplasm.

Cell Penetrating Peptides, Novel Vectors for Gene Therapy

Cell penetrating peptides (CPPs), also known as protein transduction domains (PTDs), first identified ~25 years ago, are small, 6-30 amino acid long, synthetic, or naturally occurring peptides, able to carry variety of cargoes across the cellular membranes in an intact, functional form. Since their initial description and characterization, the field of cell penetrating peptides as vectors has exploded. The cargoes they can deliver range from other small peptides, full-length proteins, nucleic acids including RNA and DNA, liposomes, nanoparticles, and viral particles as well as radioisotopes and other fluorescent probes for imaging purposes. In this review, we will focus briefly on their history, classification system, and mechanism of transduction followed by a summary of the existing literature on use of CPPs as gene delivery vectors either in the form of modified viruses, plasmid DNA, small interfering RNA, oligonucleotides, full-length genes, DNA origami or peptide nucleic acids.

Transportan-derived cell-penetrating peptide delivers siRNA to inhibit replication of influenza virus in vivo

Introduction

In this study, we report on the development of an effective delivery system for siRNAs; a novel cell-penetrating peptide (CPP), T9(dR), obtained from transportan (TP), was used for in vivo and in vitro testing.

Methods

In this study, toxicity of T9(dR) and TP and efficient delivery of siRNA were tested in 293T, MDCK, RAW, and A549 cells. Furthermore, T9(dR)- and TP-delivered siRNAs against nucleoprotein (NP) gene segment of influenza virus (siNP) were studied in both cell lines and mice.

Results

Gel retardation showed that T9(dR) effectively condensed siRNA into nanoparticles sized between 350 and 550 nm when the mole ratio of T9(dR) to siRNA was ≥4:1. In vitro studies demonstrated that T9(dR) successfully delivered siRNA with low cellular toxicity into several cell lines. It was also observed that T9(dR)-delivered siRNAs inhibited replication of influenza virus more efficiently as compared to that delivered by TP into the MDCK and A549 cells. It was also noticed that when given a combined tail vein injection of siNP and T9(dR) or TP, all mice in the 50 nmol siNP group infected with PR8 influenza virus survived and showed weight recovery at 2 weeks post-infection.

Conclusion

This study indicates that T9(dR) is a promising siRNA delivery tool with potential application for nucleotide drug delivery.

Mitochondria targeting two-photon fluorescent molecules for gene transfection and biological tracking

Mitochondria targeting two-photon fluorescent organic molecules are applied in gene transfection in vitro and in vivo.

Designing improved active peptides for therapeutic approaches against infectious diseases

Infectious diseases are one of the main causes of human morbidity and mortality. In the last few decades, pathogenic microorganisms' resistance to conventional drugs has been increasing, and it is now pinpointed as a major worldwide health concern. The need to search for new therapeutic options, as well as improved treatment outcomes, has therefore increased significantly, with biologically active peptides representing a new alternative. A substantial research effort is being dedicated towards their development, especially due to improved biocompatibility and target selectivity. However, the inherent limitations of peptide drugs are restricting their application. In this review, we summarize the current status of peptide drug development, focusing on antiviral and antimicrobial peptide activities, highlighting the design improvements needed, and those already being used, to overcome the drawbacks of the therapeutic application of biologically active peptides.

Enhancing the Therapeutic Delivery of Oligonucleotides by Chemical Modification and Nanoparticle Encapsulation

Oligonucleotide (ON) drugs, including small interfering RNA (siRNA), microRNA (miRNA) and antisense oligonucleotides, are promising therapeutic agents. However, their low membrane permeability and sensitivity to nucleases present challenges to in vivo delivery. Chemical modifications of the ON offer a potential solution to improve the stability and efficacy of ON drugs. Combined with nanoparticle encapsulation, delivery at the site of action and gene silencing activity of chemically modified ON drugs can be further enhanced. In the present review, several types of ON drugs, selection of chemical modification, and nanoparticle-based delivery systems to deliver these ON drugs are discussed.

RNAi prodrugs targeting Plk1 induce specific gene silencing in primary cells from pediatric T-acute lymphoblastic leukemia patients

Epidemiological studies of childhood leukemia survivors reveal an alarmingly high incidence of chronic health disabilities after treatment, therefore, more specific therapies need to be developed. Polo-like kinase 1 (Plk1) is a key player in mitosis and a target for drug development as it is upregulated in multiple cancer types. Small molecules targeting Plk1 are mainly ATP-competitors and, therefore, are known to elicit side effects due to lack of specificity. RNA interference (RNAi) is known for its high catalytic activity and target selectivity; however, the biggest barrier for its introduction into clinical use is its delivery. RNAi prodrugs are modified, self-delivering short interfering Ribonucleic Neutrals (siRNNs), cleaved by cytoplasmic enzymes into short interfering Ribonucleic Acids (siRNAs) once inside cells. In this study we aimed to investigate the potential of siRNNs as therapeutic tools in T-acute lymphoblastic leukemia (T-ALL) using T-ALL cell lines and patient-derived samples. We demonstrate for the first time that RNAi prodrugs (siRNNs) targeting Plk1, can enter pediatric T-ALL patient cells without a transfection reagent and induce Plk1 knockdown on both protein and mRNA levels resulting in G2/M-arrest and apoptosis. We also show that siRNNs targeting Plk1 generate less toxicity in normal cells compared to the small molecule Plk1 inhibitor, BI6727, suggesting a potentially good therapeutic index.

High-Yield Synthesis of Monomeric LMWP(CPP)-siRNA Covalent Conjugate for Effective Cytosolic Delivery of siRNA

Because of the unparalleled efficiency and universal utility in treating a variety of disease types, siRNA agents have evolved as the future drug-of-choice. Yet, the inability of the polyanionic siRNA macromolecules to cross the cell membrane remains as the bottleneck of possible clinical applications. With the cell penetrating peptides (CPP) being discovered lately, the most effective tactic to achieve the highest intracellular siRNA delivery deems to be by covalently conjugating the drug to a CPP; for instance, the arginine-rich Tat or low molecular weight protamine (LMWP) peptides. However, construction of such a chemical conjugate has been referred by scientists in this field as the “Holy Grail” challenge due to self-assembly of the cationic CPP and anionic siRNA into insoluble aggregates that are deprived of the biological functions of both compounds. Based on the dynamic motion of PEG, we present herein a concise coupling strategy that is capable of permitting a high-yield synthesis of the cell-permeable, cytosol-dissociable LMWP-siRNA covalent conjugates. Cell culture assessment demonstrates that this chemical conjugate yields by far the most effective intracellular siRNA delivery and its corresponded gene-silencing activities. This work may offer a breakthrough advance towards realizing the clinical potential of all siRNA therapeutics and, presumably, most anionic macromolecular drugs such as anti-sense oligonucleotides, gene compounds, DNA vectors and proteins where conjugation with the CPP encounters with problems of aggregation and precipitation. To this end, the impact of this coupling technique is significant, far-reaching and wide-spread.

Biomaterials for polynucleotide delivery to anchorage-independent cells

Comparison of various chemical vectors used for polynucleotide delivery to mammalian anchorage-independent cells.