Emerging landscape of cell-penetrating peptide-mediated nucleic acid delivery and their utility in imaging, gene-editing, and RNA-sequencing

The Interplay of Endosomal Escape and RNA Release from Polymeric Nanoparticles

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

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.

Engineered PepFect14 analog for efficient cellular delivery of oligonucleotides

The broad use of oligonucleotides (ON) in therapeutic and biotechnological applications is limited due to inefficient delivery methods. In parallel with lipids and polymeric carriers, cell-penetrating peptides (CPPs) are efficient vehicles for delivering nucleic acids of various types and activity into cells. In the current work, we examined the structural motifs required for the high efficacy of PepFect14, an often-used CPP for ON delivery, by introducing point mutations into the peptide sequence. We predicted the characteristics of modified CPPs, and analyzed their structure and ability to condense ONs into nanoparticles (NPs) using biophysical methods. We evaluated the ability of new PF14 analogs to deliver splicing switching oligonucleotides (SCO) and small interfering RNA (siRNA) in reporter cell lines, as well as microRNA miR-146a in human primary keratinocytes and in a mouse skin inflammation in vivo. Our findings indicate that the α-helical structure of PF14 is essential for efficient ON delivery, and mutations that disrupt the hydrophobic or cationic face in the peptide abolish NP formation and cellular internalization. PF14-Lys, an analog containing lysine residues instead of original ornithines, yielded a higher biological response to SCO and siRNA in the respective reporter cells than PF14. Furthermore, PF14-Lys efficiently delivered miRNA into keratinocytes and led to the subsequent downregulation of the target genes. Importantly, subcutaneously administered PF14-Lys-miR-146a NPs suppressed the inflammatory responses in mouse model of irritant contact dermatitis. In conclusion, our results suggest that PF14-Lys is a highly promising delivery vector for various oligonucleotides, applicable both in vitro and in vivo.

Pharmaceutical strategies for optimized mRNA expression

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

Biomaterial-based vascularization strategies for enhanced treatment of peripheral arterial disease

Peripheral arterial disease (PAD) poses a global health challenge, particularly in its advanced stages known as critical limb ischemia (CLI). Conventional treatments often fail to achieve satisfactory outcomes. Patients with CLI face high rates of morbidity and mortality, underscoring the urgent need for innovative therapeutic strategies. Recent advancements in biomaterials and biotechnology have positioned biomaterial-based vascularization strategies as promising approaches to improve blood perfusion and ameliorate ischemic conditions in affected tissues. These materials have shown potential to enhance therapeutic outcomes while mitigating toxicity concerns. This work summarizes the current status of PAD and highlights emerging biomaterial-based strategies for its treatment, focusing on functional genes, cells, proteins, and metal ions, as well as their delivery and controlled release systems. Additionally, the limitations associated with these approaches are discussed. This review provides a framework for designing therapeutic biomaterials and offers insights into their potential for clinical translation, contributing to the advancement of PAD treatments.

Revolutionizing animal husbandry: Breakthroughs in gene editing delivery systems

Gene editing technology has become an essential tool for advancing breeding practices, enhancing disease resistance, and boosting productivity in animal husbandry. Despite its potential, the delivery of gene editing reagents into cells faces several challenges, including low targeting efficiency, immunogenicity, and cytotoxicity, which have hindered its wider application in the field. This review discusses the evolution of gene editing technologies and highlights recent advancements in various delivery methods used in animal husbandry. It critically evaluates the strengths and weaknesses of these different delivery approaches while identifying potential directions for future development. The goal is to equip researchers with effective strategies to optimize delivery methods, ultimately facilitating the implementation and progress of gene editing technologies in animal husbandry.

Advances in Gene Therapy for Rare Diseases: Targeting Functional Haploinsufficiency Through AAV and mRNA Approaches

Most rare diseases (RDs) encompass a diverse group of inherited disorders that affect millions of people worldwide. A significant proportion of these diseases are driven by functional haploinsufficiency, which is caused by pathogenic genetic variants. Currently, most treatments for RDs are limited to symptom management, emphasizing the need for therapies that directly address genetic deficiencies. Recent advancements in gene therapy, particularly with adeno-associated viruses (AAVs) and lipid nanoparticle-encapsulated messenger RNA (mRNA), have introduced promising therapeutic approaches. AAV vectors offer durable gene expression, extensive tissue tropism, and a safety profile that makes them a leading choice for gene delivery; however, limitations remain, including packaging size and immune response. In contrast, mRNA therapeutics, formulated in LNPs, facilitate transient protein expression without the risk of genomic integration, supporting repeated dosing and pharmacokinetic control, though with less long-term expression than AAVs. This review analyzes the latest developments in AAV and mRNA technologies for rare monogenic disorders, focusing on preclinical and clinical outcomes, vector design, and delivery challenges. We also address key regulatory and immunological considerations impacting therapeutic success. Together, these advancements in AAV and mRNA technology underscore a new era in RD treatment, providing innovative tools to target the genetic root of these diseases and expanding therapeutic approaches for patients who currently face limited medical options.

Cell-Penetrating Peptides in infection and immunization

Bacteria and viruses pose significant threats to human health, as drug molecules and therapeutic agents are often hindered by cell membranes and tissue barriers from reaching intracellular targets. Cell-penetrating peptides (CPPs), composed of 5-30 amino acids, function as molecular shuttles that facilitate the translocation of therapeutic agents across biological barriers. Despite their therapeutic potential, CPPs exhibit limitations, such as insufficient cell specificity, low in vivo stability, reduced delivery efficiency, and limited tolerance under serum conditions. However, intelligent design and chemical modifications can enhance their cell penetration, stability, and selectivity. These advancements could significantly improve CPP-based drug delivery strategies, facilitating both infection treatment and immunization against bacterial and viral diseases. This review provides an overview of the applications of CPPs in various infections and immune diseases, summarizing their mechanisms and the challenges encountered during their application.

A cell-penetrating NS5B-specific nanobody inhibits bovine viral diarrhea virus replication

Bovine viral diarrhea virus (BVDV) causes one of the significant devastating diseases for the cattle industry worldwide. The virus can cross the placenta and result in the persistent infection of the fetus, which has hampered the efficacy and the development of vaccines. Hence, efficient antiviral strategies are urgently needed. In our previous work, a specific nanobody Nb1 against nonstructural protein 5 (NS5B) was successfully isolated, and the replication of BVDV was significantly reduced in the MDBK cell line stably expressing Nb1. Nevertheless, the Nb1 protein itself cannot enter the cells autonomously, which has severely hampered the application of the Nb1. In this work, Nb1fuses with a trans-activating transduction (TAT) peptide to form the TAT-Nb1. The TAT-Nb1 was expressed in Escherichia coli, and then purified by Ni-nitrilotriacetic acid (Ni-NTA) resin. We showed that TAT successfully delivered Nb1 into the MDBK cells, and the TAT-Nb1 efficiently inhibited the replication of BVDV in a dose-and time-dependent manner. Furthermore, the recognition site of Nb1 to NS5B was identified as NS5Baa186-487 by the yeast two-hybrid assay. In summary, this study indicates that the TAT-Nb1 can potentially to be an antiviral drug against BVDV infection, and this research may accelerate the process of Nb1 for clinical use.

Spotlight on HIV-derived TAT peptide as a molecular shuttle in drug delivery

HIV-derived TAT peptide, with a high penetration rate into cells and its nonimmunogenic and minimally toxic nature, is an attractive tool for enhancing the biodistribution of drugs and their systemic administration. Despite the presence of numerous promising preclinical investigations illustrating its capability to specifically target distinct tissues and deliver a diverse range of pharmacological agents, the efficacy of various clinical trials incorporating TAT has been impeded by several considerable obstacles. Hence, there is much need for an in-depth investigation concerning the application of TAT in drug delivery mechanisms. In this review, we have elucidated the structure of TAT and its utility in the proficient delivery of various types of bioactive molecules.

Targeted gene delivery systems for T-cell engineering

T lymphocytes are indispensable for the host systems of defense against pathogens, tumors, and environmental threats. The therapeutic potential of harnessing the cytotoxic properties of T lymphocytes for antigen-specific cell elimination is both evident and efficacious. Genetically engineered T-cells, such as those employed in CAR-T and TCR-T cell therapies, have demonstrated significant clinical benefits in treating cancer and autoimmune disorders. However, the current landscape of T-cell genetic engineering is dominated by strategies that necessitate in vitro T-cell isolation and modification, which introduce complexity and prolong the development timeline of T-cell based immunotherapies. This review explores the complexities of gene delivery systems designed for T cells, covering both viral and nonviral vectors. Viral vectors are known for their high transduction efficiency, yet they face significant limitations, such as potential immunogenicity and the complexities involved in large-scale production. Nonviral vectors, conversely, offer a safer profile and the potential for scalable manufacturing, yet they often struggle with lower transduction efficiency. The pursuit of gene delivery systems that can achieve targeted gene transfer to T cell without the need for isolation represents a significant advancement in the field. This review assesses the design principles and current research progress of such systems, highlighting the potential for in vivo gene modification therapies that could revolutionize T-cell based treatments. By providing a comprehensive analysis of these systems, we aim to contribute valuable insights into the future development of T-cell immunotherapy.

Advancing mRNA Therapeutics: The Role and Future of Nanoparticle Delivery Systems

The coronavirus (COVID-19) pandemic has underscored the critical role of mRNA-based vaccines as powerful, adaptable, readily manufacturable, and safe methodologies for prophylaxis. mRNA-based treatments are emerging as a hopeful avenue for a plethora of conditions, encompassing infectious diseases, cancer, autoimmune diseases, genetic diseases, and rare disorders. Nonetheless, the in vivo delivery of mRNA faces challenges due to its instability, suboptimal delivery, and potential for triggering undesired immune reactions. In this context, the development of effective drug delivery systems, particularly nanoparticles (NPs), is paramount. Tailored with biophysical and chemical properties and susceptible to surface customization, these NPs have demonstrated enhanced mRNA delivery in vivo and led to the approval of several NPs-based formulations for clinical use. Despite these advancements, the necessity for developing a refined, targeted NP delivery system remains imperative. This review comprehensively surveys the biological, translational, and clinical progress in NPs-mediated mRNA therapeutics for both the prevention and treatment of diverse diseases. By addressing critical factors for enhancing existing methodologies, it aims to inform the future development of precise and efficacious mRNA-based therapeutic interventions.

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.

Covalent conjugation and non-covalent complexation strategies for intracellular delivery of proteins using cell-penetrating peptides

Therapeutic proteins provided new opportunities for patients and high sales volumes. However, they are formulated for extracellular targets. The lipophilic barrier of the plasma membrane renders the vast array of intracellular targets out of reach. Peptide-based delivery systems, namely cell-penetrating peptides (CPPs), have few safety concerns, and low immunogenicity, with control over administered doses. This study investigates CPP-based protein delivery systems by classifying them into CPP-protein "covalent conjugation" and CPP: protein "non-covalent complexation" categories. Covalent conjugates ensure the proximity of the CPP to the cargo, which can improve cellular uptake and endosomal escape. We will discuss various aspects of covalent conjugates through non-cleavable (stable) or cleavable bonds. Non-cleavable CPP-protein conjugates are produced by recombinant DNA technology to express the complete fusion protein in a host cell or by chemical ligation of CPP and protein, which ensures stability during the delivery process. CPP-protein cleavable bonds are classified into pH-sensitive and redox-sensitive bonds, enzyme-cleavable bonds, and physical stimuli cleavable linkers (light radiation, ultrasonic waves, and thermo-responsive). We have highlighted the key characteristics of non-covalent complexes through electrostatic and hydrophobic interactions to preserve the conformational integrity of the CPP and cargo. CPP-mediated protein delivery by non-covalent complexation, such as zippers, CPP adaptor methods, and avidin-biotin technology, are featured. Conclusively, non-covalent complexation methods are appropriate when a high number of CPP or protein samples are to be screened. In contrast, when the high biological activity of the protein is critical in the intracellular compartment, conjugation protocols are preferred.

Genome editing and its role in vaccine, diagnosis, and therapeutic advancement

Genome editing involves precise modification of specific nucleotides in the genome using nucleases like CRISPR/Cas, ZFN, or TALEN, leading to increased efficiency of homologous recombination (HR) for gene editing, and it can result in gene disruption events via non-homologous end joining (NHEJ) or homology-driven repair (HDR). Genome editing, particularly CRISPR-Cas9, revolutionizes vaccine development by enabling precise modifications of pathogen genomes, leading to enhanced vaccine efficacy and safety. It allows for tailored antigen optimization, improved vector design, and deeper insights into host genes' impact on vaccine responses, ultimately enhancing vaccine development and manufacturing processes. This review highlights different types of genome editing methods, their associated risks, approaches to overcome the shortcomings, and the diverse roles of genome editing.

Acid-Activated TAT Peptide-Modified Biomimetic Boron Nitride Nanoparticles for Enhanced Targeted Codelivery of Doxorubicin and Indocyanine Green: A Synergistic Cancer Photothermal and Chemotherapeutic Approach

The evolution of nano-drug delivery systems addresses the limitations of conventional cancer treatments with stimulus-responsive nanomaterial-based delivery systems presenting temporal and spatial advantages. Among various nanomaterials, boron nitride nanoparticles (BNNs) demonstrate significant potential in drug delivery and cancer treatment, providing a high drug loading capacity, multifunctionality, and low toxicity. However, the challenge lies in augmenting nanomaterial accumulation exclusively within tumors while preserving healthy tissues. To address this, we introduce a novel approach involving cancer cell membrane-functionalized BNNs (CM-BIDdT) for the codelivery of doxorubicin (Dox) and indocyanine green to treat homologous tumor. The cancer cell membrane biomimetic CM-BIDdT nanoparticles possess highly efficient homologous targeting capabilities toward tumor cells. The surface modification with acylated TAT peptides (dTAT) further enhances the nanoparticle intracellular accumulation. Consequently, CM-BIDdT nanoparticles, responsive to the acidic tumor microenvironment, hydrolyze amide bonds, activate the transmembrane penetrating function, and achieve precise targeting with substantial accumulation at the tumor site. Additionally, the photothermal effect of CM-BIDdT under laser irradiation not only kills cells through thermal ablation but also destroys the membrane on the surface of the nanoparticles, facilitating Dox release. Therefore, the fabricated CM-BIDdT nanoparticles orchestrate chemo-photothermal combination therapy and effectively inhibit tumor growth with minimal adverse effects, holding promise as a new modality for synergistic cancer treatment.

Emerging Landscape of Supercharged Proteins and Peptides for Drug Delivery

Although groundbreaking biotechnological techniques such as gene editing have significantly progressed, the effective and targeted transport of therapeutic agents into host cells remains a major obstacle to the development of biotherapeutics. Confronting the unique challenge posed by large macromolecules such as proteins, peptides, and nucleic acids adds complexity to this issue. Recent findings reveal that the supercharging of proteins and peptides not only enables control over critical properties, such as temperature resistance and catalytic activity, but also holds promise as a viable strategy for their use in drug delivery. This review provides a concise summary of the attributes of supercharged proteins and peptides, encompassing both their natural occurrence and engineered variants. Furthermore, it sheds light on the present status and future possibilities of supercharged proteins and peptides as carriers for significant biomolecules in the realms of medical research and therapeutic applications.

Enhancing Neuroprotection in Mouse Model of Parkinson's Disease through Protein Nanosystem Conjugation with ApoE Peptide for miR-124 Delivery

Parkinson's disease (PD) affects millions of people's lives worldwide. The main pathogenesis of PD is dopaminergic neuron necrosis and neuroinflammation mediated by activated microglia cells. In recent years, the anti-inflammatory ability and neuroprotective effects of miR-124 in PD models were well proved, but the in vivo delivery of miR-124 remains challenging. Herein, we report a protein nanosystem modified with a brain-targeting peptide ApoE that could efficiently deliver miR-124 across the blood-brain barrier (BBB). This nanosystem showed good cell viability on brain endothelial cells and microglia cells, and administration of this nanosystem significantly decreased the neuroinflammation and dopaminergic neuron loss, as well as recovered parts of neurobehavioral deficits. This ApoE peptide-based protein nanosystem holds great promise for the delivery of RNA therapeutics to the brain and for realizing neuron protection in PD treatment.

Emerging Landscape of Osteogenesis Imperfecta Pathogenesis and Therapeutic Approaches

Osteogenesis imperfecta (OI) is an uncommon genetic disorder characterized by shortness of stature, hearing loss, poor bone mass, recurrent fractures, and skeletal abnormalities. Pathogenic variations have been found in over 20 distinct genes that are involved in the pathophysiology of OI, contributing to the disorder's clinical and genetic variability. Although medications, surgical procedures, and other interventions can partially alleviate certain symptoms, there is still no known cure for OI. In this Review, we provide a comprehensive overview of genetic pathogenesis, existing treatment modalities, and new developments in biotechnologies such as gene editing, stem cell reprogramming, functional differentiation, and transplantation for potential future OI therapy.

mRNA vaccines and their delivery strategies: A journey from infectious diseases to cancer

mRNA vaccines have evolved as promising cancer therapies. These vaccines can encode tumor-allied antigens, thus enabling personalized treatment approaches. They can also target cancer-specific mutations and overcome immune evasion mechanisms. They manipulate the body's cellular functions to produce antigens, elicit immune responses, and suppress tumors by overcoming limitations associated with specific histocompatibility leukocyte antigen molecules. However, successfully delivering mRNA into target cells destroys a crucial challenge. Viral and nonviral vectors (lipid nanoparticles and cationic liposomes) have shown great capacity in protecting mRNA from deterioration and assisting in cellular uptake. Cell-penetrating peptides, hydrogels, polymer-based nanoparticles, and dendrimers have been investigated to increase the delivery efficacy and immunogenicity of mRNA. This comprehensive review explores the landscape of mRNA vaccines and their delivery platforms for cancer, addressing design considerations, diverse delivery strategies, and recent advancements. Overall, this review contributes to the progress of mRNA vaccines as an innovative strategy for effective cancer treatment.

Zwitterionic materials for nucleic acid delivery and therapeutic applications

Nucleic acid therapeutics have demonstrated substantial potential in combating various diseases. However, challenges persist, particularly in the delivery of multifunctional nucleic acids. To address this issue, numerous gene delivery vectors have been developed to fully unlock the potential of gene therapy. The advancement of innovative materials with exceptional delivery properties is critical to propel the clinical translation of nucleic acid drugs. Cationic vector materials have received extensive attention, while zwitterionic materials remain relatively underappreciated in delivery. In this review, we outline a diverse range of zwitterionic material nucleic acid carriers, predominantly encompassing zwitterionic lipids, polymers and peptides. Their respective chemical structures, synthesis approaches, properties, advantages, and therapeutic applications are summarized and discussed. Furthermore, we highlight the challenges and future opportunities associated with the development of zwitterionic vector materials. This review will aid to understand the zwitterionic materials in aiding gene delivery, contributing to the continual progress of nucleic acid therapeutics.

Lentiviral Transduction-based CRISPR/Cas9 Editing of Schistosoma mansoni Acetylcholinesterase

Background

Recent studies on CRISPR/Cas9-mediated gene editing in Schistosoma mansoni have shed new light on the study and control of this parasitic helminth. However, the gene editing efficiency in this parasite is modest.

Methods

To improve the efficiency of CRISPR/Cas9 genome editing in schistosomes, we used lentivirus, which has been effectively used for gene editing in mammalian cells, to deliver plasmid DNA encoding Cas9 nuclease, a sgRNA targeting acetylcholinesterase (SmAChE) and a mCherry fluorescence marker into schistosomes.

Results

MCherry fluorescence was observed in transduced eggs, schistosomula, and adult worms, indicating that the CRISPR components had been delivered into these parasite stages by lentivirus. In addition, clearly changed phenotypes were observed in SmAChE-edited parasites, including decreased SmAChE activity, reduced hatching ability of edited eggs, and altered behavior of miracidia hatched from edited eggs. Next-generation sequencing analysis demonstrated that the lentiviral transduction-based CRISPR/Cas9 gene modifications in SmAChE-edited schistosomes were homology-directed repair predominant but with much lower efficiency than that obtained using electroporation (data previously published by our laboratory) for the delivery of CRISPR components.

Conclusion

Taken together, electroporation is more efficient than lentiviral transduction in the delivery of CRISPR/Cas9 into schistosomes for programmed genome editing. The exploration of tactics for enhancing CRISPR/Cas9 gene editing provides the basis for the future improvement of programmed genome editing in S. mansoni.

Synthesis of Short Peptides with Perfluoroalkyl Side Chains and Evaluation of Their Cellular Uptake Efficiency

With an increasing demand for macromolecular biotherapeutics, the issue of their poor cell-penetrating abilities requires viable and relevant solutions. Herein, we report tripeptides bearing an amino acid with a perfluoroalkyl (RF ) group adjacent to the α-carbon. RF -containing tripeptides were synthesized and evaluated for their ability to transport a conjugated hydrophilic dye (Alexa Fluor 647) into the cells. RF -containing tripeptides with the fluorophore showed high cellular uptake efficiency and none of them were cytotoxic. Interestingly, we demonstrated that the absolute configuration of perfluoroalkylated amino acids (RF -AAs) affects not only nanoparticle formation but also the cell permeability of the tripeptides. These novel RF -containing tripeptides are potentially useful as short and noncationic cell-penetrating peptides (CPPs).

Emerging Landscape of Preclinical Models for Studying COVID-19 Neurologic Diseases

COVID-19 (Coronavirus Disease 2019) is an infectious disease caused by SARS-CoV-2 (severe acute respiratory syndrome coronavirus 2) and has globally infected 768 million people and caused over 6 million deaths. COVID-19 primarily affects the respiratory system but increasing reports of neurologic symptoms associated with COVID-19 have been reported in the literature. The exact mechanism behind COVID-19 neurologic pathophysiology remains poorly understood due to difficulty quantifying clinical neurologic symptoms in humans and correlating them to findings in human post-mortem samples and animal models. Thus, robust preclinical experimental models for COVID-19 neurologic manifestations are urgently needed. Here, we review recent advances in in vitro, in vivo, and other models and technologies for studying COVID-19 including primary cell cultures, pluripotent stem cell-derived neurons and organoids, rodents, nonhuman primates, 3D bioprinting, artificial intelligence, and multiomics. We specifically focus our discussion on the contribution, recent advancements, and limitations these preclinical models have on furthering our understanding of COVID-19's neuropathic physiology. We also discuss these models' roles in the screening and development of therapeutics, vaccines, antiviral drugs, and herbal medicine, and on future opportunities for COVID-19 neurologic research and clinical management.

Neurobiochemical characteristics of arginine-rich peptides explain their potential therapeutic efficacy in neurodegenerative diseases

Neurodegenerative diseases, including Alzheimer̕ s disease (AD), Parkinson̕ s disease (PD), Huntington̕ s disease (HD), and Amyotrophic Lateral Sclerosis (ALS) require special attention to find new potential treatment methods. This review aims to summarize the current knowledge of the relationship between the biochemical properties of arginine-rich peptides (ARPs) and their neuroprotective effects to deal with the harmful effects of risk factors. It seems that ARPs have portrayed a promising and fantastic landscape for treating neurodegeneration-associated disorders. With multimodal mechanisms of action, ARPs play various unprecedented roles, including as the novel delivery platforms for entering the central nervous system (CNS), the potent antagonists for calcium influx, the invader molecules for targeting mitochondria, and the protein stabilizers. Interestingly, these peptides inhibit the proteolytic enzymes and block protein aggregation to induce pro-survival signaling pathways. ARPs also serve as the scavengers of toxic molecules and the reducers of oxidative stress agents. They also have anti-inflammatory, antimicrobial, and anti-cancer properties. Moreover, by providing an efficient nucleic acid delivery system, ARPs can play an essential role in developing various fields, including gene vaccines, gene therapy, gene editing, and imaging. ARP agents and ARP/cargo therapeutics can be raised as an emergent class of neurotherapeutics for neurodegeneration. Part of the aim of this review is to present recent advances in treating neurodegenerative diseases using ARPs as an emerging and powerful therapeutic tool. The applications and progress of ARPs-based nucleic acid delivery systems have also been discussed to highlight their usefulness as a broad-acting class of drugs.

Delivery of Oleanolic Acid with Improved Antifibrosis Efficacy by a Cell Penetrating Peptide P10

Oleanolic acid (OA), a common pentacyclic triterpenoid found in plants, has several therapeutic uses, including the treatment of hepatopathy disorders. However, due to OA's weak permeability and limited bioavailability, its therapeutic advantages are limited. Here, we showed that a short peptide known as p10 not only binds to OA but also rapidly enhances OA delivery into cultured hepatic stellate cells (HSCs), lowers their synthesis of fibrogenic proteins, and further reduces the HSC migration capacity. Our findings show that noncovalently conjugating short peptides to OA improves its pharmacological efficacy and permeability.

Emerging Landscape of Nanobodies and Their Neutralizing Applications against SARS-CoV-2 Virus

The new severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) that causes the coronavirus disease 2019 (COVID-19) has significantly altered people's way of life. Despite widespread knowledge of vaccination, mask use, and avoidance of close contact, COVID-19 is still spreading around the world. Numerous research teams are examining the SARS-CoV-2 infection process to discover strategies to identify, prevent, and treat COVID-19 to limit the spread of this chronic coronavirus illness and restore lives to normalcy. Nanobodies have advantages over polyclonal and monoclonal antibodies (Ab) and Ab fragments, including reduced size, high stability, simplicity in manufacture, compatibility with genetic engineering methods, and lack of solubility and aggregation issues. Recent studies have shown that nanobodies that target the SARS-CoV-2 receptor-binding domain and disrupt ACE2 interactions are helpful in the prevention and treatment of SARS-CoV-2-infected animal models, despite the lack of evidence in human patients. The creation and evaluation of nanobodies, as well as their diagnostic and therapeutic applications against COVID-19, are discussed in this paper.

Non-viral approaches for gene therapy and therapeutic genome editing across the blood-brain barrier

The success of brain-targeted gene therapy and therapeutic genome editing hinges on the efficient delivery of biologics bypassing the blood-brain barrier (BBB), which presents a significant challenge in the development of treatments for central nervous system disorders. This is particularly the case for nucleic acids and genome editors that are naturally excluded by the BBB and have poor chemical stability in the bloodstream and poor cellular uptake capability, thereby requiring judiciously designed nanovectors administered systemically for intracellular delivery to brain cells such as neurons. To overcome this obstacle, various strategies for bypassing the BBB have been developed in recent years to deliver biologics to the brain via intravenous administration using non-viral vectors. This review summarizes various brain targeting strategies and recent representative reports on brain-targeted non-viral delivery systems that allow gene therapy and therapeutic genome editing via intravenous administration, and highlights ongoing challenges and future perspectives for systemic delivery of biologics to the brain via non-viral vectors.

Exosomes as an Emerging Plasmid Delivery Vehicle for Gene Therapy

Despite its introduction more than three decades ago, gene therapy has fallen short of its expected potential for the treatment of a broad spectrum of diseases and continues to lack widespread clinical use. The fundamental limitation in clinical translatability of this therapeutic modality has always been an effective delivery system that circumvents degradation of the therapeutic nucleic acids, ensuring they reach the intended disease target. Plasmid DNA (pDNA) for the purpose of introducing exogenous genes presents an additional challenge due to its size and potential immunogenicity. Current pDNA methods include naked pDNA accompanied by electroporation or ultrasound, liposomes, other nanoparticles, and cell-penetrating peptides, to name a few. While the topic of numerous reviews, each of these methods has its own unique set of limitations, side effects, and efficacy concerns. In this review, we highlight emerging uses of exosomes for the delivery of pDNA for gene therapy. We specifically focus on bovine milk and colostrum-derived exosomes as a nano-delivery "platform". Milk/colostrum represents an abundant, scalable, and cost-effective natural source of exosomes that can be loaded with nucleic acids for targeted delivery to a variety of tissue types in the body. These nanoparticles can be functionalized and loaded with pDNA for the exogenous expression of genes to target a wide variety of disease phenotypes, overcoming many of the limitations of current gene therapy delivery techniques.

Nano-vaccines for gene delivery against HIV-1 infection

INTRODUCTION

Over the last four decades, human immunodeficiency virus type 1 (HIV-1) infection has been a major public health concern. It is acknowledged that an effective vaccine remains the best hope for eliminating the HIV-1 pandemic. The prophylaxis of HIV-1 infection remains a central theme because of the absence of an available HIV-1 vaccine. The incapability of conventional delivery strategies to induce potent immunity is a crucial task to overcome and ultimately lead to a major obstacle in HIV-1 vaccine research.

AREAS COVERED

The literature search was conducted in the following databases: PubMed, Web of Science, and Embase. Nano-platforms based vaccines have proven prophylaxis of various diseases for effectively activating the immune system. Nano-vaccines, including non-viral and viral vectored nano-vaccines, are in a position to improve the effectiveness of HIV-1 antigen delivery and enhance the innate and adaptive immune responses against HIV-1. Compared to traditional vaccination strategies, genetic immunization can elicit a long-term immune response to provide protective immunity for HIV-1 prevention.

EXPERT OPINION

The research progress on nano-vaccines for gene delivery against HIV-1 was discussed. The vaccine strategies based on nano-platforms that are being applied to stimulate effective HIV-1-specific cellular and humoral immune responses were particularly emphasized.

Emerging Landscape of SARS-CoV-2 Variants and Detection Technologies

In 2019, a new coronavirus was identified that has caused significant morbidity and mortality worldwide. Like all RNA viruses, severe acute respiratory syndrome coronavirus 2 (SARS-Cov-2) evolves over time through random mutation resulting in genetic variations in the population. Although the currently approved coronavirus disease 2019 vaccines can be given to those over 5 years of age and older in most countries, strikingly, the number of people diagnosed positive for SARS-Cov-2 is still increasing. Therefore, to prevent and control this epidemic, early diagnosis of infected individuals is of great importance. The current detection of SARS-Cov-2 coronavirus variants are mainly based on reverse transcription-polymerase chain reaction. Although the sensitivity of reverse transcription-polymerase chain reaction is high, it has some disadvantages, for example, multiple temperature changes, long detection time, complicated operation, expensive instruments, and the need for professional personnel, which brings considerable inconvenience to the early diagnosis of this virus. This review comprehensively summarizes the development and application of various current detection technologies for novel coronaviruses, including isothermal amplification, CRISPR-Cas detection, serological detection, biosensor, ensemble, and microfluidic technology, along with next-generation sequencing. Those findings offer us a great potential to replace or combine with reverse transcription-polymerase chain reaction detection to achieve the purpose of allowing predictive diagnostics and targeted prevention of SARS-Cov-2 in the future.

Emerging Landscape of Cell-Penetrating Peptide-Mediated Organelle Restoration and Replacement

Organelles are specialized subunits within a cell membrane that perform specific roles or functions, and their dysfunction can lead to a variety of pathophysiologies including developmental defects, aging, and diseases (cancer, cardiovascular and neurodegenerative diseases). Recent studies have shown that cell-penetrating peptide (CPP)-based pharmacological therapies delivered to organelles or even directly resulting in organelle replacement can restore cell function and improve or prevent disease. In this review, we summarized the current developments in the precise delivery of exogenous cargoes via CPPs at the organelle level, CPP-mediated organelle delivery, and discuss their feasibility as next-generation targeting strategies for the diagnosis and treatment of diseases at the organelle level.

Cell-Permeable PROTAC Degraders against KEAP1 Efficiently Suppress Hepatic Stellate Cell Activation through the Antioxidant and Anti-Inflammatory Pathway

Accumulating evidence indicates that oxidative stress and inflammation are involved in the physiopathology of liver fibrogenesis. Nuclear factor erythroid 2-related factor 2 (Nrf2) is a key transcription factor, which regulates the expression of redox regulators to establish cellular redox homeostasis. The Nrf2 modulator can serve as a primary cellular defense against the cytotoxic effects of oxidative stress. We designed a chimeric Keap1-Keap1 peptide (KKP1) based on the proteolysis-targeting chimera technology. The KKP1 peptide not only can efficiently penetrate into the rat hepatic stellate cell line (HSC-T6) cells but also can induce Keap1 protein degradation by the ubiquitination-proteasome degradation pathway, which releases Nrf2 and promotes the transcriptional activity of the Nrf2/antioxidant response element pathway. It then activates the protein expression of the downstream antioxidant factors, the glutamate-cysteine ligase catalytic subunit and heme oxygenase-1 (HO-1). Finally, Keap1 protein degradation inhibits the nuclear factor-kappaB inflammatory signal pathway, the downstream inflammatory factor tumor necrosis factor alpha, and the interleukin-1beta protein expression and further inhibits the expression of the fibrosis biomarker gene. The current research suggests that our designed KKP1 may provide a new avenue for the future treatment of liver fibrosis.

Peptide mediated therapy in fibrosis: Mechanisms, advances and prospects

Fibrosis, a disease characterized by an excess accumulation of extracellular matrix components, could lead to organ failure and death, and is to blame for up to 45 % of all fatalities in developed nations. These disorders all share the common trait of an unchecked and increasing accumulation of fibrotic tissue in the affected organs, which leads to their malfunction and eventual failure, even if their underlying causes are highly diverse and, in some cases, remain unclear. Numerous studies have identified activated myofibroblasts as the common cellular elements ultimately responsible for the replacement of normal tissues with nonfunctional fibrotic tissue. The transforming growth factor-β pathway, for instance, plays a significant role in practically all kinds of fibrosis. However, there is no specific drug for the treatment of fibrosis, several medications with anti-hepatic fibrosis properties are still in the research and development stages. Peptide, which refers to a substance consisting of 2-50 amino acids, is characterized by structural diversity, low toxicity, biological activities, easy absorption, specific targeting, few side effects, and has been proven to be effective in anti-fibrosis. Here, we summarized various anti-fibrosis peptides in fibrosis including the liver, lungs, kidneys, and other organs. This review will provide a new insight into peptide mediated anti-fibrosis and is helpful to creation of antifibrotic medications.

Improved transfer efficiency of supercharged 36 + GFP protein mediate nucleic acid delivery

The potential of nucleic acid therapeutics to treat diseases by targeting specific cells has resulted in its increasing number of uses in clinical settings. However, the major challenge is to deliver bio-macromolecules into target cells and/or subcellular locations of interest ahead in the development of delivery systems. Although, supercharged residues replaced protein 36 + GFP can facilitate itself and cargoes delivery, its efficiency is still limited. Therefore, we combined our recent progress to further improve 36 + GFP based delivery efficiency. We found that the penetration efficacy of 36 + GFP protein was significantly improved by fusion with CPP-Dot1l or treatment with penetration enhancer dimethyl sulfoxide (DMSO) in vitro. After safely packaged with plasmid DNA, we found that the efficacy of in vitro and in vivo transfection mediated by 36 + GFP-Dot1l fusion protein is also significantly improved than 36 + GFP itself. Our findings illustrated that fusion with CPP-Dot1l or incubation with DMSO is an alternative way to synergically promote 36 + GFP mediated plasmid DNA delivery in vitro and in vivo.

Cytoplasmic delivery of siRNA using human-derived membrane penetration-enhancing peptide

BACKGROUND

Although protein-based methods using cell-penetrating peptides such as TAT have been expected to provide an alternative approach to siRNA delivery, the low efficiency of endosomal escape of siRNA/protein complexes taken up into cells by endocytosis remains a problem. Here, to overcome this problem, we adopted the membrane penetration-enhancing peptide S19 from human syncytin 1 previously identified in our laboratory.

RESULTS

We prepared fusion proteins in which the S19 and TAT peptides were fused to the viral RNA-binding domains (RBDs) as carrier proteins, added the RBD-S19-TAT/siRNA complex to human cultured cells, and investigated the cytoplasmic delivery of the complex and the knockdown efficiency of target genes. We found that the intracellular uptake of the RBD-S19-TAT/siRNA complex was increased compared to that of the RBD-TAT/siRNA complex, and the expression level of the target mRNA was decreased. Because siRNA must dissociate from RBD and bind to Argonaute 2 (Ago2) to form the RNA-induced silencing complex (RISC) after the protein/siRNA complex is delivered into the cytoplasm, a dilemma arises: stronger binding between RBD and siRNA increases intracellular uptake but makes RISC formation more difficult. Thus, we next prepared fusion proteins in which the S19 and TAT peptides were fused with Ago2 instead of RBD and found that the efficiencies of siRNA delivery and knockdown obtained using TAT-S19-Ago2 were higher than those using TAT-Ago2. In addition, we found that the smallest RISC delivery induced faster knockdown than traditional siRNA lipofection, probably due to the decreased time required for RISC formation in the cytoplasm.

CONCLUSION

These results indicated that S19 and TAT-fused siRNA-binding proteins, especially Ago2, should be useful for the rapid and efficient delivery of siRNA without the addition of any endosome-disrupting agent.

An assembly-inducing PDC enabling the efficient nuclear delivery of nucleic acid for cancer stem-like cell suppression

Nucleic acid therapy is attracting great attention in diverse clinical translations because of its therapeutic advantages. As a renowned oligonucleotide therapeutical candidate in the clinical stage, AS1411 has shown outstanding tumor suppressing effects; however, its efficient delivery to the cell nucleus is critical for its anticancer effect. Herein, we identified a multifunctional peptide drug conjugate (PDC) as a safe and efficient carrier to achieve the nuclear delivery of AS1411. This PDC consists of the cell penetration peptide RW9, an HDAC inhibitor warhead (peptide C-terminus), and 5-FU (peptide N-terminus), which can coassemble with AS1411 to form nanospheres. The PDC efficiently delivered AS1411 to the nucleus of several types of cancer cells. Moreover, it reversed the stemness of a cancer stem-like cell line. Significantly, due to the assembly-induced accumulation enhancement and retention, a safe single agent concentration of PDC showed unexpected synergy with AS1411 to augment the cancer cell suppression efficiency, exemplified by the downregulation of the stemness-related proteins and the upregulation of apoptosis-related proteins. Therefore, our work presents a powerful strategy for the nuclear delivery of nucleic acid drugs by leveraging cancer-suppressing PDC as assembly inducers, which provides a powerful combination regimen in treating cancer stem-like cells.

GRP75-driven, cell-cycle-dependent macropinocytosis of Tat/pDNA-Ca2+ nanoparticles underlies distinct gene therapy effect in ovarian cancer

Practice of tumor-targeted suicide gene therapy is hampered by unsafe and low efficient delivery of plasmid DNA (pDNA). Using HIV-Tat-derived peptide (Tat) to non-covalently form Tat/pDNA complexes advances the delivery performance. However, this innovative approach is still limited by intracellular delivery efficiency and cell-cycle status. In this study, Tat/pDNA complexes were further condensed into smaller, nontoxic nanoparticles by Ca²⁺ addition. Formulated Tat/pDNA-Ca²⁺ nanoparticles mainly use macropinocytosis for intercellular delivery, and their macropinocytic uptake was persisted in mitosis (M-) phase and highly activated in DNA synthesis (S-) phase of cell-cycle. Over-expression or phosphorylation of a mitochondrial chaperone, 75-kDa glucose-regulated protein (GRP75), promoted monopolar spindle kinase 1 (MPS1)-controlled centrosome duplication and cell-cycle progress, but also driven cell-cycle-dependent macropinocytosis of Tat/pDNA-Ca²⁺ nanoparticles. Further in vivo molecular imaging based on DF (Fluc-eGFP)-TF (RFP-Rluc-HSV-ttk) system showed that Tat/pDNA-Ca²⁺ nanoparticles exhibited highly suicide gene therapy efficiency in mouse model xenografted with human ovarian cancer. Furthermore, arresting cell-cycle at S-phase markedly enhanced delivery performance of Tat/pDNA-Ca²⁺ nanoparticles, whereas targeting GRP75 reduced their macropinocytic delivery. More importantly, in vivo targeting GRP75 combined with cell-cycle or macropinocytosis inhibitors exhibited distinct suicide gene therapy efficiency. In summary, our data highlight that mitochondrial chaperone GRP75 moonlights as a biphasic driver underlying cell-cycle-dependent macropinocytosis of Tat/pDNA-Ca²⁺ nanoparticles in ovarian cancer.

Novel branched amphiphilic peptides for nucleic acids delivery

Highly efficient and safe non-viral vectors for nucleic acids delivery have attracted much attention due to their potential applications in gene therapy, gene editing and vaccination against infectious diseases, and various materials have been investigated and designed as delivery vectors. Herein, we designed a series of branched amphiphilic peptides (BAPs) and tested their applications as pDNA/mRNA delivery vectors. The BAP structure was inspired by the phospholipids, in which lysine oligomers were used as the "polar head", segments containing phenylalanine, histidine and leucine were used as the "hydrophobic tails", and a lysine residue was used as the branching point. By comparing the gel retardation, particle sizes and zeta potentials of the BAP/pDNA complexes of the short-branch BAPs (BAP-V1 ∼ BAP-V4), we determined the optimal lysine oligomer was K₆. However, their cell transfection efficiencies were not satisfactory, and thus three long-branch BAPs (BAP-V5 ∼ BAP-V7) were further designed. In these long-branch BAPs, more hydrophobic residues were added and the overall amphiphilicity increased accordingly. The results showed that these three BAPs could effectively compact the nucleic acids, including both pDNA and mRNA, and all could transfect nucleic acids into HEK 293 cells, with low cytotoxicity. Among the three long-branch BAPs, BAP-V7 (bis(FFLFFHHH)-K-K₆) showed the best transfection efficiency at N/P = 10, which was better than the commercial transfection reagent PEI-25 K. These results indicate that increased amphiphilicity would also benefit for BAP mediated nucleic acid delivery. The designed BAPs provide more documents of such novel type of nucleic acids delivery vectors, which is worth of further investigation as a new gene theranostic platforms.

Current progress of miRNA-derivative nucleotide drugs: Modifications, delivery systems, applications

INTRODUCTION

miRNA-derivative clinical nucleotide drugs (mdCNDs) effectively treat several diseases, with numerous undergoing clinical trials. In early-stage trials in disease therapeutics such as malignant pleural mesothelioma and hepatic virus C infection, mdCND's therapeutic potency is undeniably good for effectiveness and safety.

AREAS COVERED

15 mdCNDs undergoing clinical trials are introduced in this review. MiRNA modifications methods have been summarized including phosphorothioate, cholesterol, locked nucleic acid, 2'-O-methyl, N,N-diethyl-4-(4-nitronaphthalen1-ylazo)-phenylamine modifications and many more. Moreover, delivery systems, including self-assembled, inorganic ions nanoparticles, exosomes, and lipid-based nanosystems for mdCNDs targeted delivery, are presented. Among that, EnGeneIC, N-Acetylgalactosamine, liposomal nanoparticles, and cholesterol-conjugated for mdCNDs delivery are currently undergoing clinical trials. The pH, light, temperature, redox-responsive, enzyme, and specific-substance modes to trigger the release of miRNAs to target sites on-demand and the prospects of mdCNDs are discussed in this review.

EXPERT OPINION

mdNCDs are one type of promising clinical drugs, however, it is still in the infancy. During the development process, it is imperative to advance in modifying miRNAs, especially at the 5'-end, to enhance targetability and stability against nucleases, develop a stimuli-responsive mode to control the release of mdCNDs to tissue cell-type-specific sites.