RNA therapeutics are a revolutionary drug platform that can regulate the expression and splicing of specific genes. With the technological advances in chemical modification and ligand conjugation, RNA therapeutics have been successively approved for the treatment of neuromuscular diseases that were considered intractable. However, the lack of efficacy, safety, and DDS have hindered further clinical application. To overcome these issues, intensive researches have been conducted at the clinical and preclinical levels. In this article, we review these efforts, particularly in the area of RNA therapeutics for neuromuscular diseases. For central nervous system（CNS） targeting, we review gapmer antisense oligonucleotides that cross the blood-brain barrier and siRNAs that have achieved excellent distribution in the CNS by intrathecal administration. For muscle targeting, I would like to present the latest findings on splice-switch oligonucleotides to improve DDS in cardiac and skeletal muscles at the clinical and preclinical levels.

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This article provides an overview of ultrasound-mediated gene delivery, particularly focusing on the carrier-free intracellular delivery of mRNA. By combining bubble agents, such as microbubbles and ultrafine bubbles, with ultrasound, precise and minimally invasive delivery of drugs to targeted sites can be achieved through acoustic cavitation. This approach is not limited by the modality of the delivered substance, making it useful for intracellular gene delivery. While bubble agents with modified shells can serve as carriers for various drugs and genes, the physical energy utilized in this method also enables carrier-free intracellular delivery of mRNA. The current application of carrier-free mRNA delivery is primarily limited to accessible tissues such as skin and skeletal muscle. However, further advancements in technology will be necessary to achieve delivery to deeper tissues in the future.

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In this review, the author, who specializes in bioinformatics, provides a comprehensive explanation of RNA design, from fundamentals to cutting-edge technologies. The review introduces RNA design methodologies, including RNA inverse folding and mRNA design, based on the relationships between RNA sequence, structure, and function. Furthermore, it details new deep learning-based methods, RaptGen and RfamGen, demonstrating efficient design approaches for RNA aptamer sequences and functional RNA family sequences. The review also discusses future perspectives, including integration with high-throughput experimental technologies, large language models, and applications of quantum computing.

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Exosomes are nanoscale vesicles secreted by most cells. Exosomes play a crucial role in intercellular communication by transporting proteins, DNA, RNA, and other molecules from donor cells to recipient cells. This process influences various cellular functions, such as gene expression, homeostasis, and immune responses in the recipient cells. Additionally, exosomes have attracted attention as potential biomarkers for a range of diseases due to their ability to carry disease-specific molecules, especially cancer. Due to their low immunogenicity and high biocompatibility, exosomes also show great promise as RNA delivery vehicles, particularly for mRNA. Several methods have been established for loading RNA into exosomes. Advances in engineering exosomes to selectively transport mRNA to target cells have opened new therapeutic possibilities for treating diseases such as cancer, autoimmune disorders, and regenerative medicine, offering a novel approach to RNA-based therapies. In this review, we provide an overview of the roles of exosomal DNA, microRNA, and mRNA, the potential of exosomes as mRNA delivery carriers, and the challenges that still need to be addressed.

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Nucleic acid therapeutics have revolutionized the treatment landscape by directly targeting DNA and RNA, allowing for the development of treatments for diseases that were previously challenging to address with small molecule drugs. Currently, siRNA and antisense oligonucleotides are the predominant forms of nucleic acid therapeutics. However, they are not without challenges, including off-target effects, stability within the biological environment, and efficient drug delivery. Our research group has developed a new approach using short nucleic acids, which we have named “Staple oligomers,” leading to the creation of RNAh （RNA hacking） technology. This innovative technology functions by inducing the formation of RNA G-quadruplex structures on specific mRNA sequences, thereby inhibiting the translation process. This mechanism of action ensures that RNAh technology only activates when it binds to the target sequence and induces the formation of the RNA G-quadruplex, thereby significantly reducing off-target effects compared to existing nucleic acid therapies. One of the most compelling features of RNAh technology is its precision in targeting mRNA. The ability to form G-quadruplex structures specifically at the desired site allows for highly selective inhibition of translation, minimizing unintended interactions with non-targeted mRNA sequences. In our study, we targeted TRPC6, a gene implicated in pulmonary arterial hypertension （PAH）, using the RNAh technology to demonstrate its efficacy in translation inhibition. TRPC6 was chosen due to its significant role in the pathology of PAH, making it an ideal candidate to illustrate the potential therapeutic benefits of RNAh technology. The results of our experiments showed that RNAh technology effectively inhibited the translation of TRPC6 mRNA, validating its potential as a powerful tool for gene-specific therapy. This research highlights the potential of RNAh technology to overcome some of the existing challenges faced by nucleic acid therapeutics. By offering a highly targeted approach with reduced off-target effects, RNAh represents a promising advancement in the development of more effective and safer therapeutic options for complex diseases. Future studies will focus on optimizing delivery methods and further evaluating the clinical applications of RNAh technology across various disease models.

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Lipid nanoparticles（LNPs）, which are a typical DDS used in mRNA vaccines, and polyplex nanomicelles that can deliver mRNA without causing inflammation at the administration site, are evaluated using the same mRNA under the same conditions. LNP yielded high levels of protein expression with inflammation at the injection site. In contrast, nanomicelles provided less but sustained protein production, with almost no inflammation at the injection site. It is important to have a variety of DDS options, which would be suitable for various purposes and administration route, for future mRNA drug development.

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Alesion^Ⓡ eyelid cream 0.5％ is a cream-type anti-allergic conjunctivitis agent that is applied to the eyelid. Approval was obtained in March 2024, and domestic sale began in May of the same year. Unlike conventional eye drops, it is a formulation with the new concept that cream is applied to the eyelid and then acts persistently on the conjunctiva via the skin of the eyelid. Traditionally in the treatment of allergic conjunctivitis, topical eye drops（a histamine H1 receptor antagonist and an inhibitor of chemical mediator release） administered twice or four times daily are the mainstay, but this product can be treated with once-daily application by delivering active ingredient to the conjunctiva through the eyelid. In addition, this product is expected to be a new dosage form that can resolve various problems caused by instillation behavior（difficulty in turning upward when instilling eye drops, inability to get into the eyedrop successfully, spillage of this product solution from the eye after instillation, etc.）. This article presents the developmental history, characteristics of this product, differences from conventional eye drop treatment and preclinical study findings.

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