Production, Characterization, and Assessment of Permanently Cationic and Ionizable Lipid Nanoparticles for Use in the Delivery of Self-Amplifying RNA Vaccines

Advances in the design and delivery of RNA vaccines for infectious diseases

RNA medicines represent a paradigm shift in treatment and prevention of critical diseases of global significance, e.g., infectious diseases. The highly successful messenger RNA (mRNA) vaccines against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) were developed at record speed during the coronavirus disease 2019 pandemic. A consequence of this is exceptionally shortened vaccine development times, which in combination with adaptability makes the RNA vaccine technology highly attractive against infectious diseases and for pandemic preparedness. Here, we review state of the art in the design and delivery of RNA vaccines for infectious diseases based on different RNA modalities, including linear mRNA, self-amplifying RNA, trans-amplifying RNA, and circular RNA. We provide an overview of the clinical pipeline of RNA vaccines for infectious diseases, and present analytical procedures, which are paramount for characterizing quality attributes and guaranteeing their quality, and we discuss future perspectives for using RNA vaccines to combat pathogens beyond SARS-CoV-2.

Complete substitution with modified nucleotides in self-amplifying RNA suppresses the interferon response and increases potency

The use of modified nucleotides to suppress the interferon response and maintain translation of self-amplifying RNA (saRNA), which has been achieved for mRNA, has not yet succeeded. We identify modified nucleotides that, when substituted at 100% in saRNA, confer innate immune evasion and robust long-term protein expression, and when formulated as a vaccine, protect against lethal SARS-CoV-2 challenge in mice. This discovery advances saRNA therapeutics by enabling prolonged protein expression at low doses.

Microfluidics: a concise review of the history, principles, design, applications, and future outlook

Microfluidic technologies have garnered significant attention due to their ability to rapidly process samples and precisely manipulate fluids in assays, making them an attractive alternative to conventional experimental methods. With the potential for revolutionary capabilities in the future, this concise review provides readers with insights into the fascinating world of microfluidics. It begins by introducing the subject's historical background, allowing readers to familiarize themselves with the basics. The review then delves into the fundamental principles, discussing the underlying phenomena at play. Additionally, it highlights the different aspects of microfluidic device design, classification, and fabrication. Furthermore, the paper explores various applications, the global market, recent advancements, and challenges in the field. Finally, the review presents a positive outlook on trends and draws lessons to support the future flourishing of microfluidic technologies.

Complete substitution with modified nucleotides suppresses the early interferon response and increases the potency of self-amplifying RNA

Self-amplifying RNA (saRNA) will revolutionize vaccines and in situ therapeutics by enabling protein expression for longer duration at lower doses. However, a major barrier to saRNA efficacy is the potent early interferon response triggered upon cellular entry, resulting in saRNA degradation and translational inhibition. Substitution of mRNA with modified nucleotides (modNTPs), such as N1-methylpseudouridine (N1mΨ), reduce the interferon response and enhance expression levels. Multiple attempts to use modNTPs in saRNA have been unsuccessful, leading to the conclusion that modNTPs are incompatible with saRNA, thus hindering further development. Here, contrary to the common dogma in the field, we identify multiple modNTPs that when incorporated into saRNA at 100% substitution confer immune evasion and enhance expression potency. Transfection efficiency enhances by roughly an order of magnitude in difficult to transfect cell types compared to unmodified saRNA, and interferon production reduces by >8 fold compared to unmodified saRNA in human peripheral blood mononuclear cells (PBMCs). Furthermore, we demonstrate expression of viral antigens in vitro and observe significant protection against lethal challenge with a mouse-adapted SARS-CoV-2 strain in vivo . A modified saRNA vaccine, at 100-fold lower dose than a modified mRNA vaccine, results in a statistically improved performance to unmodified saRNA and statistically equivalent performance to modified mRNA. This discovery considerably broadens the potential scope of self-amplifying RNA, enabling entry into previously impossible cell types, as well as the potential to apply saRNA technology to non-vaccine modalities such as cell therapy and protein replacement.