Lipoplexes carrying mRNA encoding Gag protein modulate dendritic cells to stimulate HIV-specific immune responses

Unlocking the potential of nanocarrier-mediated mRNA delivery across diverse biomedical frontiers: A comprehensive review

Messenger RNA (mRNA) has gained marvelous attention for managing and preventing various conditions like cancer, Alzheimer's, infectious diseases, etc. Due to the quick development and success of the COVID-19 mRNA-based vaccines, mRNA has recently grown in prominence. A lot of products are in clinical trials and some are already FDA-approved. However, still improvements in line of optimizing stability and delivery, reducing immunogenicity, increasing efficiency, expanding therapeutic applications, scalability and manufacturing, and long-term safety monitoring are needed. The delivery of mRNA via a nanocarrier system gives a synergistic outcome for managing chronic and complicated conditions. The modified nanocarrier-loaded mRNA has excellent potential as a therapeutic strategy. This emerging platform covers a wide range of diseases, recently, several clinical studies are ongoing and numerous publications are coming out every year. Still, many unexplained physical, biological, and technical problems of mRNA for safer human consumption. These complications were addressed with various nanocarrier formulations. This review systematically summarizes the solved problems and applications of nanocarrier-based mRNA delivery. The modified nanocarrier mRNA meaningfully improved mRNA stability and abridged its immunogenicity issues. Furthermore, several strategies were discussed that can be an effective solution in the future for managing complicated diseases.

Emerging trends of research on mRNA vaccines: A co-citation analysis

This study was designed to evaluate the emerging trends of research on mRNA vaccines. Altogether 3056 research articles related to mRNA vaccines published since 2010 were retrieved from the Web of Science database, based on which a co-citation analysis was conducted using CiteSpace. A total of 12 clusters were derived, all of which were classified into three periods according to the content and publication time of articles: (1) The preliminary exploratory period before early 2010s, when the potential of mRNA to induce immune response was evaluated; (2) the growing up period from early 2010s to 2019, when the stability and immunogenicity of mRNA vaccines were improved and the clinical development of products were pushed forward; (3) the rapid maturity period after the outbreak of COVID-19, when two products for COVID-19 were authorized for the first time. The approval of COVID-19 vaccines is an encouraging start, while the enormous potential of mRNA vaccines remains to be explored. Future research on mRNA-based infectious disease vaccines will focus on further optimizing mRNA modification and delivery, solving problems of the approved vaccines in real world, investigating mRNA vaccines for other infectious indications, and developing self-amplifying or thermostable vaccines. Future research on mRNA-based therapeutic cancer vaccines will focus on screening proper neoantigens, enhancing the delivery of mRNA into antigen-presenting cells and overcoming suppressive tumor microenvironment.

mRNA-based therapeutics: powerful and versatile tools to combat diseases

The therapeutic use of messenger RNA (mRNA) has fueled great hope to combat a wide range of incurable diseases. Recent rapid advances in biotechnology and molecular medicine have enabled the production of almost any functional protein/peptide in the human body by introducing mRNA as a vaccine or therapeutic agent. This represents a rising precision medicine field with great promise for preventing and treating many intractable or genetic diseases. In addition, in vitro transcribed mRNA has achieved programmed production, which is more effective, faster in design and production, as well as more flexible and cost-effective than conventional approaches that may offer. Based on these extraordinary advantages, mRNA vaccines have the characteristics of the swiftest response to large-scale outbreaks of infectious diseases, such as the currently devastating pandemic COVID-19. It has always been the scientists’ desire to improve the stability, immunogenicity, translation efficiency, and delivery system to achieve efficient and safe delivery of mRNA. Excitingly, these scientific dreams have gradually been realized with the rapid, amazing achievements of molecular biology, RNA technology, vaccinology, and nanotechnology. In this review, we comprehensively describe mRNA-based therapeutics, including their principles, manufacture, application, effects, and shortcomings. We also highlight the importance of mRNA optimization and delivery systems in successful mRNA therapeutics and discuss the key challenges and opportunities in developing these tools into powerful and versatile tools to combat many genetic, infectious, cancer, and other refractory diseases.

In Vitro Investigations on Optimizing and Nebulization of IVT-mRNA Formulations for Potential Pulmonary-Based Alpha-1-Antitrypsin Deficiency Treatment

In vitro-transcribed (IVT) mRNA has come into focus in recent years as a potential therapeutic approach for the treatment of genetic diseases. The nebulized formulations of IVT-mRNA-encoding alpha-1-antitrypsin (A1AT-mRNA) would be a highly acceptable and tolerable remedy for the protein replacement therapy for alpha-1-antitrypsin deficiency in the future. Here we show that lipoplexes containing A1AT-mRNA prepared in optimum conditions could successfully transfect human bronchial epithelial cells without significant toxicity. A reduction in transfection efficiency was observed for aerosolized lipoplexes that can be partially overcome by increasing the initial number of components. A1AT produced from cells transfected by nebulized A1AT-mRNA lipoplexes is functional and could successfully inhibit the enzyme activity of trypsin as well as elastase. Our data indicate that aerosolization of A1AT-mRNA therapy constitutes a potentially powerful means to transfect airway epithelial cells with the purpose of producing functional A1AT, while bringing along the unique advantages of IVT-mRNA.

Off the beaten path: Novel mRNA-nanoformulations for therapeutic vaccination against HIV

Over the last few years, immunotherapy for HIV in general and therapeutic vaccination in particular, has received a tremendous boost, both in preclinical research and in clinical applications. This interest is based on the evidence that the immune system plays a crucial role in controlling HIV infection, as shown for long-term non-progressors and elite controllers, and that immune responses can be manipulated towards targeting conserved epitopes. So far, the most successful approach has been vaccination with autologous dendritic cells (DCs) loaded ex vivo with antigens and activation signals. Although this approach offers much promise, it also comes with significant drawbacks such as the requirement of a specialized infrastructure and expertise, as well as major challenges for logistics and storage, making it extremely time consuming and costly. Therefore, methods are being developed to avoid the use of ex vivo generated, autologous DCs. One of these methods is based on mRNA for therapeutic vaccination. mRNA has proven to be a very promising vaccine platform, as the coding information for any desired protein, including antigens and activation signals, can be generated in a very short period of time, showing promise both as an off-the-shelf therapy and as a personalized approach. However, an important drawback of this approach is the short half-life of native mRNA, due to the presence of ambient RNases. In addition, proper immunization requires that the antigens are expressed, processed and presented at the right immunological site (e.g. the lymphoid tissues). An ambivalent aspect of mRNA as a vaccine is its capacity to induce type I interferons, which can have beneficial adjuvant effects, but also deleterious effects on mRNA stability and translation. Thus, proper formulation of the mRNA is crucially important. Many approaches for RNA formulation have already been tested, with mixed success. In this review we discuss the state-of-the-art and future trends for mRNA-nanoparticle formulations for HIV vaccination, both in the prophylactic and in the therapeutic setting.

mTORC1/rpS6 regulates blood-testis barrier dynamics and spermatogenetic function in the testis in vivo

The blood-testis barrier (BTB), conferred by Sertoli cells in the mammalian testis, is an important ultrastructure that supports spermatogenesis. Studies using animal models have shown that a disruption of the BTB leads to meiotic arrest, causing defects in spermatogenesis and male infertility. To better understand the regulation of BTB dynamics, we report findings herein to understand the role of ribosomal protein S6 (rpS6), a downstream signaling protein of mammalian target of rapamycin complex 1 (mTORC1), in promoting BTB disruption in the testis in vivo, making the barrier "leaky." Overexpression of wild-type rpS6 (rpS6-WT, the full-length cDNA cloned into the mammalian expression vector pCI-neo) and a constitutively active quadruple phosphomimetic mutant cloned into pCI-neo (p-rpS6-MT) vs. control (empty pCI-neo vector) was achieved by transfecting adult rat testes with the corresponding plasmid DNA using a Polyplus in vivo-jetPEI transfection reagent. On the basis of an in vivo functional BTB integrity assay, p-rpS6-MT was found to induce BTB disruption better than rpS6-WT did (and no effects in empty vector control), leading to defects in spermatogenesis, including loss of spermatid polarity and failure in the transport of cells (e.g., spermatids) and organelles (e.g., phagosomes), to be followed by germ exfoliation. More important, rpS6-WT and p-rpS6-MT exert their disruptive effects through changes in the organization of actin- and microtubule (MT)-based cytoskeletons, which are mediated by changes in the spatiotemporal expression of actin- and MT-based binding and regulatory proteins. In short, mTORC1/rpS6 signaling complex is a regulator of spermatogenesis and BTB by modulating the organization of the actin- and MT-based cytoskeletons.

Engineering WT1-Encoding mRNA to Increase Translational Efficiency in Dendritic Cells

Dendritic cells (DCs) are the orchestrators of the immune system and are frequently used in clinical trials in order to boost the immune system in cancer patients. Among several available techniques for DC modification, mRNA electroporation is an interesting technique due to the favorable characteristics of mRNA. Antigen expression level and duration can be increased by multiple optimizations of an antigen-encoding mRNA template. Here, we describe different molecular modifications to a WT1-encoding mRNA construct in order to increase antigen expression and the subsequent introduction of mRNA into DCs.

Adjuvants may reduce in vivo transfection levels for DNA vaccination in mice leading to reduced antigen-specific CD8+ T cell responses

Adjuvants for DNA vaccination are designed to promote transformation of transgenes into target cells and increase inflammation in the site of injection, with resultant immune cell recruitment. Numerous studies indicated cationic liposomes as effective adjuvants for DNA vaccination due to their ability to promote in vivo transfection and innate immune system activation. Commercial reagents as Adjuplex and in vivo-JetPEI are also intended to facilitate DNA vaccination. Here, we evaluate the adjuvant properties of cationic liposomes, Adjuplex and in vivo-JetPEI compared to injection of DNA without adjuvant. In mice vaccinated with piggyBac pDNA vaccines, we assessed in vivo antigen expression, innate immune responses in draining lymph nodes, and antigen-specific T cell responses in spleens and blood. Surprisingly, vaccination with DNA in PBS emerged as the most efficient in promoting in vivo transfection and consequent antigen expression, while the addition of adjuvant reduced the amount of antigen expressed. On the other hand, we discovered higher numbers of innate immune cells and activated dendritic cells in the lymph nodes of mice injected with adjuvants than those vaccinated in PBS. The analysis of eGFP-specific immune responses revealed that all the different immunizations induced functional antigen-specific T cells in spleens, although only T cells generated by non-adjuvant vaccination and Adjuplex were identified in the blood of vaccinated mice. These results provide insight into the effects of these 3 adjuvants and may facilitate appropriate use off adjuvants by researchers using DNA vaccines in laboratory animals.

Self-Amplifying Replicon RNA Vaccine Delivery to Dendritic Cells by Synthetic Nanoparticles

Dendritic cells (DC) play essential roles determining efficacy of vaccine delivery with respect to immune defence development and regulation. This renders DCs important targets for vaccine delivery, particularly RNA vaccines. While delivery of interfering RNA oligonucleotides to the appropriate intracellular sites for RNA-interference has proven successful, the methodologies are identical for RNA vaccines, which require delivery to RNA translation sites. Delivery of mRNA has benefitted from application of cationic entities; these offer value following endocytosis of RNA, when cationic or amphipathic properties can promote endocytic vesicle membrane perturbation to facilitate cytosolic translocation. The present review presents how such advances are being applied to the delivery of a new form of RNA vaccine, replicons (RepRNA) carrying inserted foreign genes of interest encoding vaccine antigens. Approaches have been developed for delivery to DCs, leading to the translation of the RepRNA and encoded vaccine antigens both in vitro and in vivo. Potential mechanisms favouring efficient delivery leading to translation are discussed with respect to the DC endocytic machinery, showing the importance of cytosolic translocation from acidifying endocytic structures. The review relates the DC endocytic pathways to immune response induction, and the potential advantages for these self-replicating RNA vaccines in the near future.

mRNA-based dendritic cell vaccines

Cancer immunotherapy has been proposed as a powerful treatment modality. Active immunotherapy aspires to stimulate the patient's immune system, particularly T cells. These cells can recognize and kill cancer cells and can form an immunological memory. Dendritic cells (DCs) are the professional antigen-presenting cells of our immune system. They take up and process antigens to present them to T cells. Consequently, DCs have been investigated as a means to stimulate cancer-specific T-cell responses. An efficient strategy to program DCs is the use of mRNA, a well-defined and safe molecule that can be easily generated at high purity. Importantly, vaccines consisting of mRNA-modified DCs showed promising results in clinical trials. Therefore, we will introduce cancer immunotherapy and DCs and give a detailed overview on the application of mRNA to generate cancer-fighting DC vaccines.