A DNA microarray-based analysis of immune-stimulatory and transcriptional responses of dendritic cells to KALA-modified nanoparticles

Development of lipid-like materials for RNA delivery based on intracellular environment-responsive membrane destabilization and spontaneous collapse

Messenger RNA and small interfering RNA are attractive modalities for curing diseases by complementation or knock-down of proteins. For success of these RNAs, a drug delivery system (DDS) is required to control a pharmacokinetics, to enhance cellular uptake, to overcome biological membranes, and to release the cargo into the cytoplasm. Based on past research, developing nanoparticles that are neutrally charged have been the mainstream of their development. Also, the materials are further mounted with pH- and/or reducing environment-responsive units. In this review, we summarize progress made in the molecular design of these materials. We also focus on the importance of the hydrophobic scaffold for tissue/cell targeting, intracellular trafficking, and immune responses. As a practical example, the design concept of the SS-cleavable and pH-activated lipid-like material (ssPalm) and subsequent molecular modification tailored to the RNA-based medical application is discussed.

mRNA Delivery System for Targeting Antigen-Presenting Cells In Vivo

The encapsulation of mRNA in nanosystems as gene vaccines for immunotherapy purposes has experienced an exponential increase in recent years. Despite the many advantages envisaged within these approaches, their application in clinical treatments is still limited due to safety issues. These issues can be attributed, in part, to liver accumulation of most of the designed nanosystems and to the inability to transfect immune cells after an intravenous administration. In this context, this study takes advantage of the known versatile properties of the oligopeptide end-modified poly (β-amino esters) (OM-PBAEs) to complex mRNA and form discrete nanoparticles. Importantly, it is demonstrated that the selection of the appropriate end-oligopeptide modifications enables the specific targeting and major transfection of antigen-presenting cells (APC) in vivo, after intravenous administration, thus enabling their use for immunotherapy strategies. Therefore, with this study, it can be confirmed that OM-PBAE are appropriate systems for the design of mRNA-based immunotherapy approaches aimed to in vivo transfect APCs and trigger immune responses to fight either tumors or infectious diseases.

Modifying Antigen-Encapsulating Liposomes with KALA Facilitates MHC Class I Antigen Presentation and Enhances Anti-tumor Effects

For a successful anti-cancer vaccine, antigen presentation on the major histocompatibility complex (MHC) class I is a requirement. To accomplish this, an antigen must be delivered to the cytoplasm by overcoming the endosome/lysosome. We previously reported that a lipid nanoparticle modified with a KALA peptide (WEAKLAKALAKALAKHLAKALAKALKA), an α-helical cationic peptide, permits the encapsulated pDNA to be efficiently delivered to the cytoplasm in bone marrow-derived dendritic cells (BMDCs). Herein, we report on the use of KALA-modified liposomes as an antigen carrier, in an attempt to induce potent antigen-specific cellular immunity. The subcutaneous injection of KALA-modified ovalbumin (OVA)-encapsulating liposomes (KALA-OVA-LPs) elicited a much more potent OVA-specific cytotoxic T lymphocyte activity and anti-tumor effect in comparison with particles that were modified with octa-arginine (R8), a cell-penetrating peptide (R8-OVA-LPs). In addition, the numbers of OVA-specific CD8⁺ T cells were increased by immunization the KALA-OVA-LPs. The treatment of BMDCs with KALA-OVA-LPs induced a substantial MHC class I antigen presentation. Furthermore, the acidic pH-dependent membrane destabilization activity of KALA-OVA-LPs strongly suggests that they are able to escape from endosomes/lysosomes and thereby deliver their cargos to the cytoplasm. Collectively, the KALA-modified liposome is a potential antigen delivery platform for use as a protein vaccine.

Multifunctional enveloped nanodevices (MENDs)

It is anticipated that nucleic acid medicines will be in widespread use in the future, since they have the potential to cure diseases based on molecular mechanisms at the level of gene expression. However, intelligent delivery systems are required to achieve nucleic acid therapy, since they can perform their function only when they reach the intracellular site of action. We have been developing a multifunctional envelope-type nanodevice abbreviated as MEND, which consists of functional nucleic acids as a core and lipid envelope, and can control not only biodistribution but also the intracellular trafficking of nucleic acids. In this chapter, we review the development and evolution of the MEND by providing several successful examples, including the R8-MEND, the KALA-MEND, the MITO-Porter, the YSK-MEND, and the PALM.

A KALA-modified lipid nanoparticle containing CpG-free plasmid DNA as a potential DNA vaccine carrier for antigen presentation and as an immune-stimulative adjuvant

Technologies that delivery antigen-encoded plasmid DNA (pDNA) to antigen presenting cell and their immune-activation are required for the success of DNA vaccines. Here we report on an artificial nanoparticle that can achieve these; a multifunctional envelope-type nanodevice modified with KALA, a peptide that forms α-helical structure at physiological pH (KALA-MEND). KALA modification and the removal of the CpG-motifs from the pDNA synergistically boosted transfection efficacy. In parallel, transfection with the KALA-MEND enhances the production of multiple cytokines and chemokines and co-stimulatory molecules via the Toll-like receptor 9-independent manner. Endosome-fusogenic lipid envelops and a long length of pDNA are essential for this immune stimulation. Furthermore, cytoplasmic dsDNA sensors that are related to the STING/TBK1 pathway and inflammasome are involved in IFN-β and IL-1β production, respectively. Consequently, the robust induction of antigen-specific cytotoxic T-lymphoma activity and the resulting prophylactic and therapeutic anti-tumor effect was observed in mice that had been immunized with bone marrow-derived dendritic cells ex vivo transfected with antigen-encoding pDNA. Collectively, the KALA-MEND possesses dual functions; gene transfection system and immune-stimulative adjuvant, those are both necessary for the successful DNA vaccine.

A neutral lipid envelope-type nanoparticle composed of a pH-activated and vitamin E-scaffold lipid-like material as a platform for a gene carrier targeting renal cell carcinoma

A renal cell carcinoma (RCC) is one of the refractory tumors, since it readily acquires resistance against chemotherapy. Thus, alternative therapeutic approaches such as obstructing the neovasculature are needed. We previously reported on the development of a plasmid DNA (pDNA)-encapsulating liposomal nanoparticle (LNP) as a hepatic gene delivery system that is applicable to systemic administration. The key molecular component is a SS-cleavable and pH-activated lipid-like material (ssPalm) that mounts dual sensing motifs (ternary amines and disulfide bonding) that are responsive to the intracellular environment. The main purpose of the present study was to expand its application to a tumor-targeting gene delivery system in mice bearing tumors established from a RCC (OS-RC-2). When the modification of the surface of the particle is optimized for the polyethyleneglycol (PEG), stability in the blood circulation is improved, and consequently tumor-selective gene expression can be achieved. Furthermore, gene expression in the tumor was increased slightly when the hydrophobic scaffold of the ssPalm was replaced from the conventionally used myristic acid (ssPalmM) to α-tocopherol succinate (ssPalmE). Moreover, tumor growth was significantly suppressed when the completely CpG-free pDNA encoding the solute form of VEGFR (fms-like tyrosine kinase-1: sFlt-1) was used, especially when it was delivered by the LNP formed with ssPalmE (LNP(ssPalmE)). Thus, the PEG-modified LNP(ssPalmE) is a promising gene carrier for the cancer gene therapy of RCC.

Immunomodulation of nanoparticles in nanomedicine applications

Nanoparticles (NPs) have promising applications in medicine. Immune system is an important protective system to defend organisms from non-self matters. NPs interact with the immune system and modulate its function, leading to immunosuppression or immunostimulation. These modulating effects may bring benefits or danger. Compositions, sizes, and surface chemistry, and so forth, affect these immunomodulations. Here we give an overview of the relationship between the physicochemical properties of NPs, which are candidates to be applied in medicine, and their immunomodulation properties.

Dual-functionalized calcium carbonate based gene delivery system for efficient gene delivery

Dual-functionalized KALA/PS/CaCO₃/DNA nanoparticles containing a cell penetrating peptide (KALA) and protamine sulfate (PS) could effectively mediate gene transfection at a low DNA concentration.