Scientists demonstrate preconcept proof of concept for next-generation DNA delivery technologies

Scientists at Dr. David B. Weiner’s Wistar Institute Lab explain next-generation vaccination technology that combines plasmid DNA with lipid nanoparticle (LNP) delivery systems.

This study was conducted in collaboration with scientists at the University of Pennsylvania Perelman School of Medicine and the ready-made biotechnology company INOVIO, a research institute in Dr. Norbert Paldi. Their findings are published in Cell Reports Medicine in the paper “Modulation of lipid nanoparticle-forming plasmid DNA promotes adaptive immunity, promoting innate immune activation.”

David Weiner, executive vice president of Wistar and professor of WW Smith Charitable Trust Distinguished Crosssured, is a leading expert in the field of DNA vaccines. In a study led by Nicholas Tursi, a doctoral student at Weiner Lab, researchers have studied how to improve lipid-based formulations to better incorporate and provide DNA payloads for vaccination.

A lipid-based approach containing LNPs has successfully formulated and delivered proteins as drugs for various forms of RNA and several sales products. However, the development of such formulations using DNA has not previously shown the same stability or efficacy.

The team studied how to modify lipid-based formulations that effectively stabilize the DNA of LNPs. DNA has unique properties compared to RNA. This included its size and double-stranded nature, which previously was a hurdle for creating stable, consistent lipid-based DNA formulations.

DNA vaccines have traditionally been delivered using devices that allow for highly efficient uptake of DNA into cells at the injection site and potent T-cell immunity against important disease targets. Using LNP formulations for DNA vaccines allows administration via needles and syringes, potentially strengthening humoral immunity and providing additional tools within the DNA vaccine toolkit.

Using model DNA-LNPs expressing influenza hemagglutinin (HA), the team investigated how to modulate the formulation of DNA within the LNPs to improve the stability of particle assembly and direct injection. HA DNA-LNPs were formulated with a higher N/P ratio (relationship between lipid nanoparticles and larger DNA backbone) resulting in improved particle profiles with improved immune response development.

This study highlights some of the mechanisms of immunity conferred by DNA-LNPs. The team showed that these DNA-LNPs demonstrate a unique way to prime the immune system compared to mRNA and Adjuvant protein formulations. DNA-LNP induced a unique pattern of activation in the innate immune population. These are cells that respond early in the development of a protective immune response.

The team then looked into whether HA DNA-LNPs could induce strong and consistent adaptive immunity. This is the arm of the immune system that causes long-lived T-cells and antibody responses. Compared to the adjuvant vaccine in benchmark mRNA and proteins, HA DNA-LNP induced robust antibody and T-cell responses after a single dose. Importantly, these reactions are durable, with memory responses in small animals lasting longer than one year after vaccination.

The team also examined the immunogenicity of HA DNA-LNPs in a rabbit model, where they observed strong T-cell and antibody responses persisting in the memory phase.

Finally, the team looked into whether the DNA-LNP vaccine could be protected by the Live SARS-Cov-2 Challenge model. The team utilized a DNA-LNP vaccine expressing the SARS-COV-2 spike protein and demonstrated that single immunity with spiked DNA-LNPs succeeds in preventing morbidity and mortality.

This study supports the ongoing development of DNA-LNP vaccines as a unique vaccination modality. The ability of this approach to elicit a strong, long-term immune response highlights the possibility of complementing existing approaches, or the possibility of being developed as a next-generation vaccination platform.