Ricerc@Sapienza

NP-based DNA vaccines may be safe and easy to develop: to produce them involves making genetic material only, not the virus. Thus, compared with viral approaches (e.g. Oxford/AstraZeneca), NP-based solutions can deliver different plasmids (i.e. vaccines against different variants) simultaneously, offer a more favorable safety profile and many important advantages since they are easier and cheaper to produce and are classified as drugs rather than as biological materials by the regulatory authorities, which is very important to facilitate the development and expedite the approval of new approaches to treat medical needs. Recently, the concept is emerging that the wide gap existing between benchtop discoveries and clinical applicability of NP-based DNA vaccines is due to our poor understanding of the interactions faced by NPs in physiological environments. Upon intramuscular, intradermal or subcutaneous injection, NP-based vaccines are coated by a protein corona that shields the desired interactions with cell receptors of APC, thus leading to unpredictable off-target effects and reducing the therapeutic efficiency. On the other hand, the corona-encoded information that controls bioactivity of NPs (e.g. cellular association, cellular signaling pathways, intracellular behavior and toxicity) and decrypting this code is a priority to develop novel and efficient targeted delivery technologies. As a promising approach in this regard, quantitative structure-activity relationship (QSAR) allows prediction of the biological impact of protein corona formation on the NP bioresponse (e.g. accumulation of NP-based DNA vaccines within APC) and facilitates the identification of meaningful relationships between the synthetic/biological identity of NPs and their biological outcome.
Relevant parameters affecting cellular uptake and cell viability of lipid NPs in cancer cell lines have been identified (1) thus paving the way for the development of advanced targeted delivery strategies. In this project, QSAR approaches will be employed to develop a disruptive targeted nanoparticle DNA vaccine technology against SARS-CoV-2 that will overcome current limitations of electroporation-mediated vaccination. To this end, we will employ lipid NPs (LNPs) made of ionizable lipids that are the most clinically advanced non-viral gene delivery system (2). LNPs safely and effectively deliver nucleic acids, overcoming a major barrier preventing the development and use of genetic medicines that are usually hindered by nucleic acid delivery inefficiency. LNPs also offer many advantages over previous lipid-based nucleic acid delivery systems including: i) High nucleic acid encapsulation efficiency; ii) Improved penetration into cells to deliver genetic materials followed by massive DNA release and potent transfection; iii) Low cytotoxicity. All these characteristics make LNPs excellent candidates for DNA vaccine delivery. To surpass current technological paradigms, development of targeted LNPs is a key step. Latest studies have demonstrated that artificial protein coronas grafted to NP surface mimic viruses in their ability to lock onto receptors of target cells (3). Thus, vaccine loaded LNPs will be coated by artificial protein coronas able to target APC. The founding hypothesis of this project is that the development of a targeted delivery technology based on the LNP-protein corona will enhance safety and immunogenicity of DNA vaccine against SARS- CoV-2.

References
1. A. Bigdeli, S. Palchetti, et al., ACS Nano, 2016, 10, 3723-3737.
2. P. R. Cullis and M. J. Hope, Mol Ther, 2017, 25, 1467-1475.
3. J. Simon, et al., Nanoscale, 2018, 10, 10731-10739.