PhD defence: Ex vivo modification of natural killer cells: The Role of Lipid Nanoparticle-Mediated mRNA Delivery

Natural killer (NK) cells participate in the immune system and protect us by finding and destroying cancer and virally infected cells and thus are a powerful tool in cancer immunotherapy. However, several challenges are associated with NK cell therapies, like not surviving long enough in the body after a cell transfer, struggling to treat solid tumors effectively, and the tumor environment that weakens them.

To address these limitations, the modification of NK cells to produce or downregulate key proteins has been proposed as a strategy to enhance their survival in the body, their multiplication rate, and their effectiveness against tumor cells. One way to do this is to deliver specific instructions, in the form of messenger RNA (mRNA), into NK cells. Nevertheless, mRNA delivery into NK cells is challenging, as the most common delivery methods, such as electroporation, show limitations.

This thesis explores the use of polymer and lipid-based nanoparticles as delivery systems to efficiently deliver mRNA into NK cells without causing toxicity. Using an optimized delivery system based on lipid nanoparticles, this work further investigated the delivery of two mRNA molecules at once to target NK cells in multiple ways and examined how the addition of a cell-penetrating peptide within the nanoparticles can enhance the mRNA delivery and gene expression inside the NK cells. Finally, this thesis investigated whether the overexpression of an activating receptor in NK cells can boost their ability to work with certain antibodies and more effectively kill leukemia cells.