Molecular design and mechanistic understanding of lipo-xenopeptide carriers for nucleic acid delivery

Abstract

Initially, viral vectors represent the most efficient systems in terms of nucleic acid delivery due to their inherent evolutionary adaption for cellular entry and genomic delivery (17,18).Nonetheless, increasing interest has resulted in the development of synthetic, non-viral delivery systems as more modulable and adaptable alternatives.In general, non-viral delivery approaches rely on the spontaneous assembly of nucleic acids with ionizable materials, forming nanoscale complexes that shield the cargo and mediate interaction with biological membranes.Depending on their composition, these systems are commonly classified into lipid-derived and polymer-based nanoparticle formulations.Lipidderived formulations include lipoplexes, liposomes or lipid nanoparticles (LNPs) , whereas polymer-based platforms encompass a broad range of assemblies such as polycation complexes (polyplexes) or polymeric micelles (19).A central advantage of these synthetic systems is their ability to systematically adjust structural parameters, thereby tuning their behavior within biological environments under physiological conditions.To date, LNPs represent the most clinically advanced non-viral delivery platform.For example, LNPs have been used in the first approved siRNA-based therapy for the treatment of Hereditary Transthyretin Amyloidosis (20) and mRNA vaccines for addressing SARS-CoV2 during the COVID 19 pandemic (21-23).In addition, LNPs are currently being explored in further clinical settings beyond RNAi and vaccination, including gene editing approaches via CRISP/Cas9 in late clinical development (24).Alternatively to lipid-derived systems, polymeric carriers have been extensively investigated (25).These materials form compact nanoscale assemblies through electrostatic association with nucleic acids, resulting in structures that protect the cargo and promote cellular uptake.The modularity of polymer design allows fine control over key parameters such as particle size, surface characteristics, and charge distribution, which in turn influence systemic circulation and intracellular delivery efficiency.A wide range of polymer chemistries has been explored for this purpose.Despite significant progress in carrier design, non-viral delivery systems face multiple biological barriers following systemic administration.Upon exposure to the blood complement systems, nanoparticles are rapidly coated by adsorbed proteins, leading to the formation of a dynamic protein corona that defines their biological identity (26)(27)(28).This process can substantially alter particle behavior, including circulation time, tissue distribution, and immune recognition, and may accelerate clearance from the bloodstream.To mitigate these effects, surface modifications through shielding agents such as polyethyleneglycol (PEG) are frequently employed to reduce nonspecific interactions and improve colloidal stability, albeit such modifications may simultaneously reduce cellular association (29). Aims of the thesisNon-viral delivery systems represent a highly versatile platform for the prevention and treatment of various diseases.These systems typically encompass a wide range of material classes, including lipid-based, polymeric, and peptide-derived carriers.Continuous structural modifications may enable the development of carriers with further enhanced delivery efficiency.However, beyond carrier effectiveness, a key aspect lies in the mechanistic comprehension of how such systems act within complex biological environments and overcome extra-and intracellular barriers.In this context, elucidating structure-activity relationships and intracellular trafficking pathways, particularly endosomal escape may be crucial, as such insights could provide the foundation for a rational design of future carrier classes and formulation strategies.