Non-Viral Targeted Nucleic Acid Delivery: Apply Sequences for Optimization

Abstract

In nature, genomes have been optimized by the evolution of their nucleic acid sequences. The design of peptide-like carriers as synthetic sequences provides a strategy for optimizing multifunctional targeted nucleic acid delivery in an iterative process. The optimization of sequence-defined nanocarriers differs for different nucleic acid cargos as well as their specific applications. Supramolecular self-assembly enriched the development of a virus-inspired non-viral nucleic acid delivery system. Incorporation of DNA barcodes presents a complementary approach of applying sequences for nanocarrier optimization. This strategy may greatly help to identify nucleic acid carriers that can overcome pharmacological barriers and facilitate targeted delivery in vivo. Barcode sequences enable simultaneous evaluation of multiple nucleic acid nanocarriers in a single test organism for in vivo biodistribution as well as in vivo bioactivity.

Keywords: DNA-barcode; non-viral; nucleic acid delivery; peptide; pharmacological barriers; sequence-defined; supramolecular self-assembly; tumor-targeted.

Figure 1

(A) Structure of peptides for virus-like nanoparticles formation. (A) Sp-CC-PEG, Reproduced with permission from [81], American Chemical Society, 2013. (B) K3C6SPD with the sequence of KKKC6WLVFFAQQGSPD. Reproduced with permission from [80], American Chemical Society, 2014.

Figure 2

Chemical structure of ECO, EHCO and isotypic ECO. E: Ethylenediamine; C: Cysteine; O: Oleic acid; H: Histidines.

Figure 3

Functional elements for sequence-defined OAAs different topologies. ssbb: Disulfide building block = succinoyl-cystamine; OAA, artificial oligoamino acid; K: Lysine; C: Cysteine; FA: Fatty acid.

Figure 4

Pharmacological barriers for systemically administered non-viral targeted nucleic acid delivery. (A) Production of stable nucleic acids-loaded polyplexes. (B) After intravenous injection, nanocarriers shall avoid unspecific interactions with blood components and rapid clearance, accumulating in targeting areas during circulation. (C) After the passage of fenestrated blood vessels, nanocarriers shall be internalized by target cells via an active transport process, and realize efficient endosomal escape and release the cargos in an active form for gene expression or regulation.

Figure 5

(A) Typical 2-arm ligand-PEG-OAA for all-in-one nano-formulations with shielding and targeting domains. (B) T-shape lipo-OAA with terminal cysteine or azide group for post-modification via disulfide-formation or orthogonal cooper-free click reaction, respectively. (C) PEG-ligands with specific attachment sites for post-modification.

Figure 6

DNA-barcoded nanoparticles for high throughput in vivo carriers. (A) Nanoparticles were formulated to carry a unique DNA barcode and then the LNPs were pooled together and administered simultaneously to mice. Tissues of interest were isolated and delivery was quantified by deep sequencing the barcodes. Reproduced with permission from [188], National Academy of Sciences, 2017. (B) “FIND” strategy to quantify functional delivery of LNPs within a single mouse. Nanoparticles were formulated to carry a distinct DNA barcode and siICAM-2 and then the LNPs were pooled together and administered to mice intravenously. After 3 days, ICAM-2^Low endothelial cells were isolated and the DNA barcodes within that population were sequenced. (Reproduced with permission from [194], American Chemical Society, 2018).