Hyejung Mok

Driven by recent successful clinical translation, nucleic acid therapeutics are being actively investigated to expand their applications to various diseases, including renal genetic disorders. As life expectancy increases and the burden of renal diseases continues to rise, nucleic acid therapeutics are considered promising alternatives to conventional treatments. This review summarizes key considerations in the design and fabrication of nanocarriers for the systemic delivery of nucleic acid therapeutics to the kidneys. Key aspects of the renal microenvironment are discussed to guide the design of nanocarriers, including conjugates and nanoparticles. This review also covers renal genetic disorders and nucleic acid‐based treatment approaches, including small interfering RNAs (siRNAs), clustered regularly interspaced short palindromic repeats (CRISPR) systems, and messenger RNA (mRNA) therapeutics. In particular, recent strategies for kidney‐targeted nanocarriers are highlighted, with an emphasis on their efficacy, challenges, and limitations. Perspectives on the design of nanocarriers for systemic nucleic acid delivery to the kidneys are also provided, offering insights into potential therapeutic approaches for renal genetic disorders.

For siRNA-based therapeutics that require repeated administration, the accumulation of ionizable lipids in the body could cause in vivo safety issues. In the present study, we examined the feasibility of a bile acid-histidine decapeptide (H10) conjugate as a novel, biocompatible, and potential additive to reduce the proportion of ionizable lipids for the formulation of LNPs. A lithocholic acid (LCA)-H10 conjugate (LH conjugate) was synthesized and incorporated into the LNPs with low proportions of ionizable lipids (LiLNPs). The fabricated LH conjugate-containing LiLNPs (LiLNP-LH) exhibited more promising gene silencing activity than LiLNPs, despite their similar particle size and morphology. Additionally, LiLNP-LHs exhibited an elevated liver accumulation after intravenous injection and significantly decreased release of the inflammatory cytokines, compared with conventional LNPs with high proportions of ionizable lipids (HiLNPs). Thus, we successfully reduced the proportion of ionizable lipids in LNPs by adding LH conjugates, which could serve as carriers for diverse siRNA therapeutics with promising silencing activity and superior in vivo safety.

The diversification of lipid compositions in lipid nanoparticles (LNPs) is crucial for expanding their clinical applications and overcoming current limitations. In this study, LNPs with varying lipid compositions are fabricated using three different mixing processes (pipette, vortex, and microfluidic mixing) for small interfering RNA (siRNA) delivery. While both siRNA and hydrophobic fluorescent dye are successfully incorporated within LNPs using pipette‐ and vortex‐mixing, hydrophilic peptides cannot be encapsulated. Following optimization of ionizable lipid proportion via cost‐efficient vortex‐mixing method, LNPs with a lower ionizable lipid proportion (27.72%), termed LNP5, are selected and fabricated with histidine decapeptide (His10) during formulation via microfluidic mixing method to supplement the function of approximately half of the ionizable lipids by simple addition of His10. His10‐ incorporated LNP5 (LNP5H) exhibited a 1.6‐fold increase in gene silencing efficiency, compared to conventional LNPs (cLNPs; ionizable lipid proportion of 47.95%). Furthermore, LNP5H maintained siRNA potency for 4 weeks when stored in a 1% sucrose solution at −70 °C. Taken together, it fabricates potent LNP5H with low proportion of ionizable lipids via fast and easy processes, which can be applied to a variety of siRNA therapeutics for their efficient intracellular delivery.

In this study, histidine oligomer (oHis; 10mer)‐incorporating LNPs (H10LNPs) are developed as a novel carrier for efficient siRNA delivery. Notably, the unmodified oHis (10mer) is greatly incorporated within LNPs through ionic interaction with siRNAs, which serves as an endosome escape enhancer. H10LNPs with a size of ≈65 nm demonstrate a significantly enhanced extent of endosomal escape, as evidenced by calcein assay and confocal microscopy images of intracellular fluorescence, surpassing conventional LNPs. Furthermore, the half inhibitory concentration (IC₅₀) of the human endogenous globotriaosylceramide synthase (Gb3 synthase) gene in H10LNPs‐treated cells exhibits a significant threefold decrease, compared to that in LNP‐treated cells. Notably, H10LNPs maintain comparable biocompatibility and biodistribution both in vitro and in vivo. Considering that the fabricated siRNA H10LNPs exhibit excellent biocompatibility and superior gene silencing activity over conventional LNPs, these particles can be harnessed for the safe delivery of therapeutic siRNAs. Additionally, this study introduces promising, feasible, simple, and alternative formulation processes for integrating unmodified functional cationic peptides into LNPs to enhance the delivery efficiency of a wide range of nucleic acid‐based drugs.