DLin-KC2-DMA

DLin-KC2-DMA is a useful ionizable lipid for siRNA delivery. It was formulated and characterized in SNALP and demonstrated to have in vivo activity at siRNA doses as low as 0.01 mg/kg in rodents and 0.1 mg/kg in nonhuman primates.

DLin-KC2-DMA, also known as KC2 (2,2-dilinoleyl-4-(2-dimethylaminoethyl)-[1,3]-dioxolane) is an optimized ionizable cationic lipid (ICL) with a reported apparent pKa of 6.7. This pKa ensures an efficient encapsulation of nucleic acid polymers at low pH, a nearly neutral surface charge for the LNPs in the circulation at physiological pH, and a high positive surface charge at endosomal pH. More recently, it was determined that LNPs containing KC2 generated liposomal structures when the KC2 is protonated at pH 4, while forming electron-dense structures at pH 7.4. It is an ionizable cationic lipid that has been used to form lipid nanoparticles (LNPs) encapsulating siRNA or plasmid DNA for use in vitro and in vivo. LNPs containing DLin-KC2-DMA selectively accumulate in mice's liver after intravenous or intramuscular administration or localize to the retinal pigment epithelium and Müller glia after subretinal administration. DLin-KC2-DMA-containing LNPs encapsulating siRNA targeting F7 mRNA, which encodes Factor VII, reduce serum Factor VII levels in mice. Intravenous administration of DLin-KC2-DMA-containing LNPs encapsulating siRNA targeting AR mRNA, which encodes the androgen receptor, decreases serum prostate-specific antigen (PSA) and tumour androgen receptor levels in an LNCaP prostate cancer mouse xenograft model[1].

[1] Ramezanpour, M. et al. “Ionizable amino lipid interactions with POPC: implications for lipid nanoparticle function?.” Nanoscale 30 (2019): 14141–14146.