AP60 is a novel, biomimetic ionizable lipid, identified as the lead compound from a library of 67 aminophosphonate-derived lipids. Inspired by the structure of natural phospholipids, it forms the core component of lipid nanoparticles within the CROSS delivery platform. AP60-based LNPs demonstrate superior efficiency in delivering mRNA and circular RNA to neuronal cells and astrocytes compared to the clinically used MC3 LNP. In a mouse model of spinal cord injury, AP60 LNPs achieved significantly higher protein expression at the lesion site (13.7-fold locally, 4.6-fold intravenously) while concurrently reducing off-target accumulation in the liver by nearly 5-fold. This indicates improved targeting to the central nervous system injury site and a potentially better safety profile. Its cellular uptake is primarily mediated by clathrin-mediated endocytosis and macropinocytosis, followed by efficient endosomal escape. By encapsulating therapeutic circular RNAs encoding Sox2, Ascl1, and GDNF, AP60 LNPs enable effective in vivo reprogramming and neuroprotection, leading to significant functional recovery of bladder and locomotor functions after spinal cord injury.
