Cholesterol-Lowering Effect of Octaarginine-Appended β-Cyclodextrin in Npc1-Trap-CHO Cells

Niemann-Pick disease type C (NPC) is an autosomal recessive lysosomal storage disorder, which is an inherited disease characterized by the accumulation of unesterified cholesterol in endolysosomes. Recently, 2-hydroxypropyl-β-cyclodextrin (HP-β-CyD) has been used for the treatment of NPC, and ameliorated a hepatosplenomegaly in the patients. However, to obtain the treatment efficacy, a high dose of HP-β-CyD was necessary. Therefore, the decrease in dose by using active intracellular delivery system of β-CyD to NPC cells is expected. In this study, to efficiently deliver β-CyD to NPC-like cells, we newly synthesized octaarginine (R8)-appended β-CyD with a spacer of γ-aminobutyric acid (R8-β-CyD) and evaluated its cytotoxicity, intracellular distribution, endocytosis pathway and cholesterol-lowering effect in Npc1-trap-Chinese hamster ovary (CHO) cells, cholesterol-accumulated cells through the impairment of NPC1 function. R8-β-CyD did not show cytotoxicity in the cells. In addition, Alexa568-labeled R8-β-CyD was actively internalized into Npc1-trap-CHO cells, possibly through micropinocytosis. Notably, R8-β-CyD significantly decreased intracellular cholesterol content compared with HP-β-CyD. These results suggest that R8-β-CyD may be a promising therapeutic agent for ameliorating cholesterol accumulation in NPC.