Differential mode of cholesterol inclusion with 2-hydroxypropyl-cyclodextrins increases safety margin in treatment of Niemann-Pick disease type C.

BACKGROUND AND PURPOSE: Niemann-Pick disease type C (NPC) is a lysosomal storage disorder with disrupted intracellular cholesterol trafficking. A cyclic heptasaccharide, 2-hydroxypropyl-ß-cyclodextrin (HP-ß-CD), is a cholesterol solubilizer that is being developed to treat NPC, but its ototoxicity and pulmonary toxicity remain important issues. We have characterized 2-hydroxypropyl-γ-cyclodextrin (HP-γ-CD), a cyclic octasaccharide with a larger cavity than HP-ß-CD, as a candidate drug to treat NPC. However, the molecular target of HP-γ-CD with respect to NPC and its potential for clinical application are still unclear. EXPERIMENTAL APPROACH: We investigated the mode of interaction between HP-γ-CD and cholesterol by phase-solubility analysis, proton NMR spectroscopy and molecular dynamics simulations. We then evaluated the therapeutic effects of HP-γ-CD compared with HP-ß-CD using cellular and murine NPC models. Mouse auditory and pulmonary function tests were also conducted. KEY RESULTS: HP-γ-CD solely formed a 1:1 inclusion complex with cholesterol with an affinity similar to that of HP-ß-CD. In vitro, HP-γ-CD and HP-ß-CD amelioration of NPC-related manifestations was almost equivalent at lower concentrations. However, at higher concentrations, the cholesterol inclusion mode of HP-ß-CD shifted to the highly soluble 2:1 complex whereas that of HP-γ-CD maintained solely the 1:1 complex. The constant lower cholesterol solubilizing ability of HP-γ-CD conferred it with significantly reduced toxicity compared with HP-ß-CD, but equal efficacy in treating a mouse model of NPC. CONCLUSIONS AND IMPLICATIONS: HP-γ-CD can serve as a fine-tuned cholesterol solubilizer for the treatment of NPC with a wider safety margin than HP-ß-CD in terms of ototoxicity and pulmonary toxicity.

In Vitro and In Vivo Evaluation of 6-O-α-Maltosyl-ß-Cyclodextrin as a Potential Therapeutic Agent Against Niemann-Pick Disease Type C.

Niemann-Pick disease Type C (NPC) is a rare lysosomal storage disease characterized by the dysfunction of intracellular cholesterol trafficking with progressive neurodegeneration and hepatomegaly. We evaluated the potential of 6-O-α-maltosyl-ß-cyclodextrin (G2-ß-CD) as a drug candidate against NPC. The physicochemical properties of G2-ß-CD as an injectable agent were assessed, and molecular interactions between G2-ß-CD and free cholesterol were studied by solubility analysis and two-dimensional proton nuclear magnetic resonance spectroscopy. The efficacy of G2-ß-CD against NPC was evaluated using Npc1 deficient Chinese hamster ovary (CHO) cells and Npc1 deficient mice. G2-ß-CD in aqueous solution showed relatively low viscosity and surface activity; characteristics suitable for developing injectable formulations. G2-ß-CD formed higher-order inclusion complexes with free cholesterol. G2-ß-CD attenuated dysfunction of intercellular cholesterol trafficking and lysosome volume in Npc1 deficient CHO cells in a concentration dependent manner. Weekly subcutaneous injections of G2-ß-CD (2.9 mmol/kg) ameliorated abnormal cholesterol metabolism, hepatocytomegaly, and elevated serum transaminases in Npc1 deficient mice. In addition, a single cerebroventricular injection of G2-ß-CD (21.4 µmol/kg) prevented Purkinje cell loss in the cerebellum, body weight loss, and motor dysfunction in Npc1 deficient mice. In summary, G2-ß-CD possesses characteristics favorable for injectable formulations and has therapeutic potential against in vitro and in vivo NPC models.