A validated LC-MS/MS assay for quantification of 24(S)-hydroxycholesterol in plasma and cerebrospinal fluid

• Main Authors: Rohini Sidhu, Hui Jiang, Nicole Y. Farhat, Nuria Carrillo-Carrasco, Myra Woolery, Elizabeth Ottinger, Forbes D. Porter, Jean E. Schaffer, Daniel S. Ory, Xuntian Jiang
• Format: Article
• Language: English
• Published: Elsevier 2015-06-01
• Series: Journal of Lipid Research
• Subjects: two-dimensional liquid chromatography-tandem mass spectrometry; validation; Niemann-Pick C1 disease; 2-hydroxypropyl-β-cyclodextrin
• Online Access: http://www.sciencedirect.com/science/article/pii/S0022227520317326

24(S)-hydroxycholesterol [24(S)-HC] is a cholesterol metabolite that is formed almost exclusively in the brain. The concentrations of 24(S)-HC in cerebrospinal fluid (CSF) and/or plasma might be a sensitive marker of altered cholesterol metabolism in the CNS. A highly sensitive 2D-LC-MS/MS assay was developed for the quantification of 24(S)-HC in human plasma and CSF. In the development of an assay for 24(S)-HC in CSF, significant nonspecific binding of 24(S)-HC was observed and resolved with the addition of 2.5% 2-hydroxypropyl-β-cyclodextrin (HP-β-CD) into CSF samples. The sample preparation consists of liquid-liquid extraction with methyl-tert-butyl ether and derivatization with nicotinic acid. Good linearity was observed in a range from 1 to 200 ng/ml and from 0.025 to 5 ng/ml, for plasma and CSF, respectively. Acceptable precision and accuracy were obtained for concentrations over the calibration curve ranges. Stability of 24(S)-HC was reported under a variety of storage conditions. This method has been successfully applied to support a National Institutes of Health-sponsored clinical trial of HP-β-CD in Niemann-Pick type C1 patients, in which 24(S)-HC is used as a pharmacodynamic biomarker.