Liquid chromatography/electrospray ionisation-tandem mass spectrometry quantification of GM2 gangliosides in human peripheral cells and plasma

G(M2) gangliosidosis is a group of inherited neurodegenerative disorders resulting primarily from the excessive accumulation of G(M2) gangliosides (G(M2)) in neuronal cells. As biomarkers for categorising patients and monitoring the effectiveness of developing therapies are lacking for this group of disorders, we sought to develop methodology to quantify G(M2) levels in more readily attainable patient samples such as plasma, leukocytes, and cultured skin fibroblasts. Following organic extraction, gangliosides were partitioned into the aqueous phase and isolated using C18 solid-phase extraction columns. Relative quantification of three species of G(M2) was achieved using LC/ESI-MS/MS with d(35)G(M1) 18:1/18:0 as an internal standard. The assay was linear over the biological range, and all G(M2) gangliosidosis patients were demarcated from controls by elevated G(M2) in cultured skin fibroblast extracts. However, in leukocytes only some molecular species could be used for differentiation and in plasma only one was informative. A reduction in G(M2) was easily detected in patient skin fibroblasts after a short treatment with media from normal cells enriched in secreted beta-hexosaminidase. This method may show promise for measuring the effectiveness of experimental therapies for G(M2) gangliosidosis by allowing quantification of a reduction in the primary storage burden. (C) 2014 Elsevier Inc. All rights reserved.