Advances in glycosaminoglycan detection

Abstract

Background: Glycosaminoglycans (GAGs) are negatively charged long linear (highly sulfated) polysaccharides consisting of repeating disaccharide units that are expressed on the surfaces of all nucleated cells. The expression of GAGs is required for embryogenesis, regulation of cell growth and proliferation, maintenance of tissue hydration, and interactions of the cells via receptors. Mucopolysaccharidoses (MPS) are caused by deficiency of specific lysosomal enzymes that result in the accumulation of GAGs in multiple tissues leading to organ dysfunction. Therefore, GAGs are important biomarkers for MPS. Without any treatment, patients with severe forms of MPS die within the first two decades of life.

Scope of review: Accurate measurement of GAGs is important to understand the diagnosis and pathogenesis of MPS and to monitor therapeutic efficacy before, during, and after treatment of the disease. This review covers various qualitative and quantitative methods for measurement of GAGs, including dye specific, thin layer chromatography (TLC), capillary electrophoresis, high-performance liquid chromatography (HPLC), liquid chromatography-tandem mass spectrometry (LC-MS/MS), gas chromatography, ELISA, and automated high-throughput mass spectrometry. Major conclusion: There are several methods for GAG detection however, specific GAG detection in the various biological systems requires rapid, sensitive, specific, and cost-effective methods such as LC-MS/MS.

General significance: This review will describe different methods for GAG detection and analysis, including their advantages and limitation.

Keywords: Chondroitin sulfate; Dermatan sulfate; Glycosaminoglycans; Heparan sulfate; Keratan sulfate; Tandem mass spectrometry (MS/MS).

Figure 1.

Adapted from Karousou et al. [93]. HPLC analysis of HA, CS/DS GAG-disaccharides. The standard mixture of HA and CS/DS-disaccharide was derivatized with AMAC and analyzed with HPLC using a reversed-phase column (C-18, 4.6 × 150 mm). Products were detected with a fluorophore detector (ex = 442 nm and em = 520 nm). Panel A: separation of a mixture of commercial standard mono-sulfated-disaccharide from CS/DS and HA; I: di-mono4S; II: dimono6S; III: di-0 HA; IV: 0 CS; V: GalNAc. Panel B: separation of a mixture of commercial standard-disaccharide from HA and CS/DS GAGs. Peaks corresponds to: 1 di-tri(2,4,6)S; 2 di-di(2,4)S, 3 di-di(4,6)S, 4 di-di(2,6)S, 5 di-mono4S, 6 di-mono2S, 7 di-mono6S, 8 di-0S HA, 9 di-0S CS.

Figure 2.

Adapted from Chang et al. [108]. Electrophoregram of eight HP/HS Δ-disaccharides. The analysis was performed at 25°C, pressure injection of 50 mbar × 10 s, using 50 mM phosphate buffer, pH 3.5, under 30 kV with reversed polarity.