Instant determination of the potential biomarker heparan sulfate in human plasma by a mix-and-read fluorescence assay

Heparan sulfate (HS) is a linear, polydisperse sulfated polysaccharide belonging to the glycosaminoglycan family. HS proteoglycans are ubiquitously found at the cell surface and extracellular matrix in animal species. HS is involved in the interaction with a wide variety of proteins and the regulation of many biological activities. In certain pathologic conditions, expression and shedding of HS proteoglycans is overregulated, or enzymatic degradation of HS in lysosomes is deficient, both leading to excess circulating free HS chains in blood plasma. HS has therefore been suggested as a biomarker for various severe disease states. The structural heterogeneity makes the quantification of heparan sulfate in complex matrices such as human plasma challenging. HS plasma levels are usually quantified by either disaccharide analysis or enzyme linked immunosorbent assay (ELISA). Both methods require time-consuming multistep-protocols. We describe here the instant detection of heparan sulfate in spiked plasma samples by the Heparin Red Kit, a commercial mix-and– read fluorescence microplate assay. The method enables HS quantification in the low μg/mL range without sample pretreatment. Heparin Red appears to be sufficiently sensitive for the detection of highly elevated HS levels as reported for mucopolysaccharidosis, graft versus host disease after transplantation, dengue infection or septic shock. This study is a significant step toward the development of a convenient and fast method for the quantification of HS in human plasma, with the potential to simplify the detection and advance the acceptance of HS as a biomarker.