  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
microgram per 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.
