Differences in sulfation patterns of heparan sulfate derived from human bone marrow and umbilical vein endothelial cells

Objective. Heparan sulfates (HS), the polysaccharide side chains of HS prot eoglycans, differ in structure and composition of sulfated domains among va rious tissue types, resulting in selective protein binding. HS proteoglycan s on bone marrow endothelial cells (BMEC) could contribute to tissue specif icity of the bone marrow endothelium and play a role in the presentation of chemokines such as stromal cell-derived factor-1 (SDF-1) and adhesion of h ematopoietic progenitor cells after stem cell transplantations. We characte rized differences in HS structure and SDF-1 binding between BMEC and human umbilical vein endothelial cells (HUVEC). Materials and Methods. Expression of HS proteoglycans on human hone marrow microvessels was investigated by immunohistochemical staining. Comparison o f three human BMEC cell lines with HUVEC and an HUVEC cell line was studied by now cytometry using antibodies against different epitopes of the HS pol ysaccharide chain. HS proteoglycans were biochemically characterized after isolation from metabolically labeled cultures of the BMEC cell line 4LHBMEC and HUVEC. Binding of radiolabeled SDF-1 to 4LHBMEC and HUVEC and competit ion with heparins were investigated, Results. Bone marrow microvessels constitutively expressed HS proteoglycans . Flow cytometric experiments showed differences in HS chain composition be tween BMEC and HUVEC. Biochemical characterization revealed more O-sulfatio n of the N-sulfated domains present in cell-associated HS glycosaminoglycan s in 4LHBMEC compared to HUVEC. Binding experiments showed that 4LHBMEC bou nd more (125)[I]SDF-1 per cell than HUVEC. This could be inhibited largely by heparin and O-sulfated heparin and to a lesser extent hy N-sulfated hepa rin, Conclusions. Cellular HS from BMEC differs in composition from HUVEC. We po stulate that the presence of highly sulfated domains in the HS chains from BMEC contributes to tissue specificity of bone marrow endothelium in which HS may be involved in SDF-1 presentation and adhesion of hematopoietic prog enitor cells. (C) 2001 International Society for Experimental Hematology. P ublished by Elsevier Science Inc.