Heparin Contamination and Issues Related to Raw Materials and Controls

NMR Characterization of the Interactions Between Glycosaminoglycans and Proteins

Glycosaminoglycans (GAGs) constitute a considerable fraction of the glycoconjugates found on cellular membranes and in the extracellular matrix of virtually all mammalian tissues. The essential role of GAG-protein interactions in the regulation of physiological processes has been recognized for decades. However, the underlying molecular basis of these interactions has only emerged since 1990s. The binding specificity of GAGs is encoded in their primary structures, but ultimately depends on how their functional groups are presented to a protein in the three-dimensional space. This review focuses on the application of NMR spectroscopy on the characterization of the GAG-protein interactions. Examples of interpretation of the complex mechanism and characterization of structural motifs involved in the GAG-protein interactions are given. Selected families of GAG-binding proteins investigated using NMR are also described.

Inhibition of Tumor-Host Cell Interactions Using Synthetic Heparin Mimetics

Low-molecular-weight heparin (LMWH) is the guideline-based drug for antithrombotic treatment of cancer patients, while its direct antitumor effects are a matter of ongoing debate. Although therapeutically established for decades, LMWH has several drawbacks mainly associated with its origin from animal sources. Aiming to overcome these limitations, a library of synthetic heparin mimetic polymers consisting of homo- and copolymers of sulfonated and carboxylated noncarbohydrate monomers has recently been synthesized via reversible addition-fragmentation chain transfer polymerization. These heparin mimetics were investigated for their capacities to interfere with simulated steps of tumor cell metastasis. Among them, homo- and copolymers from sodium 4-styrenesulfonate (poly(SSS)) with acrylic acid (poly(SSS-co-AA)) with an MW between 5 and 50 kDa efficiently attenuated cancer cell-induced coagulation and thus platelet activation and degranulation similar to or even better than LMWH. Furthermore, independent of anticoagulant activities, these polymers affected other metastasis-relevant targets with impressive affinities. Hence, they blocked heparanase enzymatic activity outmatching commercial heparins or a glycosidic drug candidate. Furthermore, these polymers bind P-selectin and the integrin VLA-4 similar to or even better than heparin, indicated by a biosensor approach and thus efficiently blocked melanoma cell binding to endothelium under blood flow conditions. This is the first report on the prospects of synthetic heparin mimetics as promising nontoxic compounds in oncology to potentially substitute heparin as an anticoagulant and to better understand its role as an antimetastatic drug.