Glycosaminoglycans in biomedicine.

Glycosaminoglycans (GAGs) compose one of four classes of mammalian biopolymers, and are arguably the most complex. The research areas of glycobiology, glycopolymers, and the use of GAGs within tissue engineering and regenerative medicine have grown exponentially during the past decade. Researchers are closing in on high throughput methods for GAG synthesis and sequencing, but our understanding of glycan sequence and the information contained in this sequence lags behind. Screening methods to identify key GAG-biopolymer interactions are providing insights into important targets for nanomedicine, regenerative medicine, and pharmaceutics. Importantly, GAGs are most often found in the form of glycolipids and proteoglycans. Several studies have shown that the clustering of GAGs, as is often the case in proteoglycans, increases the affinity between GAGs and other biopolymers. In addition, GAG clustering can create regions of high anionic charge, which leads to high osmotic pressure. Recent advances have led to proteoglycan mimics that exhibit many of the functions of proteoglycans including protection of the extracellular matrix from proteolytic activity, regulation of collagen fibril assembly on the nanoscale, alteration of matrix stiffness, and inhibition of platelet adhesion, among others. Collectively, these advances are stimulating possibilities for targeting of drugs, nanoparticles, and imaging agents, opening new avenues for mimicking nanoscale molecular interactions that allow for directed assembly of bulk materials, and providing avenues for the synthesis of proteoglycan mimics that enhance opportunities in regenerative medicine.