INTRODUCTION
The advent of cosmeceuticals has revolutionized skin care. Dermatologists can now use topically applied compounds to address a variety of skin concerns with the goal of improving the signs of photodamage, such as uneven pigmentation, fine lines, tactile roughness, and skin tone. The benefits of both over-the-counter retinol and prescription retinoids such as retinoic acid (tretinoin) are well documented, as are the benefits of topical antioxidants such as vitamin C. Although certainly popular in cosmeceuticals, other agents such as peptides and growth factors have not been the subject of similar rigorous studies. Over the past several years, it has become apparent that cosmeceuticals can contribute to overall skin health by targeting certain issues that procedures cannot, namely oxidative stress and DNA repair. An extensively studied component of skin, heparan sulfate (HS), may be one of the most exciting and fascinating compounds that we now have available in the cosmetic arena. This report summarizes what we know about low molecular weight heparan sulfate (LMWHS) not only from a scientific perspective but also from initial clinical studies exploring its effectiveness on the skin.
In order to understand HS, we must first look at the skin and the building blocks that play a crucial role in skin health. These include the full spectrum of glycosaminoglycans (GAGs) besides HS, and molecules known as proteoglycans (PGs), which contain the GAG as a covalently attached side chain. PGs, with their ability to bind and alter enzymatic activity and protein-protein interactions, help to determine cellular responsiveness in development, homeostasis, and disease.1 PGs and GAGs are vital to life and have major roles in tissue remodeling, cell adhesion, growth factor responsiveness, and immune function.
Glycosaminoglycans and Proteoglycans
A GAG chain consists of repeating disaccharide pairs that usually include an acidic sugar alternating with a hexosamine. The acidic sugar may be iduronic acid or a glucuronic acid, and the hexosamine may be a glucosamine or galactosamine. GAG chains are linear and may contain up to several thousand disaccharides.2 Important GAGs and their paired disaccharide constituents in skin are shown in Table 1.
Except for hyaluronic acid, the GAGs in Table 1 are sulfated and covalently attached to core proteins. All must be enzymatically modified to become functional in skin. Dermatan sulfate (chondroitin sulfate B) is the major GAG in skin. Hyaluronic acid (hyaluran) in skin is neither sulfated nor covalently attached to a
