Polysaccharides hyaluronan/hyaluronic acid

Mammalian Polysaccharides Glycosaminoglycans (hyaluronic acid or hyaluronan, Chondroitin sulphate), gelatin and heparin sulfate, chitin and chitosan... 

Sodium hyaluronate is the predominant form of hyaluronic acid at physiological pH. The name hyaluronan is used when the polysaccharide is mentioned in general terms, and in the literature the terms hyaluronic acid and sodium hyaluronate are used interchangeably. 

The currently used term is "hyaluronan" and this name represents a combination of "hyaluronic acid" and "hyaluronate", in order to indicate the different charged states of this polysaccharide... 

As stated above, hyaluronic acid (Figure 1.1), also called hyaluronan and sometimes presented as a hyaluronate (poly)anion from the chemical/structural viewpoint, is a non-sulfated GAG, while all other glycosaminoglycans are sulfated polysaccharides (cf. Table 1.1). Another fundamental and remarkable difference between HA and the other GAGs is the mean molar mass of the native biopolymeric chains. While the value of several MDa is the most common one for HA synthesized by hyaluronan synthases (HASl, HAS2, and HASS), the molar mass of further glycosaminoglycans, on average, does not exceed the value of 50 kDa [8]. 

Dr. Soltes has been employed for over 30 years at Academic Research Institutes in Bratislava, Slovakia. His research related to the polysaccharides, which started over two decades ago, resulted in patenting a novel approach "Clathrate complexes formed by hyaluronic acid derivatives and use thereof as pharmaceuticals". His current research interests are focused on the studies of hyaluronan oxidative damage and the regulation of this process. Dr. Soltes is the sole distinguished representative of Slovakia in the International Society for Hyaluronan Sciences. In 2007 he was named Scientist of the Year of the Slovak Republic. 

Hyaluronan (also called hyaluronic acid or hyaluronate or HA) is an anionic water-soluble polysaccharide that is distributed widely throughout connective, epithelial and neural tissues. It is one of the main components of the extracellular matrix and widely contributes to cell proliferation and migration. HA is approved for injections by FDA for its... 

The term hyaluronan was introduced in 1986 to conform to the international nomenclature of polysaccharides and is attributed to Endre Balazs (Balazs E. A, et al., 1986), who coined it to encompass the different forms of the molecule can take, e.g., the acid form, hyaluronic acid, and the salts, such as sodium hyaluronate, which forms at physiological pH [10], HA was subsequently isolated from many other sources and the physicochemical stracture properties, and biological role of this polysaccharide were studied in numerous laboratories [11]. This work has been summarized in a Ciba Foundation Symposium [12] and a recent review [13]. 

At the time of the discovery of hyaluronan, the polysaccharides, which represent the major part of the organic material on our planet, were already quite well known. A number of so-called mucopolysaccharides, currently known as glycosaminoglycans, had already been discovered. Hyaluronic acid is known to belong to this class as well. Mucopolysaccharides were isolated from mucus, to which they give viscous lubricating properties. These properties, in turn, are related to glycosaminoglycan s ability to bind to a significant amount of water. 

Over the next 10 years, Meyer and other authors isolated hyaluronan from various animal organs. For example, the polysaccharide was found in joint fluid, the umbilical cord and recently it has become possible to extract HA from almost all vertebrate tissues. In 1937, F. Kendall isolated hyaluronan from the capsules of streptococci groups A and C. This work had great scientific and practical importance, as today streptococci groups are the most economical and reliable source for the industrial production of hyaluronic acid [3]. 

Using the technology of solid-state modification of polysaccharides that included the mutual action of super-high pressure and shear deformation, a group of Russian scientists have produced a number of unique products that contain hyaluronic acid. The new products could be considered drug-free (or non-drug) macromolecular therapeutics. These areas of research have made possible a broad range of new products based on the modified hyaluronan and could be used in the various fields of medicine. 

From the chemical point of view, hyaluronan possesses four different types of functional groups acetamide, carboxylic acid, hydroxyl and terminal aldehyde. After deacetylation, a free amine could be obtained from an acetamide group. All four functionalities permit characteristic chemical reactions. Such a wide variety of possible chemical modifications creates a sharp difference between hyaluronic acid and other polysaccharides whose reactivity depends mainly upon hydroxyl groups. 

In carbohydrate chemistry, a polysaccharide is a molecule having more than ten monosaccharide units [18]. Polysaccharides belong to one of three important classes of naturally occurring biopolymers, the other two being nucleic acids (DNA and RNA) and proteins. Cellulose, amylose, xylan, chitin, hyaluronic acid (hyaluronan), chondroitin, and chondroitin sulfate can be cited as typical natural polysaccharides (Scheme 1). 

Several polysaccharides, such as hyaluronan and alginate, have also been examined as potentially suitable biomaterials for hPSC expansion [80-83]. Polysaccharide is known to play an important role in regulating hPSC adhesion and self-renewal [74]. For example, hyaluronan-derived hydrogels might provide an adequate physiological environment for hPSC growth because the feeder layers that support hPSCs are composed of large amounts of hyaluronic acid in addition to abundant ECM proteins. 

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