Hyaluronan/hyaluronic acid applications

Oxidized hyaluronic acid was coupled with chitosan to form porous scaffolds after freeze drying. The proportion of porosity of the freeze-dried chitosan-hyaluronic acid dialdehyde composite (CHDA) gels enhanced with augmentation in oxidation. Fibroblast cells seeded onto CHDA porous scaffold adhered, proliferated and offered extracellular matrix components on the scaffold [99]. Chondrocytes encapsulated in CHDA gels retained their viability and specific phenotypic features. The gel material is therefore projected as a scaffold and encapsulated material for tissue engineering applications. Films of hyaluronan (HA) and a phosphoryl choline-modified chitosan (PC-CH) were constructed by the electrolyte multilayer (PEM)... 

Upon first glance, it may appear this chapter is oversaturated with technological details that would be of interest only to technologists working in hyaluronan production. However, the material is presented in this way intentionally in order to properly elucidate the difficulties of hyaluronic acid production and the potential problems caused by the technological impurities in the final product when intended for medical application. 

The major component of the synovial fluid, that is, hyaluronan, has two main functions namely lubricant and shock impulse damping [25]. Furthermore, hyaluronic acid is a major component of the extracellular matrix of the connective tissue. This kind of polymer should exhibit viscoelastic properties that directly depend on its microstructure and external parameters such as shear rate, stress and temperature. Knowledge of dependence of model synovial fluid viscosity on the shear rate, stress and temperature is very useful for biomedical applications, for example, in treatment of joint diseases. 

We realize that the description of the overall reactivity and chanical modifications of hyaluronan is a dense subject that could fill a separate monograph. However, this chapter will focus mainly on the chemical modifications of hyaluronan that lead to cross-linking. Such modifications play an important role for the creation of hyaluronic acid with valuable chemical and physical properties necessary for biological application of hyaluronan products. 

The first chapter describes the history of hyaluronic acid discovery, the main milestones of its research and practical application. The largest chapter. Chapter 2, is dedicated to the biological role of the hyaluronic acid in nature, in particular in the human body. The chapter starts from the phylogenesis of hyaluronic acid, then describes hyaluronan functions in human ontogenesis and especially the role that hyaluronan plays in the extracellular matrix of the different tissues. 

HA was first isolated from bovine vitreous humor in acid form by Karl Meyer and John Pahner of Columbia University in 1934. They named the new pwlysaccharide hyaluronic acid, meaning uronic acid from hyaloid (vitreous). The term hyaluronan was introduced by Endre Balazs in 1986 to encompass the different forms the molecule can take—for example, the add form, hyaluronic acid, and the salts, such as sodium hyaluronate, which form at physiological pH [17]. Endre Balazs pioneered the medical use of HA. He derived the main concepts for many applications and... 

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