Hydrogels: An Important Characteristics And Importance Of Scaffolds

By improvement of tissue engineering and looking forward to find an appropriate scaffold to guide the growth of new tissue, hydrogels play an important role since they can absorb large amounts of water and physiological fluids. Furthermore their special characteristics are: showing excellent biocompatibility and also the probability of causing inflammatory responses, thrombosis, and tissue damage are minimum. The hydrophilic but crosslinked structure forgive them the ability to absorb large amount of water without dissolution of the polymer. These unique characteristics make them an appropriate replacement for soft and connective tissues. In addition, hydrogels have high permeability for oxygen, nutrients, and other water-soluble metabolites.

There are two sources of scaffolds’ polymer, natural and synthetic. The advantages of natural scaffolds are their excellent biocompatibility, cell-controlled degradability, and intrinsic cellular interaction. Their disadvantage is their limited range of mechanical properties. On the other hand, one can prepared the synthetic polymers with precisely controlled structures and functions. From all above, due to the hydrogel’s characteristics and their structural similarity to the macromolecular-based components in the body, they are good candidate for cartilage regeneration’s scaffold.

In order to design a scaffold, one should pay attention to physical and biological parameters. For example, the biological parameters are stated as the hydrogel’s ability in cell adhesion and the main important physical parameters are the scaffold’s degradation and mechanics. It is believed that the degradation rates of tissue scaffolds must be as same as cellular processes.

One other characteristics of hydrogels ar...

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...ted glycosaminoglycan, composed of N-acetyl-d-glucosamine and d-glucuronic acid. HA is the main component of ECM in connective tissues and is abundant in vitreous and synovial fluids. HA improves the proliferation and differentiation of progenitor cells. It is a mucopolysaccharide found in various types of tissues and its immunoneutrality makes it an excellent building block for biomaterials to be employed for tissue engineering and drug delivery system. Knudson et al. determined that hyaluronan oligosaccharides induced chondrocytic chondrolysis, including neartotal loss of stainable proteoglycan-rich matrix and activation of gelatinolytic activity.

HA is known to interact with chondrocytes via various surface receptors including CD44. The surface receptor bound to HA triggers a sophisticated signaling pathway making chondrocytes retain their original phenotype.