A "Sweet" Support for Neuronal Growth: the Role of Polysaccharide Blends

Zheng Cao (Universoty of Tennessee)

Agarose hydrogel has been favored as scaffolding material for neural tissue engineering due to its excellent properties, including appropriate stiffness, porous structure, biocompatibility and biodegradability. However, agarose cannot support neuron attachment by itself. Functionalization of agarose hydrogel could improve cell adhesion, but it generally involves complex chemistry. The introduction of toxic organic solvents could also be potentially harmful for subsequent cell culture. A simplified approach was proposed by blending agarose with another polysaccharide, chitosan, which is known to facilitate the attachment of many types of cells. The mechanical stiffness of the hydrogel was determined by rheological tests, which revealed stiffness similarity between the blend and the plain agarose gel. The structure of the blended hydrogels was characterized using light microscopy and scanning electron microscopy (SEM). An in vitro cell study revealed that the blends promoted neuron adhesion. The concentration of chitosan in the hydrogel had great influence on the morphology of chick cortical neurons. An optimum range of chitosan concentration in agarose gel to enhance neural cell attachment and differentiation was identified based on the results. A .steric hindrance. effect of chitosan was proposed, which explained the origin of the morphological differences of neurons in the blended gels as well as the influence of the physical environment on neuron adhesion and neurite outgrowth. Our work is the first one to demonstrate this .steric hindrance. effect of substrates by correlating the morphology of single cells and a three-dimensional structured tissue scaffold. The simplicity of preparing this hydrogel system and its multi-functionality also allow for future applications for neural tissue repair.

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