Gelatin-Based Hydrogel for Three-Dimensional Neuron Culture Application

Gelatin is a biocompatible biomaterial composed of a variety of amino acids that provides a possibility to regulate the interaction between cationic amino acids and neural cells. Based on our first finding that the neuron viability was improved as the lysine on the gelatin was converted into a guanidine structure, a three-dimensional (3D) gelatin hydrogel composed of gelatin and poly(allylguanidine) (PAG) was prepared to investigate neural cell behaviors. As expected, improved neuron viability, neurite outgrowth, synaptogenesis, and inhibited glial cell growth were simultaneously observed in the gelatin cross-linked with the PAG hydrogel (G-PAG) but not in the gelatin hydrogel cross-linked with poly-d-lysine (PDL) or polyethylenimine (PEI). In addition, in vivo tests also illustrated that G-PAG could provide an environment for neural culture, with improving neuron viability and neurite outgrowth. Several hydrogel characteristics-including the swelling ratio, mechanical strength, and electric property-that theoretically can influence neural cell response showed no significant difference among them. Therefore, the guanidine structure of PAG was proposed to determine the behaviors of neural cells within the gelatin-polycation hydrogels, and we proposed that the neural cell behavior is regulated by a specific gelatin-neuron relationship. The information found in this study provides a concept to design and modify gelatin-based hydrogels for neural tissue engineering applications.