Chitosan, gelatin and poly(L-lysine) polyelectrolyte-based scaffolds and films for neural tissue engineering

Biomaterial implants are a promising strategy to replace neural tissue that is lost after traumatic nerve damage. Chitosan (Ch) is a suitable material for nerve implantation when it is used at a minimum amount of 2% (w/v). The goal of this study was to determine the best mixture of 2% Ch with gelatin (G) and poly(L-lysine) (PLL) for use in neural tissue engineering. Using different physicochemical approaches we showed that all mixtures formed polyelectrolyte complexes with distinct electrostatic interactions between their compounds. This gave rise to different gel morphologies, among which Ch + G exhibited a significantly smaller pore size, unlike Ch + G + PLL. However, thermal resistance to degradation and the wettability of the Ch-based films were not affected. Additionally, these differences affected glial cells growth in long-term (14 days) cultures performed on Ch-based films. Astrocytes and olfactory ensheathing cells proliferated on G and Ch + G films which induced both flattened and spindle cell morphologies. Meanwhile, cortical and hippocampal neurons were similarly viable in all studied films and significantly lower than those observed in controls. Lastly, neurites from dorsal root ganglia extended the most on Ch + G films. These results show that a Ch + G mixture is a promising candidate for use in neural tissue engineering.