A biomaterial for the treatment of spinal cord or of peripheral nerve injury injury, obtainable by: a) treating a hyaluronic acid derivative with a coating solution promoting Neuronal Stem Cells adhesion, branching and differentiation; b) contacting isolated Neuronal Stem Cells with the hyaluronic acid derivative obtained from step a) and culturing and expanding the absorbed cells in the presence of growth or neurotrophic factors selected from βFGF (basic fibroblast growth factor), CNTF (ciliary neurotrophic factor), BDNF (brain derived neurotrophic factor) and GDNF (glial derived neurotrophic factor) or mixtures thereof.