Restorative surgery of the central nervous system by means of tissue engineering using NeuroGel implants

A novel approach aimed at restoring tissue structure and function and enhancing axonal recovery in damaged parts of the central nervous system is described. In contrast to contemporary neurotransplantation technologies which focus on tissue reconstruction of neural parenchyma by cell replacement, this approach is based on repair by tissue engineering. The technique involves the implantation of a 3-dimensional polymer hydrogel into the site of injury. The physical properties of the hydrogel induce the organisation of migrating wound-healing cells and regenerating axons within its 3-dimensional structure. Two complementary approaches are described and illustrated using results obtained in vivo and in vitro: (1) implantation into the brain and spinal cord of the polymer hydrogel NeuroGel, which has a defined macromolecular structure that enhances tissue-building capabilities, and the implantation of advanced hydrogel derivatives carrying biologically active molecules to promote selective cell interactions, and (2) biohybrid hydrogels that contain entrapped developing neural tissue cells, embryonic carcinoma-derived neurons, or genetically modified cells which secrete neurotrophic factors. These techniques create bioartificial tissues with neural tissue specificity. The potential of this biomaterial-based approach to neural tissue engineering for restorative neurosurgery is discussed.