Spinal cord repair with PHPMA hydrogel containing RGD peptides (NeuroGel)

A biocompatible hydrogel of poly[N-(2-hydroxypropyl)methacrylamide] (PHPMA) which includes the cell-adhesive region of fibronectin Arg-Gly-Asp was synthesized and its structure, rheological and dielectric properties were characterized. The ability of a PHPMA-RGD hydrogel to promote tissue regeneration and support axonal outgrowth in the injured adult and developing rat spinal cord was evaluated. The structure of the PHPMA-RGD hydrogel displayed an interconnected porous structure, with viscoelastic properties similar to those of the neural tissue, and conductivity properties due to a peptide group. The polymer hydrogel provided a structural, three-dimensional continuity across the defect, facilitating the migration and reorganization of local wound-repair cells, as well as tissue development within the lesion. Angiogenesis and axonal growth also occurred within the microstructure of the tissue network, and supraspinal axons migrated into the reconstructed cord segment. In addition, the hydrogel induced a reduction of necrosis and cavitation in the adjacent white and gray matter. These polymer hydrogel matrices therefore display the potential to repair tissue defects in the central nervous system by enhancing the development of a tissue equivalent as well as axonal growth across the reconstructed lesion.