Prospects for the development of artificial materials for the repair of the peripheral and central nervous systems

摘要

A freeze-dried alginate sponge cross-linked with covalent bonds was developed in our laboratory, and has been demonstrated to enhance not only peripheral but also central axonal regeneration. For repair of an injured peripheral nerve, the freeze-dried alginate sponge can be used without microsurgical technique. Many axons elongated through the alginate, beyond a 50mm gap, into the distal stump of cat sciatic nerve and reinnervated both efferent and afferent systems. Freeze-dried alginate sponge may be a very useful alternative clinically. In the central nervous system, freeze-dried alginate sponge enhanced axonal regeneration in the injured spinal cord of rats. Regenerated spinal cord axons elongated beyond a 2mm gap in the rat thoracic spinal cord and reentered from the other stump of the amputated spinal cord. The elongated axons established electrophysiologically functional projections through the gap. However, Schwann cells, which were not seen in the normal spinal cord, surrounded the regenerated axons. Neuronal stem cells, embryonal stem cells and bone-marrow stem cells are all considered to be candidates for the creation of neurons, astrocytes and oligodendrocytes after implantation into the injured spinal cord gap. Further experiments using stem cells together with alginate sponge may allow amputated spinal axons to regenerate into the differentiated glial cells and neurons that are derived from the implanted stem cells.