Transplant mediated repair of the central nervous system: an imminent solution?

This article reviews recent advances in the use of cell transplantation to promote recovery from traumatic injury of the CNS, focusing on axonal regeneration in the spinal cord.

The significant recent findings reported are: (1) the increased expression of inhibitory chondroitin sulphate-proteoglycans in host tissue following Schwann cell transplantation, highlighting the effects the transplant may have on the ability of the host tissue to support regeneration; (2) the ability of embryonic and neural stem cells to promote recovery following transplantation into experimental models of spinal cord injury; (3) that delayed grafting for several weeks after transplantation does not diminish the graft effectiveness and may be advantageous; (4) the use of transplanted fibroblasts engineered to express neurotrophic genes in a conditionally regulated manner using tetracycline-inducible promoters; and (5) the initial reports on phase 1 clinical trials of foetal spinal cord grafts into patients with post-traumatic syringomyelia demonstrating their feasibility and safety.

Recent advances largely involve experimental refinements of existing approaches and the emergent application of stem cell biology to overcome spinal cord injury. While most experimental studies concentrate on single or restricted combinations of approaches, the most effective clinical strategies will be multi-component. Their formulation will require the development of intermediate models for bridging the differences between experimental models in laboratory animals and naturally occurring traumatic injury in humans.