Core of the scaffold seeded with neural stem cells (a,b). Outer portion of the scaffold, showing the axially oriented pores (c). © 2002 National Academy of Sciences, USA.

Over the past few years, we have witnessed the advent of many approaches that aim to promote functional recovery after injury to the spinal cord. Blockade of endogenous inhibitory molecules, myelin replacement by Schwann cells or olfactory ensheathing glia, and transplantation of embryonic tissue are just some of the strategies that have been developed and tested with varying degrees of success. A particularly intriguing approach is the implantation of biodegradable scaffolds into the injured region in the hope that they will promote recovery by fostering axonal growth or by supporting the survival of damaged cells. A recent paper by Teng et al. gives significant impetus to this idea by showing that a polymer scaffold that is seeded with neural stem cells promotes functional recovery in rats with spinal cord lesions.

The authors developed a scaffold, with a view to sustaining a structure akin to the spinal cord; it had a porous core that could be seeded with cells, and an outer portion with axially oriented pores that could potentially assist axon growth. They seeded scaffolds with neural stem cells, grafted them into longitudinal cavities in the spinal cords of rats, and tested whether this manipulation elicited behavioural recovery. The locomotion of animals that received cell-seeded scaffolds was better than the performance of rats that received cell-free scaffolds, which in turn was better than the locomotion of control rats or of animals that received only stem cells.

When they looked for the mechanisms that might underlie the behavioural recovery, the authors found that the presence of the scaffold diminished the formation of glial scars, leading them to suggest that this is one means by which the grafts might have a beneficial effect. Teng et al. also found evidence for axons crossing the lesion site in the presence of the scaffold, indicating that the recovery might also involve the regrowth of spared fibres.

Although it is still too early to herald this approach as the solution to spinal cord injury, the results of this study highlight the potential of bioengineering to help us develop innovative strategies to treat a variety of neurological and neurodegenerative disorders.