Nanofibres help rebuild brain cells

Massachusetts Institute of Technology (MIT) bioengineers and neuroscientists have invented a biodegradable scaffold of nanofibres through which brain cells can regrow to repair injury. The technique was proven in hamsters blinded by a severed tract in their brains' visual system, which had their sight partially restored within weeks.

This method may one day help patients with traumatic brain injuries, spinal cord injuries and stroke. The study is the first that uses nanotechnology to repair and heal the brain and restore function of a damaged brain region.

In the experiment on young and adult hamsters with severed neural pathways, the researchers injected the animals' brains with a clear solution containing a self-assembling material made of protein peptides, the building blocks of the human body.

Placing certain peptides in a salt solution causes them to assemble into thin sheets of 99 percent water and 1 percent peptides. These sheets form a mesh or scaffold of tiny interwoven fibres. Neurons are able to grow through the nanofibre mesh, which is similar to that which normally exists in the extracellular space that holds tissues together.

The process creates an environment conducive for existing cells to regrow their long branchlike projections called axons, through which neurons form synaptic connections to communicate with other neurons. These projections were able to bridge the gap created when the neural pathway was cut, and restore enough communication among cells to give the animals back useful vision within around six weeks. The researchers were surprised to find that adult brains responded as robustly as the younger animals' brains, which typically are more adaptable.

When the fluid containing the self-assembling peptides is injected into the area of the cut, it flows into gaps and starts to work as soon as it comes into contact with the fluid that bathes the brain. After serving as a matrix for new cell growth, the peptides' nanofibres break down into harmless products that are eventually excreted in urine or used for tissue repair.