The central nervous system has an inherent ability to regenerate itself and new carbon nanotube scaffolds could be used to help this process along. “Indeed, previous research by our group has already shown that carbon-based nanostructures, such as MWCNTs, can support neural growth and the formation of synapses,” explain team leaders Laura Ballerini of the International School of Advanced Studies (SISSA) in Trieste, Italy, and Maurizio Prato of the University of Trieste.

“In this new work we have used, for the first time, a 3D MWCNT self-standing framework as a tissue scaffold to interface spinal cord explants from rats,” Ballerini tells nanotechweb.org. “We found that such materials can guide central nervous system reorganisation in 3D, leading to the formation of a dense hybrid tissue that looks like a knotted tangle of tubes.”

Webs of nerve fibres spontaneously form

The researchers showed that when scaffolded to spinal segments segregated by a MWCNT bridge, webs of nerve fibres (that had sprouted from the segments in culture) spontaneously form. These webs “invade” the nanotube scaffold and intertwine with it.

To study how biocompatible their system was, Ballerini and colleagues implanted small portions of pure 3D MWCNTs into the brains of rats for four months. After an initial, and normal, inflammatory response to the material, none of the animals developed any further adverse tissue reactions. This suggests that the CNT structure can safely integrate into nerve tissue.

Towards a new therapeutic platform to regenerate the central nervous system

“These excellent results at the structural and functional level in vitro and in vivo showed biocompatibility and are encouraging us to continue this line of research,” says Ballerini. “These materials could be useful for covering electrodes used for treating movement disorders like Parkinson's because they are well accepted by tissue, while the implants being used today become less effective over time because of scar tissue. We hope this encourages other research teams with multidisciplinary expertise to expand this type of study even further."

Nicholas Kotov of the University of Michigan in the US, who was not involved in this research, says that this is a "great paper". The researchers are tackling a difficult problem of "re-wiring" severed parts of spinal cord, he explains. "They present convincing results and in a few years it could be possible to direct the growth of neurons with meshes of carbon nanotubes."

Charles Lieber of Harvard University, who was not involved either, adds: "this work is an exciting example of using 3D mesh architectures based on nanomaterials for enabling new opportunities in tissue engineering. The authors use of carbon nanotube meshes to guide the growth of neurons in 3D is very interesting from both a basic science perspective and offers unique opportunities in regenerative medicine."

Ballerini and colleagues, reporting their work in Science Advances DOI: 10.1126/sciadv.1600087, are now busy trying to exploit nanomaterial-based scaffolds like the one described here to develop a new therapeutic platform to regenerate the central nervous system.