Scientists at Northwestern University in the US have designed synthetic molecules that promote neuron growth, a development that could lead to the reversal of paralysis due to spinal cord injury.
‘We have created new materials that, because of their chemical structure, interact with cells of the central nervous system in ways that may help prevent the formation of the scar that is often linked to paralysis after spinal cord injury,’ said Samuel I Stupp, Board of Trustees Professor of Materials Science and Engineering, Chemistry and Medicine.
Similar to earlier experiments that promoted bone growth, the scientists have grown nerve cells using an artificial three-dimensional network of nanofibres, an important technique in regenerative medicine.
‘We have shown that our scaffold selectively and rapidly directs cell differentiation, driving neural progenitor cells to become neurons and not astrocytes,’ said Stupp, who led the research team in Evanston. ‘Astrocytes are a major problem in spinal cord injury because they lead to scarring and act as a barrier to neuron repair.’
The scaffold is made up of nanofibres formed by peptide amphiphile molecules. According to a statement, the scientists’ key breakthrough was designing the peptide amphiphiles so that when they self-assembled into the scaffold a specific sequence of five amino acids known to promote neuron growth were presented in enormous density on the outer surfaces.
‘This was all done by design,’ said Stupp. ‘By including a specific biological signal on the nanostructure we were able to customise the new materials for neurons.’
In collaboration with the lab of John A. Kessler, Benjamin and Virginia T. Boshes Professor of Neurology at the Feinberg School of Medicine, Stupp and his team observed that when the peptide amphiphiles were placed in solution and combined with neural progenitor cells (which are present in the central nervous system and able to differentiate into different types of cells) the nanofibre scaffolds formed and led quickly to the selective differentiation of the cells into neurons.
In subsequent experiments, the researchers successfully delivered the peptide amphiphile solution, using a simple injection, to the site of a spinal cord injury in a laboratory rat. On contact with the tissue, the solution was transformed into a solid scaffold.