A liquid that forms a gel-like mass of nanofibres on contact with water could provide the most promising vehicle yet for the regeneration of damaged spinal cords. Many groups working in regenerative medicine are trying to develop artificial scaffolds that store or attract cells and then control their growth and final identity. The most common approach has been to build fabrics, films or gels out of biopolymers such as collagen and then "seed" them with the cells to be regenerated. These have had varying degrees of success in encouraging cell growth. But when treating patients, one of the problems their designers face is how to get these scaffolds into the damaged tissue. The least invasive option would be to develop a scaffold that can be injected as a liquid and assembles itself once in place, which is exactly what a team led by Gabriel Silva of the Institute for Bioengineering and Nanoscience in Advanced Medicine (IBNAM) at Northwestern University, Chicago believes it has done. Their scaffold consists of molecules containing a fragment of the natural protein laminin, called IKVAV. This is known to promote the growth of long neuronal fibres or axons. Within seconds of these molecules coming into contact with water, electrostatic forces drive them to form a tangle of long, slender fibres that are thousands of nanometres long but only seven nanometres in diameter. In gross terms, this structural change means the solution turns into a gel. In each of the nanofibres, the molecules radiate outwards from the centre, looking in cross-section like the spokes of a wheel. This presents the IKVAV fragments on the surface of the fibre. "It is a very good architecture to generate an ultra-high density of IKVAV in the right geometric position to interact with cells," says Samuel Stupp, director of IBNAM and one of the team. When the researchers mixed their scaffold with a suspension of neural progenitor cells in a dish, they found that it stimulated the proliferation of the cells, which went on to form neurons. This is important, Stupp explains, because when spinal cords are injured another type of nervous system cell, astrocytes, usually proliferate. These form scar material which blocks attempts to repair the cord. Source: New Scientist