Disabling strokes could one day be treated by replacing damaged brain tissue with stem cells, scientists have shown.
Researchers used a new technique to insert therapeutic stem cells into the brains of rats with pinpoint accuracy.
Once implanted, the cells began to form new brain tissue and nerve connections.
The work is at an early stage and does not yet prove that stroke symptoms such as paralysis can be reversed.
But it demonstrates that lost brain tissue can be replaced with stem cells targeted at sites of damage.
Stem cells are immature cells with the ability to take on any of a number of specialist roles.
In previous animal experiments, stem cells implanted into the brain have tended to migrate to surrounding healthy tissue rather than fill up the hole left by a stroke.
Scientists from King’s College London and the University of Nottingham overcame the problem by loading the cells onto biodegradable particles.
These were then injected through a fine needle to the precise site of damage, located using a magnetic resonance imaging (MRI) scanner.
Once implanted, the particles disappeared, leaving gaps for the growth of new tissue and nourishing blood vessels.
The cells, derived from stem cells taken from mouse embryos, had already progressed some of the way to becoming neurons.
They were attached to particles made from a biodegradable plastic-like polymer called PLGA.
Dr Mike Modo, leading the King’s College team from the university’s Institute of Psychiatry, said: “The stem cell-loaded PLGA particles can be injected through a very fine needle and then adopt the precise shape of the cavity. In this process the cells fill the cavity and can make connections with other cells, which helps to establish the tissue.
“Over a few days we can see cells migrating along the scaffold particles and forming a primitive brain tissue that interacts with the host brain. Gradually the particles biodegrade, leaving more gaps and conduits for tissue, fibres and blood vessels to move into.”
Colleague Kevin Shakesheff, Professor of Advanced Drug Delivery and Tissue Engineering at the University of Nottingham, said: “This was a great collaborative project with the Kings College team and hopefully this technology will be taken to the clinical setting soon. Repairing damaged brain tissue is one of the ultimate challenges in medicine and science. It is great that we are now one step closer to achieving that goal.”