The research was led by Dr Mike Modo of the Institute of Psychiatry, King's College London and took place at the Institute of Psychiatry and University of Nottingham. It is to be published in the journal Biomaterials and was funded by the Biotechnology and Biological Sciences Research Council.
The researchers found it only took 7 days for the scaffolded stem cells to fill the stroke damage holes.
Other studies have tried to fill holes left by stroke damage with stem cells but found they just migrated to surrounding tissue. However, Modo and colleagues found this problem ceases when the stem cells have a structure to cling onto.
"We would expect to see a much better improvement in the outcome after a stroke if we can fully replace the lost brain tissue, and that is what we have been able to do with our technique," said Modo in a press statement.
For the scaffolding Modo and colleagues used individual particles of a biodegradable polymer called PLGA. They "loaded" the PLGA particles with neural stem cells and injected them into the stroke cavities.
"This works really well because the stem cell-loaded PLGA particles can be injected through a very fine needle and then adopt the precise shape of the cavity," Modo explained.
"In this process the cells fill the cavity and can make connections with other cells, which helps to establish the tissue," he added.
Over the next few days they could see the cells migrating along the scaffolding made by the PLGA particles and forming into 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," said Modo.
Modo and colleagues used an MRI scanner to find the exact spot in the brain to inject the PLGA loaded with stem cells and also to observe the growth of new tissue.
They now want to try adding VEGF (vascular endothelial growth factor) to the PLGA and stem cell scaffold to see if it encourages new blood vessels to form in the new tissue.
"Stroke is a leading cause of disability in industrialised countries," said Professor Douglas Kell, Chief Excutive of the BBSRC.
"It is reassuring to know that the technology for treating stroke by repairing brain damage is getting ever closer to translation into the clinic," he added, explaining that the work being done by Modo and colleagues provides a solid foundation for further research and better treatments.
Joe Korner, Director of Communications at The Stroke Association agrees and calls the study exciting because Modo and colleagues were able to overcome many of the challenges of converting the promising idea of stem cells into reality.
Korner said every five minutes someone in the UK has a stroke.
"This research is another step towards using stem cell therapy in treating and reversing the brain damage caused by stroke," he added, but cautioned that while this work appears to show it is possible to reverse the damage caused by stroke, therapies for stroke survivors are still a long way off since considerably more research is needed before the technique can be tried on humans.
