Stem Cells Replace Stroke-Damaged Tissue in Lab Rats

Successful stem cell treatment for strokes has taken a significant step forward as scientists reveal how they have replaced stroke-damaged brain tissue in rats.

The team of scientists project is funded by the Biotechnology and Biological Sciences Research Council (BBSRC; Swindon, UK) and led by Dr. Mike Modo of the Institute of Psychiatry, King's College London (UK). The study, performed at the Institute of Psychiatry and University of Nottingham (UK), shows that by inserting tiny scaffolding with stem cells attached, it is possible to fill a hole left by stroke damage with brand new brain tissue within seven days. The study was published in the March 2009 issue of the journal Biomaterials.

Earlier studies where stem cells have been injected into the void left by stroke damage have had some success in improving outcomes in rats. The difficulty is that in the damaged area there is no structural support for the stem cells and so they are apt to migrate into the surrounding healthy tissues instead of filling up the hole left by the stroke. Dr. Modo noted, "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.”

Using individual particles of a biodegradable polymer called poly(lactide-co-glycolide) (PLGA) that have been loaded with neural stem cells, the team of scientists have filled stroke cavities with stem cells on a ready-made support structure. Dr. Modo continued, "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. 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, fibers, and blood vessels to move into.”

The research utilizes a magnetic resonance imaging (MRI) scanner to target precisely the correct place to inject the scaffold-cell structure. MRI is also used to monitor the development of the new brain tissue over time. The next stage of the study will be to include a factor called vascular endothelial growth factor (VEGF) with the particles. VEGF will encourage blood vessels to enter the new tissue.

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