Carbon Nanotubes Help Adult Stem Cells Replace Stroke Damaged Neurons

This is an excellent example of the convergence of nanotechnology and biotechnology. According to this Technology Review story, carbon nanotubes can be used as scaffolding to allow adult stem cells to differentiate to mature neurons, replacing neurons damaged by stroke.

Stem cells are a promising therapy for stroke and other brain injuries--they can sprout into healthy neurons and may be able to re-establish brain activity in brain-injured patients. While preliminary animal research shows promise, there's often a common hurdle: adult stem cells have a hard time growing in damaged areas and tend to migrate to healthier regions of the brain.

....Webster and his collaborators in South Korea found a possible anchor in carbon nanotubes: tiny, highly conductive carbon fibers that not only act as scaffolds, helping stem cells stay rooted to diseased areas, but also seem to play an active role in turning stem cells into neurons.

....Prior to this experiment, Webster had been experimenting with the properties of carbon nanotubes as possible neural implant material. Since nanotubes are highly conductive, they're an ideal template for transmitting electrical signals to neurons. In 2004, Webster was able to stimulate neurons to grow multiple nerve endings along carbon nanotubes. The study attracted the attention of South Korean stroke researchers, who proposed a collaboration: Why not use carbon nanotubes as a template for adult stem cells to grow into neurons? Taking it one step further, the team injected this nano-cocktail directly into the stroke-damaged brain regions of rats.

In order to determine how well the two therapies work together, the team compared the effects of injections of both stem cells and nanotubes with control groups injected with only adult stem cells or carbon nanotubes. After one and three weeks, researchers sacrificed the rats and examined the diseased areas of their brains. In rats who had received only adult stem cells, the cells tended to stray to healthier regions of the brain. But rats given both nanotubes and cells showed new neural growth in stroke-damaged brain regions in as little as a week.

Researchers aren't sure what makes carbon nanotubes such an effective template for stem cells--or how they help stem cells differentiate. But Webster says a likely answer to both questions is laminin, a glycoprotein in the brain's extracellular matrix that directs the generation of healthy nerve cells. The surface of carbon nanotubes resembles the elongated shape of laminin, and previous research has shown that nanotubes easily attract and adsorb laminin. Laminin, in turn, has a key amino acid sequence that attracts stem cells, stimulating them to turn into neurons. For these reasons, nanotubes may serve as pro-active delivery devices for stem cells.

More at Source.

Of course there are many other types of brain damage besides CVA. Brain tumours, brain abscesses, neurodegenerative and demyelinating diseases--all of these might profit from a reliable means of growing new neurons in-situ, from adult stem cells.

The entire field of growing biological tissue replacements should benefit from nano-technological scaffolding.