New tool delivers and electrically stimulates stem cells to promote stroke recovery

More than 10 million strokes occur worldwide every year, leaving at least half of patients with life-altering disabilities. Yet therapies for stroke are limited, and many patients have only modest improvements in motor and cognitive function. The need for better treatments has sparked interest in two therapies in particular: transplanted stem cells and electrical current.

Although hundreds of studies in animals — and a handful in humans — have demonstrated that stem cells transplanted into the brain can improve stroke outcomes, the challenge has been finding the best way to deliver and use the cells. Another challenge: how to use electricity to stimulate those cells and the brain.

Now, Stanford Medicine researchers have developed a tool that solves both problems. It can deliver and electrically stimulate transplanted stem cells and stimulate injured brain tissue. It also helped the researchers identify a protein that encourages the brain to heal.

The device is a tiny conductive polymer implant that's 1 millimeter wide by 3 millimeters long and about a quarter as thick as a credit card. Conductive polymer is a dark-colored organic compound with the consistency of flexible plastic and the ability to conduct electrical current. The electricity that powers the device comes from an external generator that's attached with wires. The charge and surface interactions of the polymer hold the stem cells in place.

Conductive polymers have all the advantages of a polymer. You can load cells onto them, deliver drugs with them. It's the perfect platform to load cells onto and into the body. They also act in a way similar to a semiconductor to conduct electricity."

Paul George, MD, PhD, assistant professor of neurology and neurological sciences

Not only did the conductive polymer system work as intended, it helped rodents recover faster and better after a stroke.

"We found that if we electrically modulate transplanted human stem cells in our rodent stroke model, we nearly double the treatment effect from stem cells alone," George said.