Patients suffering from strokes could receive stem cell injections to help repair damage to their brains within the next five years, researchers from Stanford University School of Medicine in California claimed Tuesday.

Strokes, which occur when blood flow to the brain is blocked, can kill brain tissue and are one of the worldwide leading causes of death and permanent disability. Treatments include blood thinning drugs and attempts to lower cholesterol.

The Stanford researchers led by Gary Steinberg, a professor of neurosurgery at Stanford University School of Medicine, took embryonic stem cells, and mixed them with natural chemicals, growth factor. Then, the cells were injected into the brains of 10 laboratory rats with an induced form of stroke that left one forelimb weak. The cells were particularly put in a part of the brain that was adjacent to the most damaged part, but which still had some surviving tissue.

The researchers surprisingly discovered that the cells migrated to the damaged regions of the brain and began to help repair damage. The rats were also treated with an immunosuppressant drug to prevent possible rejection.

The researchers found that within two months the rats treated with cells knew significant improvement. These rats were able to use their forelimbs more normally than untreated injured rats. This discovery brings hopes that one day the same treatment could be used in treating stroke-suffering patients.

“This offers the very exciting potential to treat patients with a cellular therapy that can repair tissue. In the past, it was thought that once brain cells die they can't regenerate. Now we know that brain repair does happen, although not enough. Now with a therapy of putting in new cells, there is great hope that people will be able to recover from stroke in a meaningful way,” Steinberg wrote in his study.

He and his team are currently examining the brains of the rats to better understand the process of recovery.

“Now remember, this is a rat, not a human. We still have to make that step. But if we could achieve that kind of recovery in humans, we would have a great therapy," Steinberg added.

The study appeared in the Public Library of Science journal PLoS ONE.