Spleen may provide new target for treating stroke's debilitating chronic inflammation

Neuroscientists at the University of South Florida (USF) Center of Excellence for Aging and Brain Repair found that human bone marrow stem cells administered intravenously to post-stroke rats made their way to the spleen and reduced the inflammatory-plagued secondary cell death associated with stroke progression in the brain.

The study helps resolve a challenging observation by many scientists: while there can be mediocre or even negligible survival of transplant stem cells within the injured brain, there is evidence nonetheless of functional recovery in neurological disorders including stroke.

"Our findings suggest that even if stem cells do not enter the brain or survive there, as long as the transplanted cells survive in the spleen the anti-inflammatory effects they promote may be sufficient enough to therapeutically benefit the stroke brain," said principal investigator Cesario Borlongan, PhD, professor and director of the USF Center of Excellence for Aging and Brain Repair. The study is reported in the September 2015 issue of the American Heart Association journal Stroke.

Stroke is a leading cause of death and the number one cause of chronic disability in the United States, yet treatment options are limited. Stem cell therapy has emerged as a potential treatment for ischemic stroke, but most preclinical studies have looked at the effects of stem cells transplanted during acute stroke—one hour to 3 days after stroke onset.

Stem cells are not a magic bullet, but a combination of stem cells and other anti-inflammatory agents may lead to the optimal therapeutic benefit for stroke patients," he said.

Lead study author Sandra Acosta, PhD, a postdoctoral fellow in the USF Department of Neurosurgery and Brain Repair, said "We've shown (in an animal model) that it's possible to stop disease progression 60 days after the initial stroke injury, when chronic inflammation in the brain was widespread," she said. "If that can be replicated in humans, it will be powerful."