Can Stem Cells Block Stroke Damage? Yes, but in a Surprising Way

Injecting stem cells into the brains of mice that recently suffered a stroke can reduce nerve cell (neuron) damage by up to 60 percent, according to new research.

But the stem cells do not simply replace damaged tissue as previously believed. Instead, the immature cells trigger adult brain cells to switch gears and block a stroke-induced immune response that causes nerve damage.

"It is a paradigm shift," says Sean Savitz, a neurologist at the University of Texas Medical School at Houston, who was not involved in the study. "The original idea is that you put cells in there and it would reconstruct the cells that died. ? The beauty of this is there's not just one mechanism; they are acting in many different ways."

Over the past 10 years, he says, research has shown that stem cells have the potential to reduce inflammation, morph into new nerve cells, and stimulate production of fresh blood vessels (to nourish cells) and axons (the long fingerlike projections that neurons use to send information to neighboring cells).

Study co-author Darwin Prockop, director of the Texas A&M University Health Science Center's Institute for Regenerative Medicine, says that previous studies have shown that mesenchymal stromal cells (bone marrow stem cells) can reverse neurodegeneration in the brain caused by disorders such as Parkinson's disease. But scientists were not quite sure how. - sciam