Stem Cells Help Repair Neurons After Stroke

Stem cells leave the bone marrow in the first hours and days following a stroke and migrate to the injured regions of the brain where they help repair damaged tissue, according to a study by researchers at the Medical College of Georgia (MCG, Atlanta, USA).

The researchers used a mouse model in which the animal's marrow was replaced with transgenic mouse cells that make a jellyfish protein, which fluoresces green so they could trace the cells and the repair process that occurs after stroke. They discovered that the bone marrow cells not only help repair damaged tissue but also become endothelial cells that form new blood vessels and what appear to be new neurons. Now, the next phase of research is to learn what summons the cells to the injury site. The researchers are looking at specific molecules up-regulated in inflammation that they suspect are also involved in homing. Another critical phase of the research is to find out which specific stem cells are summoned and which are needed for various kinds of repair.

To improve stroke recovery, the patient's own cells could be used, which would avoid the issue of compatibility and the ethical controversy surrounding embryonic stem cells. Enhancing normal repair might be able to preserve a region of the brain that would normally die but is an area that can be targeted to recover. The research has implications for all kinds of brain damage early and late in life, such as cerebral palsy and Parkinson's and Alzheimer's disease.

"If this works out, you will be able to give individuals shots following stroke to boost their bone marrow to proliferate these stem cells to do specific tasks and to target specific groups of these stem cells important to blood vessel repair and the genesis of new neurons,” said Dr. William Hill, neuroscientist in the MCG department of cellular biology and anatomy and second author on the study, published in the May 2002 issue of Stroke.