Two years ago, a new type of stem cell was discovered in the brain that has the capacity to form new cells. The same research group at Lund University in Sweden has now revealed that these stem cells, which are located in the outer blood vessel wall, appear to be involved in the brain reaction following a stroke.
The findings show that the cells, known as pericytes, drop out from the blood vessel, proliferate and migrate to the damaged brain area where they are converted into microglia cells, the brain’s inflammatory cells.
Pericytes are known to contribute to tissue repair in a number of organs, and the researchers believe that their reparative properties could also apply to the brain. The study shows for the first time that pericytes are directly involved in the reaction of the brain tissue after stroke.
“Pericytes are a fascinating cell type with many different properties and found at high density in the brain. It was surprising that a pericyte subtype is so strongly activated after a stroke. The fact that pericytes can be converted into microglia, which have an important function in the brain after a stroke, was an unexpected finding that opens up a new possibility to influence inflammation associated with a stroke”, said Gesine Paul-Visse, neurologist at Lund University and senior author of the study.
Using a green fluorescent protein bound to the pericytes, the researchers were able to track the cells’ path to the damaged part of the brain. The migration takes place within a week after a stroke. When the cells reach the site of damage they are converted into microglia cells, the ‘cleaners’ of the central nervous system. Inflammation can, however, have both positive reparative effects and negative effects on the damaged tissue. The exact role of microglia cells in the regeneration after a stroke is not entirely clear, but we do know that pericytes play an important role in protecting the brain against disease and injury.
How Is a Stroke Treated?
Treatment for a stroke depends on whether it is ischemic or hemorrhagic. Treatment for a transient ischemic attack (TIA) depends on its cause, how much time has passed since symptoms began, and whether you have other medical conditions.
Strokes and TIAs are medical emergencies. If you have stroke symptoms, call 9–1–1 right away. Do not drive to the hospital or let someone else drive you. Call an ambulance so that medical personnel can begin life-saving treatment on the way to the emergency room. During a stroke, every minute counts.
Once you receive initial treatment, your doctor will try to treat your stroke risk factors and prevent complications.
Treating Ischemic Stroke and Transient Ischemic Attack
An ischemic stroke or TIA occurs if an artery that supplies oxygen-rich blood to the brain becomes blocked. Often, blood clots cause the blockages that lead to ischemic strokes and TIAs.
Treatment for an ischemic stroke or TIA may include medicines and medical procedures.
“We now need to elucidate how pericytes affect the brain’s recovery following a stroke. Our findings put pericytes in focus as a new target for brain repair and future research will help us understand more about the brain’s own defence and repair mechanisms.”
There is an urgent need for new drugs that can alleviate the harmful effects of a stroke as current treatment possibilities using thrombolysis are limited to the first hours following a stroke.
Treating Stroke Risk Factors
After initial treatment for a stroke or TIA, your doctor will treat your risk factors. He or she may recommend lifestyle changes to help control your risk factors.
Lifestyle changes may include quitting smoking, following a healthy diet, maintaining a healthy weight, and being physically active.
If lifestyle changes aren’t enough, you may need medicine to control your risk factors.
If you smoke or use tobacco, quit. Smoking can damage your blood vessels and raise your risk of stroke and other health problems. Talk with your doctor about programs and products that can help you quit. Also, try to avoid secondhand smoke. Secondhand smoke also can damage the blood vessels.
For more information about how to quit smoking, go to the Health Topics Smoking and Your Heart article and the National Heart, Lung, and Blood Institute’s (NHLBI’s) “Your Guide to a Healthy Heart.” Although these resources focus on heart health, they include general information about how to quit smoking.
“Because inflammation following a stroke is an event that continues after the acute stage, we hope that targeting pericytes in the subacute phase after stroke, i.e. within a longer time window following the onset of stroke, may influence the outcome”, said Gesine Paul-Visse.