New study to better understand role of the immune system in stroke

Stroke and other diseases and injuries to the brain are often followed by inflammation, caused by a reaction of the body's immune system. This reaction has been seen as something that must be combated, but perhaps the immune system could in fact help with recovery following a stroke. A major new EU project, led by Lund University in Sweden and the Weizmann Institute in Israel, is going to study this question.

Stroke is a major public health problem, with 700 000 new cases in the EU and 30 000 new cases in Sweden each year. The EU is now investing EUR 12 million in the project TargetBraIn. The goal of the project is to gain a better understanding of the role of the immune system in stroke.

The immune system protects the body when its tissues are damaged for whatever reason. The cells of the immune system often produce inflammation, which has some negative effects, but which in time helps the original damage to heal.

Stroke is most commonly caused by a cerebral infarction (a blood clot in the brain), which starves the brain of oxygen. It is the damage caused by the lack of oxygen which activates the immune system and leads to inflammation. Until now, this has been seen as a wholly undesirable reaction. To emphasise the positive aspects of the immune system's reaction is therefore something of a paradigm shift in the field. Professor Michal Schwartz and her research group in Israel have pioneered the study of the positive role of the immune system in repairing damaged nerve cells.

Professor Zaal Kokaia, head of the Stem Cell Centre at Lund University, has long worked with stem cell therapy for brain injuries. He led StemStroke, an EU project which researched the possibility of creating new nerve cells after a stroke through transplants or by encouraging the brain to form new cells. Zaal Kokaia and Michal Schwartz are now coordinator and deputy coordinator respectively of TargetBraIn (an acronym which stands for "Targeting Brain Inflammation for Improved Functional Recovery in Acute Neurodegenerative Disorders").

"Within TargetBraIn we want to reinforce the positive effects of inflammation and reduce its negative effects. This could be achieved either by trying to change the immune system's reactions or through stem cell therapy, or both! A combination of the two methods may produce the best results", says Zaal Kokaia.

The research is still at the experimental stage, and the road to general application on patients will be long. However, as the population of Europe ages, stroke is becoming an increasingly costly disease, hence the EU investment in the field.