GERMAN SCIENCE WEEKLY HIGHLIGHT - 6

Strokes happen when brain cells lose oxygen. Oxygen, as you probably know, is something we breathe in and out all day -- and then gets carried by blood all around our body. But sometimes, something stops normal blood flow to the brain -- for example, abnormally grown tissue in blood vessels (patients with the disease called arteriosclerosis have this problem). Then, the brain doesn't get oxygen -- and that's the critical moment for stroke. The victim can die, have a coma, or be paralysed, have speech problems, emotional changes, and many other difficult problems.

But there's more than one vessel bringing blood into the brain. Often, not all of them fail. If, somehow, we could make the other vessels bigger, we could bring more blood in to compensate when one vessel doesn't work. The good news is, medical scientists already have a way to make blood vessels bigger: it's called arteriogenesis and it just may save somebody's life. (Or many people's!)

That's what happened to the rat brains in the picture above. The colourful parts have blood flowing, the black parts don't. You can click on the picture to make it bigger. Researchers at the Max-Planck Institute for Neurological Research gave arteriogenesis -- bigger vessels -- to the right half of the brain on the right, but not to the brain on the left. On the top, the rat brains have had three of their four blood vessels cut off. You'll notice that the right brain has a little bit less blood flow than the left. That's already good. But what's amazing is the bottom picture. Here, the scientists dropped the blood pressure in the rats -- that's often one of the last steps before a stroke happens. Suddenly, the treated rat is showing much better signs than the untreated.

Now Dr. Konstantin-Alexander Hossmann of the Max-Plank Institute is going to tell you about how arteriogenesis has helped laboratory rats, and may someday soon help humans, too.