Understanding what protects our nerves
There are two main types of cells in our brain and nervous system. Nerve cells, also called neurons, are responsible for transmitting and processing electrical signals that enable us to think and act. The highly specialized neurons are very sensitive and are supported in their work by the second group of cells, called glial cells. Glial cells supply neurons and help with signal transmission and processing. To do this, they form, among other things, an insulating layer around the nerve fibers of the neurons. Such nerve fibers (axons) can be thought of, for example, as connecting cables between the brain and the rest of the body. In this picture, the plastic insulation of the cables would correspond to the insulating layer (myelin) formed by the glial cells. In the brain, this myelin layer is formed by a separate class of glial cells called oligodendrocytes. The name is derived from the Greek »oligos« [little], »dendron« [tree] and »cytos« [cell], since these cells form a few branches, at the ends of which such an insulating myelin layer is formed around the nerve fibers (see also figure below).
However, in some nerve diseases, for example the hereditary disease Charcot-Marie-Tooth or multiple sclerosis, the protective myelin layer is partially lost. As with a poorly insulated cable, short circuits can then occur. Neurons are destroyed and the transmission of signals no longer works. Depending on the severity of the disease, this can affect physical control and also psyche and intelligence.
It is almost impossible to repair this damage, because in humans the myelin layer is formed for the most part only once in life, during embryonic and childhood development. If the myelin is destroyed later, it hardly grows back, if at all. Perished nerve cells also hardly regenerate and leave permanent damage. Since still little is known about the regulation of myelin growth, there are few therapeutic options.
In other species, for example in the zebrafish (Danio rerio), glial cells can produce new myelin (insulating layers) and repair damage. Because these fish are transparent, under certain conditions, the growth or repair of myelin in the living animal can be observed under the microscope. Our research is dedicated to finding out what mechanisms enable zebrafish to repair damaged neural tissue and what signals the cells receive to precisely coordinate myelin buildup and repair.