Immune cells self-healing brain after stroke

After a stroke, there is inflammation in the damaged part of the brain. Until now, the inflammation has been seen as a negative consequence that needs to be abolished as soon as possible. But, as it turns out, there are also some positive sides to the inflammation, and it can actually help the brain to self-repair.

"This is in total contrast to our previous beliefs", says Professor Zaal Kokaia from Lund University in Sweden.

Zaal Kokaia, together with Professor of Neurology Olle Lindvall, runs a research group at the Lund Stem Cell Center that, in collaboration with colleagues at the Weizmann Institute in Israel, is responsible for these findings. Hopefully, these new data will lead to new ways of treating stroke in the future. The study was recently published in the Journal of Neuroscience.

When stroke occurs, the nerve cells in the damaged area of the brain die, causing an inflammation that attracts cells from the immune system. Among them you find monocytes—a type of white blood cells produced in the bone marrow.

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False-colored scanning electron micrograph of a blood clot. There are many red blood cells and

a single white blood cell held together in a meshwork of fibrin (brown).

Source: Anne Weston, LRI, CRUK, Wellcome Images

Brain signalling regulation by nerve terminal nanofilaments

State-of-the-art electron microscopy reveals the large-scale organization of the proteins that regulate neurotransmitter release

This spectacular image – which took the best part of a year to create – shows the fine structure of a nerve terminal at high resolution, revealing, for the very first time, an intricate network of fine filaments that controls the movements of synaptic vesicles.

The brain is soft and wet, with the consistency of a lump of jelly. Yet, it is the most complex and highly organized structure that we know of, containing hundreds of billions of neurons and glial cells, and something on the order of one quadrillion synaptic connections, all of which are arranged in a very specific manner.

This high degree of specificity extends down to the deepest levels of brain organization. Just beneath the membrane at the nerve terminal, synaptic vesicles store neurotransmitter molecules, and await the arrival of a nervous impulse, whereupon they fuse with the membrane and release their contents into the synaptic cleft, the miniscule gap at the junction between nerve cells, and diffuse across it to bind to receptor protein molecules embedded at the surface of the partner cell.

Read more: Brain signalling regulation by nerve terminal nanofilaments

3D reconstruction showing three types of nanofilaments that connect to synaptic
vesicles in the nerve terminals of excitatory synapses in the rat hippocampus.

Source: Cole, A. A., et al., Journal of Neuroscience (2016)