Resting Microglial Cells Are Highly Dynamic Surveillants of Brain Parenchyma in Vivo
Axel Nimmerjahn,1
Frank Kirchhoff,2
Fritjof Helmchen1*
Microglial cells represent the immune system of the mammalian brain and therefore are critically involved in various injuries and diseases. Little is known about their role in the healthy brain and their immediate reaction to brain damage. By using in vivo two-photon imaging in neocortex, we found that microglial cells are highly active in their presumed resting state, continually surveying their microenvironment with extremely motile processes and protrusions. Furthermore, blood-brain barrier disruption provoked immediate and focal activation of microglia, switching their behavior from patroling to shielding of the injured site. Microglia thus are busy and vigilant housekeepers in the adult brain.
1 Abteilung Zellphysiologie, Max Planck Institut für Medizinische Forschung, Jahnstrasse 29, 69120 Heidelberg, Germany.
2 Abteilung Neurogenetik, Max Planck Institut für Experimentelle Medizin, Hermann-Rein-Strasse 3, 37075 Göttingen, Germany.
* To whom correspondence should be addressed. E-mail: fritjof{at}mpimf-heidelberg.mpg.de
