Neuronal network activity can be assessed by the microelectrode array (MEA) technology that allows simultaneous recording of the electrical activity exhibited by entire populations of neurons over several weeks or months in vitro. We demonstrated that ES cell-derived neural precursors, cultured on MEAs for 5 to 6 weeks, develop functional neuronal networks with oscillating and synchronous spike/burst patterns via distinct states of activity and towards late maturational processes. These processes were accompanied by an increasing density of presynaptic vesicles. Furthermore, we demonstrated that ES cell-derived network activity was sensitive to synaptically acting drugs indicating that pharmacologically susceptible neuronal networks were generated. Thus, the MEA technology represents a powerful tool to describe the temporal progression of stem cell-derived neural populations towards mature, functioning neuronal networks that can also be applied to investigate pharmacologically active compounds. Actually, we are generating human functional neuronal networks from human induced pluripotent stem cells.
Effects of inflammatory cytokines on neural stem cells
Primary and secondary inflammatory processes are playing a role in nearly all brain pathologies. As endogenous neural stem cells supply the brain throughout life with new functional cells, it is important to verify the effect of inflammatory processes that include e. g. the up-regulation of cytokines on neural stem cells.
Epilepsy-associated alterations of in vitro neuronal network activity
The impact of epilepsy-associated mutation in genes encoding for ion channels on neuronal network activity is currently under investigation.
Volume transmission-mediated encephalopathies
There is strong evidence that the composition of cerebrospinal fluid (CSF) influences brain development, neurogenesis and behavior. The bi-directional exchange of CSF and interstitial fluid (ISF) across the ependymal and piaglial membranes is required for these phenomena to occur. Because ISF surrounds the parenchymal compartment, neuroactive substances in the CSF and ISF can influence neuronal activity. Functionally important neuroactive substances are distributed to distant sites of the central nervous system by the convection and diffusion of CSF and ISF, a process known as volume transmission. It has recently been shown that pathologically altered CSF from patients with acute traumatic brain injury suppresses in vitro neuronal network activity (ivNN A) recorded by multielectrode arrays measuring synchronously bursting neural populations. Functionally relevant substances in pathologically altered CSF were biochemically identified, and ivNN A was partially recovered by pharmacological intervention. When considering the concept of volume transmission, it remains unclear whether the in vivo parenchymal compartment remains unaffected by pathologically altered CSF that significantly impairs ivNN A. We hypothesize that the relevance of pathological CSF alterations goes far beyond the passive indication of brain diseases and that it includes the active and direct evocation of functional disturbances in global brain activity through the distribution of neuroactive substances, for instance, secondary to focal neurological disease. For this mechanism, we propose the new term "volume transmission-mediated encephalopathies" (VTE). Recording ivNN A in the presence of pure human CSF could help to identify, monitor and potentially suggest means for antagonizing functionally relevant CSF alterations that direct result in VTEs.
Hedrich UB, Liautard C, Kirschenbaum D, Pofahl M, Lavigne J, Liu Y, Theiss S, Slotta J, Escayg A, Dihné M, Beck H, Mantegazza M, Lerche H. Impaired action potential initiation in GABAergic interneurons causes hyperexcitable networks in an epileptic mouse model carrying a human Na(V)1.1 mutation. J Neurosci. 2014 Nov 5;34(45):14874-89. doi: 10.1523/JNEUROSCI.0721-14.2014.
Engeholm M, Leo-Kottler B, Rempp H, Lindig T, Lerche H, Kleffner I, Henes M, Dihné M. Encephalopathic Susac’s Syndrome associated with livedo racemosa in a young woman before the completion of family planning. BMC Neurol. 2013 Nov 25; 13: 185. doi: 10.1186/1471-2377-13-185.
Jantzen SU, Ferrea S, Wach C, Quasthoff K, Illes S, Scherfeld D, Hartung HP, Seitz RJ, Dihné M. In vitro neuronal network activity in NMDA receptor encephalitis. BMC Neurosci. 2013 Feb 5; 14: 17. doi: 10.1186/1471-2202-14-17.
Walter J, Hausmann S, Drepper T, Puls M, Eggert T, Dihné M. Flavin mononucleotide-based fluorescent proteins function in mammalian cells without oxygen requirement.PLoS One. 2012;7(9):e43921. doi: 10.1371/journal.pone.0043921. Epub 2012 Sep 11.
Walter J, Dihné M. Species-dependent differences of embryonic stem cell-derived neural stem cells after Interferon gamma treatment.Front Cell Neurosci. 2012 Nov 8; 6: 52. doi: 10.3389/fncel.2012.00052. eCollection 2012.
Walter J, Hartung HP, Dihné M. Interferon gamma and sonic hedgehog signaling are required to dysregulate murine neural stem/precursor cells. PLoS One. 2012; 7(8): e43338. doi: 10.1371/journal.pone.0043338. Epub 2012 Aug 29.
Wolking S, Lerche H, Dihné M. Episodic itch in a case of spinal glioma.BMC Neurol. 2013 Sep 23; 13: 124. doi: 10.1186/1471-2377-13-124.
Zentrum für Neurologie
Hertie-Institut für klinische Hirnforschung
Abteilung Neurologie mit Schwerpunkt Epileptologie