Influence of oligodendrocytes on neuronal network activity
by Michael Schüssler
Date of Examination:2024-10-23
Date of issue:2024-10-11
Advisor:Prof. Dr. Christine Stadelmann-Nessler
Referee:Prof. Dr. Christine Stadelmann-Nessler
Referee:Prof. Dr. Frauke Alves
Persistent Address:
http://dx.doi.org/10.53846/goediss-10794
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Abstract
English
Myelination of axons is an important function of oligodendrocytes. This highly complex process is influenced by a multitude of factors, not all of which are known, let alone completely understood. The myelin sheath is crucial for functioning and precise transmission of information within the nervous system. If myelin is damaged or incomplete, massive neurological deficits occur, such as in multiple sclerosis. In order to gain a better understanding of such diseases, basic research in the field of oligodendrocytes and communication between oligodendrocytes and neurons is necessary. An important aspect of this research is the in-vitro cultivation of both oligodendrocytes and neurons. The aim of the present study was to find out under which conditions co-cultivation can be reliably achieved, so that myelination and electric activity can be successfully studied in-vitro. To this end, a series of cultivation experiments was carried out. Different isolation methods were tested and analyzed, while the culture conditions were optimized in terms of purity, activity and composition. The different approaches were checked by analyzing different parameters a variety of methods, such as confocal microscopy, flow cytometry, electrical measurement of neuronal activity as well as morphological analysis. I can demonstrate here that a mechanical separation of the oligospheres is best suited for single cell isolation of vital and functioning oligodendrocytes, and that a high number of plated cells delivers the best results. The cultures treated with mechanical separation via a 40μm cell strainer and plating of 100.000 cells/μl were shown to contain oligodendrocytes able to form myelin. In both pure neuronal cultures and co-cultures of neurons and oligodendrocytes electrical activity in the form of action potentials were detected using multi-electrode arrays. By means of spike sorting I could show that the electrical activity actually occurred mainly in the form of action potentials. This allows the conclusion that neurons were kept vital and functional during the cultivation process. In addition, I could demonstrate that also oligodendrocytes survived the cultivation process without damage. Confocal microscopy provided evidence, albeit rudimentary, myelin formation. However, myelination of axons, i.e. specific myelination, could not be detected unequivocally in the cultures studied here. Therefore, future investigations need to clarify whether a directed myelination of axons can be induced under certain conditions. Moreover, this study provides the basis for investigating how electrical activity of an in-vitro neuronal culture is modified by the influence of myelinating oligodendrocytes.
Keywords: Oligodendrocytes
