Development of a Combined Stimulated Emission Depletion and Scanning Ion Conductance Microscope for Correlated Multi-Parameter Super-Resolution Live-Cell Imaging of the Tips of Processes of Oligodendrocyte Progenitor Cells

• Applicant: Professorin Dr. Irmgard Dietzel-Meyer, since 7/2021
• Subject Area: Biophysics ; Statistical Physics, Nonlinear Dynamics, Complex Systems, Soft and Fluid Matter, Biological Physics
• Term: from 2018 to 2024
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 411517989

Oligodendrocytes are cells from the brain that ensure the fast propagation of action potentials. They originate from their progenitors, the oligodendrocyte progenitor cells (OPCs) which are present in the developing and the adult brain and form the myelin that enwraps and electrically isolates the axons of neurons. To develop and maintain the proper brain function, OPCs migrate to unmyelinated axons or axons with damaged myelin to form novel or replace damaged myelin. Axons with damaged myelin or without myelin occur in patients suffering from Multiple Sclerosis, and thus the understanding of the migration machinery of OPCs is of major relevance. OPCs are cells that exhibit two processes originating at opposite sites from the cell body, and the cell body migrates along these processes. Thus, it is crucial for the understanding of OPC migration to understand the mechanism of the protrusion of the processes. However, the interplay of cell membrane extensions and the cytoskeleton at tips of the processes of OPCs has not been investigated in detail yet. The major reason for this is the size of the OPC tips, which are too small to be investigated in sufficient detail by conventional fluorescence microscopy methods. Furthermore, to be able to link membrane protrusion dynamics to cytoskeletal dynamics, the simultaneous tracing of the unbiased cell membrane and the cytoskeleton in living cells is required. This can not be achieved by electron microscopy, since the sample preparation and measurement conditions are not suitable for living cells.In recent years, super-resolution fluorescence microscopy methods like stimulated emission depletion (STED) microscopy have been developed, which allow imaging at high resolution and which should allow the investigation of single, labelled proteins in the tips of OPCs at sufficient detail, even in living cells. Furthermore, Scanning Ion Conductance Microscopy (SICM) has been established as a tool to trace the membrane contours of living cells with only minimal bias at a resolution in the same range as provided by STED microscopy.The aim of this project is the development and subsequent evaluation of a combined STED/SICM. The instrument will allow to trace the cell membrane dynamics and cytoskeleton dynamics of living cells at high resolution. In this project, we will first build and characterize a combined STED/SICM. Subsequently, we will record proof-of-concept images of fixed and living cells. In a subsequent project, we will use this instrument to unravel the molecular mechanics governing the dynamics of the tips of OPCs.

• DFG Programme: Research Grants
• Ehemaliger Antragsteller: Dr. Patrick Happel, from 7/2021 until 7/2021 (†)