*4.3. Imaging*

To obtain baseline images, immediately before the OGD experiment growth medium was exchanged for the experimental medium with additional 3 μL/mL propidium iodide (PI) and then incubated again for a minimum of 30 min at 37 ◦C and 5% CO2. Propidium iodide stains DNA of cells with impaired cell membrane and was used to assess the number of cells damaged [64] using a fluorescence microscope (Zeiss Axioplan, Carl Zeiss MicroImaging GmbH, Jena, Germany) (exposure time was calculated for every imaging session and typically ranged between 15.500 and 16.500 milliseconds) and MetaVue software (MetaVue, Molecular Devices, Sunnyvale, CA, USA). Imaging was performed at baseline for all slices and 72 h after experiments. Imaging is depicted in Figure 6a,c.
