Live/dead-assay

To optically evaluate the amount of DNA left on ac/aoPCL-scaffolds, cell viability and distribution a live/dead fluorescence staining was performed. For this, the scaffolds after decellularization resp. recellularization on day 3 were first transferred to 24-well plate containing live staining solution with 8 µg/ml fluorescein diacetate (FDA: F7378, Sigma Aldrich, USA) for 5 min and afterwards into 20 µg/ml propidium iodide (PI: P4864, Sigma Aldrich, USA) dead staining solution for 5 s. Both staining solutions were made in serum-free without phenol red DMEM (Gibco, Thermo Fisher Scientific, USA). After rinsing with PBS digital fluorescent pictures were taken with inverted epifluorescence microscope (Zeiss Axio Observer, Zeiss, Germany). The Z-stack of the images was reconstructed into a 3D image using an image processing program (FIJI Image J, V.1.52I).