2.7.4 Fluorescence characterization
At day 3, cells were fixed with 4% paraformaldehyde in PBS for 30 min at room temperature and washed again with PBS. Cell permeability was performed with 0.1% Triton X-100 (Sigma-Aldrich) for 15 min at room temperature, followed by washing with PBS. High-affinity filamentous actin probe Alexa Fluor 594 phalloidin (1:80; Invitrogen) was injected through the channels, let to incubate for 45 min at room temperature, washed with PBS, and then incubated with DAPI (1:100; Invitrogen) diluted in PBS for 20 min at room temperature. The samples were observed in an SP8 confocal microscope (Leica, Germany).