To verify the cell viability, the LIVE/DEAD™ Viability/Cytotoxicity Kit from Invitrogen (Waltham, MA, USA) was used. The cells were labeled with calcein-AM or ethidium homodimer-1 (EthD1), for live or dead cells, respec vely. The nuclei were stained with Hoechst 33342 from Invitrogen. Incuba on occurred for 30 min at 37 °C for all staining. The fluorescence images were observed using epifluorescence microscopy with a 5x or 20x objec ve lens. The excita on wavelengths were 401 nm, 493 nm and 577 nm, respec vely. Immunostaining was conducted to visualize the cell nuclei, ac n filaments and fibronec n coa ng. Cells were fixed 24 h a er seeding. The samples were incubated with an -fibronec n (0.5 µg mL -1 ) in 1% (w/v) BSA in PBS, followed by washing with PBS (3 × 5 min) and incuba on with a secondary an body an -rabbit AlexaFluor-488 (10 µg mL -1 ) in 1% (w/v) BSA in PBS. Incuba on for both an bodies occurred for 1 h at room temperature in the dark. Nuclei and ac n filaments were stained with DAPI (10 µg mL -1 ) and Alexa Fluor™ 568 Phalloidin (1.5 U mL -1 ) during incuba on of the secondary an body.