Fig. S4. Biocompatibility testing of scaffolds and human umbilical cord mesenchymal stem cells in vitro. (A) Typical cell morphology of the fourth generation HUCMSCs under a phase contrast microscopy. (B) Expression of CD90, CD105, CD73 and negative molecules (Neg PE) (CD45, CD116, CD19 and HLA-DR). (C-D) Double immunostaining with anti-CD90 antibody (green) and anti-CD105 antibody (red) to identify HUCMSCs. D was an amplified image of the yellow box in C. (E-F) Morphological observation of HUCMSCs cultured on 3D-CC+BDNF (E) and 3D-CC-BDNF (F) under a phase contrast microscope. The image on the right was an amplified image of the yellow box in the image on the left. (G-H) Scanning electron microscopy observation of HUCMSCs growth status in 3D-CC+BDNF (G) and 3D-CC-BDNF (H). (I-J) Double immunostaining with an anti-CD90 antibody (green) and an anti-CD105 antibody (red) to identify HUCMSCs in the 3D-CC+BDNF (I) and 3D-CC-BDNF (J). (K-L) HE staining observation of 3D-CC+BDNF (K) and 3D-CC-BDNF (L) co-cultured with HUCMSCs. (M) Light absorbance of HUCMSCs in the 3D-CC+BDNF and 3D-CC-BDNF co-cultured with HUCMSCs at 1, 3, 5 and 7 days after seeding HUCMSCs. Data were presented as mean ± SD, n = 5. *P < 0.05, **P < 0.01 vs 3D-CC+BDNF. Scale bars = 50 µm in panels (A, C, D, E, F, G, H, K, L), 300 µm in panels (I, J).