ABSTRACT
BACKGROUND: Micro-arc oxidation (MAO) treatment can improve the biological properties of titanium alloy implants. Previous studies mostly focused on the evaluation of titanium alloy plate, while the effects of the MAO-modified 3D titanium scaffold on the cell growth and differentiation were rarely reported. OBJECTIVE: To investigate the effect of MAO coating on the biological performance of cells seeded onto the 3D-printed porous titanium alloy scaffold. METHODS: Rat bone marrow mesenchymal stem cells were seeded onto the MAO-modified Ti6Al4V alloy scaffolds (experimental group) and unmodified scaffolds (control group). After 4 and 7 days of culture, cell/scaffold constructs were retrieved and processed for the assessment of cell morphology by using scanning electron microscopy, cytoskeletal staining analysis and cell viability assay were also evaluated. At 4, 7 and 11 days of culture, the levels of alkaline phosphatase and osteocalcin in the cell supernatant were detected. At 1, 4, 7 and 11 days of culture, the cell proliferation rate was measured using the MTT assay. RESULTS AND CONCLUSION: (1) At 4 and 7 days of culture, live/dead staining showed that the bone marrow mesenchymal stem cells grew well on the two kinds of scaffolds. The analysis of cytoskeleton staining showed that the cytoskeleton of the experimental group was stereo and polygonal, while the cells on the scaffold surface in the control group were flat and spindle-shaped, spreading along the macro structure of the scaffolds. Under the scanning electron microscopy, the cells in the experimental group arranged closely and spread in a good condition, with interconnected lamellipodia and filopodia that firmly adhered to the scaffold surface in an anchor-shaped structure; in the control group, less filopodia interconnected, less extracellular matrix, and flat and sheet-like cells were observed. (2) With the time increase, the levels of alkaline phosphatase and osteocalcin increased gradually in both groups. The alkaline phosphatase level in the experimental group was significantly higher than that in the control group at 7 and 11 days of culture (P < 0.05), while the osteocalcin level was higher in the experimental group than the control group at 11 days of culture (P < 0.05). (3) With the prolongation of culture time, the number of cells in the two groups increased gradually. The number of cells cultured in the experimental group was significantly higher than that in the control group at 7 and 11 days of culture (P < 0.05). To conclude, the MAO-modified titanium alloy scaffold is favorable for cell adhesion, proliferation and differentiation.