Evaluation of Ti-6Al-4V Alloy Biocompatibility Fabricated by Electron Beam Melting In Vitro and In Vivo

This study is to evaluate the biocompatibility of Ti-6Al-4V alloy fabricated with electron beam melting for bone tissue engineering. Ti-6Al-4V alloy specimens were fabricated with electron beam melting (EBM). A wrought form of Ti-6Al-4V alloy was used as a control. Experiments were processed in vitro and in vivo, respectively. Experiment in vitro, the number of bone marrow stem cells (BMSC) increased obviously from the 30th minute till the 7th day. The shape of cells changed significantly (from sphere shape to spindle shape) and formed nets with time prolonged. Pseudopodium, microvillus and extracellular matrix were observed. On the basis of the TEM result, the ultrastructure of cell was normal, and its cytomembrane was intact. Based on cell counting result, the cell number of EBM and wrought specimens was similar (P > 0.05) at the same time points. As for the same material, the cell number increased obviously from the 30th minute till the 7th day (P < 0.05). Regarding cell culture medium analysis, the contents of Ti, Al and V ions of EBM and wrought specimens were very low which did not affect the cell attachment and proliferation. As for experiment in vivo, in the soft tissue, the porous implant showed thinner fibrous encapsulation and no sign of intolerance was observed. Histology showed matured and slightly vascularized fibrous tissue was surrounding the specimen and struts. Based on the TEM result, the ultrastructure of liver and kidney tissue was normal. The result of comet assay showed EBM and control group had very similar tail cells and value of OTM. In general, the present experimental results suggest that EBM Ti-6Al-4V implants have valuable properties suited to implantation in vivo.