Objective: To investigate the effect of TiO₂nanotube arrays covalently modified by recombinant human bone morphogenetic protein- 2(rhBMP- 2) on the early bioactivity of mesenchymal stem cells (MSC) in vitro and to provide experimental evidence for the biochemical modification of titanium implants.
Methods: In the experiment group, double titanium nanotube arrays were prepared by anodization, and were chemically grafted with rhBMP- 2. Mechanically polished pure titanium was used as blank control group, and titanium dioxide nanotubes was used as negative control A group, and titanium dioxide nanotubes + carbonyldiimidazole as negative control B group. Field emission scanning electron microscope (FE- SEM) and X- ray photoelectron spectroscopy (XPS) were used to detect the morphology and physicochemical properties of the experiment group, blank control group and the negative control group. Cell adhesion on the specimen surface of the experiment group, blank control group and negative control group on the 1st day was tested. Cell proliferation on the 1st, 3rd and 5th day and alkaline phosphatase activity on the 5th, 7th and 11th day was also tested.
Results: FE- SEM showed that the surface of titanium nanotubes loaded with rhBMP- 2 possessed visible miliary particulate matter. XPS showed that nitrogen peak in the group of titanium nanotubes loaded with rhBMP-2 was significantly greater that those in the other groups. FE- SEM showed that the cells on the surface of the experimental group on the 1st day spread well, better than those in the control group and negative control group. Cell proliferation activity on the 1st day in different groups was not obvious (P>0.05), the A value of the experimental group on the 3rd and 5th day (3.295 ± 0.153, 3.823 ± 0.059) were significantly higher than those in the control group (2.479 ± 0.064, 3.131 ± 0.096) and negative control A group (2.715 ± 0.075, 3.371 ± 0.047) and negative control B group (2.756 ± 0.132, 3.637 ± 0.047) (P<0.05). Alkaline phosphatase activity on the 5th, 7th and 11th day in the experimental group (0.0477 ± 0.0287, 0.0615 ± 0.0016, 0.0667 ± 0.0018) were better than those in the control group, negative control A group and negative control B group (P<0.05).
Conclusions: Titanium nanotube arrays can be loaded with rhBMP-2 by biochemical methods and have good biocompatibility.