Effects of different concentrations of TiAl6V4 particles on MC3T3-E1 cells and bone in rats

Three-dimensional (3D)-printed porous Ti6Al4V implants have good mechanical properties and excellent biocompatibility. As such, these implants are widely used in orthopedics. Particles adhere between the sintered and nonsintered interfaces of the porous samples during 3D printing. These excess particles can be cleaned by blowing the particles and via ultrasound, but the excess internal particles of complex structural parts are difficult to remove. During long-term cyclic loading, stress and strain can cause residual Ti6Al4V particles in the pores of the implant to shed. These detached Ti6Al4V particles are in extensive contact with osteoblasts and scattered around the implant. In this study, we examined the effects of different concentrations of Ti6Al4V particles on osteoblasts and bones. MC3T3-E1 cells were used to evaluate the effects of different concentrations of Ti6Al4V particles on cells after 72 ​h on the basis of the expression levels of genes, involving osteopontin, alkaline phosphatase, bone morphogenetic protein-2 and runt-related transcription factor-2. Microtubule-associated protein 1 light chain 3 was used to detect the autophagy of MC3T3-E1 with different concentrations of Ti6Al4V particles. The distal femoral defects of rats were examined to examine bone growth with different concentrations of Ti6Al4V particles. All rats were accepted by micro-CT and biochemical analyses after 12 weeks. The results indicated that 10 and 100 ​μg/ml of Ti6Al4V particles may improve osteogenic differentiation. Micro-CT revealed that low concentrations of Ti6Al4V particles may improve the osteogenesis of the rats. However, the (cortical and trabecular) BMD of middle and high dose groups was no significant change compared with control group. In conclusion, low-dose residual particles do not inhibit osteoblast differentiation and do not decrease the bone mineral density of rats.