Effect Of Near β Titanium Alloy TLM Modified By The Double Glow Plasma Nitriding Technology On The Initial Functions Of Osteoblast

Objective:To evaluate the adhesion,proliferation,alkaline phosphatase activity and the expression of osteogenesis-related genes of osteoblast cells on a near β titanium alloy Ti-5Zr-3Sn-5Mo-15Nb(TLM)modified by the double glow plasma nitriding technology,and to investigate the effect of the modified surfaces on the initial functions of osteoblasts.Methods:The surfaces of TLM were modified by the double glow plasma nitriding technology.TLM without modification were used as control.Cell morphology was observed with scanning electron microscopy(SEM).MTT method was used to measure cell proliferation.Cell alkaline phosphatase activity(ALP)was evaluated by using reagent kits.The mRNA expression of Runt-related transcription factor-2(RUNX2),typeⅠcollagen alpha 1 chain(COLⅠα1)osteoprotegerin(OPG)and the receptor activator of nuclear factor-kappa B ligand(RANKL)were examined by quantitative real time-polymerase chain reaction(qRT-PCR).Results:At 4h point,cells on modified surfaces extend filopodias and the intercellular junction was tight.Three days later,cell proliferation(0.277±0.007)was significantly higher than that in control group(0.249±0.004)(P=0.004),but there were no significant differences between the two groups in fifth day and seventh day.After two weeks,the alkaline phosphatase(ALP)activity on TLM modified layer(173.606 ±1.884)was significantly higher than that on unmodified TLM(162.582±2.426)(P=0.003).The mRNA expression of osteoblast marker RUNX2,COLⅠα1 and OPG were stronger than that in control group(P<0.05).And RANKLmRN A expression was significantly lower than that in control group(P=0.016).Conclusion:The TLM modified by the double glow plasma nitriding technology has a positive effect on osteoblasts initial adhesion and differentiation,which also can improve expression of OPG mRNA and has an inhibitory effect on RANKL mRNA expression of osteoblasts.The osseointegration may be finished faster on this modified surface.