Treatments Of Chromium And Cobalt Ion Abnormal Increase In Rats With A Self-controlled Sustained-release System

OBJECTIVE: The serum chromium and cobalt ion concentration of patients increased continuously after metal-on-metal(MOM)Arthroplasty,which is about to cause a sieries of side effects ? To control the metal ion persistently and effectively,a sustained-release system is designed.Methods:First,We constructed a sustained-release system loaded with Ethylene Diamine Tetraacetic Acid(EDTA):the hollow mesoporous silica nanoparticles(HMSNs)are synthesized using a sol-gel procedure and functionalized with borophenylic acid,then Ig G was added to form ester bond with borophenylic acid.Second:we test the efficiency of the system:80 adult male rats received intra-articular injection of Co Cr Mo nanoparticles once a week for 10 consecutive weeks.Meanwhile,20 rats in the control group received intra-articular injections of physiological saline.After the last injection,all rats were held for a post-exposure week.Blood samples of all rats were then collected from the inner canthus vein to measure serum chromium and cobalt ion concentrations to ascertain the models is sucessfully constructed.Then,the 80 rats was randomly divided into 4 groups,20 each,injected intraperitoneally with 0.4ml of normal saline,EDTA,silica microsphere empty carrier solution and EDTA-loaded system solution,respectively for two weeks,three times a week,during which,the rats were injected with Co Cr Mo nanoparticles once a week as before.We measured the blood chromium and cobalt ion concentration every 4 weeks until the 24 th week.Results:Compared with the control group,the concentration of serum chromium and cobalt ions in the model group was significantly increased after Co Cr Mo nanoparticles injections.The concentration of metal ions in groups receiving EDTA and EDTA-loaded system solution decreased significantly 8 weeks after the therapy.However,as the time goes,the concentration of metal ions in group injected with EDTA increased and with EDTA-loaded system solution,stayed low,relatively,there was a statistically significant difference between these 2 groups.The concentrations of metal ions of the groups injected with normal saline or silica microsphere empty carrier solution increased constantly while the serum ion concentration of the rats in the control group kept steady all along.Conclusion : This sustained release system can effectively reduce the continuous increase of metal ions in the serum of rats,which can offer an alternative treatment for the abnormally increased metal ion after arthroplasty.