Biocompatibility Of Silk Fibroin/Calcium Sulfate Cement

Objective: The silk fibroin/calcium sulfate cement(SF/CSC),which is synthesized in the previous study,is expected to be a new bone filling and repairing material.Although silk fibroin,calcium sulfate each have a good biocompatibility,but the two components of the new material SF/CSC biocompatibility is unknown.In this paper,the biocompatibility of SF/CSC is studied according to GB/T 16886 and ISO 10993,which can be used as reference for the next study.Methods: According to GB/T 16886 and ISO 10993 standards,and according to SF/CSC in the future in vivo for bone repair purposes,implantation test,hemolysis test,stimulation test,sensitization test,acute toxicity test,pyrogen test.(1)Implantation test using their own control,the SF/CSC implanted in New Zealand rabbits side of the paraspinal muscles,the other side of the incision is not implanted,3 weeks and 9 weeks were killed in five New Zealand rabbits,both sides of the paravertebral muscle for the naked eye and pathological observation.(2)In the hemolysis test,New Zealand white rabbits were added to the experimental group and the control group.The optical density of each group was measured and the hemolysis rate was calculated.(3)Stimulation test using their own control method,in New Zealand rabbits back coated with leaching solution and control solution to observe the local skin irritation.(4)The sensitization test was injected into the guinea pig’s skin by injecting extract or control solution.After induction and excitation,the skin condition of the excitation site was evaluated.(5)In the acute toxicity test,the leaching solution and the control solution were injected into the experimental group and the control group mice intraperitoneally,0h,24 h,48h,72 h,7d to observe the general situation of mice,record the time of mice weight.(6)In the pyrogen test,the extract was injected into the rabbit body through the ear vein to observe the change of body temperature.Results:(1)Implantation test in New Zealand rabbits on both sides of surgical wound healing is good,no infection occurred.3 weeks of visual observation of the control side,the experimental side were no obvious edema and abscess,SF/CSC no leakage,a slight degradation.9 weeks of reference to the control side,the experimental side are noedema,abscess and necrosis,SF/CSC degradation significantly,no leakage,no implant discharge phenomenon.Pathological observation showed that 3 weeks after implantation,the control of muscle tissue see striated muscle necrosis,fibroblasts hyperplasia,part of the region see the new capillaries,necrotic area visible inflammatory cell infiltration,inflammatory cell type to lymphocytes,eosinophils Main;experimental side see striated muscle necrosis,inflammatory cell infiltration to lymphocytes,eosinophils mainly.Pathological observation showed that the morphology of the control muscle tissue was normal,no necrosis and inflammatory cell infiltration at 9 weeks after implantation.On the experimental side,the fibroblasts were divided into the island-like areas with different sizes.Lymphocytes,monocytes,plasma cells,eosinophils infiltration.Over time,the inflammatory response subsided,indicating that SF/CSC had good histocompatibility.(2)Hemolysis test,the positive control group hemolysis phenomenon,negative control group and experimental group did not see hemolysis occurred,the experimental group hemolysis rate of 2.37%,hemolysis rate of less than 5%,SF/CSC meet the medical requirements of hemolysis.(3)In the stimulation test,SF/CSC extract was applied to the back of the New Zealand white rabbits for 4 hours.No erythema and edema were observed for 3 days.The total score of the experimental group and the control group was 0,and the SF/CSC extract No irritation.(4)Sensitization test showed that 24 h,48h after the excitation,the positive control group guinea pigs were erythema edema,100% sensitization,and the experimental group and negative control group were no erythema,edema,no allergenic.(5)Acute toxicity test showed that there was no significant change in behavior,activity,loss of appetite and sleep during the whole trial,and there was no significant difference in body weight gain between the two groups at each time point(P> 0.05).After the mice were sacrificed,no abnormal swelling or necrosis was observed in the brain,heart,liver,spleen,lung,kidney and peritoneum specimens,suggesting that SF/CSC extract had no acute toxicity.(6)The elevated body temperature of the three rabbits tested in the pyrogen test was less than 0.6 ° C,and the sum of the elevated body temperature of the three rabbits was less than 1.4 ° C.It was determined that the heat-generating substances contained in the SF/CSC extract were in compliance.Conclusion: SF/CSC has good biocompatibility,is expected to implant into the body,as a new type of bone cement.