The In Vivo Study Of Osteogenesis Mechanism Of The Interface Between Bone And Porous Tantalum Coated With RGD Pepdes Implanted In Rabbit's Femoral

Objectives To observe the ossification and tissue growth of the tantalum-bone interface after implanted the RGD peptide modified porous tantalum in the femoral condyle of rabbits,and to explore the effect of RGD peptide modification on osteogenic formation of porous tantalum material.To observing the expression of integrin,FAK,ERK,P-ERK and COL-I at the tantalum-bone interface,and exploring the mechanism of RGD-modified porous tantalum for promoting osteogenesis and osseointegration,providing the basis for the clinical application of the porous tantalum and RGD peptide modification.Methods Porous tantalum is made into a cylinder of about 7mm long and 3.5mm in diameter.Disinfection of standby.28 experimental animals were selected and divided into 3 groups;12 in RGD group,12 in Tantalum group and 4 in Sham group.Modeling: The rabbit femoral condyle is made of a cylindrical bone defect of about 7 mm in length and 3.5 mm in diameter.The material is implanted and the wound is washed and sutured.RGD group,Implantation of RGD peptide modified porous tantalum.Tantalum group,Implantation of unmodified porous tantalum.Sham group,Surgery only,no implants.Taking out specimens at four time points at 2,4,8 and 16 weeks after operation.1.Gross observation: Visual observation of the repair of bone defect and the surrounding tissue.2.SEM observation of the tissue growth at the tantalum-bone interface,porous tantalum surface,and pores.3.Specimens were made into paraffin sections after decalcification,the interface tissues were observed by HE staining.4.Immunohistochemistry was used to detect the expression of integrin,FAK,ERK,P-ERK and COL-I protein in the tantalum-bone interface tissues of each group.5.The specimens were made into hard tissue sections stained with VG and Goldner's for observing the tissue growth at the tantalum-bone interface and the internal porosity of the porous tantalum.Results 1 Gross observation,No infection and rejection occurred in the each groups,In group RGD and group Tantalum,there was no loosening of the tantalum at various time points after the implantation.With the extension of implantation time,the tissue coverage of the end of the tantalum rod was more,bone defects in the sham group were gradually filled and covered.2 SEM observation,With the prolongation of the implantation time,the closer the binding between the rod and the host bone in the RGD group and the tantalum group,both groups achieved osseointegration at 16 weeks.3 HE staining results,There was no obvious inflammatory cell aggregation in the interface tissues of each groups,with the prolongation of implantation time,the new bone tissue in the tantalum-bone interface also increased;the new bone tissue in the RGD group grew faster than the other two groups.4 Immunohistochemistry results,Integrins.At 2 and 4 weeks after surgery,The expression of RGD group was significantly higher than other groups(p<0.05),there was no significant difference in the expression of the tantalum group and the sham group.At 8 and 16 weeks after surgery,there was no significant difference in the three groups.FAK,At 2,4and 16 weeks after surgery,The expression of RGD group was significantly higher than other groups(p<0.05),there was no significant difference in the expression of the tantalum group and the sham group.At 8 weeks after surgery,there was no significant difference in the three groups.ERK,At 2 weeks after surgery,there was no significant difference in the expression of the three groups.At 4 and 16 weeks after surgery,the expression of the RGD group was significantly higher than the tantalum group(p<0.05).At 8 weeks,The expression of the RGD group was significantly higher than the tantalum group(p<0.05),the tantalum group higher than the sham group(p<0.05).P-ERK,At 2,4 and 16 weeks after surgery,the expression of the RGD group was significantly higher than the other group(P<0.05),there was no significant difference in the expression of the tantalum group and the sham group.At 8 weeks after surgery,there was no significant difference in the three groups.COL-?,At 2 and 4 weeks after surgery,the expression of the RGD group was significantly higher than the other group(p<0.05),there was no significant difference in the expression of the tantalum group and the sham group.At 8 weeks after surgery,there was no significant difference in the three groups.At 16 weeks after surgery,the expression of the RGD group was significantly lower than the other group(p<0.05),there was no significant difference in the expression of the tantalum group and the sham group.5 VG staining results,The percentage of new bone growth area and implant surface contact in the RGD group was higher than the other group(p<0.05).6 Goldner's staining results: The new bone tissue in the RGD group and the tantalum group matured with the prolongation of the implantation time;the bone tissue maturity in the RGD group was significantly higher than that in the tantalum group.At 16 weeks,the new bone tissue in the RGD group was converted to mature mineralized bone.Conclusions 1 The RGD-modified porous tantalum has excellent histocompatibility in the repair of bone defects,and can achieve osseointegration.2 RGD modification promotes the formation of new bone tissue at the tantalum-bone interface,promotes the maturation of new bone,and accelerates the rate of osseointegration.3 RGD-modified porous tantalum can promote the high expression of osteogenic related factors Integrin,FAK,ERK,P-ERK and COL-I,activation of MAPK pathway,promote osteoblast secretion,increase expression of COL-I,and promote bone formation at the interface,improve the osseointegration effect.