An Experimental Study On Bone Defect Angiogenesis And Bone Repair Of Non-vascularized Structural Bone Graft With Platelet-rich Plasma

Objective：Through the establishment of the animal bone defectexperimental model, to study the effects of platelet-rich plasma（PRP） onbone defect angiogenesis of non-vascularized structural graft bone and bonehealing.Methods：This experiment was conducted using45New Zealand whiterabbits aged between6and8months and weighing between2.0and2.5kg,that were divided into A,B,C groups at randomly（n=15）. Group A iscontrolgroup, and group B for A use of PRP once, group C use for many timesPRP.Group B and C separate PRP by secondary centrifugation from the5mlwhole blood of rabbits，which draw form femoral vein by the anticoagul-ation tube under local anesthesia，and count the number of platelet of wholeblood and PRP.Prior to using to the defect site，calcium chloride and bovinethrombin were mixed with PRP in a ratio of1:4for platelet activation.Bone defect （1cm in length） were created in the mid-upper part of radius,selected by randomly,for all the experimental anima and implantedautogenous iliac to defect site. Group A was implanted autogenous iliaconly, and group B and C was implanted with platelet-rich plasma combinedautogenous iliac. After1,3,6weeks in bone defect area，group C was injected0.5ml PRP, and by contrast, group A and group B was injected thesame amount of activation agent. Five rabbits were executed and thespecimens were procured at2,4,8weeks for general observation,X-rayexamination, histology of HE staining and CD34immunohistochemistry.Analyzing the results with statistical methods，that come form microvesseldensity（MVD）,Lane-Sandhu X-ray grade and percentage of new bone area.Result: The PRP platelets in the average concentration of1308.6×109/L，that is4.05times in the whole blood，which in the average concentration of325.25×109/L. Two weeks after operation，there are no osseointegration inthree groups from radiological and gross examination，the percentage of newbone and microvessel density of group B,C is more than group A (P_A-B=0.001, P_A-C<0.001), there is no statistical difference between group B and Cin the percentage of new bone(P_B-C=0.451),but it’s difference between groupB and C in microvessel density(P_B-C=0.018). Four weeks after operation,the bone radiology score of group B,C is more than group A(P_A-B=0.047，P_A-C<0.001),and group C more than group B(P_B-C=0.024), and thepercentage of new bone and microvessel density of group B,C is more thangroup A(P_A-B=0.047，P_A-C<0.001),and group C more than group B(P_B-C=0.024). Eight weeks after operation, the bone radiology score of groupB,C is more than group A(P_A-B=0.001，P_A-C<0.001), and there is nostatistical difference between group B and C(P_B-C=0.827), and thepercentage of new bone and microvessel density of group B,C is more than group A(P_A-B<0.001，P_A-C<0.001), and the percentage of new bonegroup C more than group B(P_B-C=0.035),and there is no statistical differencebetween microvessel density of group B and C(P_B-C=0.82).Conclusion:1.PRP can improve the healing of rabbit radial defect in theearly stage.2. injecting PRP to area of bone defect，by more frequency, canimprove the angiogenesis of non-vascularized structural graftbone and bone healing.