Repairing Femoral Bone Defect In Rabbits With N-HA/LDIG Composites

Objective: To observe the healing process of n-HA/LDIG compositesrestore the rabbits femoral bone defect. Following observations andevaluations were carried out of optimizing composites for bone regenera-tion. The mainly purpose of this experiment was to give a preliminaryexperimental evidence and to prove the novel composites as potential bonesubstitutions or bone tissue engineering scaffold.Methods: 1. Preparation of materials: the material was provided byNational Key Laboratory of Technology. This composite is compounded byL-lysine diiosocyanate-glycercol(LDIG) and nano-hydroxyapatite(n-HA)which named nano-hydroxyapatite/L-lysine diiosocyanate-glycerol (n-HA/LDIG) polymer. Its characteristics including biodegradable, nontoxic,nonpyrogen, nonhemolysis have been confirmed in the experiments ofacute toxicity, pyrogen, hemolysis etc. It has right biological characteristicswhich met the basic conditions demended in bone tissue engineering. Afterpreparation, the physical and chemical properties of the composites werepreliminary studied. 2. Animal experiments: 36 adult rabbits,solo femoralbone defect in which following materials were implanted were made andthen were divided into 3 groups randomly: A: n-HA/LDIG group; B:homograft bone group; C: no graft group. After 2, 4, 8 and 12 weeks,the experimental rabbits were analyzed by radiographic, following, theanimals of every group were killed according to different operation periodand the implantations were taken off and studied by gross observation,X-ray density, histological analysis, X-ray gray extent analysis.Results:①After 12 weeks post-operation,the n-HA/LDIG group and homograft bone group restored the wane completely, and in every periodtheir X-ray evaluation were all better than that in no graft group, and thedifference had exponential correlation(P＜0.05).②The n-HA/LDIG grouphad no exponential correlation compared with the homograft group(P＞0.05)③The bending strength of callus and the X-ray density of callus have anexponential correlation(P＜0.05).The X-ray density of callus increasedcoincidently with the fracture healing process. It also confirmed that therewas a high correlation between the character of bending strength of callusand the X-ray density of callus.Conclusions: The n-HA/LDIG composite has a strong power ofcoordination with mature bone, and it has very good biocompatibility andbiodegradability. It has some potential bone conducting, it can replacehomograft bone, and it is suitable for the growth of osteoblasts and newlittle blood vessels as well as reformation of new bone tissues.