Repair Of Bone Defects In Rabbits With Encapsulated Extracts Of Eucommia For Sustained-release Combined With Calcium Phosphate Cement

Background:As a new generation of bone repair, Calcium phosphate cement has became a hot spot of clinical application and modified research in recent years. Since there are some problems that lack of bone induction activity and slow degradation of the issue in the solidification of calcium phosphate cement scaffold. The research show that extracts of Eucommia promote osteoblast proliferation significantly, while Chlorogenic Acid which the main component of Eucommia extract is very unstable, without protection of other media, light, heat and oxygen are likely to get the role of oxidation hydrolysis, For the advantages of its controlled release, targeting and stability, traditional Chinese medicine with the microencapsulate will be extensively researched and applied.Objective:This study intends to assemble the Eucommia extract in capsules with calcium phosphate cement (CPC) for composite, fill femur defect, by general concept, X ray, histology, electron microscopy and immunohistochemical observation of quantitative statistics, comprehensive evaluate the effect of CPC/microcapsules Eucommia composite repairing bone defects and the best ratio.Method:1. Arab gum andβ-cyclodextrin as a wall material, leaf extract for the core of a capsule made into Eucommia microcapsules by spray drying method. With simple leaf extract for in vitro release.2. Eucommia microcapsules to 0.304mg/ml and 0.608mg/ml composite of two different concentrations and CPC, with a diameter of 6mm,4mm height of the mold filling material into the first pre-CPC+Eucommia 1 (0.304mg/ml), CPC+Eucommia 2 (0.608mg/ml). Select 16 New Zealand rabbits were randomly divided into 4 groups, n= 4, in the bilateral femoral condyle bone drill 6* 12mm hole, so different materials were filled or not filled, according to a balanced incomplete block experimental design method as follows:Left CPC/Right blank group, left CPC+Eucommia 1/right CPC group, the left CPC+Eucommia 1/the right CPC+Eucommia 2 group and left CPC+ Eucommia 2/right blank group.3. The rabbits were sacrificed after 2,4,8,12 weeks, X-ray, histological examination, scanning electron microscopy, immunohistochemistry, statistical test were used to evaluate the degree of bone repair and the speed of degradation.Result:1. Eucommia microcapsule diameter was 50.40±2.34um, micro-encapsulation efficiency of 93%. In the release medium the original powder 2 hours cumulative release rate was 90%, while the 8-hour cumulative release rate of Eucommia microcapsules was 63%.2. CPC+Eucommia 2 groups after 12 weeks in the X line has been the healing of cortical bone, marrow cavity through, almost no residual implant material, CPC+ Eucommia 1 group of small retention, CPC Group has significant material existence. Light microscopy after 4 weeks CPC+Eucommia 2 groups shows that rich multinucleated macrophages and angiogenesis, a large number of spindle cell infiltrate bone cement, cartilage formation of multiple nested, material began to degrade. In the 12th week new bone tissue in the group no CPC particles, marrow cavity through, the normal bone formation; new bone tissue of CPC+Eucommia 1 group can be seen small CPC particles, fusion of trabecular bone, marrow cavity through; CPC group of fat cells appear, Trabecular and woven bone interspersed CPC particles, pulp cavity is not completely through. At electron microscopy the 4th weeks CPC+Eucommia2 group woven trabecular bone climbed out into bone cement interface, bone cement powder into smaller pieces; CPC and CPC+gutta-1 group was honeycomb-like trabecular bone cement bulk connection. Eucommia microcapsules rupture. after 4 weeks BMP-2 and VEGF was highly expressed in statistical examination was significant at immunohistochemistry in CPC+Eucommia 2 groups.Conclusion:Eucommia microcapsules were prepared convenient, under the protection of the microcapsules can maintain performance, the ability of sustained release were accurate and reliable. Added to calcium phosphate bone cement in 0.608mg/ml concentration can promote bone formation, give it a certain degree of bone induction, and fundamental degradate in 3 months. Eucommia leaf was cheap, the composite material that is stressed in use can be any plastic possess clinical feasibility.