Li Meng, Liu Xu-dong, Liu Xing-yan, Ge Bao-feng
Department of Orthopaedics, Lanzhou General Hospital of PLA, Lanzhou 730050, Gansu, China.
Zhongguo Gu Shang. 2011 May;24(5):411-5.
To prepare macroporous bone substitute composed of calcium phosphate cements and rhBMP-2 loaded gelatin microspheres, and to investigate ectopic osteoinduction of the composite.
After being prepared by improved emulsified cold-condensation method and crosslinked by 5% genipin solution,gelatin microspheres (GMs) were observed by scanning electron microscope (SEM) and loaded with rhBMP-2 by adsorption. Macroporous bone substitute was developed by mixing calcium phosphate cement (CPC) with 2.5% GMs, being as the experimental group,and CPC with rhBMP-2 was the control group. After the both composites had been soaked in the sodium chloride for 1 week or 3 weeks, compressive strength of the composites were tested, and the cross-sections were observed by SEM. Concentrations of rhBMP-2 in the solutions at different time by ELISA method and the cumulative drug release amount was calculated. The composites had been implanted in the muscle bags of the mouses for 3 weeks. Then the tissues around the materials were collected, stained by hematoxylin and eosin, and Ca and ALP in the tissues were also measured.
Gelatin microspheres were spherical with diameters of (62 +/- 18) microm. Macropores appeared in the experimental materials 1 week and 3 weeks after being soaked,and total porosity, macroporosity, cumulative release amount of rhBMP-2 in the experimental group were higher than that in the control. But compressive strength of the experimental group was lower than that of the control group 3 weeks after being soaked. Results of HE stain showed chondral formation in both groups, but there were more chondral tissues in the experiment group, and so were the concentrations of Ca and ALP.
Macroporous calcium phosphate cement can be prepared by using rhBMP-2 loaded gelatin microspheres, and it is an excellent bone substitute due to it's proterty of promoting rhBMP release and powerful ectopic osteoinduction.
制备由磷酸钙骨水泥和负载重组人骨形态发生蛋白-2（rhBMP-2）的明胶微球组成的大孔骨替代物，并研究该复合材料的异位骨诱导作用。
采用改进的乳化冷凝聚法制备明胶微球（GMs），并用5%京尼平溶液交联，通过扫描电子显微镜（SEM）观察，采用吸附法负载rhBMP-2。将磷酸钙骨水泥（CPC）与2.5%的GMs混合制成大孔骨替代物作为实验组，将CPC与rhBMP-2混合作为对照组。将两种复合材料在氯化钠中浸泡1周或3周后，测试其抗压强度，通过SEM观察其横截面。采用酶联免疫吸附测定（ELISA）法检测不同时间溶液中rhBMP-2的浓度，并计算累积药物释放量。将复合材料植入小鼠肌袋中3周。然后收集材料周围的组织，进行苏木精-伊红染色，并测定组织中的钙和碱性磷酸酶（ALP）含量。
明胶微球呈球形，直径为（62±18）μm。实验组材料浸泡1周和3周后出现大孔，实验组的总孔隙率、大孔隙率、rhBMP-2的累积释放量均高于对照组。但浸泡3周后实验组的抗压强度低于对照组。苏木精-伊红染色结果显示两组均有软骨形成，但实验组的软骨组织更多，钙和ALP的浓度也更高。
负载rhBMP-2的明胶微球可制备大孔磷酸钙骨水泥，该复合材料具有促进rhBMP释放的特性和强大的异位骨诱导能力，是一种优良的骨替代物。
