Objective:To prepare macroporous bone substitute composed of calcium phosphate cements and rhBMP-2 loaded gelatin microspheres,and to investigate ectopic osteoinduction of the composite. Methods: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 developod 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. Results:Gelatin microspheres were spherical with diameters of (62±18) μm. Macropores appeared in the experimental materials 1 week and 3 weeks after being soaked,and total porosity,maeroporosity,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. Conclusion: 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.%目的:制备多孔复合材料明胶微球/rhBMP-2/CPC并研究其异位成骨效应.方法:双相乳化冷凝聚合法制备明胶微球,京尼平进行交联,喷金后电镜观察.交联微球携载rhBMP-2,以2.5%的比例掺入磷酸钙骨水泥(calcium phosphate cements,CPC)固化,制成实验用多孔明胶微球/rhBMP-2/CPC,rhBMP-2/CPC作为对照组.两组材料固化后分别浸入生理盐水,1、3周后进行生物力学压缩实验.扫描电镜观察材料断面.ELISA法测定不同时间点生理盐水中rhBMP-2浓度,计算rhBMP-2的累积释放量.材料植入小鼠大腿肌袋,术后3周处死小鼠,切取材料及周围组织,HE染色后进行组织学观察,同时测定材料周围组织中碱性磷酸酶及钙舍量.结果:交联的明胶微球呈规则圆形,粒径(62±18)μm,分散性好.1、3周后实验组材料断面可见大量大孔形成,对照组未见明显大孔,实验组的总孔径率、大孔率及rhBMP-2的累积释放量均高于对照组.3周后实验组最大压缩强度(7.8±1.2)MPa,较对照组(11.2±1.6)MPa稍低.HE染色两组均可见软骨形成,但实验组更多,碱性磷酸酶及钙含量测定实验组分别为(4.33±0.52)IU/g和(6.12±1.22)μg/mg,高于对照组的(2.67±0.23)IU/g和(3.12±0.41)μg/mg.结论:明胶微球/rhBMP-2/CPC在微球降解后形成多孔磷酸钙复合材料,使rhBMP-2的释放量增加,具有强大的异住成骨性能,是一种优秀的骨组织工程材料.
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