载甲氨蝶呤磷酸钙骨水泥体系的体内药物释放及成骨活性的组织学评价

Release Kinetics of Methotrexate-loaded Calcium Phosphate Cement and Histological Evaluation of the Osteogenesis in Rabbits

目的观察载甲氨蝶呤磷酸钙骨水泥(MTX-CPC)体系的体内药物释放规律,并对其吸收及骨生成进行组织学评价。方法预制1%(质量比w/w)的MTX-CPC标本,将其植入24只新西兰兔股部肌袋中,随机分为术后1、2、5、10、15、20、25、30d8组,每组3只,测定甲氨蝶呤(MTX)局部释放浓度、外周血浓度、释放后植入物剩余MTX百分比。然后将预制MTX-CPC标本及空白磷酸钙骨水泥(CPC)(作为对照)分别植入兔股骨髁上骨缺损处,于植入后1d,1、3、6个月时行X线检查及组织学检查,定量分析新成骨面积、破骨细胞数量及成骨细胞数量。结果 MTX-CPC体系符合均相基质释放体系,有突释效应,随后缓慢释放;术后30d的释放浓度为0.372μg/ml,仍高于药物有效浓度,理论上体内释放可持续2～3个月。MTX-CPC和空白CPC均显示了良好的骨降解性和骨传导性。尽管MTX的释放对成骨过程有一定抑制作用,尤其在药物释放初期,但在植入6个月时,MTX-CPC组的新成骨面积、成骨细胞数量及破骨细胞数量与CPC组比较,差异无统计学意义(P均>0.05)。结论 MTX-CPC是一个有效的缓释系统,MTX-CPC和CPC均具有良好的骨降解性和骨传导性,提示MTX-CPC体系是一种既可以填充骨缺损又可以控制局部复发的良好材料。

Objective To observe the release kinetics of methotrexate-loaded calcium phosphate cement（MTX-CPC）implanted in vivo and histologically investigate its resorption and osteogenesis.Methods MTX-CPC consisting of 1% methotrexate（MTX）（weight/weight）was pre-set and implanted into femoral muscles of 24 New Zealand rabbits.The in vivo MTX release kinetics was determined on the 1st,2nd,5th,10th,15th,20th,25th,and 30th post-implantation day.The local concentrations and the residual percentage of MTX were determined.Then the pre-set MTX-CPC was implanted into femoral condyle.Calcium phosphatecement（CPC）without MTX was used as a control.The femurs were harvested at the 1st day and the 1st,3rd,and 6th month and examined by X ray.Then histomorphometrical analyses including percentage of newly formed bone and amount of osteoblast and osteoclast were performed.Results The MTX release kinetics in vivo confirmed that MTX-CPC was a monolithic matrix system,with a burst effect in the initial stage and a sudden drop thereafter.The local concentration of the released MTX was 0.372 μg/ml on the 30th post-implantation day;with a concentration higher than the effective concentration,the incorporated MTX was expected to be continuously released over the following 2-3 months.Both MTX-CPC and CPC showed good biodegradability and osteoconduction.Although the release of MTX had an inhibitory effect on osteogenesis,especially in the initial stage,the area of newly formed bone,the amount of osteoblasts,and the amount of osteoclasts were not significantly different between MTX-CPC group and CPC group on the 6th post-implantation month.Conclusions MPX-CPC system is an effective drug delivery system.Both MTX-CPC and CPC has good biodegradability and osteoconduction.Therefore,MTX-CPC system can be an ideal material for filling defects and controlling local recurrence.