海藻酸钠-明胶共混体系凝胶修复颅骨极限缺损过程中血清无机盐及碱性磷酸酶的变化**

背景：将各种凝胶系统作为支架材料进行骨缺损的修复日益受到重视，同时在骨修复过程中需要选择相对准确又方便的检测方式，以明确体内成骨过程。 目的：观察血清钙、磷和碱性磷酸酶浓度在可注射组织工程骨修复过程中的变化并对其作用进行初步探索。 设计、时间及地点：观察性实验，于2007-10/2008-03在北京世纪坛医院、北京大学医学部组织胚胎学教研室进行。 材料：分离培养兔成骨细胞，并引入海藻酸钠-明胶凝胶中构建细胞/支架材料复合体。 方法：36只新西兰纯种大白兔随机分为实验组、对照组和空白组3组，所有动物颅骨制备直径1.5 cm的极限缺损。1周后实验组在缺损处植入自体细胞/支架材料复合体，对照组植入单纯海藻酸钠-明胶凝胶，空白组不予材料修复。 主要观察指标：苏木精-伊红染色和Mallory三色染色观察观察骨组织的形成修复情况；于不同时间点抽取各组兔静脉血，统一条件下使用生化仪检测血清中钙、磷及碱性磷酸酶水平并做配对比较。 结果：实验组的血清碱性磷酸酶高峰出现得比其他2组早，且其高峰值高于对照组和空白组(P < 0.05)，并维持在一个较高的水平，随着修复的完成逐渐降低，到骨缺损后10周时接近正常值。术后2周，各组血钙均有不同程度升高，而血磷有所降低，但组间无显著性差异；术后4，8周，实验组血钙降低，血磷升高，较其他2组钙、磷沉积高峰提前出现(P < 0.05)。组织学结果也证实了以上各时间段骨愈合情况。 结论：在利用凝胶可注射组织工程骨修复兔颅骨极限骨缺损的过程中，血清钙、磷及碱性磷酸酶活性在不同的阶段有所差异, 可以反映体内成骨过程，并且可能在骨缺损的修复与成骨这一过程中参与调节作用。

Changes of inorganic salts and alkaline phosphatase in serum during the repair of critical-sized calvarial defects using algin-gelatin gel

BACKGROUND: Various gel systems are served as scaffolds and receive more and more interest in the repair of bone defects, meanwhile, accurate and convenient indications are required to judge the status of in vivo bone formation. OBJECTIVE: To observe the changes and investigate the roles of calcium, phosphorus and alkaline phosphatase concentration in serum during the repair of bone defects in rabbit calvariums by injectable tissue engineering bone. DESIGN, TIME AND SETTING: An observation experiment was carried out at Beijing Shijitan Hospital and Department of Anatomy and Histoembryology, Peking University Health Science Center from October 2007 to March 2008. MATERIALS: Rabbit osteoblasts were isolated, cultured and then introduced into algin-gelatin gel to construct cell/scaffold complex. METHODS: A total of 36 New Zealand purebred rabbits were divided into three groups, experimental group, control group and blank group. Critical-sized calvarial defects were created in diameter of 1.5 cm. After 1 week, cell/scaffold complex was implanted in the experimental group, algin-gelatin gel in control group, and no material in blank control. MAIN OUTCOME MEASURES: Hematoxylin-eosin staining and Mallory trichrism staining were applied to observe the bone formation and repair. After rabbit venous blood wasere collected at different time, the calcium, phosphorus and alkaline phosphatase concentration in serum were determined by biochemistry machine. RESULTS: Compared with control group and blank group, the alkaline phosphatase concentration in serum appeared earliyest and the peal value was the highest (P < 0.05). The peak value gradually reduced along with the accomplishment of the repairing process and restored to the normal value at 10 weeks following bone defects. At postoperative 2 weeks, the blood calcium levels were increased whereas the blood phosphorus levels were decreased, there was no significant difference between the groups; At postoperative 4 and 8 weeks, the blood calcium levels were decreased whereas the blood phosphorus levels were increased in the experimental group. The peaks of calcium and phosphorus wereas earlier than those in other two groups (P < 0.05). Hhistological outcomes also proved the bone healing at different time. CONCLUSION: During the repair of bone defects in rabbit calvariums by injectable tissue engineering bone, the calcium, phosphorus and alkaline phosphatase concentration in serum are varied at different periods, which could reflect in vivo osteogenesis process and may play a regulatory role in this process.