组织工程骨修复兔颅骨缺损中骨形态发生蛋白的表达

EXPRESSION OF ENDOGENIC BONE MORPHOGENETIC PROTEIN IN REPAIRING RABBIT SKULL WITH TISSUE ENGINEERING TECHNIQUE

目的 探讨组织工程骨修复骨缺损 ,内源性骨形态发生蛋白 (BMP)在组织工程骨再生过程中的分布及作用。方法 将自体成骨样细胞即刻种植在胶原包埋的聚羟基乙酸 (PGA)基质材料上 ,然后将该复合体或单纯基质材料移植到兔颅骨的一侧全层骨缺损区 ,作为实验侧 或实验侧 。对侧设对照 ,不作任何植入。 18只新西兰兔分别于术后 3、8及 14天处死 ,标本行组织学及 BMP免疫组织化学检查。切片上 ,确定骨缺损区中央 ,距骨断端 2 mm、5 m m为 A、B、C三区 ,利用真彩色计算机图像分析系统在各区间测量 BMP值。结果 术后 3天 ,实验侧 基质材料间存在 BMP阳性细胞。8天时 ,实验侧 新骨形成明显优于实验侧 及对照侧。14天时 ,实验侧 可见骨小梁形成 ,对照侧为纤维组织修复。 BMP定量分析中 ,实验侧 ( 、 )三区的 BMP值高于对照侧 ,但实验侧的浓度梯度差值小于对照侧。结论 即刻种植于 PGA基质材料上的成骨样细胞在体内可合成和分泌 BMP,利用组织工程技术将内源性 BMP局限于骨缺损区 ,提高内源性 BMP浓度并改善其分布 ,可能是组织工程骨诱导骨再生机制之一。

Objective To explore the distribution and effect of endogenic bone morphogenetic protein (BMP) in repairing rabbit skull with tissue engineered bone. Methods The autologous osteoblast like cells were instantly implanted onto polyglycolic acid (PGA) matrix coated with collagen. The rabbit skull defect models were established by resection of bilateral 1.5 cm×1.0 cm full thickness parietal bone in 18 New Zealand rabbits, which were randomly divided into two groups. In one group, the composite of osteoblast like cells and PGA matrix were grafted into the defect on one side of the skull as experimental group Ⅰ, leaving the same defect area on the other side as control group without any graft implanted. In the other group, simply PGA was done in the same way as experimental group Ⅱ. The tissue samples were harvested at 3、8 and 14 days postoperatively and examinated by histological and immunohistochemistry methods. The concentrations of BMP in different regions of the samples were measured using computer image analysis system. Results After 3 days of operation, the BMP positive cells were found in the matrix of experimental groupⅠ. At 8 days postoperatively, the formation of new bone on experimental group Ⅰwas prior to that of experimental group Ⅱ and control group. On the 14th day, bone trabecula was formed on the experimental group Ⅰ,but there was only fibrous tissue on control group. The concentration of BMP on the experimental group Ⅰ and Ⅱ were higher than that of corresponding region on control side. Conclusion The osteoblast like cells instantly implanted onto PGA matrix can synthesize and secrete BMP. It may be one of the reasons of tissue engineered bone inducing new bone regeneration that localizing endogenic BMP in bone defect area, increasing the concentration of endogenic BMP and improving its distribution by tissue engineering technique.