Local mechanism of new bone formatior in bone grafting-interaotion between cells in the graft and cells in host-

虽然自体骨移植是目前可用的治疗方法。新骨形成的局部机制还没有得到明确的分析。这项研究的目的是检查移植物中的细胞和宿主之间的关系，以促进新骨形成。以GFP转基因大鼠和野生型大鼠为研究对象，建立异位同种异体股骨移植模型。随机分为两组，未处理组(试验组)和液氮处理组(对照组)。用免疫组织化学方法检测成骨细胞和破骨细胞的来源，实时RT-PCR检测成骨细胞来源，原位杂交检测BMP信号的时空表达。移植后7d，实验组髓管内可见异位新骨形成，并伴有改建。对照组未见骨形成。第7天，成骨细胞主要来源于移植物。BMP-4、BMPRIA、2和noggin的表达在实验组有一过性增加，而对照组仅有BMPRIA和2mRNA的表达。BMP-4mRNA在移植后第7天在移植物细胞中有表达，在第14天在移植物和宿主细胞中均有表达。

Although autogenous bone grafting is currently available treatment. local mechanism of new bone formation has riot been analyzed clearly. The aim of this study was to examine the relationship between cells in the graft and host for new bone formation. We used GFP transgenic rats and wild-type rats, and ectopic isograft model that harvested femur was transplanted into back muscles between these kinds of rats was established. Gratis were divided into two groups, without treatment(experimental group) and treated by liquid nitrogen(control croup). Specimens were examined by immunohistochemistry for origin of osteoblast and osteoclast, real time RT-PCR, and in situ hybridization for temporal and spatial expression of BMP signaling. Eclopic new bone formation was found in the medullary canal at day 7 after grafting, and remodeling was followed in experimental group. No bone formation was found in control group. At day 7, osteoblasts were mainly originated from graft. Osteoblasts originated from host increased at day 14.and almost all of the osteoblasts were replaced by host at day 42.Transient increase of BMP-4.BMPRIA, 2, and noggin mRNA was found in experimental group, but only BMPRIA and 2 mRNA in control group. BMP-4 mRNA was expressed in graft cells at day 7 and in both graft and host cells at day 14.Collectively our results indicated the possibility for the First time that cells in graft induced host cells to bone formation by expressing BMP-4 mRNA.