Gene expression ground biomaterials implanted into bone

用I型胶原(Col)、骨连接蛋白(On)、骨钙素(OC)、骨桥蛋白(OPN)等核糖核酸探针进行原位杂交，分析β-磷酸三钙(可吸收材料)或聚甲基丙烯酸甲酯(非生物活性材料)颗粒植入大鼠胫骨后的组织反应。分别于术后3、5、7、10d取材。未植入的孔洞作为对照。各组均有向心性新骨形成，四种基因在活化的成骨细胞中均有表达，表达模式相似。成骨细胞在7d时也有表达。这些活跃的成骨细胞多见于成骨细胞表面，而在PMMA颗粒上未见表达。对照组和磷酸三钙组的成骨细胞活性相近，而PMMA组的成骨细胞活性较弱。在PMMA颗粒表面长期观察到OPN阳性细胞和Col阴性细胞。它们被推测为巨噬细胞和破骨细胞，因为它们显示出酸性磷酸酶活性。这些细胞在磷酸三钙颗粒上很少观察到，在对照组中也没有。这些发现表明，早期的细胞反应和基因表达反映了植入的生物材料的生物活性或生物相容性。

Tissue response around β-tricalciumphosphate (TCP, absorbable material) or poltmethylmethacrylate (PMMA, non-bioactive material) particles implanted into rat tibiae was analyzed by in stu hybridization with type I collagen (COL), osteonectin (ON), osteocalcin (OC) and osteopontin (OPN) RNA probes. Specimens were collected at 3, 5, 7, 10 days after operation. Holes without implantation were used as control. In all groups, new bone was formed centripetally and all four kinds of mRNA were expressed in activated osteoblasts with a similar pattern. A COL signal was expressed most strongly and widely, and was detected at the peripheral region of the hole at day 3. The other three mRNAs were also expressed in bone forming osteoblasts by day 7. These active osteoblasts were often observed on the surface of the TCP but not on the PMMA particles. The activities of osteoblasts in the control and the TCP groups were similar, whereas that in the PMMA group was weaker. On the other hand, OPN-positive and COL-negative cells were observed on the surface of the PMMA particles strongly for a long time. They were speculated to be macrophages and osteoclasts because they showed acid phosphatase activity. These cells were rarely observed on the TCP particles and were not observed in the control. These findings suggest that the early cell responses and gene expressions reflect the bioactivity or biocompatibility of the implanted biomaterials.