Development of bioresorbable porous sintered apatities as bone substitutes

研究了烧结型碳酸盐磷灰石(CAP)作为骨替代材料的体外和体内应用。为了进行体外评估，我们使用了大鼠骨髓细胞培养。在此细胞培养中，我们还使用了烧结型羟基磷灰石(HAP)、β-磷酸三钙(β-TcP)、含镁β-Tcp(mgβ-Tcp)和HAP(70wt%)-Mg，β-Tcp(30wt%)基质进行比较，并观察了成骨细胞在这些基质上的黏附、增殖和分化情况。培养7d时，钙化结节的贴壁细胞数、DNA含量、碱性磷酸酶活力、钙磷含量等参数均显著高于塑料培养板基质。Hap、β-Tcp、Mgβ-Tcp、Hap-Mgβ-Tcp和Cap之间的碱性磷酸酶活力无显著差异，但β-Tcp与…的碱性磷酸酶活力趋于最小更多的细胞数与其他钙磷酸酶活性基本相同，细胞数与其他磷酸钙底物几乎相同。在培养14天时，塑料培养板基质的各项参数趋于接近包括帽状基质在内的磷酸钙基质。然而，扫描电子显微镜清楚地显示，成骨细胞在CaP、HAP、HAp-mgβ-Tcp基质上比在塑料平板、β-Tcp和mgβ-Tcp基质上表现出更多的活性和更多的增殖。对于后三种基质，培养过程中形成的钙化结节的钙磷含量较低。为了进行体内评估，将多孔碳酸盐磷灰石植入大鼠颅骨缺损中，每个颗粒的粒度在300-500μm(粗颗粒)和小于200μm(细颗粒)之间。微焦点X射线计算机断层扫描显示，未填充材料的缺损区在植入后至少3周内几乎没有成骨，而填充材料的缺损区在2周后才形成骨。组织切片TRAP染色显示，在骨吸收材料周围有大量TRAP阳性细胞，提示烧结型碳酸盐磷灰石颗粒的骨吸收部分类似于破骨细胞性骨吸收。植入后4、6、8周，新生骨含有破骨细胞，与宿主骨一样矿化致密。这些发现表明，烧结型碳酸盐磷灰石可作为生物可吸收骨替代材料。较少

The usefulness of sintered carbonate apatites (CAp) as bone substitutes were investigated in vitro and in vivo. For in vitro evaluation, we used a rat bone marrow cell culture. In this cell culture, we also used sintered hydroxyapatite (HAp), β-tricalcium phosphate ( β-TCP), magnesium-containing β-TCP (Mgβ-TCP) and Hap(70wt%)-Mg, β-TCP(30wt%) substrates for comparison and the adhesion, proliferation, and differentiation of osteoblastic cells on these substrates including standard plastic culture plate substrates were investigated. At 7-day culture, parameters such as the number of cells adhered, DNA contents, alkaline phosphatase activity, calcium and phosphate contents originating from the calcified nodules were significantly higher with Cap substrates than with the plastic culture plate substrates. No great significant differences were noted among Hap, β-TCP, Mg β-TCP, Hap-Mg β-TCP and Cap in the parameters, though β-TCP tended to show smallest alkaline phosphatese activity with the … More number of cells being almost the same with the other calcium phosphatase activity with the number of cells being almost the same with the other calcuim phosphate substrates. At 14-day culture, the parameters with the plastic culture plate substrates tended to become close to those of the calcuim phosphate substrates including CAp substrates. Neverless, SEM micrographs clearly suggested that osteoblasitc cells appeared much more active and more proliferated on CAp, HAp, HAp-Mgβ-TCP substrates than on plastic plate, β-TCP and Mgβ-TCP substrates. For the latter three substrates, the calcium and phosphate contents of calcified nudules formed during culture were found to be smaller.For in vivo evaluation, sintered carbonate apatites in porous form with each particle size being in the range of 300-500μm (coarse particles) and less than 200μm (fine particles) were implanted in rat skull defects. Micro-focus X-ray computed tomography showed that bone hardly formed in the defects filled with no materials at least till 3 weeks after implantation but in the defects filled with the materials bone formed by two weeks. Staining of sectioned specimens by TRAP showed that there were many TRAP-positive cells around the resorbing material, suggesting that the resorption of the sintered carbonate apatite particles is, in part, similar to osteoclastic bone resorption. At 4, 6 and 8 weeks after implantation, the new bone contained osteoclastic and was a mineralized and dense as the host bone. These findings suggest that sintered carbonate apatites would be useful as bioresorbable bone substitutes. Less