Fabrication of bioresorbable porous ceramics for bone regeneration and its bone reconstruction using transplantation with the blood vessel pattern

本研究的目的是：(1)利用可生物降解的磷酸钙制备用于骨再生的多孔陶瓷；(2)在体内和体外评价该陶瓷和培养的骨髓细胞的骨再生。采用羟基磷灰石或碳酸盐磷灰石溶液浸渍不同孔径的聚氨酯泡沫塑料制备多孔可生物降解磷酸钙陶瓷。通过离心操作，试样干燥后，多余的浆料被去除，并被烧制。在部分试样上，重复浸渍、干燥和烧制过程。用扫描电镜对样品进行观察。结果表明，随着循环次数的增加，陶瓷的小梁增厚，孔径减小。结果表明，陶瓷小梁的平均直径、孔的直径和孔隙率可以通过循环次数来调节。大鼠骨髓细胞在添加抗坏血酸、β -甘油磷酸酯和地塞米松的培养基中培养2周。测定细胞增殖、碱性磷酸酶活性、I型胶原合成和骨钙素生成，并对体外成骨进行评价。结果表明，孔径在100 m以下时，孔径增大有利于体外成骨，孔径大于100 m时，对体外成骨没有影响。将培养2周的陶瓷/骨髓细胞复合物植入7周龄同基因大鼠体内。植入后8周进行体内成骨组织学评价。结果表明，孔径在100 ~ 200 μ m之间为最佳。然而，陶瓷在这一时期的吸收是轻微的。需要进一步研究陶瓷的长期吸收和骨的稳定性。

The purposes of this study are (1) to fabricate the porous ceramics for bone regeneration using biodegradable calcium phosphate and (2) to evaluate bone regeneration by the ceramics and cultured bone marrow cells in vivo and in vitro.Porous biodegradable calcium phosphate ceramics were fabricated by following methods : the polyurethane foams with different pore size were impregnated with hydroxyapatite or carbonate apatite solution. By the centrifugal operation, the specimens dried, after the surplus slurry was removed, and they were fired. On a part of the specimens, the impregnation, drying, and firing process was repeated. The specimens were observed by scanning electron microscopy. As the result, the trabecula of the ceramics thickened, and the pore size decreased with the increase of the cycles. This result indicates that average diameter of the ceramic trabecula, diameter of the pore and porosity of the ceramics could be adjusted by the number of the cycles.Rat marrow cells were cultured for 2 weeks with in medium supplemented with ascorbic acid, beta-glycerophosphate, and dexamethasone. Cell proliferation, alkaline phosphatase activity, type I collagen synthesis, and osteocalcin production were measured, and the osteogenesis in vitro was evaluated. As the result, the osteogenesis in vitro was promoted with the increase in the pore size under 100 _m, however, the pore size over 100_m, did not affect the osteogenesis.The ceramics/marrow cell complex cultured for 2 weeks were implanted into 7-week-old syngeneic rats. The osteogenesis in vivo was histologically evaluated at 8 weeks after the implantation. As the result, pore sizes between 100 to 200 U m were optimum. However, the absorption of ceramics in this period was slight. Further studies of the long-term resorption of the ceramics and stability of the bone will be needed.