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

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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.