Papers by Author: J.T. Kim

Abstract: To improve ostegenic healing efficiency by demineralized bone matrix, we evaluated the ectopic bone formation induced by variously demineralized allogenic cortical bone matrices at subcutaneous and muscular sites in rats. The rat tubular cortical bone matrices were demineralized in heated 0.6N HCl at 60 °C for 5 and 20 mins, respectively, using a controlledheat ultrasonic cleaner and implanted in rat dorsal subcutaneous pouches and thigh muscles for 1-3 weeks. The influence of the demineralized condition of bone matrix on cellular proliferation and osteogenic differentiation was also evaluated in vitro by MTT assay and ALP staining. The cortical matrices were completely demineralized within 20 mins by sonication and heating of diluted 0.6 N HCl. The sonicated bone matrices in heated acidic solution at 60 °C revealed no adverse immunogenic and inflammatory response in vivo regardless of demineralized condition. Cellular proliferation and osteoblastic differentiation was facilitated by more fully demineralized. Ectopic bone formation was induced only by demineralized bone matrices and were more favorable in fully demineralized matrices. The ectopic bone induction was more favorably in subcutaneous pouches than in muscular tissue. These findings suggest that a fully demineralized cortical bone matrix maximizes osteogenic repair by exposing more bioactive molecules which in turn induce chondro- and osteognic differentiation of mesenchymal cells around the implanted matrices, and that the sonication of diluted 0.6 N HCl heated at 60 ° C is a rapid and effective method for sterile demineralized graft preparation.

Abstract: As a part of the effort to develop a suitable scaffold for tissue-engineered bone regeneration, we modified calcium metaphosphate (CMP) ceramic with Na20 and evaluated its efficiency as a scaffold. We incorporate 5% Na20 into pure CMP and prepare for an average pore size of 250 or 450 µm average pore sizes. The incorporation of 5% Na2O caused reduced compressive strength and there was no change in biodegradability. The in vitro cellular attachment and proliferation rate, however, were slightly improved. The 5% Na2O-incorporated macroporous CMP ceramic-cell constructs treated with Emdogain induced ectopic bone formation more effectively than those without Emdogain treatment. These results suggest that the incorporation of 5% Na2O into pure CMP is not effective for improving the physical characteristics of pure CMP but it is positive for improving the cellular reaction and osteogenic effect with the addition of Emdogain.