Papers by Author: J.M. Lee

Abstract: To develop a suitable scaffold for tissue-engineered bone regeneration, we compared the efficiency of tissue-engineered bone regeneration according to the porous structure of calcium metaphosphate (CMP) ceramic scaffolds. Each scaffold was prepared with a sponge method and a foam-gel method, respectively. Both scaffolds, having either interconnected trabecular pores formed by the sponge method or fully interconnected globular pores formed by the foam-based technology, were not cytotoxic and elicited neither an immune nor an inflammatory response regardless of geometry and fabrication method. The fully interconnected globular porous scaffold showed more favorable compression strength and facilitated osteogenic repair by favoring cellular attachment and osteogenic differentiation with good osteoconductivity compared to the interconnected trabecular pore structured scaffold. These results suggest that the fully interconnected globular porous structure would be more suitable for both a bone substitute and scaffold for bioactive material-based or cell-based tissue bone regeneration.

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: Osteogenic repair is highly dependant upon the substrate carrier or matrix. As a part of the effort to develop a suitable scaffold optimizing bone regeneration, we evaluated the efficiency of bovine bone ash particles, prepared by ashing at 600 °C for 8 hrs and pulverizing to 150-250 µm size particles, as a scaffold for bone tissue regeneration. The non-cytotoxic bovine bone ash particles, evaluated by Agar over lay test, showed no disturbance in cellular proliferation and osteogenic differentiation in an in vitro cell culture system. Furthermore, the implanted bone ash particles in artificial bone defects on rat mandible revealed favorable biocompatibility and regeneration of bone and dentin associated with bone ash particles. The new bone and reparative dentin were well integrated with bone ash particles. These findings suggest that allogenic bone ash particles composed mainly of hydroxyapatite are applicable for repair of tooth related bone defects as well as pulp damaged tooth repair.