Tadakatsu Kasai

Dentinogenic ghost cell tumor: histologic aspects, immunohistochemistry, lectin binding profiles, and biophysical studies.

Dentinogenic ghost cell tumor accompanied with calcifying odontogenic cyst (COC) was described in terms of its clinical, histological, immunohistochemical, lectin binding and biophysical properties. The case was a 38-year-old Japanese female, in whom the tumor had arisen in the right mandibular premolar and molar region. Material obtained by partial mandibulectomy was used. Decalcified paraffin sections were used to detect keratins, involucrin, and lectin binding; and non-decalcified thin sections were used for biophysical analysis. The lesion comprising dentinogenic ghost cell tumor and COC contained odontogenic epithelium with ghost cells, eosinophilic amorphous materials and osteodentin. Some of the eosinophilic material had undergone transformation into osteodentin. Keratins in odontogenic epithelia showed positive PKK1 staining in peripheral tumor cells, and stainings with KL1 and involucrin were positive in centrally located cells. Lectin binding in the amorphous materials was comparatively strong for PNA, and SBA, moderate for WGA, RCA-1, and UEA-1, and slight for DBA and ConA. Lectin binding affinities were higher in the amorphous materials than in the osteodentin. Elemental analysis with an electron probe X-ray microanalysis of the amorphous materials and osteodentin showed a pattern similar to that found in the normal dentin. The biologic properties of the eosinophilic amorphous materials suggested the material to be poorly calcified osteodentin, which gradually transformed into the well-calcified type.

Bone tissue engineering using porous carbonate apatite and bone marrow cells.

Porous blocks of carbonate apatite (CA) were prepared by holding together CA particles ranging in size from 300 to 500 &mgr;m through sintering at 750°C for 2 hours. Bone marrow cells taken from Fischer rats were seeded onto and inside the CA blocks and cultured for 14 days to allow stem cells to proliferate to osteoblasts capable of inducing bone formation. Hybrids made of CA blocks and cultured bone marrow cells were then implanted into the back of syngeneic rats. Microfocus x-ray computed tomographic images of tissues containing CA blocks before decalcification suggested that new bone was formed in this extraosseous site 4 and 8 weeks after implantation. These data indicate that the hybrid made of CA and bone marrow cells is capable of inducing heterotopic bone formation in vivo.