Papers by Author: Akira Oshima

Abstract: This study focused on in vivo osteogenic capability of bone marrow mesenchymal stem cells (MSCs) seeded on ceramic scaffold. Human MSCs from a single donor were seeded on hydroxyapatite porous ceramic (HAP) and were induced to the osteogenic lineage during in vitro culture condition, then the MSCs/HAP composites were implanted subcutaneously into immunodeficient rats. The cellular activities of the composites were assayed in order to evaluate the distribution and differentiation capability of seeded MSCs before and after implantation. These results showed that the new bone, after implantation, was derived from the donor MSCs, which adhered to the surface of the ceramics pore areas during in vitro culture. Therefore, the engrafted donor cells proliferated and showed continuous osteogenic differentiation within the recipients. Consequently, our study demonstrates the usefulness of MSCs/HAP composites for clinical applications.

Abstract: After culture expansion of mesenchymal stem cells (MSCs) from a few milliliter of fresh patient’s bone marrow, we applied the MSCs on alumina ceramic ankle prosthesis and further cultured in an osteogenic medium for 2 weeks. After the culture, the MSCs differentiated into osteoblasts, which fabricated bone matrix on the surface of ceramic prosthesis. The expansion of MSCs followed by osteogenic differentiation was done using the commercially available medium with some chemicals and patient’s own serum. The MSCs well proliferated and differentiated into osteoblasts, even the MSCs were from old aged (more than 70 years old) patients. The tissue engineered ceramic prostheses were implanted into osteoarthritic patients. Typical X-ray findings showed that radiodense areas began to appear around the cell-seeded areas on the prosthesis about 2 to 3 months after the operation. These findings confirmed the importance of tissue engineering approach for early bone fixation and the approach can be done using small number of bone marrow cells and patient’s own serum without adding animal-derived products.

Abstract: Cultured osteoblasts with mineralized matrix (regenerative cultured bone; RCB) have been used for patients having osseous defects. The RCB can be fabricated on various ceramic substrata using patient’s mesenchymal stem cells (MSCs) at our cell processing center (CPC). Since we have to transport the RCB for hospitals outside of our town, the RCB should maintain the cell viability for a long time. To determine a suitable condition for transportation of the RCB, stability of the RCB was analyzed by biochemical assays. Even outside CO2 incubator, the RCB kept high level of viability until 24 hours at 25°C and also showed low level of cytotoxicity for 24 hours at 37°C and 25°C. On the other hand, the RCB incubated for 24 hours at 4°C outside CO2 incubator resulted in extremely low level of viability with obvious cytotoxicity. These data indicated that stability of the RCB can be maintained for 24 hours at 37°C and 25°C, but not at 4°C. Therefore, the RCB derived from patient’s MSCs can be transported and utilized for the patients at hospitals far away from the CPC.

Abstract: Alumina ceramics have excellent mechanical and biocompatible properties, but are bioinert and hence have no bone-bonding properties. We took a tissue engineering approach in an attempt to modify the ceramic surface and so provide an osteogenic/osteoconductive milieu. We used fresh human bone marrow cells obtained from the iliac crest by needle aspiration for culture expansion of mesenchymal stem cells (MSC) followed by in vitro osteogenic differentiation on both tissue culture polystyrene (TCPS) and alumina ceramics. We have succeeded in expanding the number of MSC from all 35 cases and compared the differentiation capability of selected MSC on alumina ceramics to that on TCPS. The cells on both substrata showed extensive alkaline phosphatase staining and mineralization as evidenced by calcein uptake. Biochemical analyses revealed high levels of alkaline phosphatase activity, osteocalcin expression, and calcium content. These data indicate that an alumina ceramic surface can support a differentiation cascade of MSC resulting in osteoblastic phenotype expression of the cells. Based on these results, we have performed clinical applications of tissue engineered total joint replacements for osteoarthritic patients.