Mesenchymal stem cells (MSCs) are multipotent cells and can be induced to differentiate into a variety of mesenchymal tissues, including bone and cartilage. We have developed technologies for the regenerative medicine using the MSCs. In order to manipulate patient cells, a cell processing center (CPC) having clean rooms is mandatory. We established a CPC in 2001 and obtained the ISO 13485 quality system certificate in 2005. Clinical applications of more than 80 cases were conducted using the CPC in tandem with hospitals.

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・Research on MSCs as a new cell source for regenerative medicine
Although bone marrow is a potential cell source for the preparation/expansion of MSCs, we succeeded in isolation of MSCs from human dental germ. The cells are isolated from extracted teeth which are usually discarded. We reported their proliferation and differentiation capabilities of many types of tissues. Therefore, the dental germ might be a better source of adult stem cells than bone marrow. Furthermore, we are trying to fabricate MSCs with high proliferation and differentiation potential using gene manipulation techniques.

・Research on cell culture scaffolds for MSCs In vitro culturing of MSCs
from bone marrow on a culture dish or on a ceramic surface could induce bone forming active osteoblasts as well as bone matrix consisting of low-crystalline hydroxyapatite. The in vitro osteogenic differentiation also can be demonstrated by culturing human MSCs on the surface of prosthetic devices. The osteoblasts/bone matrix construct (regenerative cultured bone) exhibits an immediate new bone-forming capability after in vivo implantation. This new bone-forming capability can be attributed to the implanted cultured osteoblasts as well as the bone matrix, which contains cytokines and mineralized crystals. For effective bone regeneration by using MSCs, we are trying to utilize several types of ceramics, biodegradable polymer and metals as scaffolds for MSCs.

・Development of evaluation/measurement technology for bone tissue regeneration In order to evaluate in situ bone forming ability of human MSCs, osteogenic differentiation capability of the MSCs should be investigated. In this regard, we examined the calcium contents of mineralized matrices by measuring calcein incorporation into the matrices during the MSCs culture with a fluorescence image analyzer. On standardization activity, we registered the protocol as a New Work Item Proposal to ASTM (American Society for Testing and Materials) international. In collaboration with a company, we are now developing a new instrument on measuring fluorescence emission of calcein. .

In considering the clinical applications of MSCs, in vitro processing of MSCs is needed. The process may carry risks of bacterial/fungal contaminations. To avoid these risks, biologically safe areas such as a CPC having clean rooms are required. Our CPC consists of three clean rooms (class 1000) and safety cabinets (class 100). Importantly, our CPC has been certified by ISO-13485:2003 on processing of patients’ MSCs. In collaboration with hospitals, we have conducted more than 80 cases of the clinical applications using the CPC..

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