| Budget Amount *help |
¥3,500,000 (Direct Cost: ¥3,500,000)
Fiscal Year 2006: ¥1,800,000 (Direct Cost: ¥1,800,000)
Fiscal Year 2005: ¥1,700,000 (Direct Cost: ¥1,700,000)
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| Research Abstract |
Embryonic, stem (ES) cells are pluripotent cells derived from the inner cell mass of blastocysts, which differentiate into all three germ layers. Because of this property, ES cells offer a great promise for regenerative medicine. Experimental manipulation of ES cell differentiation provides a model of mammalian development that is amenable to molecular and cellular analysis. To develop an application method for maxillofacial regeneration therapy, we should understand the mechanisms of maxillofacial development. Activin A can induce the Xenopus presumptive ectoderm (animal cap) to form different types of mesoderm and endoderm at different concentrations and the animal cap treated with activin can function as an organizer during early development. The dissociated Xenopus animal cap cells treated with activin form an aggregate and it develops into various tissues in vitro. To induce jaw cartilage from undifferentiated cells effectively, we developed a culture method to manipulate body pat
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terning in vitro, using activin A and dissociated animal cap cells. When activin A-treated cells were mixed with untreated cells at a ratio of 1:5, the aggregate developed cartilage with the maxillofacial regional marker genes, goosecoid, Xenopus Distal-less 4 and X-Hoxa2. When this aggregate was transplanted into the abdominal region of host embryos, maxillofacial structures containing cartilage and eye developed. We raised these embryos to adulthood and found that tooth germ had developed in the transplanted tissue. This differentiation system will help to promote a better understanding of the regulating mechanisms of body patterning and tooth induction in vertebrates.
We have developed a serum-free medium, designated ESF7, in which leukemia inhibitory factor (LIF) clearly stimulated murine embryonic stem (ES) cell proliferation accompanied by increased expression of nanog and Rex-1 and decreased FGF-5 expression. Addition of BMP4 promoted ES cell differentiation into simple epithelial-like cells. In contrast, FGF-2 promoted ES cell differentiation into neuronal and glial-like cells. Under serum-free culture conditions, LIF was sufficient to stimulate cell proliferation, it inhibited cell differentiation, and it maintained self-renewal of ES cells. Because this simple serum-free adherent monoculture system supports the long-term propagation of pluripotent ES cells in vitro, it will allow the elucidation of ES cell responses to growth factors under defined conditions. We predict that these basic scientific studies will promote a step toward the development of the application for maxillofacial regeneration therapy. Less
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