1994 Fiscal Year Final Research Report Summary
A study on the mechanism of decreased osteo genic capacity with aging by rat bone marrow cells
| Project/Area Number |
04836022
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| Research Category |
Grant-in-Aid for General Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Research Field |
老化(加齢)
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| Research Institution | Nara Medical University |
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Principal Investigator |
DOHI Yoshiko Medical School Nara Medical University, Associate Prof, 医学部, 助教授 (50155628)
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| Co-Investigator(Kenkyū-buntansha) |
TABATA Shiro Medical School Nara Medical University, Professor, 医学部, 教授 (40041652)
OHGUSHI Hajime Medical School Nara Medical University, Research Associate, 医学部, 助手 (80213669)
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| Project Period (FY) |
1992 – 1994
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| Keywords | Osteoblast / Ectopic osteogenesis / Aging / Bone marrow / Bone matrix proteins / Osteocalcin / Osteopontin / Differentiation |
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| Research Abstract |
It is presently unclear whether osteoporosis is due to increased bone resorption or to decreased bone formation. A major difficulty has been the scarcity of animal models available for examining the effect of age on bone formation and resorption. We have demonstrated the ability of bone marrow cells to differentiate to form cartilage and bonewithin a diffusion chamber (J.Bone Miner.Res.7 : 1173-1180,1992). Using the diffusion chamber implantation method, we analyzed the bone formation capacity of 8-, 12- and 23-week-old rat bone marrow cells. Measurements of Ca, phosphorus and bone Gla protein (BGP) contents in the DC implants with different aged rat bone marrow clearly demonstrates that bone formation decrease dramatically with over 23-week-old rat bone marrow. Northern blot analysis showed either osteopontin (OP) or BGP mRNAs was expressed intensely in the DC implants with young rat bone marrow. In the DC implants with older rat bone marrow OP mRNA could be detected weakly, whereas BGP mRNA could not.
On the other hand, in vitro subculture of both young and aged rat bone marrow cells showed mineralized nodules and showed the osteoblastic phenotype expression. However, DNA content and alkaline phosphatase (ALP) activity in cultured old marrow cells were slightly lower than those in cultured young marrow cells. These results indicate that osteogenic differentiation of bone marrow declines with age.
And dexamethasone, a differentiation-inducing reagent, seems to be crucial for the osteoblastic differentiation for rat cells, especially old marrow cells.
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