| Budget Amount *help |
¥2,300,000 (Direct Cost: ¥2,300,000)
Fiscal Year 1987: ¥900,000 (Direct Cost: ¥900,000)
Fiscal Year 1986: ¥1,400,000 (Direct Cost: ¥1,400,000)
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| Research Abstract |
Mature white fat cells (unilocular fat cells) have generally been consifered to be in terminal differentiation and, hence, to have no proliferative ability. A new method, referred to as "ceiling culture", has been devised in our laboratory to culture unilocular fat cells in vitro. Under such culture conditions, the fat cells continue to exhibit specific functions of lipid metabolism and proliferate extensively. Intracytoplasmic lipid droplets did not inhibit division of the cells. There were two modes of proliferation of unilocular fat cells: "loculus-dividing" cell division, in which the single loculus of fat in the dividing cell was broken down into multiple droplets and distributed evenly between the daughter cells, and loculus-preserving" cell division, in which the loculus in the dividing cell was minimally broken down and inherited with its shape preserved by one of the daughter cells with the other getting only a small number of fine lipid droplets. Such findings suggest that unilocular fat tissue in vivo are probably capable of proliferation in such modes under some conditions. With such results, fat cells of the obese was examined under the culture condition. First, insulin which is a lipogenie factor is one of the major factors of obesity. Therefore, "loculus-preserving" cell division of fat cells by insulin is compatible with the hyperinsulinemia of the obese. Secondly, large unilocular fat cells derived from the obese could also proliferate under the culture condition.
We hope that the culture system described here will be valuable in studies of the biology of fat cells and the mechanism of obesity.
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