Change of Responsiveness to Growth Stimulation of Normal Cells during Aging
The sole determinant of life span of normal diploid cells in vitro has been considered to be the intrinsic doubling number of the cells (1,2,3). Recent investigations, however, suggest that extracellular factors can affect the proliferative potential of the cells. For example, hydrocortisone (4) and epidermal growth factor (5) elongate the life span of fibroblasts and keratinocytes, respectively. In vivo experiments also suggest that the milieu in old animals reduces the growth potential of hematopoietic stem cells (6). However, quantitative relationships between cellular growth potential and factors which are supposed, or have been known, to influence cellular growth potential are obscure. This report describes the relationship between the amount of growth stimulating factors and cellular growth potential in the course of aging in vitro, and discusses a possible growth property of divergent cells in a cell population.
KeywordsConstant Growth Rate Human Lung Fibroblast Growth Stimulate Factor Population Doubling Level Dialyze Fetal Bovine Serum
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- 4.V. J. Cristofalo, Metabolic aspects of aging in diploid human cells, in “Aging in Cell and Tissue Culture,” E. Holeckova and V. J. Cristofalo, eds., Plenum Press, New York (1970).Google Scholar
- 10.H. Orimo and H. Ito, Glucose intolerance in the aged, Jap. J. Geriat. 13:157, 1976.Google Scholar