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ECOLOGY OF HUMAN HEMIC CELLS EDWIN E. OSGOOD* The purpose ofthis paper is to emphasize and illustrate the importance of thinking in terms of an ecology of cells in planning and interpreting all experiments with cells either in culture or in vivo. Ecology may be defined as the interaction ofliving things with each other and with thelr total environment.Twodramaticillustrations ofthe importance ofecology in the mammalian body are the marrow transplant experiments [i] which show that cells injected intravenously grow not primarily in the lungs, where the greatest number lodge, but in the blood-forming organs, and the observation that malignant tumors have a predilection for particular sites ofspontaneous metastases [2] or growth [3] ifexperimentally injected intravenously. Our concepts of the alpha-2 alpha, alpha-?, and n-2n cell divisions in a multicellular organism, which we now regard as established [4-^7], aids in understanding these interactions. To make our concept completely general , we call the cell capable ofdivision which remains immature to divide again the alpha cell. This cell alone makes possible culture, transplants, or malignancies. Ifthe alpha-2 alpha division occurs, the population and all products ofthese cells will double. This cell alone maintains somatic genetic continuity. Such alpha-2 alpha divisions occur at long, unequal intervals during growth [8] but may occur at frequent, equal intervals in the single- * Division ofExperimental Medicine, University ofOregon Medical School, Portland, Oregon This research was supported in part by grants from the U.S. Atomic Energy Commission, Contract AT(45-i)-58r, the U.S. Public Health Service, National Cancer Institute grant CY-3374, and the Medical Research Foundation ofOregon. This paper was presentedat the Conference on Blood-Bone Marrow Tissue Culture and Cell Separation, October 20, 1961, in Bethesda, Maryland,joindy sponsored by the National Cancer Institute and Oak Ridge National Laboratory. The author is indebted to all those from the Division ofExperimental Medicine at the University ofOregon Medical School whose names appear in the references cited for their contributions to this paper. 228 Edwin E. Osgood · Ecology ofHuman Hemic Cells Perspectives in Biology and Medicine · Winter 1963 celled organism or in culture. In the healthy adult, essentially all divisions are ofthe alpha-? variety—one cell matures and dies and the other remains immature as an alpha cell. However, n-2n divisions may also occur—both cells mature and die but, ofcourse, are lost to all genetic continuity. For each such n-2n division, the alpha-? division must be at twice the interval otherwise necessary to maintain a steady ratio of? cells to alpha cells. The primary regulator of growth is a pair of specific inhibitors feeding back from the ? cell ofa series to an alpha cell ofthe same series. Inhibitors of alpha-2 alpha divisions are produced early in the life span of the ? cell, and the inhibitor ofthe alpha-? division is produced late in the life span of the ? cell. The letter ? was chosen for this cell since one can divide this table l Ecologic Factors Major CategoriesSubcategories Physical factors (soil) ....... Space, time, surface, fluid suspension, viscosity of media, flow rates, shearing forces, charge distribution, radiation Microclimate (gradient). . . .Temperature, pH, O3 tension, COi tension, oxidation-reduction potential, osmolarity, colloid osmolarity Essential nutrients .........H2O, amino acids, dextrose, lipids, electrolytes, trace elements, vitamins Bioenvironment...........Adjacent cells and their products; Specific: inhibitors (alpha-2 alpha, alpha-?), accelerators, or antibodies; Less specific: hormones, inducers, organizers; Nonspecific: blood flow, lymph flow, membrane permeability, cell density; Infection Pharmacologic............Agent, dose rate= concentration/time life span into as many stages as desired. The number ofcells will be proportionate to the duration of time in that stage when there is essentially no reproduction ffigs. 3 to 7 in ref. 5], just as there are approximately eight times as many children in a primary school of eight grades as there are children in die fourth grade. The major groups ofecologic factors which must be considered in every tissue culture experiment and in all thinking about living cells in the body are outlined in Table 1 opposite die major categories shown. The subdivisions ofthe categories are far from complete and, ofcourse, it would take a bookto summarize the subdivisions ofthe pharmacologic categories. Table 2 summarizes measurable criteria ofthe...

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Additional Information

ISSN
1529-8795
Print ISSN
0031-5982
Pages
pp. 228-232
Launched on MUSE
2015-01-07
Open Access
No
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