Journal of Applied Physiology, Vol 67, Issue 4 1585-1590, Copyright © 1989 by American Physiological Society
Endothelial cell subpopulations in vitro: cell volume, cell cycle, and radiosensitivity
D. B. Rubin, E. A. Drab and K. D. Bauer
Department of Medicine and Therapeutic Radiology, Rush-Presbyterian-St. Luke's Medical Center, and Department of Pathology, Northwestern University Medical School, Chicago, Illinois 60612
Vascular endothelial cells (EC) are important clinical targets of radiation
and other forms of free radical/oxidant stresses. In this study, we found
that the extent of endothelial damage may be determined by the different
cytotoxic responses of EC subpopulations. The following characteristics of
EC subpopulations were examined: 1) cell volume; 2) cell cycle position;
and 3) cytotoxic indexes for both acute cell survival and proliferative
capacity after irradiation (137Cs, gamma, 0-10 Gy). EC cultured from bovine
aortas were separated by centrifugal elutriation into subpopulations of
different cell volumes. Through flow cytometry, we found that cell volume
was related to the cell cycle phase distribution. The smallest EC were
distributed in G1 phase and the larger cells were distributed in either
early S, middle S, or late S + G2M phases. Cell cycle phase at the time of
irradiation was not associated with acute cell loss. However, distribution
in the cell cycle did relate to cell survival based on proliferative
capacity (P < 0.01). The order of increasing radioresistance was cells
in G1 (D0 = 110 cGy), early S (135 cGy), middle S (145 cGy), and late S +
G2M phases (180 cGy). These findings 1) suggest an age-related response to
radiation in a nonmalignant differentiated cell type and 2) demonstrate EC
subpopulations in culture.
