Radiation Sensitivity of Human Bone Marrow Cells Measured by a Cell Culture Method

By J. S. SENN AND E. A. MCCULLOCH A METHOD IS NO\V AVAILABLE for testing the proliferative capacity of a class of human hemopoietic precursor cells.’ The technique is a modification of that developed by Bradley and Metcalf2 for the study of mouse marrow in culture, and depends upon the production of colonies from aspirated marrow cells in the presence of suitable “feeder cells.” The precise significance of the human cells of origin of these colonies is unknown; however, it is likely that they play a significant role in granulopoiesis, since peroxidase positive granulocytes are among their progeny. Further, cells from mice that give rise to colonies under similar cultural conditions also contain granulocytes,2’3 and have been shown to be closely correlated with the mouse hemopoietic stem cells that give rise to spleen colonies.4’5 It seems reasonable, therefore, to use the culture method for the investigation of human hemopoiesis. In the present paper, the culture method has been used to assess the radiation sensitivity of human bone marrow cells. Previous studies of the radiation sensitivity of marrow have been made either in rodents6-8 or in cell culture systems less obviously related to hemopoiesis than the one employed in our studies.#{176} These measurements of radiation sensitivity have all yielded values of the same order as that found for the proliferative integrity of mammalian cells in general.’#{176} This finding led to the conclusion that human bone marrow cells might be expected to have a similar radiation sensitivity. The availability of a culture technique applicable to human marrow cells permitted us to test this view directly by comparing the radiation sensitivity of human and mouse marrow using the same technique to assess survival. The results indicate that a class of human marrow cells has a radiation sensitivity similar to that of a comparable class of mouse marrow cells.