DIFFERENTIATION AND DELAYED CELL-DEATH IN EMBRYONAL STEM-CELLS EXPOSED TO LOW-DOSES OF IONIZING-RADIATION

Embryonal stem cells have been used to study the effects of environmen tally relevant doses of radiation on cell death and differentation. Th e ES cells were found to have a greater than 60% chance of surviving t he traversal of a single a-particle, the lowest possible dose of high linear energy transfer radiation a cell may receive. The ES cells appe ared to possess the cell cycle checkpoints believed to prevent the tra nsmission of the radiation damage. However, delayed effects were obser ved in the progeny. An increased incidence of apoptosis and haempoieti c differentiation capacity was found to persist in the ES cell populat ion over many cell divisions. Since both cell death and differentiatio n are known to play a key role in tissue kinetics, an ES cell model wi ll provide a valuable and versatile cell system for studying the role of cell death and differentiation in the pathology of radiogenic disea ses.