Irradiation of cells in tissue culture

Summary

• 1. Rose chambers, uniformly seeded with 10,000 human amnion cells (Fernandes strain), received gamma irradiation doses from a Cobalt⁶⁰ source in a range from 0–25,000 r and under three different levels of oxygen tension.

• 2. Radiation damage was measured in terms of the number of surviving average sized cells and the number of giant cells found in preparations fixed and stained 5 days after irradiation.

• 3. Population studies of the non-giant cells yielded a survival curve which decreased to near extinction in the 0–800 r range. No significant difference in sensitivity was found between the air (21% O₂) series and the oxygen (100% O₂) series for this effect, but some protection against radiation damage was demonstrated when the cells were radiated in an atmosphere of nitrogen.

• 4. The number of giant cells increased between the range of 1000–10,000 r. The maximum numbers of giant cells produced, as related to 1000 control cells, were 42, 74 and 99 for the nitrogen, air and oxygen series, respectively, suggested a rate increase in giant cell formation with increasing oxygen concentration.

• 5. A comparison of the rate of survival of non-giants with the rate of giant cell formation yielded some apparent differences in terms of effective dosage ranges, the form of the curves and the response to increased oxygen tension. These differences suggest that two unrelated mechanisms are involved in the production of these two effects.