Pathophysiological changes associated with multiple exposure of ionizing radiation on MRC-5 cells in culture.

The primary mechanism of biological damage to macromolecules from ionizing radiation is an indirect interaction that begins with the radiolysis of water. Ionization of water molecules causes them to split by a process called radiolysis. The event is a cascade of chemical transformations that result in the formation of free radicals. Free radicals are highly reactive particles that can indirectly harm DNA and cause cellular damage. In this study the researchers wanted to observe the cellular damage microscopically. The aim of this study was to assess cell proliferation and structural integrity of the fibroblast by evaluating the MRC-5 cells morphologically after multiple exposures to ionizing radiation. Following exposure 2, 3, or 4 times with a single dose of X-radiation (10Gy), the cells were incubated for 24, 48 and 72 hours. An interesting finding occurred with 3(X) and 4(X) exposure to a dose of 10 Gy. With 3(X) exposure, the cell number decreased after 24, 48 and 72 hours. However, after 4(X) exposure, the cell number increased after all durations. Data analysis revealed that there was a statistically significant difference in the mean values between the treatment groups and the control (p=<0.001) for all durations. The morphological evaluation revealed detached cells, severely swollen cells, and vacuolated cells. After 24, 48 and 72 hours the cells were swollen and pleomorphic, the nucleoli were not as prominent as the groups exposed 3(X) and 4(X) to a dose of 10Gy. After 72 hours the group receiving 2(X) radiation dose revealed a characteristic owl eye nucleoli, usually seen after radiation exposure. After 3(X) and 4(X) the cells showed hydropic swelling and pleomorphism with multiple nucleoli present; these findings showed significant effects caused by free radicals generated from X-radiation.