Differences in the X-ray sensitivity of cells in different regions of the sandwich, a diffusion-limited system for...

The sandwich system was recently developed as a tumor analog; like spheroids, sandwiches are diffusion-limited multicellular systems which exhibit a necrotic center and a viable cell border. Using sandwiches of the 9L cell line, we compared the X-ray sensitivity of cells in the inner half of the viable border, adjacent to the necrotic center, with that of cells in the outer half of the viable border, adjacent ot the medium. No cells were hypoxic at the time of irradiation. The cells in the inner half of the viable border exhibited an increased radioresistance over cells in the outer half. The effect was dose multiplying with a multiplying factor of 1.5. Besides the sandwich studies, the X-ray sensitivity of 9L plateau monolayer cultures (induced by starvation) was compared to exponentially growing monolayer cultures. The plateau cultures exhibited an increased radioresistance over the exponentially growing cultures. The effect was also dose multiplying with a multiplying factor of 1.5.