Radiation survival of vascular smooth muscle cells as a function of age.

Late damage to normal tissues is an important consideration in determining the dose of radiation which can be delivered to a given target volume in clinical radiation therapy. The response of large blood vessels to radiation injury is undoubtedly complex and is influenced by (1) the cellular composition of the vessel wall, (2) the slow turnover of vascular cells, and (3) vascular repair mechanisms. As a first order model for radiation effects in large vessels, we have studied the radiobiologic properties of cultured vascular smooth muscle cells. We have measured survival curves and repair of sublethal radiation damage in exponentially growing cultures of rat aortic smooth muscle cells as a function of animal age and site of origin (thoracic versus abdominal aorta). Radiation survival parameters (utilizing two different mathematical models for the survival curve) and repair of sublethal damage did not appear to vary significantly as a function of animal age (3-23 months) or site or origin.