In vitro response of human and porcine vascular cells exposed to high doserate gamma-irradiation

Aim: The objective of this study was to compare the in vitro response of hu man and pig endothelial cells, smooth muscle cells and fibroblasts exposed to conventional high dose-rate gamma-irradiation. Materials and methods: Clonogenic cell survival and growth responses were o btained after irradiation of plateau-phase cells with a Co-60 source at a d ose-rate of 1.5 Gy/min. DNA single-strand breaks were also evaluated using an alkaline filter elution technique. Results: Overall, both the pig and human cell lines showed a similar respon se to conventional high dose-rate irradiation. Using clonogenic assays, the human aortic smooth muscle cell line was more sensitive than the fibroblas t and endothelial cell lines, whereas the pig endothelial cell line was mor e sensitive than smooth muscle cells and fibroblasts. Shortly after irradia tion (10 days) there was a temporary growth arrest, which was similar for e ndothelial, smooth muscle cells and fibroblasts with doses above 6 Gy. Ther e was also a non-linear, dose-dependent growth delay up to 4 weeks after ir radiation. This effect was also consistent between the different cell lines . Using alkaline filter elution, there was no significant difference in rel ative elution between endothelial cells, smooth muscle cells and fibroblast s, indicating similar DNA damage among the different cell lines. Conclusion: The in vitro response of human and pig endothelial cells, smoot h muscle cells and fibroblasts exposed to high dose-rate irradiation appear ed similar. The pig model seems well suited to evaluate the short- and long -term effects of ionizing radiation in the prevention of restenosis after v essel injury.