Background Vessel wall responses to percutaneous transluminal coronary angioplasty include neointimal proliferation and arterial remodeling. The contraction of a collagen gel is a good in vitro model of wound repair and vascular remodeling. Because irradiation is an important new therapeutic modality capable of preventing restenosis, the purpose of this study was to evaluate the effect of irradiation on the contraction of a collagen gel by smooth muscle cells (SMCs), on SMCs viability, and on DNA synthesis.
Methods We studied the effect of different doses of gamma-irradiation (0 [control], 6, 12, and 18 Gy) on the contraction of a collagen gel seeded with SMCs (calf carotid arteries) during a period of 15 days.
Results Maximal gel diameter reduction (from 35 to 6.8 mm, ±0.5 mm in control) was markedly inhibited in the 6-, 12-, and 18-Gy groups (35 to 13.7 mm, ±0.8 mm; 35 to 15.5 mm, ±0.9 mm; and 35 to 16.1 mm, ±0.9 mm, respectively; P<0.0001). The irradiated gels showed a dose-dependent reduction in the SMC proliferation rate (P<0.0001) and an increase in the number of nonviable SMCs (P<0.002) 15 days after irradiation.
Conclusions Gamma-irradiation produces a significant dose-dependent inhibition of the contraction of collagen gels seeded with arterial SMCs. This effect is related to a significant decrease in SMC viability and a decrease in SMC proliferation rate. These findings shed light on mechanisms whereby irradiation may positively affect arterial remodeling after percutaneous transluminal coronary angioplasties.