Experimental study of endovascular irradiation using liquid ~(32)P-filled balloon catheter

Objective:To evaluate the effects of endovascular irradiation on restenosis after interventional therapy and investigate the possible mechanism of restenosis prevention of endovascular irradiation. Method: Balloon injury was performed on rat thoracic aorta. The rats were divided into irradiated group, followed immediately by ionizing radiation using liquid 32P-filled balloon catheter, and injured group, not followed by ionizing radiation. In situ hybridization method was used to detect the mRNA expression of matrix metalloproteinase-9(MMP-9) in the vessel. The proliferation of vascular cells was evaluated by means of immunohistochemistry of the proliferation of cellular nuclear antigen(PCNA). Pathological sections of thoracic aorta were observed to estimate the changes of vascular histomorphology by computer analysis of photomicrogram. The expression of MMP-9mRNA and PCNA was analyzed by image analysis. Result:Founteen days after injury, morphometric analysis indicated that the lumen area and external elastic lamina (EEL) area of the irradiated vessels were significantly larger than that of non irradiated vessels, and these changes appear dose-dependent increase. 1, 3, 7days after injury, there were fewer mRNA expression of MMP-9 in the irradiated vessels, with dose-dependent decrease, than in nonirradiated ones. Conclusion: Endovascular irradiation using liquid 32P-filled balloon catheter system could prevent restenosis. One of its mechanism might be improvement on vascular remodeling, through inhibiting the expression of MMP-9 mRNA.