[High-dose external ionizing radiation prevents intimal hyperplasia and limits secretion of growth factors PDGFbb, bFGF, and TGFb1. Experiments and results]

To evaluate the ionizing radiation for intimal hyperplasia prevention and to assess the production of growth factors.An oversized injury using an embolectomy catheter was performed on a rabbit distal aorta (N=23), associated (test group; N=12) or not (control group; N=11) with a post-operative external radiation (25 Gy). At t=45 days, histological studies and morphometric studies were performed on the aorta. Smooth muscular cells and endothelial cells were stained using immuno-histologic revelation. Immuno-histological analysis was performed on arteries for growth factors PDGFbb, bFGF and TGFb1.Twenty-one animals survived the procedure, 11 were in the test group and 10 in the control group. Intimal thickness and ratio intima/media were significantly lower after radiation (respectively p=0.008, p=0.008). There was no difference for the medial thickness (p=0.155). Immuno-histochemical positive staining for PDGF and TGFb1 was lower after radiation (respectively 18.44 +/- 2.963% versus 47.64 +/- 6.86%, p0.001 and 10.11 +/- 3.18% versus 29.45 +/- 4.156%, p0.001). There was no difference for the expression of bFGF growth factor. After radiation, the media was found to be reduced and replaced by interstitial fibrosis.After external radiation the thickness parameter of the intima and the ratio intima/media decreased significantly in comparison with the control group. PDGF and TGFb1 were also less expressed in the artery irradiated. Fibrosis recasting needs to be confirmed by further investigation.