Microbeam radiation-induced tissue damage depends on the stage of vascular maturation.

摘要: Purpose To explore the effects of microbeam radiation (MR) on vascular biology, we used chick chorioallantoic membrane (CAM) model an almost pure system with immature vessels (lacking periendothelial coverage) at Day 8 and mature (with 12 development. Methods Materials CAMs were irradiated microplanar beams (width, ∼25 μm; interbeam spacing, ∼200 μm) entrance doses 200 or 300 Gy and, for comparison, a broad beam (seamless [SLR]), 5 to 40 Gy. Results In vivo monitoring Day-8 CAM vasculature 6 h after MR revealed near total destruction capillary plexus. Conversely, barely affected Day-12 microvasculature. Morphological evaluation dose was increased opened interendothelial junctions, which could explain transient mesenchymal edema immediately irradiation. Electron micrographs cytoplasmic vacuolization endothelial cells in path, disrupted luminal surfaces; often lumen engorged erythrocytes leukocytes. After 30 min, plexus adopted striated metronomic pattern, alternating destroyed intact zones, corresponding paths within array. SLR 10 caused growth retardation, resulting remarkable reduction endpoint density 24 postirradiation. A damaged entire vasculature. Conclusions The are mediated by damage, tissue injury insufficient blood supply. Vascular toxicity physiological depend stage maturation appear first 15 60 min SLR, due arrest cell proliferation, persist longer time.