title: Quantification of rat retinal growth and vascular population changes after single and split doses of proton irradiation: translational study using stereology methods.
abstract: This study quantified architectural and population changes in the rat retinal vasculature after proton irradiation using stereology. A 100 MeV conformal proton beam delivered 8, 14, 20 and 28 Gy as single and split doses to the whole eye. The vascular networks were prepared from retinal digests. Stereological methods were used to obtain the area of the retina and unbiased estimates of microvessel/artery/vein endothelial, pericyte and smooth muscle population, and vessel length. The retinal area increased progressively in the unirradiated, age-matched controls and in the retinas irradiated with 8 and 14 Gy, indicating uniform progressive retinal growth. No growth occurred after 20 and 28 Gy. Regression analysis of total endothelial cell number in all vessels (arteries, veins and capillaries) after irradiation documented a progressive time- and dose-dependent cell loss occurring over 15 to 24 months. The difference from controls was significant (P<0.01) after 28 Gy given in single and split doses and after 20 Gy given as a split dose (P<0.05). Total vessel length in microvessel was significantly shortened at 20 and 28 Gy compared to that of controls (P<0.05). No evident dose recovery was observed in the endothelial populations after split doses. At 10 Gy, the rate of endothelial cell loss, a dose parameter used to characterize the time- and dose-dependent loss of the endothelial population, was doubled.
authors.affiliation: Radiobiology Program, Department of Radiation Medicine, Loma Linda University Medical Center, Loma Linda, California, USA.
authors.forename: Xiao W
authors.initials: XW
authors.lastname: Mao
authors.forename: John O
authors.initials: JO
authors.lastname: Archambeau
authors.forename: Lucie
authors.initials: L
authors.lastname: Kubínová
authors.forename: Soames
authors.initials: S
authors.lastname: Boyle
authors.forename: Georgia
authors.initials: G
authors.lastname: Petersen
authors.forename: Roger
authors.initials: R
authors.lastname: Grove
mesh_terms: D000818:Animals; D004307:Dose-Response Relationship, Radiation; D004730:Endothelium, Vascular / Q000166:cytology / Q000528:radiation effects; D008297:Male; D008833:Microcirculation; D010196:Pancreatic Elastase / Q000378:metabolism; D011522:Protons; D051381:Rats; D017207:Rats, Sprague-Dawley; D012044:Regression Analysis; D012160:Retina / Q000473:pathology / Q000528:radiation effects*; D012171:Retinal Vessels / Q000528:radiation effects; D013997:Time Factors
chemical_list: D011522:Protons; D010196:Pancreatic Elastase