Low dose cranial irradiation-induced cerebrovascular damage is reversible in mice.
BACKGROUND
High-dose radiation-induced blood-brain barrier breakdown contributes to acute radiation toxicity syndrome and delayed brain injury, but there are few data on the effects of low dose cranial irradiation. Our goal was to measure blood-brain barrier changes after low (0.1 Gy), moderate (2 Gy) and high (10 Gy) dose irradiation under in vivo and in vitro conditions.


METHODS
Cranial irradiation was performed on 10-day-old and 10-week-old mice. Blood-brain barrier permeability for Evans blue, body weight and number of peripheral mononuclear and circulating endothelial progenitor cells were evaluated 1, 4 and 26 weeks postirradiation. Barrier properties of primary mouse brain endothelial cells co-cultured with glial cells were determined by measurement of resistance and permeability for marker molecules and staining for interendothelial junctions. Endothelial senescence was determined by senescence associated β-galactosidase staining.


RESULTS
Extravasation of Evans blue increased in cerebrum and cerebellum in adult mice 1 week and in infant mice 4 weeks postirradiation at all treatment doses. Head irradiation with 10 Gy decreased body weight. The number of circulating endothelial progenitor cells in blood was decreased 1 day after irradiation with 0.1 and 2 Gy. Increase in the permeability of cultured brain endothelial monolayers for fluorescein and albumin was time- and radiation dose dependent and accompanied by changes in junctional immunostaining for claudin-5, ZO-1 and β-catenin. The number of cultured brain endothelial and glial cells decreased from third day of postirradiation and senescence in endothelial cells increased at 2 and 10 Gy.


CONCLUSIONS
Not only high but low and moderate doses of cranial irradiation increase permeability of cerebral vessels in mice, but this effect is reversible by 6 months. In-vitro experiments suggest that irradiation changes junctional morphology, decreases cell number and causes senescence in brain endothelial cells.
Division of Molecular Radiobiology and Biodosimetry, "Frédéric Joliot-Curie" National Research Institute for Radiobiology and Radiohygiene, Budapest, Hungary; Doctoral Schools of Pathological Sciences, Semmelweis University, Budapest, Hungary.
Nikolett
N
Sándor
Biological Barriers Research Group, Institute of Biophysics, Biological Research Centre, Hungarian Academy of Sciences, Szeged, Hungary.
Fruzsina R
FR
Walter
Biological Barriers Research Group, Institute of Biophysics, Biological Research Centre, Hungarian Academy of Sciences, Szeged, Hungary.
Alexandra
A
Bocsik
Biological Barriers Research Group, Institute of Biophysics, Biological Research Centre, Hungarian Academy of Sciences, Szeged, Hungary.
Petra
P
Sántha
Division of Molecular Radiobiology and Biodosimetry, "Frédéric Joliot-Curie" National Research Institute for Radiobiology and Radiohygiene, Budapest, Hungary.
Boglárka
B
Schilling-Tóth
Division of Molecular Radiobiology and Biodosimetry, "Frédéric Joliot-Curie" National Research Institute for Radiobiology and Radiohygiene, Budapest, Hungary; Department of Morphology and Physiology, Faculty of Health Care, Semmelweis University, Budapest, Hungary.
Violetta
V
Léner
Department of Oncotherapy, University of Szeged, Szeged, Hungary.
Zoltán
Z
Varga
Department of Oncotherapy, University of Szeged, Szeged, Hungary.
Zsuzsanna
Z
Kahán
Biological Barriers Research Group, Institute of Biophysics, Biological Research Centre, Hungarian Academy of Sciences, Szeged, Hungary.
Mária A
MA
Deli
Division of Molecular Radiobiology and Biodosimetry, "Frédéric Joliot-Curie" National Research Institute for Radiobiology and Radiohygiene, Budapest, Hungary.
Géza
G
Sáfrány
Division of Molecular Radiobiology and Biodosimetry, "Frédéric Joliot-Curie" National Research Institute for Radiobiology and Radiohygiene, Budapest, Hungary; Department of Morphology and Physiology, Faculty of Health Care, Semmelweis University, Budapest, Hungary.
Hargita
H
Hegyesi
D000418:Albumins / Q000737:chemistry; D000818:Animals; D001812:Blood-Brain Barrier / Q000528:radiation effects; D001835:Body Weight; D001921:Brain / Q000098:blood supply* / Q000528:radiation effects*; D001930:Brain Injuries / Q000209:etiology*; D016922:Cellular Senescence; D002560:Cerebrovascular Circulation / Q000528:radiation effects*; D062507:Claudin-5 / Q000378:metabolism; D018920:Coculture Techniques; D004307:Dose-Response Relationship, Radiation; D042783:Endothelial Cells / Q000166:cytology; D005070:Evans Blue / Q000737:chemistry; D005260:Female; D019793:Fluorescein / Q000737:chemistry; D007963:Leukocytes, Mononuclear / Q000166:cytology; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D009457:Neuroglia / Q000166:cytology; D010539:Permeability; D013234:Stem Cells / Q000166:cytology; D062826:Zonula Occludens-1 Protein / Q000378:metabolism; D051176:beta Catenin / Q000378:metabolism
D000418:Albumins; D062507:Claudin-5; C569043:Tjp1 protein, mouse; D062826:Zonula Occludens-1 Protein; D051176:beta Catenin; D005070:Evans Blue; D019793:Fluorescein