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Low dose cranial irradiation-induced cerebrovascular damage is reversible in mice.

Sándor N, Walter FR, Bocsik A, Sántha P, Schilling-Tóth B, Léner V, Varga Z, Kahán Z, Deli MA, Sáfrány G, Hegyesi H - PLoS ONE (2014)

Bottom Line: 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.Endothelial senescence was determined by senescence associated β-galactosidase staining.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.

View Article: PubMed Central - PubMed

Affiliation: 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.

ABSTRACT

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.

Methodology: 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.

Principle findings: 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.

Conclusion: 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.

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Effect of irradiation on senescence of mouse brain endothelial cells.Ratio of senescence associated-β-galactosidase positive primary mouse brain endothelial cells was determined 5 days after exposure to a single dose of 0, 0.1, 2 or 10 Gy irradiation. Values presented are means ± SD, n = 19 from 2 separate experiments. Data is expressed as percentage of positively stained cells. Statistical analysis: one-way ANOVA followed by Bonferroni post-test. Statistically significant difference p<0.001 (***) is indicated.
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pone-0112397-g009: Effect of irradiation on senescence of mouse brain endothelial cells.Ratio of senescence associated-β-galactosidase positive primary mouse brain endothelial cells was determined 5 days after exposure to a single dose of 0, 0.1, 2 or 10 Gy irradiation. Values presented are means ± SD, n = 19 from 2 separate experiments. Data is expressed as percentage of positively stained cells. Statistical analysis: one-way ANOVA followed by Bonferroni post-test. Statistically significant difference p<0.001 (***) is indicated.

Mentions: Considering that regenerative capacity contributes greatly to endothelial function, we further examined the radiation-induced dose dependency of cellular senescence in MBECs. SA-β-gal staining, a characteristic feature of senescent cells [43] was tested in irradiated MBECs. The percentage of SA-β-gal-positive cells did not change in the 0.1 Gy irradiation group, but significantly increased by 30 and 40% at 2 and 10 Gy exposure as compared to unirradiated controls at day 5 (Figure 9). A flow cytometric method (Text S1) was used to analyze the repair kinetics of double strand DNA breaks in irradiated MBECs. Irradiation induced a dose-dependent increase in the phosphorylation of H2A.X at 10 min (Figure S4). In 0.1 and 2 Gy irradiation group repair was complete by 1 h posttreatment. In the 10 Gy irradiation group phosphorylation of H2A.X was still elevated not only at 1 and 4 h, but remained higher than the baseline level by 24 h indicating impaired repair capacity in MBECs.


Low dose cranial irradiation-induced cerebrovascular damage is reversible in mice.

Sándor N, Walter FR, Bocsik A, Sántha P, Schilling-Tóth B, Léner V, Varga Z, Kahán Z, Deli MA, Sáfrány G, Hegyesi H - PLoS ONE (2014)

Effect of irradiation on senescence of mouse brain endothelial cells.Ratio of senescence associated-β-galactosidase positive primary mouse brain endothelial cells was determined 5 days after exposure to a single dose of 0, 0.1, 2 or 10 Gy irradiation. Values presented are means ± SD, n = 19 from 2 separate experiments. Data is expressed as percentage of positively stained cells. Statistical analysis: one-way ANOVA followed by Bonferroni post-test. Statistically significant difference p<0.001 (***) is indicated.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4231057&req=5

pone-0112397-g009: Effect of irradiation on senescence of mouse brain endothelial cells.Ratio of senescence associated-β-galactosidase positive primary mouse brain endothelial cells was determined 5 days after exposure to a single dose of 0, 0.1, 2 or 10 Gy irradiation. Values presented are means ± SD, n = 19 from 2 separate experiments. Data is expressed as percentage of positively stained cells. Statistical analysis: one-way ANOVA followed by Bonferroni post-test. Statistically significant difference p<0.001 (***) is indicated.
Mentions: Considering that regenerative capacity contributes greatly to endothelial function, we further examined the radiation-induced dose dependency of cellular senescence in MBECs. SA-β-gal staining, a characteristic feature of senescent cells [43] was tested in irradiated MBECs. The percentage of SA-β-gal-positive cells did not change in the 0.1 Gy irradiation group, but significantly increased by 30 and 40% at 2 and 10 Gy exposure as compared to unirradiated controls at day 5 (Figure 9). A flow cytometric method (Text S1) was used to analyze the repair kinetics of double strand DNA breaks in irradiated MBECs. Irradiation induced a dose-dependent increase in the phosphorylation of H2A.X at 10 min (Figure S4). In 0.1 and 2 Gy irradiation group repair was complete by 1 h posttreatment. In the 10 Gy irradiation group phosphorylation of H2A.X was still elevated not only at 1 and 4 h, but remained higher than the baseline level by 24 h indicating impaired repair capacity in MBECs.

Bottom Line: 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.Endothelial senescence was determined by senescence associated β-galactosidase staining.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.

View Article: PubMed Central - PubMed

Affiliation: 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.

ABSTRACT

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.

Methodology: 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.

Principle findings: 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.

Conclusion: 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.

Show MeSH
Related in: MedlinePlus