Planar Proton Minibeam Irradiation Elicits Spatially Confined DNA Damage in a Human Epidermis Model

Scherthan, Harry; Wagner, Stephanie-Quinta; Grundhöfer, Jan; Matejka, Nicole; Müller, J. W.; Müller, Steffen; Rudigkeit, Sarah; Sammer, Matthias; Schoof, Sarah; Port, Matthias; Reindl, Judith

doi:10.3390/cancers14061545

Cited by 6 publications

(4 citation statements)

References 49 publications

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“…The immunofluorescent staining of the ethanol-fixed PBMCs with γ-H2AX and 53BP1 antibodies was carried out as described by Scherthan et al [ 27 ]. The classification and evaluation of DNA damage followed the protocol described by Schumann et al [ 6 ].…”

Section: Methodsmentioning

confidence: 99%

Repair of α-particle-induced DNA damage in peripheral blood mononuclear cells after internal ex vivo irradiation with 223Ra

Göring

Schumann

Müller

et al. 2022

Eur J Nucl Med Mol Imaging

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Purpose As α-emitters for radiopharmaceutical therapies are administered systemically by intravenous injection, blood will be irradiated by α-particles that induce clustered DNA double-strand breaks (DSBs). Here, we investigated the induction and repair of DSB damage in peripheral blood mononuclear cells (PBMCs) as a function of the absorbed dose to the blood following internal ex vivo irradiation with [223Ra]RaCl2. Methods Blood samples of ten volunteers were irradiated by adding [223Ra]RaCl2 solution with different activity concentrations resulting in absorbed doses to the blood of 3 mGy, 25 mGy, 50 mGy and 100 mGy. PBMCs were isolated, divided in three parts and either fixed directly (d-samples) or after 4 h or 24 h culture. After immunostaining, the induced γ-H2AX α-tracks were counted. The time-dependent decrease in α-track frequency was described with a model assuming a repair rate R and a fraction of non-repairable damage Q. Results For 25 mGy, 50 mGy and 100 mGy, the numbers of α-tracks were significantly increased compared to baseline at all time points. Compared to the corresponding d-samples, the α-track frequency decreased significantly after 4 h and after 24 h. The repair rates R were (0.24 ± 0.05) h−1 for 25 mGy, (0.16 ± 0.04) h−1 for 50 mGy and (0.13 ± 0.02) h−1 for 100 mGy, suggesting faster repair at lower absorbed doses, while Q-values were similar. Conclusion The results obtained suggest that induction and repair of the DSB damage depend on the absorbed dose to the blood. Repair rates were similar to what has been observed for irradiation with low linear energy transfer.

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Section: Methodsmentioning

confidence: 99%

Repair of α-particle-induced DNA damage in peripheral blood mononuclear cells after internal ex vivo irradiation with 223Ra

Göring

Schumann

Müller

et al. 2022

Eur J Nucl Med Mol Imaging

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“…Since the results of the alkaline comet assay cannot differentiate between the formation of SSBs and DSBs, we also applied the γH2AX+53BP1 foci method to detect DSBs. This in situ stinging method can discriminate apoptotic cells [ 18 , 35 ]. The analysis of DSB-indicating foci [ 15 ] revealed that HBO exposure as well as the exposure to ambient air in the experimental chamber failed to induce an increased number of DSB foci in either cell line.…”

Section: Discussionmentioning

confidence: 99%

Analysis of Single- and Double-Stranded DNA Damage in Osteoblastic Cells after Hyperbaric Oxygen Exposure

Schönrock¹,

Tillmans²,

Sebens

et al. 2023

Antioxidants

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(1) Background: Hyperbaric oxygen (HBO) exposure induces oxidative stress that may lead to DNA damage, which has been observed in human peripheral blood lymphocytes or non-human cells. Here, we investigated the impact of hyperbaric conditions on two human osteoblastic cell lines: primary human osteoblasts, HOBs, and the osteogenic tumor cell line SAOS-2. (2) Methods: Cells were exposed to HBO in an experimental hyperbaric chamber (4 ATA, 100% oxygen, 37 °C, and 4 h) or sham-exposed (1 ATA, air, 37 °C, and 4 h). DNA damage was examined before, directly after, and 24 h after exposure with an alkaline comet assay and detection of γH2AX+53BP1 colocalizing double-strand break (DSB) foci and apoptosis. The gene expression of TGFß-1, HO-1, and NQO1, involved in antioxidative functions, was measured with qRT-PCR. (3) Results: The alkaline comet assay showed significantly elevated levels of DNA damage in both cell lines after 4 h of HBO, while the DSB foci were similar to sham. γH2AX analysis indicated a slight increase in apoptosis in both cell lines. The increased expression of HO-1 in HOB and SAOS-2 directly after exposure suggested the induction of an antioxidative response in these cells. Additionally, the expression of TGF-ß1 was negatively affected in HOB cells 4 h after exposure. (4) Conclusions: in summary, this study indicates that osteoblastic cells are sensitive to the DNA-damaging effects of hyperbaric hyperoxia, with the HBO-induced DNA damage consisting largely of single-strand DNA breaks that are rapidly repaired.

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“…The protons were accelerated by a 14 MV tandem accelerator to 20.5 MeV with an LET of 2.6 keV/µm. For irradiation, the SNAKE beamline was used, which is equipped to perform biological experiments with cells, tissues, and animals 26 – 28 . The proton beam was focused to a homogenous broad beam irradiation field with a field size of 6.5 mm × 6.5 mm.…”

Section: Methodsmentioning

confidence: 99%

Proton-FLASH: effects of ultra-high dose rate irradiation on an in-vivo mouse ear model

Rudigkeit,

Schmid,

Dombrowsky

et al. 2024

Sci Rep

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FLASH-radiotherapy may provide significant sparing of healthy tissue through ultra-high dose rates in protons, electrons, and x-rays while maintaining the tumor control. Key factors for the FLASH effect might be oxygen depletion, the immune system, and the irradiated blood volume, but none could be fully confirmed yet. Therefore, further investigations are necessary. We investigated the protective (tissue sparing) effect of FLASH in proton treatment using an in-vivo mouse ear model. The right ears of Balb/c mice were irradiated with 20 MeV protons at the ion microprobe SNAKE in Garching near Munich by using three dose rates (Conv = 0.06 Gy/s, Flash9 = 9.3 Gy/s and Flash930 = 930 Gy/s) at a total dose of 23 Gy or 33 Gy. The ear thickness, desquamation, and erythema combined in an inflammation score were measured for 180 days. The cytokines TGF-β1, TNF-α, IL1α, and IL1β were analyzed in the blood sampled in the first 4 weeks and at termination day. No differences in inflammation reactions were visible in the 23 Gy group for the different dose rates. In the 33 Gy group, the ear swelling and the inflammation score for Flash9 was reduced by (57 ± 12) % and (67 ± 17) % and for Flash930 by (40 ± 13) % and (50 ± 17) % compared to the Conv dose rate. No changes in the cytokines in the blood could be measured. However, an estimation of the irradiated blood volume demonstrates, that 100-times more blood is irradiated when using Conv compared to using Flash9 or Flash930. This indicates that blood might play a role in the underlying mechanisms in the protective effect of FLASH.

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Planar Proton Minibeam Irradiation Elicits Spatially Confined DNA Damage in a Human Epidermis Model

Cited by 6 publications

References 49 publications

Repair of α-particle-induced DNA damage in peripheral blood mononuclear cells after internal ex vivo irradiation with 223Ra

Repair of α-particle-induced DNA damage in peripheral blood mononuclear cells after internal ex vivo irradiation with 223Ra

Analysis of Single- and Double-Stranded DNA Damage in Osteoblastic Cells after Hyperbaric Oxygen Exposure

Proton-FLASH: effects of ultra-high dose rate irradiation on an in-vivo mouse ear model

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