Comet Assay Profiling of FLASH-Induced Damage : Mechanistic Insights into the Effects of FLASH Irradiation
(2023) In International Journal of Molecular Sciences 24(8).- Abstract
Numerous studies have demonstrated the normal tissue-sparing effects of ultra-high dose rate ‘FLASH’ irradiation in vivo, with an associated reduction in damage burden being reported in vitro. Towards this, two key radiochemical mechanisms have been proposed: radical–radical recombination (RRR) and transient oxygen depletion (TOD), with both being proposed to lead to reduced levels of induced damage. Previously, we reported that FLASH induces lower levels of DNA strand break damage in whole-blood peripheral blood lymphocytes (WB-PBL) ex vivo, but our study failed to distinguish the mechanism(s) involved. A potential outcome of RRR is the formation of crosslink damage (particularly, if any organic radicals recombine), whilst a possible... (More)
Numerous studies have demonstrated the normal tissue-sparing effects of ultra-high dose rate ‘FLASH’ irradiation in vivo, with an associated reduction in damage burden being reported in vitro. Towards this, two key radiochemical mechanisms have been proposed: radical–radical recombination (RRR) and transient oxygen depletion (TOD), with both being proposed to lead to reduced levels of induced damage. Previously, we reported that FLASH induces lower levels of DNA strand break damage in whole-blood peripheral blood lymphocytes (WB-PBL) ex vivo, but our study failed to distinguish the mechanism(s) involved. A potential outcome of RRR is the formation of crosslink damage (particularly, if any organic radicals recombine), whilst a possible outcome of TOD is a more anoxic profile of induced damage resulting from FLASH. Therefore, the aim of the current study was to profile FLASH-induced damage via the Comet assay, assessing any DNA crosslink formation as a putative marker of RRR and/or anoxic DNA damage formation as an indicative marker of TOD, to determine the extent to which either mechanism contributes to the “FLASH effect”. Following FLASH irradiation, we see no evidence of any crosslink formation; however, FLASH irradiation induces a more anoxic profile of induced damage, supporting the TOD mechanism. Furthermore, treatment of WB-PBLs pre-irradiation with BSO abrogates the reduced strand break damage burden mediated by FLASH exposures. In summary, we do not see any experimental evidence to support the RRR mechanism contributing to the reduced damage burden induced by FLASH. However, the observation of a greater anoxic profile of damage following FLASH irradiation, together with the BSO abrogation of the reduced strand break damage burden mediated by FLASH, lends further support to TOD being a driver of the reduced damage burden plus a change in the damage profile mediated by FLASH.
(Less)
- author
- Cooper, Christian R. ; Jones, Donald J.L. ; Jones, George D.D. and Petersson, Kristoffer LU
- organization
- publishing date
- 2023-04
- type
- Contribution to journal
- publication status
- published
- subject
- keywords
- comet assay, DNA damage, electrons, FLASH, humans, oxygen, radiation
- in
- International Journal of Molecular Sciences
- volume
- 24
- issue
- 8
- article number
- 7195
- publisher
- MDPI AG
- external identifiers
-
- pmid:37108360
- scopus:85158034165
- ISSN
- 1661-6596
- DOI
- 10.3390/ijms24087195
- language
- English
- LU publication?
- yes
- id
- b99e25b2-ffd8-4880-90ba-98f3dd2e9c8e
- date added to LUP
- 2023-08-11 14:45:18
- date last changed
- 2024-04-20 00:26:43
@article{b99e25b2-ffd8-4880-90ba-98f3dd2e9c8e,
abstract = {{<p>Numerous studies have demonstrated the normal tissue-sparing effects of ultra-high dose rate ‘FLASH’ irradiation in vivo, with an associated reduction in damage burden being reported in vitro. Towards this, two key radiochemical mechanisms have been proposed: radical–radical recombination (RRR) and transient oxygen depletion (TOD), with both being proposed to lead to reduced levels of induced damage. Previously, we reported that FLASH induces lower levels of DNA strand break damage in whole-blood peripheral blood lymphocytes (WB-PBL) ex vivo, but our study failed to distinguish the mechanism(s) involved. A potential outcome of RRR is the formation of crosslink damage (particularly, if any organic radicals recombine), whilst a possible outcome of TOD is a more anoxic profile of induced damage resulting from FLASH. Therefore, the aim of the current study was to profile FLASH-induced damage via the Comet assay, assessing any DNA crosslink formation as a putative marker of RRR and/or anoxic DNA damage formation as an indicative marker of TOD, to determine the extent to which either mechanism contributes to the “FLASH effect”. Following FLASH irradiation, we see no evidence of any crosslink formation; however, FLASH irradiation induces a more anoxic profile of induced damage, supporting the TOD mechanism. Furthermore, treatment of WB-PBLs pre-irradiation with BSO abrogates the reduced strand break damage burden mediated by FLASH exposures. In summary, we do not see any experimental evidence to support the RRR mechanism contributing to the reduced damage burden induced by FLASH. However, the observation of a greater anoxic profile of damage following FLASH irradiation, together with the BSO abrogation of the reduced strand break damage burden mediated by FLASH, lends further support to TOD being a driver of the reduced damage burden plus a change in the damage profile mediated by FLASH.</p>}},
author = {{Cooper, Christian R. and Jones, Donald J.L. and Jones, George D.D. and Petersson, Kristoffer}},
issn = {{1661-6596}},
keywords = {{comet assay; DNA damage; electrons; FLASH; humans; oxygen; radiation}},
language = {{eng}},
number = {{8}},
publisher = {{MDPI AG}},
series = {{International Journal of Molecular Sciences}},
title = {{Comet Assay Profiling of FLASH-Induced Damage : Mechanistic Insights into the Effects of FLASH Irradiation}},
url = {{http://dx.doi.org/10.3390/ijms24087195}},
doi = {{10.3390/ijms24087195}},
volume = {{24}},
year = {{2023}},
}