|
1
|
El Khatib M, Motlagh AO, Beyer JN, Troxler T, Allu SR, Sun Q, Burslem GM, Vinogradov SA. Direct Measurements of FLASH-Induced Changes in Intracellular Oxygenation. Int J Radiat Oncol Biol Phys 2024; 118:781-789. [PMID: 37729972 DOI: 10.1016/j.ijrobp.2023.09.019] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2023] [Revised: 08/01/2023] [Accepted: 09/13/2023] [Indexed: 09/22/2023]
Abstract
PURPOSE The goal of our study was to characterize the dynamics of intracellular oxygen during application of radiation at conventional (CONV) and FLASH dose rates and obtain evidence for or against the oxygen depletion hypothesis as a mechanism of the FLASH effect. METHODS AND MATERIALS The measurements were performed by the phosphorescence quenching method using probe Oxyphor PtG4, which was delivered into the cellular cytosol by electroporation. RESULTS Intracellular radiochemical oxygen depletion (ROD) g-value for a dose rate of 100 Gy/s in the normoxic range was found to be 0.58 ± 0.03 μM/Gy. Intracellular ROD g-values for FLASH and CONV dose rates in the normoxic range were found to be nearly equal. As in solution-based studies, intracellular ROD was found to exhibit strong dependence on oxygen concentration in the range of 0 to ∼40 μM [O2]. CONCLUSIONS Depletion of oxygen in cells in vitro by a clinical dose of proton radiation delivered as FLASH is unable to produce a transient state of hypoxia and, therefore, unable to induce radioprotection. The difference between ROD g-values for FLASH and CONV dose rates, detected previously in solutions-based experiments, disappears when measurements are conducted inside cells. Understanding this phenomenon should provide additional insight into the role of oxygen in FLASH radiation therapy and help to decipher the mechanism of the FLASH effect.
Collapse
Affiliation(s)
- Mirna El Khatib
- Department of Biochemistry and Biophysics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania; Department of Chemistry, School of Arts and Sciences, University of Pennsylvania, Philadelphia, Pennsylvania.
| | - Azar O Motlagh
- Department of Radiation Oncology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania
| | - Jenna N Beyer
- Department of Biochemistry and Biophysics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania
| | - Thomas Troxler
- Department of Biochemistry and Biophysics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania; Department of Chemistry, School of Arts and Sciences, University of Pennsylvania, Philadelphia, Pennsylvania
| | - Srinivasa Rao Allu
- Department of Biochemistry and Biophysics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania; Department of Chemistry, School of Arts and Sciences, University of Pennsylvania, Philadelphia, Pennsylvania
| | - Qi Sun
- Department of Biochemistry and Biophysics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania; Department of Chemistry, School of Arts and Sciences, University of Pennsylvania, Philadelphia, Pennsylvania
| | - George M Burslem
- Department of Biochemistry and Biophysics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania
| | - Sergei A Vinogradov
- Department of Biochemistry and Biophysics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania; Department of Chemistry, School of Arts and Sciences, University of Pennsylvania, Philadelphia, Pennsylvania.
| |
Collapse
|
|
2
|
Wardman P. Mechanisms of the 'FLASH' effect: radiation chemistry should not be ignored in developing models. Radiother Oncol 2023; 184:109673. [PMID: 37086975 DOI: 10.1016/j.radonc.2023.109673] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2023] [Revised: 04/05/2023] [Accepted: 04/06/2023] [Indexed: 04/24/2023]
Affiliation(s)
- Peter Wardman
- 20 Highover Park, Amersham, Buckinghamshire HP7 0BN, United Kingdom.
| |
Collapse
|
|
3
|
Vozenin MC, Schüller A, Dutreix M, Kirkby K, Baumann M, Coppes RP, Thwaites D. FLASH Radiotherapy & Particle Therapy conference, FRPT2021. Radiother Oncol 2022; 175:167-168. [DOI: 10.1016/j.radonc.2022.09.013] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2022] [Accepted: 09/20/2022] [Indexed: 11/05/2022]
|