Objective:To observe the tumor control and the degree of radiation-induced lung injury (RILI) between FLASH irradiation and conventional dose rate (CONV) irradiation, and compare the changes in plasma proteomic profiles of mice following whole-lung FLASH and CONV irradiation using proteomics method.Methods:A mouse model with metastatic lung cancer was established. After whole-lung irradiation, changes in normal lung capacity were monitored using CT scans. Then, a RILI model was constructed to examine pathological alterations in lung tissues following whole-lung CONV and FLASH irradiation. Plasma samples were collected from mice receiving whole-lung CONV irradiation ( n = 5) and whole-lung FLASH irradiation ( n = 5), followed by comparison with samples from the control group of healthy mice (also referred to as the healthy control group). These plasma samples were analyzed using isobaric tags for relative and absolute quantification (iTRAQ)-based proteomics, followed by the screening and identification of differentially expressed proteins using high-throughput bioinformatics. Moreover, protein-protein interaction (PPI) network analysis was conducted to identify hub genes using the STRING database and Cytoscape software. Results:Whole-lung FLASH and CONV irradiation produced consistent tumor control, with the former significantly reducing RILI compared to the latter. A total of 609 proteins were identified through proteomic analysis. Among them, 89 differentially expressed proteins were detected in the whole-lung FLASH group. Gene Ontology (GO) enrichment analysis indicated that up-regulated genes were primarily associated with stress and inflammatory responses, whereas down-regulated genes were related to ATP metabolism and angiogenesis regulation. Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analysis revealed that up-regulated genes were predominantly enriched in unfolded protein response pathways, while down-regulated genes were mainly involved in metabolic pathways and oxidative phosphorylation. Integrated PPI analysis and subsequent validation via reverse transcription-polymerase chain reaction (RT-PCR) revealed four key genes.Conclusions:Compared to the whole-lung CONV irradiation, whole-lung FLASH irradiation reduces the RILI of normal lung tissues while maintaining equivalent tumor control in metastatic lung cancer. Proteomic analysis of differentially expressed proteins in plasma after whole-lung FLASH and CONV irradiation provides valuable insights into the molecular mechanisms underlying the FLASH effect.

Objective:To conduct a comparative analysis of the oxygen depletion and oxygen effect of FLASH irradiation and conventional irradiation by direct measurement of oxygen content.Methods:The oxygen content in different tissues and organs of mice was measured using a phosphorescent probe. A subcutaneous xenograft tumor model in mice was established, to receive electron-beam irradiation at different doses and dose rates. The oxygen depletion of tumor and normal tissue was analyzed, and tumor control was evaluated. The oxygen depletion of conventional irradiation and FLASH irradiation was further analyzed using an in vitro model. The survival fraction (SF) of normal cells after conventional irradiation and FLASH irradiation was calculated using colony formation assay under different partial pressures of oxygen, and the data were fitted to the oxygen enhancement ratio (OER) curve. Results:The mean oxygen content of subcutaneous xenograft tumor in mice was 1.28%, suggesting hypoxia. The mean oxygen content of normal tissue ranged from 3.51% to 6.53%, suggesting physioxia. In animal experiments, oxygen depletion was not observed during conventional irradiation. High-dose-rate (20 Gy/s) and ultra-high-dose-rate (FLASH, 40 Gy/s) irradiation produced oxygen depletion. During FLASH irradiation, with the increase of oxygen content, the oxygen depletion was 0.1-0.2 mm Hg/Gy for tumor tissue and 0.19-0.21 mm Hg/Gy for skin tissue, which tended to stabilize. FLASH irradiation maintained equivalent tumor control compared to conventional irradiation. The tumoricidal effect was significantly enhanced with the increase of oxygen content in the tissue ( t=3.46, P<0.01). In in vitro experiments, the mean oxygen depletion rate was about 0.16 mm Hg/Gy for conventional irradiation and 0.16-0.18 mm Hg/Gy for FLASH irradiation, which did not change significantly with the increase of oxygen content. FLASH irradiation was associated with an oxygen effect. When the partial pressure of oxygen decreased from physioxia to hypoxia, the OER value significantly reduced. Conclusions:Normal tissues and organs are in physioxia, which exhibits a lower oxygen content than that in the air. FLASH irradiation can consume a proportion of oxygen, producing an oxygen effect. When oxygen content decreases, the oxygen depletion rate slows down after FLASH irradiation.

In recent years,FLASH radiotherapy(FLASH-RT),as a cutting-edge radiotherapy technology,has developed rapidly in basic research and clinical trials.FLASH-RT can deliver ultra-high dose rate(average dose rate≥40 Gy/s,instantaneous dose rate≥100 Gy/s)irradia-tion in a very short time(usually≤500 ms).Under the premise of maintaining equivalent tumor control rates,the normal tissue injury is less than that of conventional irradiation at the same dose,that is known as the FLASH effect.FLASH-RT has unique advantages and is currently the frontier field of radiation oncology.The research and development of FLASH-RT have progressed rapidly in China,this paper elucidated the new challenges and opportunities of FLASH-RT in China.

Objective:To observe the tumor control and the degree of radiation-induced lung injury (RILI) between FLASH irradiation and conventional dose rate (CONV) irradiation, and compare the changes in plasma proteomic profiles of mice following whole-lung FLASH and CONV irradiation using proteomics method.Methods:A mouse model with metastatic lung cancer was established. After whole-lung irradiation, changes in normal lung capacity were monitored using CT scans. Then, a RILI model was constructed to examine pathological alterations in lung tissues following whole-lung CONV and FLASH irradiation. Plasma samples were collected from mice receiving whole-lung CONV irradiation ( n = 5) and whole-lung FLASH irradiation ( n = 5), followed by comparison with samples from the control group of healthy mice (also referred to as the healthy control group). These plasma samples were analyzed using isobaric tags for relative and absolute quantification (iTRAQ)-based proteomics, followed by the screening and identification of differentially expressed proteins using high-throughput bioinformatics. Moreover, protein-protein interaction (PPI) network analysis was conducted to identify hub genes using the STRING database and Cytoscape software. Results:Whole-lung FLASH and CONV irradiation produced consistent tumor control, with the former significantly reducing RILI compared to the latter. A total of 609 proteins were identified through proteomic analysis. Among them, 89 differentially expressed proteins were detected in the whole-lung FLASH group. Gene Ontology (GO) enrichment analysis indicated that up-regulated genes were primarily associated with stress and inflammatory responses, whereas down-regulated genes were related to ATP metabolism and angiogenesis regulation. Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analysis revealed that up-regulated genes were predominantly enriched in unfolded protein response pathways, while down-regulated genes were mainly involved in metabolic pathways and oxidative phosphorylation. Integrated PPI analysis and subsequent validation via reverse transcription-polymerase chain reaction (RT-PCR) revealed four key genes.Conclusions:Compared to the whole-lung CONV irradiation, whole-lung FLASH irradiation reduces the RILI of normal lung tissues while maintaining equivalent tumor control in metastatic lung cancer. Proteomic analysis of differentially expressed proteins in plasma after whole-lung FLASH and CONV irradiation provides valuable insights into the molecular mechanisms underlying the FLASH effect.

Objective:To conduct a comparative analysis of the oxygen depletion and oxygen effect of FLASH irradiation and conventional irradiation by direct measurement of oxygen content.Methods:The oxygen content in different tissues and organs of mice was measured using a phosphorescent probe. A subcutaneous xenograft tumor model in mice was established, to receive electron-beam irradiation at different doses and dose rates. The oxygen depletion of tumor and normal tissue was analyzed, and tumor control was evaluated. The oxygen depletion of conventional irradiation and FLASH irradiation was further analyzed using an in vitro model. The survival fraction (SF) of normal cells after conventional irradiation and FLASH irradiation was calculated using colony formation assay under different partial pressures of oxygen, and the data were fitted to the oxygen enhancement ratio (OER) curve. Results:The mean oxygen content of subcutaneous xenograft tumor in mice was 1.28%, suggesting hypoxia. The mean oxygen content of normal tissue ranged from 3.51% to 6.53%, suggesting physioxia. In animal experiments, oxygen depletion was not observed during conventional irradiation. High-dose-rate (20 Gy/s) and ultra-high-dose-rate (FLASH, 40 Gy/s) irradiation produced oxygen depletion. During FLASH irradiation, with the increase of oxygen content, the oxygen depletion was 0.1-0.2 mm Hg/Gy for tumor tissue and 0.19-0.21 mm Hg/Gy for skin tissue, which tended to stabilize. FLASH irradiation maintained equivalent tumor control compared to conventional irradiation. The tumoricidal effect was significantly enhanced with the increase of oxygen content in the tissue ( t=3.46, P<0.01). In in vitro experiments, the mean oxygen depletion rate was about 0.16 mm Hg/Gy for conventional irradiation and 0.16-0.18 mm Hg/Gy for FLASH irradiation, which did not change significantly with the increase of oxygen content. FLASH irradiation was associated with an oxygen effect. When the partial pressure of oxygen decreased from physioxia to hypoxia, the OER value significantly reduced. Conclusions:Normal tissues and organs are in physioxia, which exhibits a lower oxygen content than that in the air. FLASH irradiation can consume a proportion of oxygen, producing an oxygen effect. When oxygen content decreases, the oxygen depletion rate slows down after FLASH irradiation.

In recent years,FLASH radiotherapy(FLASH-RT),as a cutting-edge radiotherapy technology,has developed rapidly in basic research and clinical trials.FLASH-RT can deliver ultra-high dose rate(average dose rate≥40 Gy/s,instantaneous dose rate≥100 Gy/s)irradia-tion in a very short time(usually≤500 ms).Under the premise of maintaining equivalent tumor control rates,the normal tissue injury is less than that of conventional irradiation at the same dose,that is known as the FLASH effect.FLASH-RT has unique advantages and is currently the frontier field of radiation oncology.The research and development of FLASH-RT have progressed rapidly in China,this paper elucidated the new challenges and opportunities of FLASH-RT in China.

FLASH radiotherapy (FLASH-RT) has garnered considerable attention globally in recent years. Compared to conventional radiotherapy, FLASH-RT can deliver the total radiation dose to the target volume in an extremely short time, reducing the radiation-induced damage to normal tissue while maintaining similar anti-tumor effects. FLASH-RT has been in the clinical trial stage, with several clinical research result being reported. Based on the collected global clinical research result of FLASH-RT in recent years, this study systematically reviewed FLASH-RT′s safety, radiation-related side effects, treatment efficacy, opportunities, and challenges in clinical trials.

Objective:To conduct a comparative analysis of the radiation damage to zebrafish embryos and the associated biological mechanism after ultra-high dose rate (FLASH) and conventional dose rate irradiation.Methods:Zebrafish embryos at 4 h post-fertilization were exposed to conventional and FLASH irradiation (9 MeV electron beam). The mortality and hatchability of zebrafish after radiation exposure were recorded. Larvae at 96 h post-irradiation underwent morphological scoring, testing of reactive oxygen species (ROS) levels, and analysis of changes in oxidative stress indicators.Results:Electron beam irradiation at doses of 2-12 Gy exerted subtle effects on the mortality and hatchability of zebrafish embryos. However, single high-dose irradiation (≥ 6 Gy) could lead to developmental malformation of larvae, with conventional irradiation showing the most significant effects ( t = 0.87-9.75, P < 0.05). In contrast, after FLASH irradiation (≥ 6 Gy), the ROS levels in zebrafish and its oxidative stress indicators including superoxide dismutase (SOD), catalase (CAT), and malondialdehyde (MDA) were significantly reduced ( t = 0.42-15.19, P < 0.05). There was no statistically significant difference in ROS levels in incubating solutions after conventional and FLASH irradiation ( P > 0.05). Conclusions:Compared to conventional irradiation, FLASH irradiation can reduce radiation damage to zebrafish embryos, and this is in a dose-dependent manner. The two irradiation modes lead to different oxidative stress levels in zebrafish, which might be a significant factor in the reduction of radiation damage with FLASH irradiation.

Traumatic brain injury(TBI)is caused by the direct or indirect effects of external factors that result in structural or functional loss of brain tissue.Astrocytes are homeostatic cells in the central nervous system that proliferate and activate rapidly in the early stages of TBI.They then participate in a series of pathological processes,such as neuroinflammation,blood-brain barrier disruption,glial scarring,and excitotoxicity after injury,and thus play a crucial role in secondary neurological injury following TBI.This paper reviews the role of astrocytes in the repair of TBI damage,with the aim of providing new strategies for the prevention and treatment of TBI.

Traumatic brain injury(TBI)is caused by the direct or indirect effects of external factors that result in structural or functional loss of brain tissue.Astrocytes are homeostatic cells in the central nervous system that proliferate and activate rapidly in the early stages of TBI.They then participate in a series of pathological processes,such as neuroinflammation,blood-brain barrier disruption,glial scarring,and excitotoxicity after injury,and thus play a crucial role in secondary neurological injury following TBI.This paper reviews the role of astrocytes in the repair of TBI damage,with the aim of providing new strategies for the prevention and treatment of TBI.