Brain Damage and Patterns of Neurovascular Disorder after Ionizing Irradiation. Complications in Radiotherapy and Radiation Combined Injury

Central Nervous System Response Against Ionizing Radiation Exposure: Cellular, Biochemical, and Molecular Perspectives

Gamma radiation is known to induce several detrimental effects on the nervous system. The hippocampus region, specifically the dentate gyrus (DG) and subventricular zone (SVZ), have been identified as a radiation-sensitive neurogenic niche. Radiation alters the endogenous redox status of neural stem cells (NSCs) and other proliferative cells, especially in the hippocampus region, leading to oxidative stress, neuroinflammation, and cell death. Planned (i.e., radiotherapy of brain tumor patients) or unplanned radiation exposure (i.e., accidental radiation exposure) can induce nonspecific damage to neuronal tissues, resulting in chronic or acute radiation syndrome. Although anatomical alterations in the neuronal tissues have been reported at higher doses of gamma radiation, biochemical and molecular perturbations may be evident even at much lower radiation doses. They may manifest in the form of neuronal deficits and cognitive impairment. In the present review, several molecular events and signaling pathways, such as oxidative stress, neuroinflammation, apoptosis, cognition, neuroplasticity, and neurotoxicity induced in neuronal cells upon ionizing radiation exposure, are reviewed. Furthermore, brain-specific radioprotectors and mitigators that protect normal neuronal cells and tissues against ionizing radiation during radiotherapy of cancer patients or nuclear emergencies are also discussed.

Radiation Exposure Induced Blood-Brain Barrier Injury via Mitochondria-Mediated Sterile Inflammation

Radiation-induced brain injury (RIBI) is caused by exposure to high doses of ionizing radiation and characterized by severe cognitive dysfunction and brain necrosis. However, the pathogenesis of RIBI is not fully understood, and no effective intervention is available. This work describes a blood-brain barrier (BBB) microphysiological system (MPS), that allowed to explore the responses of BBB and distinct brain cells to radiation exposure. Following acute exposure to radiation of X-ray or γ-ray, characteristic RIBI-associated pathological responses are observed, including BBB compromise, DNA breaks, inhibited cell proliferation, cell hypertrophy, and proinflammatory cytokine release. Among the distinctive types of cells, brain endothelial cells show the highest radiosensitivity as compared to other cells in the MPS. Intriguingly, X-ray and γ-ray radiation consistently induce prominent sterile inflammation responses, especially type I interferon response, in the BBB MPS. These responses are mediated by radiation-induced mitochondrial DNA release and subsequent activation of cGAS-STING signaling pathway. Furthermore, it is found abrocitinib (JAK1 inhibitor) and idebenone (mitochondrial protectant) can attenuate radiation-induced inflammation and ameliorate injuries in the BBB MPS. These findings reveal the involvement of mitochondria-mediated sterile inflammation in RIBI pathogenesis, identifying mitochondria as a potential target for new radioprotective measures.

Comparison of the effects of IMRT and IMPT on MRI features of normal brain tissue: a retrospective study

OBJECTIVE

This study aims to analyze magnetic resonance imaging (MRI) feature changes across different dose regions to investigate the differences in imaging feature alterations induced by Intensity-Modulated Radiation Therapy (IMRT) and Intensity-Modulated Proton Therapy (IMPT) in normal brain tissue. And evaluate the potential application value of radiomic features in dose optimization and biological dose assessment.

METHODS

A retrospective analysis included 113 patients undergoing brain-target radiotherapy: 44 receiving IMPT (average total dose: 5713.63 ± 774.32 cGy) and 69 receiving IMRT (average total dose: 5489.86 ± 627.05 cGy). There was no significant difference in prescribed doses between groups (p < 0.05). MRI data were collected pre-treatment and one month post-treatment, including T1, enhanced T1, T2, T2-FLAIR, and ADC sequences. Images underwent preprocessing and rigid registration on the 3D Slicer platform. Dose regions (90%, 70%, 50%, 30% of the total dose) were segmented and classified into high (70-90%), medium (50-70%), and low (30-50%) dose regions as volumes of interest (VOI). Radiomic features were extracted from pre- and post-treatment MRI datasets, and Delta features were calculated as the difference between pre- and post-treatment data. Non-parametric tests, t-tests, and Mann-Whitney U tests were used to identify significant feature changes, with effect size analysis to compare the magnitude of changes. Multiple testing correction was applied to reduce false positives. Finally, box plots and the Mapping of Dose Distribution and Differences in Radiomics Feature Variation were utilized to visually illustrate the extent of brain tissue changes in each dose region following radiotherapy.

RESULTS

Non-parametric tests indicated that more radiomic features exhibited significant changes in the IMRT group (p < 0.001). Effect size analysis also showed that the majority of features demonstrated greater and more pronounced changes within dose regions in the IMRT group (p < 0.05). Further correlation analysis revealed that most features (33/34) had weak correlations with dose-volume parameters (r < 0.3), suggesting that treatment modality itself may be the primary driver of these alterations rather than dose distribution alone. This finding highlights the need to refine traditional dose-based radiotherapy evaluation by incorporating biological effect considerations. Additionally, Moreover, the feature Delta_wavelet-HHL.65 exhibited the most significant change, with an effect size of -0.8 in the IMRT group. It demonstrated a moderate-to-high correlation with dose-volume parameters in the medium-to-high dose regions, with a maximum correlation coefficient of 0.65 (p < 0.001). This suggests that Delta_wavelet-HHL.65 may serve as a potential biomarker for reflecting local dose effects, contributing to the optimization of radiotherapy dose distribution.

CONCLUSIONS

This study revealed that IMRT and IMPT induce distinct radiomic feature changes under comparable dose conditions, and these differences are not solely determined by dose distribution. This suggests that radiotherapy evaluation should extend beyond physical dose metrics to incorporate biological effect dimensions. Furthermore, Delta_wavelet-HHL.65 demonstrated the most pronounced change in the IMRT group and exhibited correlations with dose-volume parameters in the low-to-medium dose regions, highlighting its potential for radiotherapy optimization.

CLINICAL TRIAL NUMBER

Not applicable.

A Combined Therapy of Pegylated G-CSF with Ciprofloxacin Mitigates Damage Induced by Lethal Ionizing Radiation to the Bone Marrow, Spleen, and Ileum by Increasing AKT Activation but Decreasing IL-18, C3, and miR-34a

Ciprofloxacin (CIP) was found to enhance pegylated G-CSF therapy (PEG, Neulasta®)-induced survival from 30% to 85% after ionizing radiation exposure. This combined therapy significantly mitigated radiation-induced brain hemorrhage through its capability to improve platelet recovery. This study tested whether this combined treatment also mitigated gastrointestinal damage from radiation. B6D2F1 female mice were exposed to 60Co γ radiation. CIP was fed daily to mice for up to 14 days. PEG was injected on day 1, and then weekly up to day 14. For the early time point study, blood, femurs, spleen, and ileum were collected on days 2, 4, 9, and 15 postirradiation. Bone marrow cells were counted; spleen weights and splenocyte counts were measured; and ileum histopathology was examined and analyzed. AKT, ERK, JNK, p38, claudin 2, NF-kB, Bax, Bcl-2, and gasdermin D were measured in ileum lysates using Western blotting while miR-34a was measured by reverse transcription followed by real-time-PCR, and citrulline was measured by colorimetric assay. In serum, interleukin-18 (IL-18) was measured by Luminex assay and complement protein 3 (C3) was detected by ELISA. The bacterial DNA load in livers was measured by real-time PCR. Radiation depleted bone marrow cells in femurs beginning day 2 through day 15 postirradiation, which was mitigated by PEG or CIP+PEG on day 9 through day 15 and by CIP on day 15, respectively. Radiation exposure led to decreased spleen weight on day 2 through day 15, while PEG or CIP+PEG significantly mitigated the reduction on day 9 through day 15. Radiation exposure reduced splenocyte counts on day 2 through day 15 postirradiation, but that was mitigated by PEG or CIP+PEG on day 15. Ileum histology showed that radiation decreased villus height on day 2 through day 15; CIP mitigated the reduction on day 15, whereas PEG+CIP mitigated it on day 2 through 15. Villus widths were increased on day 2 through day 15, while PEG+CIP effectively decreased them on day 4 through day 15. Crypt depth was reduced by radiation on day 2, but returned to the baseline on day 4 through 15. CIP or CIP+PEG transiently increased the depth only on day 4. Crypt counts were reduced by radiation on days 2 and 4, but returned to the baseline on days 9 and 15, regardless of individual drugs or combinations. Citrulline data confirmed the villus height recovery. Radiation significantly increased pro-inflammatory cytokine IL-18 on days 4 and 9, which was mitigated by PEG alone or PEG+CIP, but not by CIP alone. Radiation increased C3 on day 9 in ileum and serum. The serum C3 was positively associated with the serum IL-18 levels and negatively correlated with the crypt depth. Radiation-induced decreases in claudin 2 (a tight junction marker) in ileum and increases in bacterial DNA in livers were mitigated by PEG+CIP. Radiation did not reduce NF-kB and its activation but reduced Bcl-2 expression, which was not significantly recovered by any individual drug or combination. However, the PEG and CIP combination significantly decreased NF- kB and BAX. In contrast, radiation increased miR-34a and cleaved gasdermin D, which CIP+PEG effectively mitigated. This was confirmed by immunohistochemistry. The results taken together suggest that PEG+CIP combined treatment was effective in mitigating the radiation-induced bone marrow, spleen, and ileum injury. The mitigative effect of this combined treatment was mediated by increases in G-CSF levels that suppress miR-34a, thereby probably leading to decreased gasdermin D-mediated pyroptosis.

Drug protection against radiation-induced neurological injury: mechanisms and developments

In daily life, individuals are frequently exposed to various forms of radiation, which, when adhering to safety standards, typically result in relatively minor health effects. However, accidental exposure to radiation levels that exceed these safety standards can lead to significant health consequences. This study focuses on the analysis of radiation-induced damage to the nervous system and the mechanisms of pharmacological protection. The findings indicate that radiation can adversely affect neural structures, memory, and neurobehaviour. A range of pharmacological agents, including traditional Chinese medicine, Western medicine, and other therapeutic drugs, can be employed to safeguard the nervous system from radiation damage. The primary protective mechanisms of these agents encompass antioxidant effects, attenuation of apoptosis, and reduction of neurogenesis. A comprehensive review of these topics will offer new insights for the development and investigation of drugs aimed at mitigating radiation-induced damage to the nervous system.

Metal-organic framework-edaravone nanoparticles for radiotherapy-induced brain injury treatment

Cranial radiotherapy may cause damage to normal brain tissues and induce cognitive dysfunction, so developing an effective strategy to prevent radiotherapy-induced brain injury is essential. Metal-organic frameworks (MOFs) can be used as vectors for the delivery of neuroprotective drugs due to their high drug loading capacity and low toxicity. In this study, we synthesized MIL-53(Cr) nanoparticles, which were used to deliver edaravone, and modified the surface of the nanoparticles with polyethylene glycol and Angiopep-2 (EDA@MIL-53(Cr)-P/A) to improve their oral bioavailability and ability to cross the blood-brain barrier (BBB). We confirmed that MIL-53(Cr)-P/A nanoparticles could achieve the sustained release of edaravone and enhance its ability to cross the BBB. The results of in vitro experiments showed that EDA@MIL-53(Cr)-P/A could exert radioprotective effects on HT22 and BV2 cells. We also demonstrated that EDA@MIL-53(Cr)-P/A could alleviate brain injury and cognitive dysfunction in mice receiving whole-brain irradiation. Mechanistically, EDA@MIL-53(Cr)-P/A alleviated irradiation-induced brain damage by inhibiting oxidative stress, DNA damage, apoptosis and inflammatory reactions. This study provides a new strategy for the protection against radiotherapy-induced brain injury.

The current research status of the mechanisms and treatment of radioactive brain injury

Radioactive brain injury, a severe complication ensuing from radiotherapy for head and neck malignancies, frequently manifests as cognitive impairment and substantially diminishes patients' quality of life. Despite its profound impact, the pathogenesis of this condition remains inadequately elucidated, and efficacious treatments are notably absent in clinical practice. Consequently, contemporary interventions predominantly focus on symptom alleviation rather than achieving a radical cure or reversing the injury process. This article provides a comprehensive review of the various pathogenic mechanisms and therapeutic strategies associated with radioactive brain injury, offering insights that may guide the development of novel therapeutic strategies.

Exosomes: A new perspective for radiation combined injury as biomarker and therapeutics

Radiation Combined Injuries (RCI) pose formidable public health risks, particularly in the context of nuclear incidents, necessitating specialized treatments and development of biomarkers. RCI encompasses instances where ionizing radiation exposure coincides with burns, wounds, or trauma. However, the limited understanding of cellular responses hinders progress in developing effective therapies. This article underscores the pivotal role of exosomes, nano-sized particles (30-120 nm) actively secreted by cells, in addressing the intricate challenges posed by RCI. Exosomes serve as vehicles for the transportation of bioactive molecules, including proteins, lipids, and miRNA, thereby facilitating processes critical to radiotherapy, burn injury, and wound healing. Exosomes hold significant promise for the transformation of RCI management by reducing inflammation, promoting wound healing, managing sepsis, altering immunological responses, and modulating signal transduction pathways. Moreover, exosomes are also being explored as biomarker for various diseases and stress conditions including radiation exposure and associated injuries. This comprehensive review highlights the burgeoning potential of exosomes in advancing the management of RCI, thereby enhancing public health preparedness and response.

The initial implementation of the transverse bone transport technique in the post-radiation region of the mandible. A pre-clinical in vivo study

BACKGROUND

To link the treatment of radiation injury with angiogenesis, and to design and seek a new therapeutic technique for the prevention and treatment of radiation injury.

METHODS

The transverse bone transport device for rabbit mandible was designed and manufactured. Eighteen New Zealand white rabbits were randomly divided into a radiotherapy group and a normal group. The radiotherapy group received 18 Gy of radiation, and the device was implanted two weeks later. After a 7-day incubation period, transverse transportation was performed at a speed of 0.5 circles (0.4 mm) per day, with an 8-day cycle and a total traction distance of 3.2 mm. CBCT, Micro CT, and histological staining were employed to assess the dynamics of movement, osteogenesis, and angiogenesis.

RESULTS

The transverse bone transport model of rabbit mandible was successfully established. CBCT revealed that the transport height in the normal and radiotherapy groups were 3.24 ± 0.17 mm and 3.22 ± 0.19 mm respectively. Micro CT analysis showed an increase in BV/TV and Tb.N over time, while Tb.Sp decreased; differences in BV/TV existed at 2 weeks but disappeared thereafter; differences in Tb.N and Tb.Sp persisted at 2 and 4 weeks. Histological staining using HE, Masson, and IHC demonstrated good bone maturity accompanied by rich neovascularization, and this was also confirmed by ImageJ software analysis.

CONCLUSIONS

The transverse bone transport was employed for the first time in the radiation-induced mandibular damage, thereby establishing a basis for further investigation into its clinical efficacy, application value, and underlying mechanisms. This breakthrough offers novel prospects for clinical interventions.

Cognitive dysfunction induced by cranial radiotherapy: mechanisms and therapeutic methods

Cranial radiotherapy can damage normal brain tissues, inducing cognitive dysfunction in patients. Radiotherapy-induced cognitive dysfunction is associated with hippocampal injury, white matter damage and microvascular injury. In this study, the mechanisms of cognitive dysfunction induced by cranial radiotherapy and combined chemoradiotherapy are reviewed, and the advances in therapeutic methods for radiotherapy-induced brain injury are summarized. The mechanisms of radiotherapy-induced brain injury include a decline of neurogenesis, impairment of neurons and glial cells, vascular injury, oxidative stress and DNA damage, cell death, and inflammatory response. Disruption of the bloodbrain barrier (BBB) increases the exposure of the brain to chemotherapeutic agents, thus exacerbating radiotherapy-induced brain damage. The current methods used to prevent radiotherapy-induced brain injury mainly include precision radiotherapy, stem cell transplantation, and treatment with neuroprotective drugs. The combined application of precision radiotherapy and neuroprotective drugs, including antioxidants, anti-inflammatory agents and other drugs, might exert better neuroprotective effects. To resolve the issues of neuroprotective drugs, such as difficulty in crossing the BBB, nanoenzymes and drug delivery nano-systems could be applied in the future.

Decoding Patient Heterogeneity Influencing Radiation-Induced Brain Necrosis

PURPOSE

In radiotherapy (RT) for brain tumors, patient heterogeneity masks treatment effects, complicating the prediction and mitigation of radiation-induced brain necrosis. Therefore, understanding this heterogeneity is essential for improving outcome assessments and reducing toxicity.

EXPERIMENTAL DESIGN

We developed a clinically practical pipeline to clarify the relationship between dosimetric features and outcomes by identifying key variables. We processed data from a cohort of 130 patients treated with proton therapy for brain and head and neck tumors, utilizing an expert-augmented Bayesian network to understand variable interdependencies and assess structural dependencies. Critical evaluation involved a three-level grading system for each network connection and a Markov blanket analysis to identify variables directly impacting necrosis risk. Statistical assessments included log-likelihood ratio, integrated discrimination index, net reclassification index, and receiver operating characteristic (ROC).

RESULTS

The analysis highlighted tumor location and proximity to critical structures such as white matter and ventricles as major determinants of necrosis risk. The majority of network connections were clinically supported, with quantitative measures confirming the significance of these variables in patient stratification (log-likelihood ratio = 12.17; P = 0.016; integrated discrimination index = 0.15; net reclassification index = 0.74). The ROC curve area was 0.66, emphasizing the discriminative value of nondosimetric variables.

CONCLUSIONS

Key patient variables critical to understanding brain necrosis post-RT were identified, aiding the study of dosimetric impacts and providing treatment confounders and moderators. This pipeline aims to enhance outcome assessments by revealing at-risk patients, offering a versatile tool for broader applications in RT to improve treatment personalization in different disease sites.

Mechanisms of radiation-induced tissue damage and response

Radiation-induced tissue injury (RITI) is the most common complication in clinical tumor radiotherapy. Due to the heterogeneity in the response of different tissues to radiation (IR), radiotherapy will cause different types and degrees of RITI, which greatly limits the clinical application of radiotherapy. Efforts are continuously ongoing to elucidate the molecular mechanism of RITI and develop corresponding prevention and treatment drugs for RITI. Single-cell sequencing (Sc-seq) has emerged as a powerful tool in uncovering the molecular mechanisms of RITI and for identifying potential prevention targets by enhancing our understanding of the complex intercellular relationships, facilitating the identification of novel cell phenotypes, and allowing for the assessment of cell heterogeneity and spatiotemporal developmental trajectories. Based on a comprehensive review of the molecular mechanisms of RITI, we analyzed the molecular mechanisms and regulatory networks of different types of RITI in combination with Sc-seq and summarized the targeted intervention pathways and therapeutic drugs for RITI. Deciphering the diverse mechanisms underlying RITI can shed light on its pathogenesis and unveil new therapeutic avenues to potentially facilitate the repair or regeneration of currently irreversible RITI. Furthermore, we discuss how personalized therapeutic strategies based on Sc-seq offer clinical promise in mitigating RITI.

A bibliometric analysis of radiation-induced brain injury: a research of the literature from 1998 to 2023

BACKGROUND

Radiation-induced brain injury (RIBI) is a debilitating sequela after cranial radiotherapy. Research on the topic of RIBI has gradually entered the public eye, with more innovations and applications of evidence-based research and biological mechanism research in the field of that. This was the first bibliometric analysis on RIBI, assessing brain injury related to radiation articles that were published during 1998-2023, to provide an emerging theoretical basis for the future development of RIBI.

METHODS

Literature were obtained from the Web of Science Core Collection (WOSCC) from its inception to December 31, 2023. The column of publications, author details, affiliated institutions and countries, publication year, and keywords were also recorded.

RESULTS

A total of 2543 journal articles were selected. The annual publications on RIBI fluctuated within a certain range. Journal of Neuro-oncology was the most published journal and Radiation Oncology was the most impactful one. LIMOLI CL was the most prolific author with 37 articles and shared the highest h-index with BARNETT GH. The top one country and institutions were the USA and the University of California System, respectively. Clusters analysis of co-keywords demonstrated that the temporal research trends in this field primarily focused on imaging examination and therapy for RIBI.

CONCLUSION

This study collects, visualizes, and analyzes the literature within the field of RIBI over the last 25 years to map the development process, research frontiers and hotspots, and cutting-edge directions in clinical practice and mechanisms related to RIBI.

An Overview of Radiation Countermeasure Development in Radiation Research from 1954 to 2024

Preparation for medical responses to major radiation accidents, further driven by increases in the threat of nuclear warfare, has led to a pressing need to understand the underlying mechanisms of radiation injury (RI) alone or in combination with other trauma (combined injury, CI). The identification of these mechanisms suggests molecules and signaling pathways that can be targeted to develop radiation medical countermeasures. Thus far, the United States Food and Drug Administration (U.S. FDA) has approved seven countermeasures to mitigate hematopoietic acute radiation syndrome (H-ARS), but no drugs are available for prophylaxis and no agents have been approved to combat the other sub-syndromes of ARS, let alone delayed effects of acute radiation exposure or the effects of combined injury. From its inception, Radiation Research has significantly contributed to the understanding of the underlying mechanisms of radiation injury and combined injury, and to the development of radiation medical countermeasures for these indications through the publication of peer-reviewed research and review articles.

Secretome from iPSC-derived MSCs exerts proangiogenic and immunosuppressive effects to alleviate radiation-induced vascular endothelial cell damage

BACKGROUND

Radiation therapy is the standard of care for central nervous system tumours. Despite the success of radiation therapy in reducing tumour mass, irradiation (IR)-induced vasculopathies and neuroinflammation contribute to late-delayed complications, neurodegeneration, and premature ageing in long-term cancer survivors. Mesenchymal stromal cells (MSCs) are adult stem cells that facilitate tissue integrity, homeostasis, and repair. Here, we investigated the potential of the iPSC-derived MSC (iMSC) secretome in immunomodulation and vasculature repair in response to radiation injury utilizing human cell lines.

METHODS

We generated iPSC-derived iMSC lines and evaluated the potential of their conditioned media (iMSC CM) to treat IR-induced injuries in human monocytes (THP1) and brain vascular endothelial cells (hCMEC/D3). We further assessed factors in the iMSC secretome, their modulation, and the molecular pathways they elicit.

RESULTS

Increasing doses of IR disturbed endothelial tube and spheroid formation in hCMEC/D3. When IR-injured hCMEC/D3 (IR ≤ 5 Gy) were treated with iMSC CM, endothelial cell viability, adherence, spheroid compactness, and proangiogenic sprout formation were significantly ameliorated, and IR-induced ROS levels were reduced. iMSC CM augmented tube formation in cocultures of hCMEC/D3 and iMSCs. Consistently, iMSC CM facilitated angiogenesis in a zebrafish model in vivo. Furthermore, iMSC CM suppressed IR-induced NFκB activation, TNF-α release, and ROS production in THP1 cells. Additionally, iMSC CM diminished NF-kB activation in THP1 cells cocultured with irradiated hCMEC/D3, iMSCs, or HMC3 microglial lines. The cytokine array revealed that iMSC CM contains the proangiogenic and immunosuppressive factors MCP1/CCL2, IL6, IL8/CXCL8, ANG (Angiogenin), GROα/CXCL1, and RANTES/CCL5. Common promoter regulatory elements were enriched in TF-binding motifs such as androgen receptor (ANDR) and GATA2. hCMEC/D3 phosphokinome profiling revealed increased expression of pro-survival factors, the PI3K/AKT/mTOR modulator PRAS40 and β-catenin in response to CM. The transcriptome analysis revealed increased expression of GATA2 in iMSCs and the enrichment of pathways involved in RNA metabolism, translation, mitochondrial respiration, DNA damage repair, and neurodevelopment.

CONCLUSIONS

The iMSC secretome is a comodulated composite of proangiogenic and immunosuppressive factors that has the potential to alleviate radiation-induced vascular endothelial cell damage and immune activation.

Microglia in radiation-induced brain injury: Cellular and molecular mechanisms and therapeutic potential

BACKGROUND

Radiation-induced brain injury is a neurological condition resulting from radiotherapy for malignant tumors, with its underlying pathogenesis still not fully understood. Current hypotheses suggest that immune cells, particularly the excessive activation of microglia in the central nervous system and the migration of peripheral immune cells into the brain, play a critical role in initiating and progressing the injury. This review aimed to summarize the latest advances in the cellular and molecular mechanisms and the therapeutic potential of microglia in radiation-induced brain injury.

METHODS

This article critically examines recent developments in understanding the role of microglia activation in radiation-induced brain injury. It elucidates associated mechanisms and explores novel research pathways and therapeutic options for managing this condition.

RESULTS

Post-irradiation, activated microglia release numerous inflammatory factors, exacerbating neuroinflammation and facilitating the onset and progression of radiation-induced damage. Therefore, controlling microglial activation and suppressing the secretion of related inflammatory factors is crucial for preventing radiation-induced brain injury. While microglial activation is a primary factor in neuroinflammation, the precise mechanisms by which radiation prompts this activation remain elusive. Multiple signaling pathways likely contribute to microglial activation and the progression of radiation-induced brain injury.

CONCLUSIONS

The intricate microenvironment and molecular mechanisms associated with radiation-induced brain injury underscore the crucial roles of immune cells in its onset and progression. By investigating the interplay among microglia, neurons, astrocytes, and peripheral immune cells, potential strategies emerge to mitigate microglial activation, reduce the release of inflammatory agents, and impede the entry of peripheral immune cells into the brain.

Physical Activity Attenuates Brain Irradiation-Associated Skeletal Muscle Damage in the Rat

PURPOSE

Radiation therapy for brain tumors increases patient survival. Nonetheless, side effects are increasingly reported such as cognitive deficits and fatigue. The etiology of fatigue remains poorly described. Our hypothesis is that the abscopal effects of radiation therapy on skeletal muscle may be involved in fatigue. The present study aims to assess the effect of brain irradiation on skeletal muscles and its relationship with fatigue and to analyze whether physical activity could counteract brain radiation-induced side effects.

METHODS AND MATERIALS

Adult Wistar rats were randomly distributed between 4 groups: control (CTL), irradiated (IR), nonirradiated with physical activity (PA), and irradiated with physical activity (IR+PA). IR rats were exposed to a whole-brain irradiation (WBI) of 30 Gy (3 × 10 Gy). Rats subjected to PA underwent sessions of running on a treadmill, 3 times/week for 6 months. The effects of WBI on muscles were evaluated by complementary approaches: behavioral tests (fatigue, locomotion activity), magnetic resonance imaging, and histologic analyses.

RESULTS

IR rats displayed a significant fatigue and a reduced locomotor activity at short term compared with the CTL group, which were attenuated with PA at 6 months after WBI. The IR rat's gastrocnemius mass decreased compared with CTL rats, which was reversed by physical activity at 14 days after WBI. Multiparametric magnetic resonance imaging of the skeletal muscle highlighted an alteration of the fiber organization in IR rats as demonstrated by a significant decrease of the mean diffusivity in the gastrocnemius at short term. Alteration of fibers was confirmed by histologic analyses: the number of type I fibers was decreased, whereas that of type IIa fibers was increased in IR animals but not in the IR+PA group.

CONCLUSIONS

The data show that WBI induces skeletal muscle damage, which is attenuated by PA. This muscle damage may explain, at least in part, the fatigue of patients treated with radiation therapy.

Alterations in hypothalamic-pituitary axis (HPA) hormones 6 months after cranial radiotherapy in adult patients with primary brain tumors outside the HPA region

BACKGROUND

Cranial radiotherapy is a common treatment for brain tumors, but it can affect the hypothalamic-pituitary (H-P) axis and lead to hormonal disorders. This study aimed to compare serum levels of HPA hormones before and after cranial radiation.

MATERIALS AND METHODS

This study involved 27 adult patients who underwent brain tumor resection before the initiation of radiotherapy, and none had metastatic brain tumors. All participants had the HPA within the radiation field, and their tumors were located in brain areas outside from the HPA. Serum levels of HPA hormones were recorded both before and 6 months after cranial radiotherapy.

RESULTS

A total of 27 adult patients, comprising 16 (59.3%) males and 11 (40.7%) females, with a mean age of 56.37 ± 11.38 years, were subjected to evaluation. Six months post-radiotherapy, serum levels of GH and TSH exhibited a significant decrease. Prior to radiotherapy, a substantial and direct correlation was observed between TSH and FSH (p = 0.005) as well as LH (p = 0.014). Additionally, a significant and direct relationship was noted between serum FSH and LH (p < 0.001) before radiotherapy. After radiotherapy, a significant and direct correlation persisted between TSH and FSH (p = 0.003) as well as LH (p = 0.005), along with a significant and direct relationship between serum FSH and LH (p < 0.001). Furthermore, a significant and direct association was identified between changes in serum GH levels and FSH (p = 0.04), as well as between serum LH and FSH (p < 0.001).

CONCLUSION

Reduced serum levels of HPA hormones are a significant complication of cranial radiotherapy and should be evaluated in follow-up assessments.

Dynamics of Chromosome Aberrations and Cell Death in Zebrafish Embryos Exposed to 137Cs Total-Body Irradiation

Ionizing radiation exposure induces significant DNA damage and cell death in aquatic species. Accurate sensing and quantification play pivotal roles in environmental monitoring and surveillance. Zebrafish (Danio rerio) is a well-suited animal model for research into this aspect, especially with recent development of cytogenetic and transgenic tools. In this study, we present time-course studies of chromosome aberrations and cell death in zebrafish embryos exposed to 2 Gy 137Cs total-body irradiation. Using a cytogenetic approach, we quantified chromosome and chromatid aberrations in irradiated embryos at 6, 14, 20, and 24 h postirradiation. Metaphases with aberrations showed rapid declining kinetics, accompanied by incomplete karyotypes and irregular chromatin contents. Using an apoptosis-reporting transgenic zebrafish, we found increasing cell death along these time points, with the embryonic eyes and brain contributing the majority of the cell death volumes. We provide evidence that self-proliferating progenitor cells form the underlying linkage between the two kinetics and their positions define radiosensitive niches in zebrafish embryos. Our results provide detailed chromosome aberration and cell death dynamics in 137Cs-irradiated zebrafish embryos and unveil the appropriate timeline and tissue positions for accurate sensing and quantification of radiation-induced damages in zebrafish embryos.

Neurotoxicity-sparing radiotherapy for brain metastases in breast cancer: a narrative review

Breast cancer brain metastasis (BCBM) has a devastating impact on patient survival, cognitive function and quality of life. Radiotherapy remains the standard management of BM but may result in considerable neurotoxicity. Herein, we describe the current knowledge on methods for reducing radiation-induced cognitive dysfunction in patients with BCBM. A better understanding of the biology and molecular underpinnings of BCBM, as well as more sophisticated prognostic models and individualized treatment approaches, have appeared to enable more effective neuroprotection. The therapeutic armamentarium has expanded from surgery and whole-brain radiotherapy to stereotactic radiosurgery, targeted therapies and immunotherapies, used sequentially or in combination. Advances in neuroimaging have allowed more accurate screening for intracranial metastases, precise targeting of intracranial lesions and the differentiation of the effects of treatment from disease progression. The availability of numerous treatment options for patients with BCBM and multidisciplinary approaches have led to personalized treatment and improved therapeutic outcomes. Ongoing studies may define the optimal sequencing of available and emerging treatment options for patients with BCBM.

Effects of X-ray cranial irradiation on metabolomics and intestinal flora in mice

Cranial radiotherapy is an important treatment for intracranial and head and neck tumors. To investigate the effects of cranial irradiation (C-irradiation) on gut microbiota and metabolomic profile, the feces, plasma and cerebral cortex were isolated after exposing mice to cranial X-ray irradiation at a dose rate of 2.33 Gy/min (5 Gy/d for 4 d consecutively). The gut microorganisms and metabolites were detected by 16 S rRNA gene sequencing method and LC-MS method, respectively. We found that compared with sham group, the gut microbiota composition changed at 2 W and 4 W after C-irradiation at the genus level. The fecal metabolomics showed that compared with Sham group, 44 and 66 differential metabolites were found to be annotated into metabolism pathways at 2 W and 4 W after C-irradiation, which were significantly enriched in the arginine and proline metabolism. Metabolome analysis of serum and cerebral cortex showed that, at 4 W after C-irradiation, the expression pattern of metabolites in serum samples of mice was similar to that of sham group, and the cerebral cortex metabolites of the two groups were completely separated. KEGG functional analysis showed that serum and brain tissue differential metabolites were respectively enriched in tryptophan metabolism, and arginine proline metabolism. The correlation analysis showed that the changes of gut microbiota genera were significantly correlated with the changes of metabolism, especially Helicobacter, which was significantly correlated with many different metabolites at 4 W after C-irradiation. These data suggested that C-irradiation could affect the gut microbiota and metabolism profile, even at relatively long times after C-irradiation.

Bibliometric and visualization analysis of radiation brain injury from 2003 to 2023

Background

Over the past two decades, the field of radiation brain injury has attracted the attention of an increasing number of brain scientists, particularly in the areas of molecular pathology and therapeutic approaches. Characterizing global collaboration networks and mapping development trends over the past 20 years is essential.

Objective

The aim of this paper is to examine significant issues and future directions while shedding light on collaboration and research status in the field of radiation brain injury.

Methods

Bibliometric studies were performed using CiteSpaceR-bibliometrix and VOSviewer software on papers regarding radiation brain injury that were published before November 2023 in the Web of Science Core Collection.

Results

In the final analysis, we found 4,913 records written in 1,219 publications by 21,529 authors from 5,007 institutions in 75 countries. There was a noticeable increase in publications in 2014 and 2021. The majority of records listed were produced by China, the United States, and other high-income countries. The largest nodes in each cluster of the collaboration network were Sun Yat-sen University, University of California-San Francisco, and the University of Toronto. Galldiks N, Barnett GH, Langen KJ and Kim JH are known to be core authors in the field. The top 3 keywords in that time frame are radiation, radiation necrosis, and radiation-therapy.

Conclusions

The objective and thorough bibliometric analysis also identifies current research hotspots and potential future paths, providing a retrospective perspective on RBI and offering useful advice to researchers choosing research topics. Future development directions include the integration of multi-omics methodologies and novel imaging techniques to improve RBI's diagnostic effectiveness and the search for new therapeutic targets.

A 3D In Vitro Cortical Tissue Model Based on Dense Collagen to Study the Effects of Gamma Radiation on Neuronal Function

Studies on gamma radiation-induced injury have long been focused on hematopoietic, gastrointestinal, and cardiovascular systems, yet little is known about the effects of gamma radiation on the function of human cortical tissue. The challenge in studying radiation-induced cortical injury is, in part, due to a lack of human tissue models and physiologically relevant readouts. Here, a physiologically relevant 3D collagen-based cortical tissue model (CTM) is developed for studying the functional response of human iPSC-derived neurons and astrocytes to a sub-lethal radiation exposure (5 Gy). Cytotoxicity, DNA damage, morphology, and extracellular electrophysiology are quantified. It is reported that 5 Gy exposure significantly increases cytotoxicity, DNA damage, and astrocyte reactivity while significantly decreasing neurite length and neuronal network activity. Additionally, it is found that clinically deployed radioprotectant amifostine ameliorates the DNA damage, cytotoxicity, and astrocyte reactivity. The CTM provides a critical experimental platform to understand cell-level mechanisms by which gamma radiation (GR) affects human cortical tissue and to screen prospective radioprotectant compounds.

Ciprofloxacin and pegylated G-CSF combined therapy mitigates brain hemorrhage and mortality induced by ionizing irradiation

Introduction

Brain hemorrhage was found between 13 and 16 days after acute whole-body 9.5 Gy 60Co-γ irradiation (IR). This study tested countermeasures mitigating brain hemorrhage and increasing survival from IR. Previously, we found that pegylated G-CSF therapy (PEG) (i.e., Neulasta®, an FDA-approved drug) improved survival post-IR by 20-40%. This study investigated whether Ciprofloxacin (CIP) could enhance PEG-induced survival and whether IR-induced brain hemorrhage could be mitigated by PEG alone or combined with CIP.

Methods

B6D2F1 female mice were exposed to 60Co-γ-radiation. CIP was fed to mice for 21 days. PEG was injected on days 1, 8, and 15. 30-day survival and weight loss were studied in mice treated with vehicles, CIP, PEG, or PEG + CIP. For the early time point study, blood and sternums on days 2, 4, 9, and 15 and brains on day 15 post-IR were collected. Platelet numbers, brain hemorrhage, and histopathology were analyzed. The cerebellum/pons/medulla oblongata were detected with glial fibrillary acidic protein (GFAP), p53, p16, interleukin-18 (IL-18), ICAM1, Claudin 2, ZO-1, and complement protein 3 (C3).

Results

CIP + PEG enhanced survival after IR by 85% vs. the 30% improvement by PEG alone. IR depleted platelets, which was mitigated by PEG or CIP + PEG. Brain hemorrhage, both surface and intracranial, was observed, whereas the sham mice displayed no hemorrhage. CIP or CIP + PEG significantly mitigated brain hemorrhage. IR reduced GFAP levels that were recovered by CIP or CIP + PEG, but not by PEG alone. IR increased IL-18 levels on day 4 only, which was inhibited by CIP alone, PEG alone, or PEG + CIP. IR increased C3 on day 4 and day 15 and that coincided with the occurrence of brain hemorrhage on day 15. IR increased phosphorylated p53 and p53 levels, which was mitigated by CIP, PEG or PEG + CIP. P16, Claudin 2, and ZO-1 were not altered; ICAM1 was increased.

Discussion

CIP + PEG enhanced survival post-IR more than PEG alone. The Concurrence of brain hemorrhage, C3 increases and p53 activation post-IR suggests their involvement in the IR-induced brain impairment. CIP + PEG effectively mitigated the brain lesions, suggesting effectiveness of CIP + PEG therapy for treating the IR-induced brain hemorrhage by recovering GFAP and platelets and reducing C3 and p53.

Short report: Plasma based biomarkers detect radiation induced brain injury in cancer patients treated for brain metastasis: A pilot study

BACKGROUND

Radiotherapy has an important role in the treatment of brain metastases but carries risk of short and/or long-term toxicity, termed radiation-induced brain injury (RBI). As the diagnosis of RBI is crucial for correct patient management, there is an unmet need for reliable biomarkers for RBI. The aim of this proof-of concept study is to determine the utility of brain-derived circulating free DNA (BncfDNA), identified by specific methylation patterns for neurons, astrocytes, and oligodendrocytes, as biomarkers brain injury induced by radiotherapy.

METHODS

Twenty-four patients with brain metastases were monitored clinically and radiologically before, during and after brain radiotherapy, and blood for BncfDNA analysis (98 samples) was concurrently collected. Sixteen patients were treated with whole brain radiotherapy and eight patients with stereotactic radiosurgery.

RESULTS

During follow-up nine RBI events were detected, and all correlated with significant increase in BncfDNA levels compared to baseline. Additionally, resolution of RBI correlated with a decrease in BncfDNA. Changes in BncfDNA were independent of tumor response.

CONCLUSIONS

Elevated BncfDNA levels reflects brain cell injury incurred by radiotherapy. further research is needed to establish BncfDNA as a novel plasma-based biomarker for brain injury induced by radiotherapy.

Imaging the radioprotective effect of amifostine in the developing brain using an apoptosis-reporting transgenic zebrafish

PURPOSE

Normal tissue radioprotectants alleviate radiation-induced damages and preserve critical organ functions. Investigating their efficacy in vivo remains challenging, especially in enclosed organs like the brain. An animal model that enables direct visualization of radiation-induced apoptosis while possessing the structural complexity of a vertebrate brain facilitates these studies in a precise and effective manner.

MATERIALS AND METHODS

We employed a secA5 transgenic zebrafish expressing secreted Annexin V fused with a yellow fluorescent protein to visualize radiation-induced apoptosis in vivo. We developed a semi-automated imaging method for standardized acquisition of apoptosis signals in batches of zebrafish larvae. Using these approaches, we studied the protective effect of amifostine (WR-2721) in the irradiated zebrafish larval brain.

RESULTS

Upon 2 Gy total-body 137Cs irradiation, increased apoptosis could be visualized at high resolution in the secA5 brain at 2, 24, and 48 hour post irradiation (hpi). Amifostine treatment (4 mM) during irradiation reduced apoptosis significantly at 24 hpi and preserved Wnt active cells in the larval brain. When the 2 Gy irradiation was delivered in combination with cisplatin treatment (0.1 mM), the radioprotective effect of amifostine was also observed.

CONCLUSIONS

Our study reveals the radioprotective effect of amifostine in the developing zebrafish larval brain, and highlights the utility of secA5 transgenic zebrafish as a novel system for investigating normal tissue radioprotectants in vivo.

Radioprotective effect of Ginkgolide B on brain: the mediating role of DCC/MST1 signaling

PURPOSE

The risk of brain exposure to ionizing radiation increases gradually due to the extensive application of nuclear technology in medical, industrial, and aerospace fields. Radiation-induced brain injury (RBI) is highly likely to cause a wide range of neurological complications, including schizophrenia, Alzheimer's disease (AD), depression. Ginkgolide B (GB) is one of the effective active components extracted from ginkgo biloba leaves, exerts protective effects on CNS, which is involved in the regulation of the Hippo signaling pathway. MST1, as one of the core kinases of the Hippo pathway, participated in regulating cell proliferation, differentiation, and apoptosis. However, it remains unclear whether GB attenuates radiation brain injury (RBI) and whether the radioprotective effect of GB refers to MST1 signaling. Hence, our study aimed to explore the radiation protection effect and the potential mechanism of GB.

MATERIALS AND METHODS

C57BL/6 mice were stimulated with an X-ray (20 Gy) to establish an RBI model. Then, morris water maze test (MWM) and step-down passive avoidance test (SDPAT) were used to assess the learning and memory function of mice. The open field test (OFT), tail suspension test (TST), and forced swimming test (FST) were used to assess changes in locomotor activity and hopelessness. Besides, X-ray-stimulated SH-SY5Y cells were used to verify the radioprotective effect of GB. Immunofluorescence double staining, Dihydroethidium (DHE), western blot, and flow cytometry were used to explore the role of DCC/MST1 signaling in RBI.

RESULTS

In this study, X-ray-treated mice exhibited cognitive impairment and depression-like behavior, which was ameliorated by GB treatment. GB also reduced the ROS production and the number of TUNEL-positive cells in the hippocampus. Moreover, GB increased the protein levels of p-AKT and Bcl2, while decreased the protein levels of MST1, p-p38, p-JNK, cleaved-caspase-3 and Bax both in vivo and in vitro. Additionally, exogenous Netrin-1 alleviated X-ray-induced ROS production and apoptosis, whereas knockout of Netrin-1 receptor DCC abolished the protective effect of GB.

CONCLUSION

Oxidative stress and MST1-mediated neuronal apoptosis participated in radiation-induced cognitive impairment and depression-like behaviors, and modulation of DCC by GB was an effective intervention against RBI.

Radiation induces acute and subacute vascular regression in a three-dimensional microvasculature model

Radiation treatment is one of the most frequently used therapies in patients with cancer, employed in approximately half of all patients. However, the use of radiation therapy is limited by acute or chronic adverse effects and the failure to consider the tumor microenvironment. Blood vessels substantially contribute to radiation responses in both normal and tumor tissues. The present study employed a three-dimensional (3D) microvasculature-on-a-chip that mimics physiological blood vessels to determine the effect of radiation on blood vessels. This model represents radiation-induced pathophysiological effects on blood vessels in terms of cellular damage and structural and functional changes. DNA double-strand breaks (DSBs), apoptosis, and cell viability indicate cellular damage. Radiation-induced damage leads to a reduction in vascular structures, such as vascular area, branch length, branch number, junction number, and branch diameter; this phenomenon occurs in the mature vascular network and during neovascularization. Additionally, vasculature regression was demonstrated by staining the basement membrane and microfilaments. Radiation exposure could increase the blockage and permeability of the vascular network, indicating that radiation alters the function of blood vessels. Radiation suppressed blood vessel recovery and induced a loss of angiogenic ability, resulting in a network of irradiated vessels that failed to recover, deteriorating gradually. These findings demonstrate that this model is valuable for assessing radiation-induced vascular dysfunction and acute and chronic effects and can potentially improve radiotherapy efficiency.

Skin Wound following Irradiation Aggravates Radiation-Induced Brain Injury in a Mouse Model

Radiation injury- and radiation combined with skin injury-induced inflammatory responses in the mouse brain were evaluated in this study. Female B6D2F1/J mice were subjected to a sham, a skin wound (SW), 9.5 Gy ⁶⁰Co total-body gamma irradiation (RI), or 9.5 Gy RI combined with a skin puncture wound (RCI). Survival, body weight, and wound healing were tracked for 30 days, and mouse brain samples were collected on day 30 after SW, RI, RCI, and the sham control. Our results showed that RCI caused more severe animal death and body weight loss compared with RI, and skin wound healing was significantly delayed by RCI compared to SW. RCI and RI increased the chemokines Eotaxin, IP-10, MIG, 6Ckine/Exodus2, MCP-5, and TIMP-1 in the brain compared to SW and the sham control mice, and the Western blot results showed that IP-10 and p21 were significantly upregulated in brain cells post-RI or -RCI. RI and RCI activated both astrocytes and endothelial cells in the mouse brain, subsequently inducing blood-brain barrier (BBB) leakage, as shown by the increased ICAM1 and GFAP proteins in the brain and GFAP in the serum. The Doublecortin (DCX) protein, the "gold standard" for measuring neurogenesis, was significantly downregulated by RI and RCI compared with the sham group. Furthermore, RI and RCI decreased the expression of the neural stem cell marker E-cadherin, the intermediate progenitor marker MASH1, the immature neuron cell marker NeuroD1, and the mature neuron cell marker NeuN, indicating neural cell damage in all development stages after RI and RCI. Immunohistochemistry (IHC) staining further confirmed the significant loss of neural cells in RCI. Our data demonstrated that RI and RCI induced brain injury through inflammatory pathways, and RCI exacerbated neural cell damage more than RI.

Radiation-Induced Brain Injury: Age Dependency of Neurocognitive Dysfunction Following Radiotherapy

Cranial radiotherapy is a known risk factor for neurocognitive impairment in cancer survivors. Although radiation-induced cognitive dysfunction is observed in patients of all ages, children seem to be more vulnerable than adults to suffering age-related deficits in neurocognitive skills. So far, the underlying mechanisms by which IR negatively influences brain functions as well as the reasons for the profound age dependency are still insufficiently known. We performed a comprehensive Pubmed-based literature search to identify original research articles that reported on age dependency of neurocognitive dysfunction following cranial IR exposure. Numerous clinical trials in childhood cancer survivors indicate that the severity of radiation-induced cognitive dysfunction is clearly dependent on age at IR exposure. These clinical findings were related to the current state of experimental research providing important insights into the age dependency of radiation-induced brain injury and the development of neurocognitive impairment. Research in pre-clinical rodent models demonstrates age-dependent effects of IR exposure on hippocampal neurogenesis, radiation-induced neurovascular damage and neuroinflammation.

Role of Orai3-Mediated Store-Operated Calcium Entry in Radiation-Induced Brain Microvascular Endothelial Cell Injury

Radiation-induced brain injury is a serious complication with complex pathogenesis that may accompany radiotherapy of head and neck tumors. Although studies have shown that calcium (Ca²⁺) signaling may be involved in the occurrence and development of radiation-induced brain injury, the underlying molecular mechanisms are not well understood. In this study, we used real-time quantitative polymerase chain reaction and Western blotting assays to verify our previous finding using next-generation sequencing that the mRNA and protein expression levels of Orai3 in rat brain microvascular endothelial cells (rBMECs) increased after X-ray irradiation. We next explored the role of Orai3 and Orai3-mediated store-operated Ca²⁺ entry (SOCE) in radiation-induced brain injury. Primary cultured rBMECs derived from wild-type and Orai3 knockout (Orai3^(-/-)) Sprague-Dawley rats were used for in vitro experiments. Orai3-mediated SOCE was significantly increased in rBMECs after X-ray irradiation. However, X-ray irradiation-induced SOCE increase was markedly reduced in Orai3 knockout rBMECs, and the percentage of BTP2 (a nonselective inhibitor of Orai channels)-inhibited SOCE was significantly decreased in Orai3 knockout rBMECs. Functional studies indicated that X-ray irradiation decreased rBMEC proliferation, migration, and tube formation (a model for assessing angiogenesis) but increased rBMEC apoptosis, all of which were ameliorated by BTP2. In addition, occurrences of all four functional deficits were suppressed in X-ray irradiation-exposed rBMECs derived from Orai3^(-/-) rats. Cerebrovascular damage caused by whole-brain X-ray irradiation was much less in Orai3^(-/-) rats than in wild-type rats. These findings provide evidence that Orai3-mediated SOCE plays an important role in radiation-induced rBMEC damage and brain injury and suggest that Orai3 may warrant development as a potential therapeutic target for reducing or preventing radiation-induced brain injury.

In Vivo Imaging of Radiation-Induced Apoptosis at Single-Cell Resolution in Transgenic Zebrafish Embryos

Among the various types of cell death induced by ionizing radiation, apoptosis is a highly regulated and well-characterized form. Investigating radiation-induced apoptosis in an intact organism offers advantages in capturing the dynamics of apoptosis under preserved physiology, although high resolution imaging remains challenging. Owing to their optical transparency and genetic amenability, zebrafish is an ideal animal model for research into this aspect. In this study, we present a secA5 transgenic zebrafish expressing genetically encoded secreted ANNEXIN V fused with mVenus, a yellow fluorescent protein that enables reporting of radiation-induced apoptosis. Using in vivo imaging approach, we show that after 2 Gy total-body irradiation, apoptosis could be visualized at single-cell resolution in different cell types throughout the embryo. Elevated apoptosis could be imaged and quantified in the neuroepithelium of the embryonic brain, as well as the proliferative zone and parenchyma of the larval brain. In addition, clearance of apoptotic cells by microglia, the professional phagocytes residing in the brain, could be imaged at single-cell resolution in irradiated larvae. These results establish transgenic secA5 zebrafish as a useful and versatile in vivo system for investigating the dynamic process of radiation-induced apoptosis.

Nanowired Delivery of Cerebrolysin with Mesenchymal Stem Cells Attenuates Heat Stress-Induced Exacerbation of Neuropathology Following Brain Blast Injury

Blast brain injury (bBI) following explosive detonations in warfare is one of the prominent causes of multidimensional insults to the central nervous and other vital organs injury. Several military personnel suffered from bBI during the Middle East conflict at hot environment. The bBI largely occurs due to pressure waves, generation of heat together with release of shrapnel and gun powders explosion with penetrating and/or impact head trauma causing multiple brain damage. As a result, bBI-induced secondary injury causes breakdown of the blood-brain barrier (BBB) and edema formation that further results in neuronal, glial and axonal injuries. Previously, we reported endocrine imbalance and influence of diabetes on bBI-induced brain pathology that was significantly attenuated by nanowired delivery of cerebrolysin in model experiments. Cerebrolysin is a balanced composition of several neurotrophic factors, and active peptide fragment is capable of neuroprotection in several neurological insults. Exposure to heat stress alone causes BBB damage, edema formation and brain pathology. Thus, it is quite likely that hot environment further exacerbates the consequences of bBI. Thus, novel therapeutic strategies using nanodelivery of stem cell and cerebrolysin may further enhance superior neuroprotection in bBI at hot environment. Our observations are the first to show that combined nanowired delivery of mesenchymal stem cells (MSCs) and cerebrolysin significantly attenuated exacerbation of bBI in hot environment and induced superior neuroprotection, not reported earlier. The possible mechanisms of neuroprotection with MSCs and cerebrolysin in bBI are discussed in the light of current literature.

Dose Reduction to Motor Structures in Adjuvant Fractionated Stereotactic Radiotherapy of Brain Metastases: nTMS-Derived DTI-Based Motor Fiber Tracking in Treatment Planning

Background: Resection of brain metastases (BM) close to motor structures is challenging for treatment. Navigated transcranial magnetic stimulation (nTMS) motor mapping, combined with diffusion tensor imaging (DTI)-based fiber tracking (DTI-FTmot.TMS), is a valuable tool in neurosurgery to preserve motor function. This study aimed to assess the practicability of DTI-FTmot.TMS for local adjuvant radiotherapy (RT) planning of BM. Methods: Presurgically generated DTI-FTmot.TMS-based corticospinal tract (CST) reconstructions (FTmot.TMS) of 24 patients with 25 BM resected during later surgery were incorporated into the RT planning system. Completed fractionated stereotactic intensity-modulated RT (IMRT) plans were retrospectively analyzed and adapted to preserve FTmot.TMS. Results: In regular plans, mean dose (Dmean) of complete FTmot.TMS was 5.2 ± 2.4 Gy. Regarding planning risk volume (PRV-FTTMS) portions outside of the planning target volume (PTV) within the 17.5 Gy (50%) isodose line, the DTI-FTmot.TMS Dmean was significantly reduced by 33.0% (range, 5.9−57.6%) from 23.4 ± 3.3 Gy to 15.9 ± 4.7 Gy (p < 0.001). There was no significant decline in the effective treatment dose, with PTV Dmean 35.6 ± 0.9 Gy vs. 36.0 ± 1.2 Gy (p = 0.063) after adaption. Conclusions: The DTI-FTmot.TMS-based CST reconstructions could be implemented in adjuvant IMRT planning of BM. A significant dose reduction regarding motor structures within critical dose levels seems possible.

Acute ischemic stroke secondary to ventriculoperitoneal shunt dysfunction in a child with Moyamoya syndrome

Background:

Patients with brain vascular disease and hydrocephalus may be predisposed to acute ischemic stroke in case of shunt dysfunction and subsequent increased intracranial pression. Patients with brain tumor may develop hydrocephalus as a consequence of obstruction of cerebrospinal fluid pathways and radiation-induced moyamoya syndrome secondary (RIMS) to radiotherapy (RT).

Case Description:

A 15-year-old male patient, affected by hydrocephalus and RIMS, presented acute cerebral ischemia after an episode of shunt malfunction. The shunt was promptly revised and the areas of ischemia visible at magnetic resonance imaging significantly decreased.

Conclusion:

Children who receive RT for brain tumor, particularly if the circle of Willis region is involved, require close surveillance for the development of vasculopathy and consequent stroke. This surveillance must be even tighter if the patient has been treated with ventricular shunt for the possible synergistic interaction between the two causes on reducing cerebral perfusion and increasing the risk of acute ischemic events.

Pathogenic mechanisms and therapeutic promise of phytochemicals and nanocarriers based drug delivery against radiotherapy-induced neurotoxic manifestations

Radiotherapy is one of the extensively used therapeutic modalities in glioblastoma and other types of cancers. Radiotherapy is either used as a first-line approach or combined with pharmacotherapy or surgery to manage and treat cancer. Although the use of radiotherapy significantly increased the survival time of patients, but its use has been reported with marked neuroinflammation and cognitive dysfunction that eventually reduced the quality of life of patients. Based on the preclinical and clinical investigations, the profound role of increased oxidative stress, nuclear translocation of NF-kB, production of proinflammatory cytokines such as TNF-α, IL-6, IL-β, increased level of MMPs, increased apoptosis, reduced angiogenesis, neurogenesis, and histological aberrations in CA1, CA2, CA3 and DG region of the hippocampus have been reported. Various pharmacotherapeutic drugs are being used as an adjuvant to counteract this neurotoxic manifestation. Still, most of these drugs suffer from systemic adverse effect, causes interference to ongoing chemotherapy, and exhibit pharmacokinetic limitations in crossing the blood-brain barrier. Therefore, various phytoconstituents, their nano carrier-based drug delivery systems and miRNAs have been explored to overcome the aforementioned limitations. The present review is focused on the mechanism and evidence of radiotherapy-induced neuroinflammation and cognitive dysfunction, pathological and molecular changes in the brain homeostasis, available adjuvants, their limitations. Additionally, the potential role and mechanism of neuroprotection of various nanocarrier based natural products and miRNAs have been discussed.

Potential Molecular Biomarkers of Central Nervous System Damage in Breast Cancer Survivors

Damage of the central nervous system (CNS), manifested by cognitive impairment, occurs in 80% of women with breast cancer (BC) as a complication of surgical treatment and radiochemotherapy. In this study, the levels of ICAM-1, PECAM-1, NSE, and anti-NR-2 antibodies which are associated with the damage of the CNS and the endothelium were measured in the blood by ELISA as potential biomarkers that might reflect pathogenetic mechanisms in these patients. A total of 102 patients enrolled in this single-center trial were divided into four groups: (1) 26 patients after breast cancer treatment, (2) 21 patients with chronic brain ischemia (CBI) and asymptomatic carotid stenosis (ICA stenosis) (CBI + ICA stenosis), (3) 35 patients with CBI but without asymptomatic carotid stenosis, and (4) 20 healthy female volunteers (control group). Intergroup analysis demonstrated that in the group of patients following BC treatment there was a significant increase of ICAM-1 (mean difference: −368.56, 95% CI −450.30 to −286.69, p < 0.001) and PECAM-1 (mean difference: −47.75, 95% CI −68.73 to −26.77, p < 0.001) molecules, as compared to the group of healthy volunteers. Additionally, a decrease of anti-NR-2 antibodies (mean difference: 0.89, 95% CI 0.41 to 1.48, p < 0.001) was detected. The intergroup comparison revealed comparable levels of ICAM-1 (mean difference: −33.58, 95% CI −58.10 to 125.26, p = 0.76), PECAM-1 (mean difference: −5.03, 95% CI −29.93 to 19.87, p = 0.95), as well as anti-NR-2 antibodies (mean difference: −0.05, 95% CI −0.26 to 0.16, p = 0.93) in patients after BC treatment and in patients with CBI + ICA stenosis. The NSE level in the group CBI + ICA stenosis was significantly higher than in women following BC treatment (mean difference: −43.64, 95% CI 3.31 to −83.99, p = 0.03). Comparable levels of ICAM-1 were also detected in patients after BC treatment and in the group of CBI (mean difference: −21.28, 95% CI −111.03 to 68.48, p = 0.92). The level of PECAM-1 molecules in patients after BC treatment was also comparable to group of CBI (mean difference: −13.68, 95% CI −35.51 to 8.15, p = 0.35). In conclusion, among other mechanisms, endothelial dysfunction might play a role in the damage of the CNS in breast cancer survivors.