Hematologic consequences of exposure to ionizing radiation

Predictive DNA damage signaling for low‑dose ionizing radiation

Numerous studies have attempted to develop biological markers for the response to radiation for broad and straightforward application in the field of radiation. Based on a public database, the present study selected several molecules involved in the DNA damage repair response, cell cycle regulation and cytokine signaling as promising candidates for low‑dose radiation‑sensitive markers. The HuT 78 and IM‑9 cell lines were irradiated in a concentration‑dependent manner, and the expression of these molecules was analyzed using western blot analysis. Notably, the activation of ataxia telangiectasia mutated (ATM), checkpoint kinase 2 (CHK2), p53 and H2A histone family member X (H2AX) significantly increased in a concentration‑dependent manner, which was also observed in human peripheral blood mononuclear cells. To determine the radioprotective effects of cinobufagin, as an ATM and CHK2 activator, an in vivo model was employed using sub‑lethal and lethal doses in irradiated mice. Treatment with cinobufagin increased the number of bone marrow cells in sub‑lethal irradiated mice, and slightly elongated the survival of lethally irradiated mice, although the difference was not statistically significant. Therefore, KU60019, BML‑277, pifithrin‑α, and nutlin‑3a were evaluated for their ability to modulate radiation‑induced cell death. The use of BML‑277 led to a decrease in radiation‑induced p‑CHK2 and γH2AX levels and mitigated radiation‑induced apoptosis. On the whole, the present study provides a novel approach for developing drug candidates based on the profiling of biological radiation‑sensitive markers. These markers hold promise for predicting radiation exposure and assessing the associated human risk.

Thrombopoietin mimetic stimulates bone marrow vascular and stromal niches to mitigate acute radiation syndrome

BACKGROUND

Acute radiation syndrome (ARS) manifests after exposure to high doses of radiation in the instances of radiologic accidents or incidents. Facilitating regeneration of the bone marrow (BM), namely the hematopoietic stem and progenitor cells (HSPCs), is key in mitigating ARS and multi-organ failure. JNJ-26366821, a PEGylated thrombopoietin mimetic (TPOm) peptide, has been shown as an effective medical countermeasure (MCM) to treat hematopoietic-ARS (H-ARS) in mice. However, the activity of TPOm on regulating BM vascular and stromal niches to support HSPC regeneration has yet to be elucidated.

METHODS

C57BL/6J mice (9-14 weeks old) received sublethal or lethal total body irradiation (TBI), a model for H-ARS, by 137Cs or X-rays. At 24 h post-irradiation, mice were subcutaneously injected with a single dose of TPOm (0.3 mg/kg or 1.0 mg/kg) or PBS (vehicle). At homeostasis and on days 4, 7, 10, 14, 18, and 21 post-TBI with and without TPOm treatment, BM was harvested for histology, BM flow cytometry of HSPCs, endothelial (EC) and mesenchymal stromal cells (MSC), and whole-mount confocal microscopy. For survival, irradiated mice were monitored and weighed for 30 days. Lastly, BM triple negative cells (TNC; CD45-, TER-119-, CD31-) were sorted for single-cell RNA-sequencing to examine transcriptomics after TBI with or without TPOm treatment.

RESULTS

At homeostasis, TPOm expanded the number of circulating platelets and HSPCs, ECs, and MSCs in the BM. Following sublethal TBI, TPOm improved BM architecture and promoted recovery of HSPCs, ECs, and MSCs. Furthermore, TPOm elevated VEGF-C levels in normal and irradiated mice. Following lethal irradiation, mice improved body weight recovery and 30-day survival when treated with TPOm after 137Cs and X-ray exposure. Additionally, TPOm reduced vascular dilation and permeability. Finally, single-cell RNA-seq analysis indicated that TPOm increased the expression of collagens in MSCs to enhance their interaction with other progenitors in BM and upregulated the regeneration pathway in MSCs.

CONCLUSIONS

TPOm interacts with BM vascular and stromal niches to locally support hematopoietic reconstitution and systemically improve survival in mice after TBI. Therefore, this work warrants the development of TPOm as a potent radiation MCM for the treatment of ARS.

Optimizing chemical-induced premature chromosome condensation assay for rapid estimation of high-radiation doses

In the event of exposure to high doses of radiation, prompt dose estimation is crucial for selecting appropriate treatment modalities, such as cytokine therapy or stem cell transplantation. The chemical-induced premature chromosome condensation (PCC) method offers a simple approach for such dose estimation with significant radiation exposure, but its 48-h incubation time poses challenges for early dose assessment. In this study, we optimized the chemical-induced PCC assay for more rapid dose assessment. A sufficient number of PCC and G2/M-PCC cells were obtained after 40 h of culture for irradiated human peripheral blood up to 20 Gy. By adding caffeine (final concentration of 1 mM) at 34 h from the start of culture, G2/M-PCC index increased by 1.4-fold in 10 Gy cultures. There was also no significant difference in the G2/M-PCC ring frequency induced for doses 0 to 15 Gy between our 40-h caffeine-supplemented chemical-induced PCC method and the conventional 48-h PCC assay.

Unraveling the Role of RNase L Knockout in Alleviating Immune Response Activation in Mice Bone Marrow after Irradiation

Ionizing radiation (IR) induces severe hematopoietic injury by causing DNA and RNA damage as well as activating the immune responses, necessitating the development of effective therapeutic strategies. Ribonuclease L (RNase L) as an innate immune response pathway is triggered by exogenous and endogenous abnormal dsRNA under viral infection and dyshomeostasis, thereby activating the immune responses. Thus, we investigated the effect of RNase L on irradiation-induced bone marrow damage using RNase L knockout (RNase L-/-) mice. Phenotypic analysis revealed that RNase L knockout mitigates irradiation-induced injury in the bone marrow. Further investigation into the mechanism of RNase L by RNA-seq, qRT-PCR, and CBA analysis demonstrated that RNase L deficiency counteracts the upregulation of genes related to immune responses induced by irradiation, including cytokines and interferon-stimulated genes. Moreover, RNase L deficiency inhibits the increased levels of immunoglobulins in serum induced by irradiation. These findings indicate that RNase L plays a role in the immune response induced by irradiation in the bone marrow. This study further enhances our understanding of the biological functions of RNase L in the immune response induced by irradiation and offers a novel approach for managing irradiation-induced bone marrow injury through the regulation of RNase L activation.

Thrombopoietin mimetic stimulates bone marrow vascular and stromal niches to mitigate acute radiation syndrome

Background

Acute radiation syndrome (ARS) manifests after exposure to high doses of radiation in the instances of radiologic accidents or incidents. Facilitating the regeneration of the bone marrow (BM), namely the hematopoietic stem and progenitor cells (HSPCs), is a key in mitigating ARS and multi-organ failure. JNJ-26366821, a PEGylated thrombopoietin mimetic (TPOm) peptide, has been shown as an effective medical countermeasure (MCM) to treat hematopoietic-ARS (H-ARS) in mice. However, the activity of TPOm on regulating BM vascular and stromal niches to support HSPC regeneration has not yet been elucidated.

Methods

C57BL/6J mice (9-14 weeks old) received sublethal or lethal total body irradiation (TBI), a model for H-ARS, by 137Cs or X-rays. At 24 hours post-irradiation, mice were subcutaneously injected with a single dose of TPOm (0.3 mg/kg or 1.0 mg/kg) or PBS (vehicle). At homeostasis and on days 4, 7, 10, 14, 18, and 21 post-TBI with and without TPOm treatment, BM was harvested for histology, BM flow cytometry of HSPCs, endothelial (EC) and mesenchymal stromal cells (MSC), and whole-mount confocal microscopy. For survival, irradiated mice were monitored and weighed for 30 days. Lastly, BM triple negative cells (TNC; CD45-, TER-119-, CD31-) were sorted for single-cell RNA-sequencing to examine transcriptomics after TBI with or without TPOm treatment.

Results

At homeostasis, TPOm expanded the number of circulating platelets and HSPCs, ECs, and MSCs in the BM. Following sublethal TBI, TPOm improved BM architecture and promoted recovery of HSPCs, ECs, and MSCs. Furthermore, TPOm elevated VEGF-C levels in normal and irradiated mice. Following lethal irradiation, mice improved body weight recovery and 30-day survival when treated with TPOm after 137Cs and X-ray exposure. Additionally, TPOm reduced vascular dilation and permeability. Finally, single-cell RNA-seq analysis indicated that TPOm increased the expression of collagens in MSCs to enhance their interaction with other progenitors in BM and upregulated the regeneration pathway in MSCs.

Conclusions

TPOm interacts with BM vascular and stromal niches to locally support hematopoietic reconstitution and systemically improve survival in mice after TBI. Therefore, this work warrants the development of TPOm as a potent radiation MCM for the treatment of ARS.

DAMPs and radiation injury

The heightened risk of ionizing radiation exposure, stemming from radiation accidents and potential acts of terrorism, has spurred growing interests in devising effective countermeasures against radiation injury. High-dose ionizing radiation exposure triggers acute radiation syndrome (ARS), manifesting as hematopoietic, gastrointestinal, and neurovascular ARS. Hematopoietic ARS typically presents with neutropenia and thrombocytopenia, while gastrointestinal ARS results in intestinal mucosal injury, often culminating in lethal sepsis and gastrointestinal bleeding. This deleterious impact can be attributed to radiation-induced DNA damage and oxidative stress, leading to various forms of cell death, such as apoptosis, necrosis and ferroptosis. Damage-associated molecular patterns (DAMPs) are intrinsic molecules released by cells undergoing injury or in the process of dying, either through passive or active pathways. These molecules then interact with pattern recognition receptors, triggering inflammatory responses. Such a cascade of events ultimately results in further tissue and organ damage, contributing to the elevated mortality rate. Notably, infection and sepsis often develop in ARS cases, further increasing the release of DAMPs. Given that lethal sepsis stands as a major contributor to the mortality in ARS, DAMPs hold the potential to function as mediators, exacerbating radiation-induced organ injury and consequently worsening overall survival. This review describes the intricate mechanisms underlying radiation-induced release of DAMPs. Furthermore, it discusses the detrimental effects of DAMPs on the immune system and explores potential DAMP-targeting therapeutic strategies to alleviate radiation-induced injury.

Adoption of Total Neoadjuvant Therapy in the Treatment of Locally Advanced Rectal Cancer

Local and metastatic recurrence are primary concerns following the treatment of locally advanced rectal cancer (LARC). Chemoradiation (CRT) can reduce the local recurrence rates and has subsequently moved to the neoadjuvant setting from the adjuvant setting. Pathological complete response (pCR) rates have also been noted to be greater in patients treated with neoadjuvant CRT prior to surgery. The standard approach to treating LARC would often involve CRT followed by surgery and optional adjuvant chemotherapy and remained the treatment paradigm for almost two decades. However, patients were often unable to complete adjuvant chemotherapy due to a decreased tolerance of chemotherapy following surgery, which led to upfront treatment with both CRT and chemotherapy, and total neoadjuvant therapy, or TNT, was created. The efficacy outcomes of local recurrence, disease-free survival, and pCR have improved in patients receiving TNT compared to the standard approach. Additionally, more recent data suggest a possible improvement in overall survival as well. Patients with a complete clinical response following TNT have the opportunity for watch-and-wait surveillance, allowing some patients to undergo organ preservation. Here, we discuss the clinical trials and studies that led to the adoption of TNT as the standard of care for LARC, with the possibility of watch-and-wait surveillance for patients achieving complete responses. We also review the possibility of overtreating some patients with LARC.

The role of PKC in X-ray-induced megakaryocyte apoptosis and thrombocytopenia

Thrombocytopenia is a critical complication after radiation therapy and exposure. Dysfunction of megakaryocyte development and platelet production are key pathophysiological stages in ionizing radiation (IR)-induced thrombocytopenia. Protein kinase C (PKC) plays an important role in regulating megakaryocyte development and platelet production. However, it remains unclear how PKC regulates IR-induced megakaryocyte apoptosis. In this study, we found that pretreatment of PKC pan-inhibitor Go6983 delayed IR-induced megakaryocyte apoptosis, and inhibited IR-induced mitochondrial membrane potential and ROS production in CMK cells. Moreover, suppressing PKC activation inhibited cleaved caspase3 expression and reduced p38 phosphorylation levels, and IR-induced PKC activation might be regulated by p53. In vivo experiments confirmed that Go6983 promoted platelet count recovery after 21 days of 3 Gy total body irradiation. Furthermore, Go6983 reduced megakaryocyte apoptosis, increased the number of megakaryocyte and polyploid formation in bone marrow, and improved the survival rate of 6 Gy total body irradiation. In conclusion, our results provided a potential therapeutic target for IR-induced thrombocytopenia.

Metabolomic Insight into Implications of Induction Chemotherapy Followed by Concomitant Chemoradiotherapy in Locally Advanced Head and Neck Cancer

The present study compares two groups of locally advanced patients with head and neck squamous cell carcinoma (LA-HNSCC) undergoing concurrent chemoradiotherapy (cCHRT), specifically those for whom it is a first-line treatment and those who have previously received induction chemotherapy (iCHT). The crucial question is whether iCHT is a serious burden during subsequent treatment for LA-HNSCC and how iCHT affects the tolerance to cCHRT. Of the 107 LA-HNSCC patients, 54 received cisplatin-based iCHT prior to cCHRT. The patients were clinically monitored at weekly intervals from the day before until the completion of the cCHRT. The 843 blood samples were collected and divided into two aliquots: for laboratory blood tests and for nuclear magnetic resonance (NMR) spectroscopy (a Bruker 400 MHz spectrometer). The NMR metabolites and the clinical parameters from the laboratory blood tests were analyzed using orthogonal partial least squares analysis (OPLS) and the Mann-Whitney U test (MWU). After iCHT, the patients begin cCHRT with significantly (MWU p-value < 0.05) elevated blood serum lipids, betaine, glycine, phosphocholine, and reticulocyte count, as well as significantly lowered NMR inflammatory markers, serine, hematocrit, neutrophile, monocyte, red blood cells, hemoglobin, and CRP. During cCHRT, a significant increase in albumin and psychological distress was observed, as well as a significant decrease in platelet, N-acetyl-cysteine, tyrosine, and phenylalanine, in patients who received iCHT. Importantly, all clinical symptoms (except the decreased platelets) and most metabolic alterations (except for betaine, serine, tyrosine, glucose, and phosphocholine) resolve until the completion of cCHRT. In conclusion, iCHT results in hematological toxicity, altered lipids, and one-carbon metabolism, as well as downregulated inflammation, as observed at the beginning and during cCHRT. However, these complications are temporary, and most of them resolve at the end of the treatment. This suggests that iCHT prior to cCHRT does not pose a significant burden and should be considered as a safe treatment option for LA-HNSCC.

The effect of radioiodine therapy on blood cell count in patients with differentiated thyroid cancer

PURPOSE

This study aimed to investigate the long-term effects of radioiodine treatment (RAI) on blood cell counts in patients with differentiated thyroid cancer (DTC) and to describe the characteristics of patients at high risk for blood cell count abnormalities.

METHODS

The study included patients with DTC who underwent RAI treatment between 2007 and 2017. Patients with regular complete blood counts for at least 5 years were included, while those with diseases or treatments that could influence blood count parameters were excluded. Blood cell count abnormalities were defined according to the Common Terminology Criteria for Adverse Events version 5.0, and factors influencing these abnormalities were examined.

RESULTS

A total of 225 patients were analyzed. The mean age at diagnosis was 45.8 ± 13.9 years, and 76.5% of patients were female. In the first year after RAI, leukocyte, neutrophil, and lymphocyte counts were significantly reduced compared with baseline values. The leukocyte and neutrophil counts returned to baseline values by the third year, while the decrease in lymphocytes continued until the fifth year. Blood cell count abnormalities developed in 16 patients (7.1%) within the first year after RAI. Risk factors for blood cell count abnormalities within the first year after RAI included male sex, older age, T4, N1, and M1 disease, as well as higher RAI doses. In logistic regression analysis, only RAI dose remained independently associated with blood cell count abnormalities.

CONCLUSION

These results suggest an association between RAI dose and blood cell count abnormalities, characterized by mild lymphopenia, and indicate that the risk of mild lymphopenia persists over time. Careful consideration should be given when planning high-dose RAI for patients at a high risk of blood cell count abnormalities, such as males with metastatic disease and of advanced age.

Immune Dysfunction from Radiation Exposure

Exposure to ionizing radiation causes acute damage and loss of bone marrow and peripheral immune cells that can result in high mortality due to reduced resistance to infections and hemorrhage. Besides these acute effects, tissue damage from radiation can trigger inflammatory responses, leading to progressive and chronic tissue damage by radiation-induced loss of immune cell types that are required for resolving tissue injuries. Understanding the mechanisms involved in radiation-induced immune system injury and repair will provide new insights for developing medical countermeasures that help restore immune homeostasis. For these reasons, The Radiation and Nuclear Countermeasures Program (RNCP) and the Basic Immunology Branch (BIB) under the Division of Allergy, Immunology, and Transplantation (DAIT) within the National Institute of Allergy and Infectious Diseases (NIAID) convened a two-day workshop, along with partners from the Biomedical Advanced Research and Development Authority (BARDA), and the Radiation Injury Treatment Network (RITN). This workshop, titled "Immune Dysfunction from Radiation Exposure," was held virtually on September 9-10, 2020; this Commentary provides a high-level overview of what was discussed at the meeting.

Immune Dysfunction from Radiation Exposure

The hematopoietic system is highly sensitive to ionizing radiation. Damage to the immune system may result in opportunistic infections and hemorrhage, which could lead to mortality. Inflammation triggered by tissue damage can also lead to additional local or widespread tissue damage. The immune system is responsible for tissue repair and restoration, which is made more challenging when it is in the process of self-recovery. Because of these challenges, the Radiation and Nuclear Countermeasures Program (RNCP) and the Basic Immunology Branch (BIB) under the Division of Allergy, Immunology, and Transplantation (DAIT) within the National Institute of Allergy and Infectious Diseases (NIAID), along with partners from the Biomedical Advanced Research and Development Authority (BARDA), and the Radiation Injury Treatment Network (RITN) sponsored a two-day meeting titled Immune Dysfunction from Radiation Exposure held on September 9-10, 2020. The intent was to discuss the manifestations and mechanisms of radiation-induced immune dysfunction in people and animals, identify knowledge gaps, and discuss possible treatments to restore immune function and enhance tissue repair after irradiation.

Benefits and challenges of in vivo EPR nail biodosimetry in a second tier of medical triage in response to a large radiation event

Following large-scale radiation events, an overwhelming number of people will potentially need mitigators or treatment for radiation-induced injuries. This necessitates having methods to triage people based on their dose and its likely distribution, so life-saving treatment is directed only to people who can benefit from such care. Using estimates of victims following an improvised nuclear device striking a major city, we illustrate a two-tier approach to triage. At the second tier, after first removing most who would not benefit from care, biodosimetry should provide accurate dose estimates and determine whether the dose was heterogeneous. We illustrate the value of using in vivo electron paramagnetic resonance nail biodosimetry to rapidly assess dose and determine its heterogeneity using independent measurements of nails from the hands and feet. Having previously established its feasibility, we review the benefits and challenges of potential improvements of this method that would make it particularly suitable for tier 2 triage. Improvements, guided by a user-centered approach to design and development, include expanding its capability to make simultaneous, independent measurements and improving its precision and universality.

PEGylated thrombopoietin mimetic, JNJ‑26366821 a novel prophylactic radiation countermeasure for acute radiation injury

Thrombopoietin (TPO) is the primary regulator of platelet generation and a stimulator of multilineage hematopoietic recovery following exposure to total body irradiation (TBI). JNJ‑26366821, a novel PEGylated TPO mimetic peptide, stimulates platelet production without developing neutralizing antibodies or causing any adverse effects. Administration of a single dose of JNJ‑26366821 demonstrated its efficacy as a prophylactic countermeasure in various mouse strains (males CD2F1, C3H/HeN, and male and female C57BL/6J) exposed to Co-60 gamma TBI. A dose dependent survival efficacy of JNJ‑26366821 (- 24 h) was identified in male CD2F1 mice exposed to a supralethal dose of radiation. A single dose of JNJ‑26366821 administered 24, 12, or 2 h pre-radiation resulted in 100% survival from a lethal dose of TBI with a dose reduction factor of 1.36. There was significantly accelerated recovery from radiation-induced peripheral blood neutropenia and thrombocytopenia in animals pre-treated with JNJ‑26366821. The drug also increased bone marrow cellularity and megakaryocytes, accelerated multi-lineage hematopoietic recovery, and alleviated radiation-induced soluble markers of bone marrow aplasia and endothelial damage. These results indicate that JNJ‑26366821 is a promising prophylactic radiation countermeasure for hematopoietic acute radiation syndrome with a broad window for medical management in a radiological or nuclear event.

Protein biomarkers for radiation injury and testing of medical countermeasure efficacy: promises, pitfalls, and future directions

INTRODUCTION

Radiological/nuclear accidents, hostile military activity, or terrorist strikes have the potential to expose a large number of civilians and military personnel to high doses of radiation resulting in the development of acute radiation syndrome and delayed effects of exposure. Thus, there is an urgent need for sensitive and specific assays to assess the levels of radiation exposure to individuals. Such radiation exposures are expected to alter primary cellular proteomic processes, resulting in multifaceted biological responses.

AREAS COVERED

This article covers the application of proteomics, a promising and fast developing technology based on quantitative and qualitative measurements of protein molecules for possible rapid measurement of radiation exposure levels. Recent advancements in high-resolution chromatography, mass spectrometry, high-throughput, and bioinformatics have resulted in comprehensive (relative quantitation) and precise (absolute quantitation) approaches for the discovery and accuracy of key protein biomarkers of radiation exposure. Such proteome biomarkers might prove useful for assessing radiation exposure levels as well as for extrapolating the pharmaceutical dose of countermeasures for humans based on efficacy data generated using animal models.

EXPERT OPINION

The field of proteomics promises to be a valuable asset in evaluating levels of radiation exposure and characterizing radiation injury biomarkers.

Effectiveness of oral famotidine in reducing the hematologic complications of radiotherapy in patients with esophageal and cardia cancers: a randomized controlled trial

BACKGROUND

Chemoradiotherapy complications has always been of great concern to both clinicians and patients during the course of treatment. The purpose of the present study was to examine the effectiveness of oral famotidine on the reduction of hematologic complications of patients with esophageal and gastric cardia cancers undergoing radiotherapy.

METHODS

A single-blind controlled trial was conducted on 60 patients with esophageal and cardia cancers, who were undergoing chemoradiotherapy. Patients were randomly assigned to 2 groups with 30 patients to receive either 40 mg of oral famotidine (daily and 4 h before each session) or placebo. Complete blood count with differential, platelet counts, and hemoglobin levels were obtained weekly during treatment. The main outcome variables were lymphocytopenia, granulocytopenia, thrombocytopenia, and anemia.

RESULTS

The findings indicated a significant effect of famotidine on reduction of thrombocytopenia among intervention group compared to control group (P < 0.0001). Even so, the effect of intervention was not significant for other outcome variables (All, P ≥ 0.05). The lymphocyte (P = 0.007) and platelet (P = 0.004) counts were also significantly greater in famotidine group in comparison with placebo group at the end of the study.

CONCLUSION

As evidenced by the findings of the current study, famotidine might be recommended as an effective radioprotective agent among patients with esophageal and gastric cardia cancers to prevent Leukocyte and platelet reduction to some extent. Trial registration This study was prospectively registered at irct.ir (Iranian Registry of Clinical Trials) with the code IRCT20170728035349N1, 2020-08-19.

Hematopoietic System under Physiological Conditions and Following Hematopoietic Reconstitution or Stress

The hematopoietic system performs the most vital functions in the human body, integrating the work of various organs while producing enormous numbers of mature cells daily [...].

StemRegenin 1 Mitigates Radiation-Mediated Hematopoietic Injury by Modulating Radioresponse of Hematopoietic Stem/Progenitor Cells

Hematopoietic injury resulting from the damage of hematopoietic stem/progenitor cells (HSPCs) can be induced by either nuclear accident or radiotherapy. Radiomitigation of HSPCs is critical for the development of medical countermeasure agents. StemRegenin 1 (SR1) modulates the maintenance and function of HSPCs under non-stress conditions. However, the impact of SR1 in radiation-induced hematopoietic injury both in vivo and in vitro remains unknown. In this study, we found that treatment with SR1 after irradiation of C57BL/6 mice significantly mitigates TBI-induced death (80% of SR1-treated mice survival vs. 30% of saline-treated mice survival) with enhanced recovery of peripheral blood cell counts, with the density and cell proliferation of bone marrow components as observed by Hematoxylin and Eosin (H&E) and Ki-67 staining. Interestingly, in vitro analysis of human HSPCs showed that SR1 enhanced the population of human HSPCs (CD34+) under both non-irradiating and irradiating conditions, and reduced radiation-induced DNA damage and apoptosis. Furthermore, SR1 attenuated the radiation-induced expression of a member of the pro-apoptotic BCL-2 family and activity of caspase-3. Overall, these results suggested that SR1 modulates the radioresponse of HSPCs and might provide a potential radiomitigator of hematopoietic injury, which contributes to increase the survival of patients upon irradiation.

Exposure to ionizing radiations and changes in blood cells and interleukin-6 in radiation workers

Long-term exposure to ionizing radiation (IR) can cause dire health consequences even less than the dose limits. Previous biomonitoring studies have focused more on complete blood counts (CBCs), with non-coherent results. In this study, we aimed to investigate the association between exposure to IR and cytokine interleukin-6 (IL-6) along with hematological parameters in Tabriz megacity's radiation workers. In this hospital-based study, blood samples were taken from 33 radiation workers (exposed group) and 34 non-radiation workers (control group) in 4 hospitals. Absorbed radiation dose was measured by a personal film badge dosimeter in radiation workers. The studied biomarkers and all of the selected covariates were measured and analyzed using adjusted multiple linear regression models. The exposed doses for all radiation workers were under the dose limits (overall mean = 1.18 mSv/year). However, there was a significant association between exposure to ionizing radiation and IL-6 (49.78 vs 36.17; t = 2.4; p = 0.02) and eosinophils (0.17 vs 0.14; t = 2.02; p = 0.049). The difference between the mean of the other biomarkers in radiation workers was not statistically significant compared to the control group. This study demonstrated that long-term exposure to ionizing radiation, even under the dose limits, is related to a significantly increased level of some blood biomarkers (Il-6 and eosinophil) that, in turn, can cause subsequent health effects such as cancer.

Haematological and renal toxicity of radiation therapy in neuroblastoma paediatric patients

PURPOSE

The objective of this study was to evaluate the renal and hematologic toxicity in paediatric patients with adrenal high-risk neuroblastoma who have received radiation therapy (RT) as part of radical treatment.

MATERIAL AND METHODS

Pediatric patients diagnosed with high-risk adrenal neuroblastoma who received RT as part of the definitive treatment between January 2004 and May 2020 in a single institution were selected. Complete blood counts (CBC) and creatinine clearance (CrCl) pre-RT and post-RT were compared through the Wilcoxon signed-rank test and correlated with survival analysis by Cox regression.

RESULTS

Forty-two children with a median age of 3 years at diagnosis and 2.8 years of follow-up were selected. A significant and acute decrease in lymphocytes was found (p = 0.002) 1 month from RT. Patients with a drop higher than 50% of the previous value experimented a significant reduction in overall survival (55 vs 10%; p = 0.031). At the end of the follow-up, a significant increase in all blood counts was observed. With respect to renal function, an acute and significant decrease in CrCl was observed tin patients younger than 4 years who received RT (p = 0.013). However, it was not clinically relevant.

CONCLUSION

Our data suggest that acute lymphopenia occurs after RT and could be associated with a poorer prognosis. Other blood counts are reduced after RT and all of them are in physiological range at the end of follow-up. Our cohort presented excellent renal outcomes without any case of chronic renal dysfunction.

Total Skin Treatment with Helical Arc Radiotherapy

For widespread cutaneous lymphoma, such as mycosis fungoides or leukemia cutis, in patients with acute myeloid leukemia (AML) and for chronic myeloproliferative diseases, total skin irradiation is an efficient treatment modality for disease control. Total skin irradiation aims to homogeneously irradiate the skin of the entire body. However, the natural geometric shape and skin folding of the human body pose challenges to treatment. This article introduces treatment techniques and the evolution of total skin irradiation. Articles on total skin irradiation by helical tomotherapy and the advantages of total skin irradiation by helical tomotherapy are reviewed. Differences among each treatment technique and treatment advantages are compared. Adverse treatment effects and clinical care during irradiation and possible dose regimens are mentioned for future prospects of total skin irradiation.

The biomedical potential of tardigrade proteins: A review

Tardigrades are ubiquitous microinvertebrates exhibiting extreme tolerance to various environmental stressors like low and high temperatures, lack of water, or high radiation. Although exact pathways behind the tardigrade extremotolerance are yet to be elucidated, some molecules involved have been identified. Their evidenced properties may lead to novel opportunities in biomedical and pharmacological development. This review aims to present the general characteristics of tardigrade intrinsically disordered proteins (TDPs: Dsup, CAHS, SAHS, MAHS) and late embryogenesis-abundant proteins (LEA) and provide an updated overview of their features and relevance for potential use in biomedicine and pharmacology. The Dsup reveals a promising action in attenuating oxidative stress, DNA damage, and pyrimidine dimerization, as well as increasing radiotolerance in transfected human cells. Whether Dsup can perform these functions when delivered externally is yet to be understood by in vivo preclinical testing. In turn, CAHS and SAHS demonstrate properties that could benefit the preservation of pharmaceuticals (e.g., vaccines) and biomaterials (e.g., cells). Selected CAHS proteins can also serve as inspiration for designing novel anti-apoptotic agents. The LEA proteins also reveal promising properties to preserve desiccated biomaterials and can act as anti-osmotic agents. In summary, tardigrade molecules reveal several potential biomedical applications advocating further research and development. The challenge of extracting larger amounts of these molecules can be solved with genetic engineering and synthetic biology tools. With new species identified each year and ongoing studies on their extremotolerance, progress in the medical use of tardigrade proteins is expected shortly.

Establishing a Murine Model of the Hematopoietic Acute Radiation Syndrome

The hematopoietic system is one of the most sensitive tissues to ionizing radiation, and radiation doses from 2 to 10 gray can result in death from bleeding and infection if left untreated. Reviewing the range of radiation doses reported in the literature that result in similar lethality highlights the need for a more consistent model that would allow a better comparison of the hematopoietic acute radiation syndrome (H-ARS) studies carried out in different laboratories. Developing a murine model of H-ARS to provide a platform suited for efficacy testing of medical countermeasures (MCM) against radiation should include a review of the Food and Drug Administration requirements outlined in the Animal Rule. The various aspects of a murine H-ARS model found to affect consistent performance will be described in this chapter including strain, sex, radiation type and dose, mouse restraint, and husbandry.

Gamma-Tocotrienol Modulates Total-Body Irradiation-Induced Hematopoietic Injury in a Nonhuman Primate Model

Radiation exposure causes acute damage to hematopoietic and immune cells. To date, there are no radioprotectors available to mitigate hematopoietic injury after radiation exposure. Gamma-tocotrienol (GT3) has demonstrated promising radioprotective efficacy in the mouse and nonhuman primate (NHP) models. We determined GT3-mediated hematopoietic recovery in total-body irradiated (TBI) NHPs. Sixteen rhesus macaques divided into two groups received either vehicle or GT3, 24 h prior to TBI. Four animals in each treatment group were exposed to either 4 or 5.8 Gy TBI. Flow cytometry was used to immunophenotype the bone marrow (BM) lymphoid cell populations, while clonogenic ability of hematopoietic stem cells (HSCs) was assessed by colony forming unit (CFU) assays on day 8 prior to irradiation and days 2, 7, 14, and 30 post-irradiation. Both radiation doses showed significant changes in the frequencies of B and T-cell subsets, including the self-renewable capacity of HSCs. Importantly, GT3 accelerated the recovery in CD34⁺ cells, increased HSC function as shown by improved recovery of CFU-granulocyte macrophages (CFU-GM) and burst-forming units erythroid (B-FUE), and aided the recovery of circulating neutrophils and platelets. These data elucidate the role of GT3 in hematopoietic recovery, which should be explored as a potential medical countermeasure to mitigate radiation-induced injury to the hematopoietic system.

Countermeasure efficacy of apigenin for silicon-ion-induced early damage in blood and bone marrow of exposed C57BL/6J mice

We investigated the countermeasure efficacy of apigenin (AP), given as a diet supplement, for radiation-induced damage in the hematopoietic tissues collected on day 7 after a total-body exposure of male C57BL/6J mice to 0 or 0.5 Gy of 260 MeV/n silicon (²⁸Si) ions. We gave food with AP at the concentration of 20 mg/kg body weight (bw) (AP20) or without AP (AP0) to mice before and after irradiation. There were four groups of mice (six mice in each): Group 1- Control, i.e. No Radiation (0 Gy) with AP0; Group 2 - Radiation (0.5 Gy) with AP0; Group 3 - No Radiation (0 Gy) with AP20; and Group 4 - Radiation (0.5 Gy) with AP20. The complete blood count (CBC) and differential blood count were performed for each mouse. In the same mouse, an anti-clastogenic activity of AP was evaluated using the in vivo blood-erythrocyte micronucleus (MN) assay. Further in each mouse, bone marrow (BM) cells were collected and used for measuring the levels of activated nuclear factor-kappa B (NF-κB), and pro-inflammatory cytokines (i.e. tumor necrotic factor-alpha (TNF-α), interleukin-1α (IL-1α), IL-1 beta (IL-1β), and IL-6). We used the colony-forming unit assay (CFU-A) as a tool to study the countermeasure efficacy of AP against the harmful effects of ²⁸Si ions on the proliferation of the hematopoietic stem/progenitor cells (HSPCs). Our results showed that AP is highly effective not only in the prevention of leukopenia and thrombocytopenia but also in the enhancement of erythropoiesis and the proliferation of HSPCs. We also observed the potent anti-clastogenic activity of AP given to mice as a diet supplement. Further, we found that AP is very effective in the suppression of activated NF-κB and pro-inflammatory cytokines, suggesting that AP given as a diet supplement protects mice from ²⁸Si-ion-induced damage in the hematopoietic tissues of irradiated male C57BL/6J mice via its anti-inflammation activity.

Medical countermeasures for the hematopoietic-subsyndrome of acute radiation syndrome in space

More than 50 years after the Apollo missions ended, the National Aeronautical and Space Administration (NASA) and other international space agencies are preparing a return to the moon as a step towards deep space exploration. At doses ranging from a fraction of a Gray (Gy) to a few Gy, crew will be at risk for developing bone marrow failure associated with the hematopoietic subsyndrome of acute radiation syndrome (H-ARS) requiring pharmacological intervention to reduce risk to life and mission completion. Four medical countermeasures (MCM) in the colony stimulating factor class of drugs are now approved for treatment of myelosuppression associated with ARS. When taken in conjunction with antibiotics, fluids, antidiarrheals, antiemetics, antipyretics, and other treatments for symptomatic illness, the likelihood for recovery and mission completion can be greatly improved. The current review describes the performance and health risks of deep space flight, ionizing radiation exposure during crewed missions to the moon and Mars, and U.S. Food and Drug Administration (FDA)-approved medical interventions to treat ARS. With an expansion of human exploration missions beyond low Earth orbit (LEO), including near-term Lunar and future Mars missions, inclusion of MCMs to counteract ARS in the spaceflight kit will be critical for preserving crew health and performance.

Radioprotection of deinococcal exopolysaccharide BRD125 by regenerating hematopoietic stem cells

There is a substantial need for the development of biomaterials for protecting hematopoietic stem cells and enhancing hematopoiesis after radiation damage. Bacterial exopolysaccharide (EPS) has been shown to be very attractive to researchers as a radioprotectant owing to its high antioxidant, anti-cancer, and limited adverse effects. In the present study, we isolated EPS from a novel strain, Deinococcus radiodurans BRD125, which produces EPS in high abundance, and investigated its applicability as a radioprotective biomaterial. We found that EPS isolated from EPS-rich D. radiodurans BRD125 (DeinoPol-BRD125) had an excellent free-radical scavenging effect and reduced irradiation-induced apoptosis. In addition, bone-marrow and spleen-cell apoptosis in irradiated mice were significantly reduced by DeinoPol-BRD125 administration. DeinoPol-BRD125 enhanced the expression of hematopoiesis-related cytokines such as GM-CSF, G-GSF, M-CSF, and SCF, thereby enhancing hematopoietic stem cells protection and regeneration. Taken together, our findings are the first to report the immunological mechanism of a novel radioprotectant, DeinoPol-BRD125, which might constitute an ideal radioprotective and radiation mitigating agent as a supplement drug during radiotherapy.

Impact of Age, Sex, and Genetic Diversity in Murine Models of the Hematopoietic Acute Radiation Syndrome (H-ARS) and the Delayed Effects of Acute Radiation Exposure (DEARE)

Purpose of review

Malicious or accidental radiation exposure increases risk for the hematopoietic acute radiation syndrome (H-ARS) and the delayed effects of acute radiation exposure (DEARE). Radiation medical countermeasure (MCM) development relies on robust animal models reflective of all age groups and both sexes. This review details critical considerations in murine H-ARS and DEARE model development including divergent radiation responses dependent on age, sex, and genetic diversity.

Recent findings

Radioresistance increases with murine age from pediatrics through geriatrics. Between sexes, radioresistance is higher in male weanlings, pubescent females, and aged males, corresponding with accelerated myelopoiesis. Jackson diversity outbred (JDO) mice resemble non-human primates in radiation response for modeling human diversity. Weanlings and JDO models exhibit less DEARE than other models.

Summary

Highly characterized age-, sex- and diversity-conscious murine models of H-ARS and DEARE provide powerful and essential tools in MCM development for all radiation victims.

Medical management of acute radiation syndrome

Acute radiation syndrome (ARS) is a clinical syndrome involving four organ systems, resulting in the hematopoietic syndrome (HS), gastrointestinal subsyndrome (GIS), neurovascular subsyndrome (NVS) and cutaneous subsyndrome (CS). Since few healthcare providers have seen an ARS case, evidence-based recommendations are needed to guide medical management in a mass casualty scenario. The authors reviewed recommendations from evidence-based and narrative reviews by expert consultants to the World Health Organisation (WHO), a subsequent review of published HS cases, and infectious disease guidelines for management of febrile neutropenia. The WHO Consultancy applied a rigorous grading system to evaluate treatment strategies described in published ARS cases as of 2009, strategies to manage HS in unirradiated persons, results of ARS studies in animal models of ARS, and recommendations of prior expert panels. Major findings for HS were (a) no randomised controlled studies have been performed, (b) data are restricted by the lack of comparator groups, and (c) reports of countermeasures for management of injury to non-hematopoietic organs are often incomplete. Strength of recommendations ranged from strong to weak. Countermeasures of potential benefit include cytokines and for a subgroup of HS patients, hematopoietic stem cell transplantation. These recommendations did not change in a subsequent analysis of HS cases. Recommendations also included fluoroquinolones, bowel decontamination, serotonin receptor antagonists, loperamide and enteral nutrition for GIS; supportive care for NVS; and topical steroids, antihistamines and antibiotics, and surgical excision/grafting for CS. Also reviewed are critical care management guidelines, the role of mesenchymal stem cells for CS, the potential of a platelet-stimulating cytokine for HS, and the author's approach to clinical management of microbial infections associated with ARS based on published guidelines of infectious disease experts. Today's management of HS is supported by evidence-based guidelines. Management of non-HS subsyndromes is supported by a narrative review of the literature and recommendations of infectious disease societies.

Transient expansion and myofibroblast conversion of adipogenic lineage precursors mediate bone marrow repair after radiation

Radiation causes a collapse of bone marrow cells and elimination of microvasculature. To understand how bone marrow recovers after radiation, we focused on mesenchymal lineage cells that provide a supportive microenvironment for hematopoiesis and angiogenesis in bone. We recently discovered a nonproliferative subpopulation of marrow adipogenic lineage precursors (MALPs) that express adipogenic markers with no lipid accumulation. Single-cell transcriptomic analysis revealed that MALPs acquire proliferation and myofibroblast features shortly after radiation. Using an adipocyte-specific Adipoq-Cre, we validated that MALPs rapidly and transiently expanded at day 3 after radiation, coinciding with marrow vessel dilation and diminished marrow cellularity. Concurrently, MALPs lost most of their cell processes, became more elongated, and highly expressed myofibroblast-related genes. Radiation activated mTOR signaling in MALPs that is essential for their myofibroblast conversion and subsequent bone marrow recovery at day 14. Ablation of MALPs blocked the recovery of bone marrow vasculature and cellularity, including hematopoietic stem and progenitors. Moreover, VEGFa deficiency in MALPs delayed bone marrow recovery after radiation. Taken together, our research demonstrates a critical role of MALPs in mediating bone marrow repair after radiation injury and sheds light on a cellular target for treating marrow suppression after radiotherapy.

Pattern of chromosomal aberrations persisting over 30 years in a Chernobyl Nuclear Power Plant accident survivor: study using mFISH

The long-term in vivo cytogenetic effects of high-dose radiation exposure can be traced in accidentally irradiated persons, and particularly useful for developing strategies of monitoring and therapy of such patients, as well as for elucidating the fundamental aspects of hematopoiesis and radiobiology. Using 24-color fluorescent in situ hybridization (mFISH), we analysed the frequency and the spectrum of chromosomal aberrations (CA) in peripheral blood lymphocytes of the Chernobyl Nuclear Power Plant (NPP) accident victim 30, 31, 32 and 33 years after acute accidental exposure to high-dose gamma radiation of the whole body. Totally, 993 metaphase cells were analyzed (or 219, 272, 258, 244 cells each year), of which 297 were aberrant. Our study demonstrated a constant aberrant cell frequency at 28% in 2016-2018 years, while in 2019, a significant increase up to 35% occurred due to contribution of significantly elevated frequency of simple aberrations in the absence of evident recent genotoxic factors. Four clonal aberrations were detected, three of which persisted for more than one year at a frequency up to 2.5% of analyzed cells. The distribution of 731 breakpoints per individual chromosomes was nearly proportional to their physical length, excepting Chromosomes 13 and 20, which were significantly breakpoint-deficient compared to the genome median rate. Monitoring of the long-term effects on chromosomal instability caused by radiation exposure is important for understanding and predicting the long-term effects of ionizing radiation.

The concept of intrinsic versus extrinsic apoptosis

Regulated cell death is a vital and dynamic process in multicellular organisms that maintains tissue homeostasis and eliminates potentially dangerous cells. Apoptosis, one of the better-known forms of regulated cell death, is activated when cell-surface death receptors like Fas are engaged by their ligands (the extrinsic pathway) or when BCL-2-family pro-apoptotic proteins cause the permeabilization of the mitochondrial outer membrane (the intrinsic pathway). Both the intrinsic and extrinsic pathways of apoptosis lead to the activation of a family of proteases, the caspases, which are responsible for the final cell demise in the so-called execution phase of apoptosis. In this review, I will first discuss the most common types of regulated cell death on a morphological basis. I will then consider in detail the molecular pathways of intrinsic and extrinsic apoptosis, discussing how they are activated in response to specific stimuli and are sometimes overlapping. In-depth knowledge of the cellular mechanisms of apoptosis is becoming more and more important not only in the field of cellular and molecular biology but also for its translational potential in several pathologies, including neurodegeneration and cancer.

Residual effects of busulfan and irradiation on murine hematopoietic stem and progenitor cells

Exposure of young C57BL/6 (B6) mice to two courses of busulfan (BSF) injections or two rounds of sublethal total-body irradiation (TBI) induced significant damage to the function of hematopoietic stem and progenitor cells (HSPCs). Fifteen weeks after treatment, BSF- and TBI-treated mice had reduced white blood cells without significant change in red blood cells or platelets, indicating that BSF and TBI hematotoxicity was chronic, with leukocytes being the major targets. Hematopoietic damage induced by BSF or TBI persisted long term. Residual adverse effects were reflected by significantly decreased CD45R B cells and reduced recovery of total bone marrow cells, especially HSPCs carrying markers for KSL (Kit⁺Sca-1⁺Lin^-) cells, multipotent progenitor (MPP) cells (KSLCD34⁺CD135⁺), myeloid progenitor (MP) cells (Kit⁺Sca-1^-Lin^-), and common lymphoid progenitor (CLP) cells 62 wk posttreatment. Transplantation of bone marrow (BM) cells from BSF and TBI donors at 49 weeks after treatment into lethally irradiated hosts resulted in decreased engraftment of CD45R B cells in blood and reduced reconstitution of BM HSPCs including KSL cells, short-term hematopoietic stem cells (KSLCD34⁺CD135^-), MPP cells, and MP cell subsets. TBI donor had better reconstitution of CLP cells in recipients posttransplantation than did BSF donor, suggesting an impact of TBI and BSF on B cells at different development stages. In summary, BSF and TBI exposure produced long-lasting adverse effects on hematopoiesis with pronounced effects on mature B cells, immature ST-HSCs, and hematopoietic progenitor cells. Our results may have implications for therapy of human diseases.

Caffeic acid attenuates irradiation-induced hematopoietic stem cell apoptosis through inhibiting mitochondrial damage

Hematopoietic stem cells (HSCs) are sensitive to ionizing radiation (IR) damage, and its injury is the primary cause of bone marrow (BM) hematopoietic failure and even death after exposure to a certain dose of IR. However, the underlying mechanisms remain incompletely understood. Here we show that mitochondrial oxidative damage, which is characterized by mitochondrial reactive oxygen species overproduction, mitochondrial membrane potential reduction and mitochondrial permeability transition pore opening, is rapidly induced in both human and mouse HSCs and directly accelerates HSC apoptosis after IR exposure. Mechanistically, 5-lipoxygenase (5-LOX) is induced by IR exposure and contributes to IR-induced mitochondrial oxidative damage through inducing lipid peroxidation. Intriguingly, a natural antioxidant, caffeic acid (CA), can attenuate IR-induced HSC apoptosis through suppressing 5-LOX-mediated mitochondrial oxidative damage, thus protecting against BM hematopoietic failure after IR exposure. These findings uncover a critical role for mitochondria in IR-induced HSC injury and highlight the therapeutic potential of CA in BM hematopoietic failure induced by IR.

Training of clinical triage of acute radiation casualties: a performance comparison ofon-siteversusonlinetraining due to the covid-19 pandemic

A collection of powerful diagnostic tools have been developed under the umbrellas of NATO for ionising radiation dose assessment (BAT, WinFRAT) and estimate of acute health effects in humans (WinFRAT, H-Module). We assembled a database of 191 ARS cases using the medical treatment protocols for radiation accident victims (n= 167) and the system for evaluation and archiving of radiation accidents based on case histories (n= 24) for training purposes of medical personnel. From 2016 to 2019, we trained 39 participants comprising MSc level radiobiology students in an on-site teaching class. Enforced by the covid-19 pandemic in 2020 for the first time, an online teaching of nine MSc radiobiology students replaced the on-site teaching. We found that: (a) limitations of correct diagnostic decision-making based on clinical signs and symptoms were experienced unrelated to the teaching format. (b) A significant performance decrease concerning online (first number in parenthesis) versus on-site teaching (reference and second number in parenthesis) was seen regarding the estimate time (31 vs 61 cases per hour, two-fold decrease,p= 0.005). Also, the accurate assessment of response categories (89.9% vs 96.9%,p= 0.001), ARS (92.4% vs 96.7%,p= 0.002) and hospitalisation (93.5% vs 97.0%,p= 0.002) decreased by around 3%-7%. The performances of the online attendees were mainly distributed within the lower quartile performance of on-site participants and the 25%-75% interquartile range increased 3-7-fold. (c) Comparison of dose estimates performed by training participants with hematologic acute radiation syndrome (HARS) severity mirrored the known limitations of dose alone as a surrogate parameter for HARS severity at doses less than 1.5 Gy, but demonstrated correct determination of HARS 2-4 and support for clinical decision making at dose estimates >1.5 Gy, regardless of teaching format. (d) Overall, one-third of the online participants showed substantial misapprehension and insecurities of elementary course content that did not occur after the on-site teaching.

Platelets in Wound Healing: What Happens in Space?

Beyond their fundamental role in hemostasis, platelets importantly contribute to other processes aimed at maintaining homeostasis. Indeed, platelets are a natural source of growth factors and also release many other substances-such as fibronectin, vitronectin, sphingosine 1-phosphate-that are important in maintaining healthy tissues, and ensuring regeneration and repair. Despite rare thrombotic events have been documented in astronauts, some in vivo and in vitro studies demonstrate that microgravity affects platelet's number and function, thus increasing the risk of hemorrhages and contributing to retard wound healing. Here we provide an overview about events linking platelets to the impairment of wound healing in space, also considering, besides weightlessness, exposure to radiation and psychological stress. In the end we discuss the possibility of utilizing platelet rich plasma as a tool to treat skin injuries eventually occurring during space missions.

Hematopoietic Recovery using Multi-Cytokine Therapy in 8 Patients Presenting Radiation-Induced Myelosuppression after Radiological Accidents

Treatment of accidental radiation-induced myelosuppression is primarily based on supportive care and requires specific treatment based on hematopoietic growth factors injection or hematopoietic cell transplantation for the most severe cases. The cytokines used consisted of pegylated erythropoietin (darbepoetin alfa) 500 IU once per week, pegylated G-CSF (pegfilgrastim) 6 mg × 2 once, stem cell factor 20 μg.kg-1 for five days, and romiplostim (TPO analog) 10 μg.kg-1 once per week, with different combinations depending on the accidents. As the stem cell factor did not have regulatory approval for clinical use in France, the French regulatory authorities (ANSM, formerly, AFSSAPS) approved their compassionate use as an investigational drug "on a case-by-case basis". According to the evolution and clinical characteristics, each patient's treatment was adopted on an individual basis. Daily blood count allows initiating G-CSF and SCF delivery when granulocyte <1,000/mm3, TPO delivery when platelets <50,000/mm3, and EPO when Hb<80 g/L. The length of each treatment was based on blood cell recovery criteria. The concept of "stimulation strategy" is linked to each patient's residual hematopoiesis, which varies among them, depending on the radiation exposure's characteristics and heterogeneity. This paper reports the medical management of 8 overexposed patients to ionizing radiation. The recovery of bone marrow function after myelosuppression was accelerated using growth factors, optimized by multiple-line combinations. Particularly in the event of prolonged exposure to ionizing radiation in dose ranges inducing severe myelosuppression (in the order of 5 to 8 Gy), with no indication of hematopoietic stem cell transplantation.

The Oxidative Stress Parameters as Useful Tools in Evaluating the DNA Damage and Changes in the Complete Blood Count in Hospital Workers Exposed to Low Doses of Antineoplastic Drugs and Ionizing Radiation

Hospital workers at the Oncology Department are occupationally exposed to antineoplastic drugs (ANTNP) or low doses of ionizing radiation (Irrad). Therefore, the aim of this study was to evaluate the level of DNA damage, the oxidative stress parameters and complete blood count (CBC) of hospital workers in order to analyze the negative health effects of ANTNP and low dose Irrad. The frequency of micronuclei (MN) and proliferation index (PI) were analyzed by cytokinesis-block test. The oxidative stress biomarkers evaluated were the level of lipid peroxidation in plasma and catalase activity (CAT) in erythrocytes. A group of 86 hospital workers (35 exposed to ANTPN and 51 to Irrad) had increased MN frequency, CAT activity and level of lipid peroxidation compared to the control group, which consisted of 24 volunteers. The hemoglobin level was lower in the ANTNP group compared to thecontrol group, while a significant difference in RBC was recorded between thecontrol and Irrad groups, and in platelet count betweentheIrrad and ANTNP group. The results showed increased DNA damage, oxidative stress parameters, as well as impairment on complete blood count in hospital workers occupationally exposed to antineoplastic drugs and low-dose ionizing radiation. As this research has shown the importance of oxidative stress, we suggest that in addition to routine methods in periodic medical evaluation, the possibility of applying oxidative stress parameters is considered. Moreover, hospital workers exposed to ANTNP and Irrad in the workplace should undergo not only a more complete health prevention procedure but also have a more appropriate health promotion.

Radiation-induced bystander effects impair transplanted human hematopoietic stem cells via oxidative DNA damage

Total body irradiation (TBI) is commonly used in host conditioning regimens for human hematopoietic stem cell (HSC) transplantation to treat various hematological disorders. Exposure to TBI not only induces acute myelosuppression and immunosuppression, but also injures the various components of the HSC niche in recipients. Our previous study demonstrated that radiation-induced bystander effects (RIBE) of irradiated recipients decreased the long-term repopulating ability of transplanted mouse HSCs. However, RIBE on transplanted human HSCs have not been studied. Here, we report that RIBE impaired the long-term hematopoietic reconstitution of human HSCs as well as the colony-forming ability of human hematopoietic progenitor cells (HPCs). Our further analyses revealed that the RIBE-affected human hematopoietic cells showed enhanced DNA damage responses, cell-cycle arrest, and p53-dependent apoptosis, mainly because of oxidative stress. Moreover, multiple antioxidants could mitigate these bystander effects, though at different efficacies in vitro and in vivo. Taken together, these findings suggest that RIBE impair human HSCs and HPCs by oxidative DNA damage. This study provides definitive evidence for RIBE on transplanted human HSCs and further justifies the necessity of conducting clinical trials to evaluate different antioxidants to improve the efficacy of HSC transplantation for the patients with hematological or nonhematological disorders.

[Patients treated with palbociclib and endocrine therapy for metastatic breast cancer: Can we predict the occurrence of severe early hematological toxicity?]

INTRODUCTION

The addition of palbociclib to endocrine therapy has been shown to improve progression free survival in hormone receptor positive metastatic breast cancer patients. This cyclin CDK4/6 inhibitor could expose patients to a grade 3-4 hematological toxicity, leading to treatment discontinuation or treatment interruption that is potentially associated with a lack of efficiency. The aim of this study was to identify predictive factors of severe early hematotoxicity (ESHT).

METHODS

This retrospective cohort study included patients who started palbociclib in the Institut Sainte Catherine between December 1, 2016 and January 1, 2019 for the treatment of metastatic breast cancer. Individual data and hematological toxicity were collected from electronic medical records. ESHT was defined as the occurrence, during the first 3 cycles, of grade 4 or grade 3 hematological toxicity requiring palbociclib dose reduction.

RESULTS

In total, 181 patients (180 females) were included; median age was 67 years. Forty-six patients (25.4%) experienced an ESHT. Predictive factors of ESHT in multivariate analysis were a performance status (PS) of 2 or more (P=0.024) and an history of radiotherapy of bone metastasis in the previous year (P=0.003). Before palbociclib initiation, a neutrophil count below 3.37g/L was predictive of ESHT with a sensibility of 76% and a specificity of 71%.

CONCLUSIONS

ECOG PS, bone radiotherapy within the year and low baseline neutrophils count are associated with ESHT in palbociclib-treated metastatic breast cancer patients. These elements could be useful for a careful monitoring leading to adapted therapy.

Establishing Pediatric Mouse Models of the Hematopoietic Acute Radiation Syndrome and the Delayed Effects of Acute Radiation Exposure

Medical countermeasures (MCMs) for hematopoietic acute radiation syndrome (H-ARS) should be evaluated in well-characterized animal models, with consideration of at-risk populations such as pediatrics. We have developed pediatric mouse models of H-ARS and delayed effects of acute radiation exposure (DEARE) for efficacy testing of MCMs against radiation. Male and female C57BL/6J mice aged 3, 4, 5, 6, 7 and 8 weeks old (±1 day) were characterized for baseline hematopoietic and gastrointestinal parameters, radiation response, efficacy of a known MCM, and DEARE at six and 12 months after total-body irradiation (TBI). Weanlings (age 3 weeks) were the most radiosensitive age group with an estimated LD50/30 of 712 cGy, while mice aged 4 to 8 weeks were more radioresistant with an estimated LD50/30 of 767-787 cGy. Female weanlings were more radiosensitive than males at 3 and 4 weeks old but became significantly more radioresistant after the pubertal age of 5 weeks. The most dramatic increase in body weight, RBC counts and intestinal circumference length occurred from 3 to 5 weeks of age. The established radiomitigator Neulasta® (pegfilgrastim) significantly increased 30-day survival in all age groups, validating these models for MCM efficacy testing. Analyses of DEARE among pediatric survivors revealed depressed weight gain in males six months post-TBI, and increased blood urea nitrogen at 12 months post-TBI which was more severe in females. Hematopoietic DEARE at six months post-TBI appeared to be less severe in survivors from the 3- and 4-week-old groups but was equally severe in all age groups by 12 months of age. Similar to our other acute radiation mouse models, there was no appreciable effect of Neulasta used as an H-ARS MCM on the severity of DEARE. In summary, these data characterize a pediatric mouse model useful for assessing the efficacy of MCMs against ARS and DEARE in children.

Prophylactic administration of podophyllotoxin and rutin combination assists the revival of radiation-induced hematopoietic suppression in lethally irradiated mice

Hematopoietic syndrome contributes to mortality after exposure to high doses of low LET radiation. In this context, we have earlier demonstrated the potential of G-003 M (a combination of podophyllotoxin and rutin) in alleviating radiation-induced bone marrow suppression. Similarly, we here demonstrate that G-003 M protected mice from death (>83% protection) and increased the populations of CD 34 (Cluster of differentiation 34) as well as CD 117 (Cluster of differentiation 117) positive cell population and their colony forming capacity. This was accompanied with increase in the serum titre of granulocyte colony stimulating factor (G-CSF), granulocyte-macrophage colony stimulating factor (GM-CSF). Interestingly, G-003 M lowered down the titre of fms-like tyrosine kinase (Flt-3) ligands. Our results furthermore demonstrates that G-003 M facilitated the nuclear translocation of β-catenin and upregulated the expression of Wnt 10b. Conditioning of animal with G-003 M activated the expression of survivin, inhibited the activation of Caspase-3 in CD 34/117+ progenitor stem cells and protected the bone marrow vascularity and splenic colonies in lethally irradiated animals, which collectively promoted hemopoietic recovery in lethally irradiated mice.

Night shift schedule causes circadian dysregulation of DNA repair genes and elevated DNA damage in humans

Circadian disruption has been identified as a risk factor for health disorders such as obesity, cardiovascular disease, and cancer. Although epidemiological studies suggest an increased risk of various cancers associated with circadian misalignment due to night shift work, the underlying mechanisms have yet to be elucidated. We sought to investigate the potential mechanistic role that circadian disruption of cancer hallmark pathway genes may play in the increased cancer risk in shift workers. In a controlled laboratory study, we investigated the circadian transcriptome of cancer hallmark pathway genes and associated biological pathways in circulating leukocytes obtained from healthy young adults during a 24-hour constant routine protocol following 3 days of simulated day shift or night shift. The simulated night shift schedule significantly altered the normal circadian rhythmicity of genes involved in cancer hallmark pathways. A DNA repair pathway showed significant enrichment of rhythmic genes following the simulated day shift schedule, but not following the simulated night shift schedule. In functional assessments, we demonstrated that there was an increased sensitivity to both endogenous and exogenous sources of DNA damage after exposure to simulated night shift. Our results suggest that circadian dysregulation of DNA repair may increase DNA damage and potentiate elevated cancer risk in night shift workers.

Early- and late-occurring damage in bone marrow cells of male CBA/Ca mice exposed whole-body to 1 GeV/n 48Ti ions

PURPOSE

To determine the early- and late-occurring damage in the bone marrow (BM) and peripheral blood cells of male CBA/Ca mice after exposure to 0, 0.1, 0.25, or 0.5 Gy of 1 GeV/n titanium (48Ti) ions (one type of space radiation).

METHOD

We used the mouse in vivo blood-erythrocyte micronucleus (MN) assay for evaluating the cytogenetic effects of various doses of 1 GeV/n 48Ti ions. The MN assay was coupled with the characterization of epigenetic alterations (the levels of global 5-methylcytosine and 5-hydroxymethylcytosine) in DNA samples isolated from BM cells. These analyses were performed in samples collected at an early time-point (1 week) and a late time-point (6 months) post-irradiation.

RESULTS

Our results showed that 48Ti ions induced genomic instability in exposed mice. Significant dose-dependent loss of global 5-hydroxymethylcytosine was found but there were no changes in global 5-methylcytosine levels.

CONCLUSION

Since persistent genomic instability and loss of global 5-hydroxymethylcytosine are linked to cancer, our findings suggest that exposure to 48Ti ions may pose health risks.

Commonalities Between COVID-19 and Radiation Injury

As the multi-systemic components of COVID-19 emerge, parallel etiologies can be drawn between SARS-CoV-2 infection and radiation injuries. While some SARS-CoV-2-infected individuals present as asymptomatic, others exhibit mild symptoms that may include fever, cough, chills, and unusual symptoms like loss of taste and smell and reddening in the extremities (e.g., "COVID toes," suggestive of microvessel damage). Still others alarm healthcare providers with extreme and rapid onset of high-risk indicators of mortality that include acute respiratory distress syndrome (ARDS), multi-organ hypercoagulation, hypoxia and cardiovascular damage. Researchers are quickly refocusing their science to address this enigmatic virus that seems to unveil itself in new ways without discrimination. As investigators begin to identify early markers of disease, identification of common threads with other pathologies may provide some clues. Interestingly, years of research in the field of radiation biology documents the complex multiorgan nature of another disease state that occurs after exposure to high doses of radiation: the acute radiation syndrome (ARS). Inflammation is a key common player in COVID-19 and ARS, and drives the multi-system damage that dramatically alters biological homeostasis. Both conditions initiate a cytokine storm, with similar pro-inflammatory molecules increased and other anti-inflammatory molecules decreased. These changes manifest in a variety of ways, with a demonstrably higher health impact in patients having underlying medical conditions. The potentially dramatic human impact of ARS has guided the science that has identified many biomarkers of radiation exposure, established medical management strategies for ARS, and led to the development of medical countermeasures for use in the event of a radiation public health emergency. These efforts can now be leveraged to help elucidate mechanisms of action of COVID-19 injuries. Furthermore, this intersection between COVID-19 and ARS may point to approaches that could accelerate the discovery of treatments for both.

Antitumor and Radiosensitizing Effects of Zinc Oxide-Caffeic Acid Nanoparticles against Solid Ehrlich Carcinoma in Female Mice

This study aimed to evaluate the anticancer and radio-sensitizing efficacy of Zinc Oxide-Caffeic Acid Nanoparticles (ZnO-CA NPs). ZnO-CA NPs were formulated by the conjugation of Zinc Oxide nanoparticles (ZnO NPs) with caffeic acid (CA) that were characterized by Fourier Transform Infrared Spectra (FT-IR), X-ray Diffractometer (XRD), and Transmission Electron Microscopy (TEM). In vitro anticancer potential of ZnO-CA NPs was evaluated by assessing cell viability in the human breast (MCF-7) and hepatocellular (HepG2) carcinoma cell lines. In vivo anticancer and radio-sensitizing effects of ZnO-CA NPs in solid Ehrlich carcinoma-bearing mice (EC mice) were also assessed. Treatment of EC mice with ZnO-CA NPs resulted in a considerable decline in tumor size and weight, down-regulation of B-cell lymphoma 2 (BCL2) and nuclear factor kappa B (NF-κB) gene expressions, decreased vascular cell adhesion molecule 1 (VCAM-1) level, downregulation of phosphorylated-extracellular-regulated kinase 1 and 2 (p-ERK1/2) protein expression, DNA fragmentation and a recognizable peak at sub-G0/G1 indicating dead cells' population in cancer tissues. Combined treatment of ZnO-CA NPs with γ-irradiation improved these effects. In conclusion: ZnO-CA NPs exhibit in-vitro as well as in-vivo antitumor activity, which is augmented by exposure of mice to γ-irradiation. Further explorations are warranted previous to clinical application of ZnO-CA NPs.

Near-infrared photoimmunotherapy of cancer: a new approach that kills cancer cells and enhances anti-cancer host immunity

Near-infrared photoimmunotherapy (NIR-PIT) is a recently developed hybrid cancer therapy that directly kills cancer cells as well as producing a therapeutic host immune response. Conventional immunotherapies, such as immune-activating cytokine therapy, checkpoint inhibition, engineered T cells and suppressor cell depletion, do not directly destroy cancer cells, but rely exclusively on activating the immune system. NIR-PIT selectively destroys cancer cells, leading to immunogenic cell death that initiates local immune reactions to released cancer antigens from dying cancer cells. These are characterized by rapid maturation of dendritic cells and priming of multi-clonal cancer-specific cytotoxic T cells that kill cells that escaped the initial direct effects of NIR-PIT. The NIR-PIT can be applied to a wide variety of cancers either as monotherapy or in combination with conventional immune therapies to further activate anti-cancer immunity. A global Phase 3 clinical trial (https://clinicaltrials.gov/ct2/show/NCT03769506) of NIR-PIT targeting the epidermal growth factor receptor (EGFR) in patients with recurrent head and neck cancer is underway, employing RM1929/ASP1929, a conjugate of anti-EGFR antibody (cetuximab) plus the photo-absorber IRDye700DX (IR700). NIR-PIT has been given fast-track recognition by regulators in the USA and Japan. A variety of imaging methods, including direct IR700 fluorescence imaging, can be used to monitor NIR-PIT. As experience with NIR-PIT grows, additional antibodies will be employed to target additional antigens on other cancers or to target immune-suppressor cells to enhance host immunity. NIR-PIT will be particularly important in patients with localized and locally advanced cancers and may help such patients avoid side-effects associated with surgery, radiation and chemotherapy.

[Pelvic irradiation and hematopoietic toxicity: A review of the literature]

Pelvic bone marrow is the site of nearly 50% of total hematopoiesis. Radiation therapy of pelvic lymph node areas, and cancers located near the bony structures of the pelvis, exposes to hematological toxicity in the range of 30 to 70%. This toxicity depends on many factors, including the presence or absence of concomitant chemotherapy and its type, the volume of irradiated bone, the received doses, or the initial hematopoietic reserve. Intensity modulated radiation therapy allows the optimisation of dose deposit on at risk organs while providing optimal coverage of target volumes. However, this suggests that dose constraints should be known precisely to limit the incidence of radiation side effects. This literature review focuses firstly on pelvic lymph node areas and bony volumes nearby, then on the effects of irradiation on bone marrow and the current dosimetric constraints resulting from it, and finally on hematological toxicities by carcinologic location and progress in reducing these toxicities.

Short-term bone marrow suppression in differentiated thyroid cancer patients after radioactive iodine treatment

After thyroidectomy in differentiated thyroid cancer (DTC), radioactive iodine (RAI) treatment is often used for remnant ablation. However, RAI treatment has been associated with bone marrow suppression, and leukopenia, anemia, and thrombocytopenia may occur after a single RAI administration. In this study, we examined the change in complete blood counts at 1 week after RAI administration; this is less well studied. A group of 189 DTC patients who received RAI treatment and underwent blood tests before and after treatment, were included. Peripheral blood counts at baseline were compared to those obtained at 1 week, 1-6 months, and 6-12 months after RAI treatment in order to test for bone marrow suppression. At 1 week after RAI treatment, there was a significant decrease in the white blood cell count (WBC, 5.8 ± 1.6 × 10⁹/L vs. 5.4 ± 1.5 × 10⁹/L, p < 0.001) and hemoglobin level (Hb, 13.5 ± 1.7 g/dL vs. 13.3 ± 1.4 g/dL, p = 0.001). The WBC decrease was mostly due to lymphocyte counts (2.2 ± 0.6 × 10⁹/L vs. 1.6 ± 0.5 × 10⁹/L, p < 0.001), with no decrease in the neutrophil count. Although not significantly changed at 1 week, platelets counts were altered within 6 months (265 ± 69 × 10⁹/L vs. 239 ± 53 × 10⁹/L, p < 0.001). The decline in the WBC count recovered within 6 months; lymphocyte and platelet counts recovered within 12 months. In conclusion, RAI treatment after a thyroidectomy was associated with a statistically significant but temporary decline in WBC counts and Hb levels at 1 week. Physicians treating DTC patients should not decrease usage of moderate dose RAI treatments.

How Hematopoietic Stem Cells Respond to Irradiation: Similarities and Differences between Low and High Doses of Ionizing Radiations

In this review, we will specifically address the newest insights on the effect of low doses of ionizing radiations on the hematopoietic stem cells, which are prone to long-term deleterious effects. Impact of high doses of irradiation on hematopoietic cells has been widely studied over the years, in line with the risk of accidental or terrorist exposure to irradiation and with a particular attention to the sensitivity of the hematopoietic system. Recently, more studies have focused on lower doses of irradiation on different tissues, due to the increasing exposure caused by medical imaging, radiotherapy or plane travelling for instance. Hence, we will delineate similarities and discrepancies in HSC response to high and low doses of irradiation from these studies.