Cutaneous and local radiation injuries

Advances in the study of polysaccharide-based hydrogel wound dressings

Due to the complexity of wound healing, the rapid promotion of wound healing has been a major unresolved challenge for the medical community. If a suitable wound dressing is not found, it can easily induce wound infection and slow down the wound repair process. Hydrogels have been recognized as the best alternative to traditional wound dressings due to their unique water-retention properties as well as their drug-carrying properties. We first outlined the entire process of wound healing, while introducing the biological activities of ten different natural polysaccharides and their mechanisms for promoting wound healing. Subsequently, we summarized the advantages and limitations of various polysaccharides in use and proposed corresponding solutions. In addition, wound dressings for a wide range of wounds, including diabetes, burns, and radiation, have also been reviewed, providing a comprehensive understanding of the applications of these hydrogels in different wound types. This paper provides an important reference for the biomedical application and clinical research of natural polysaccharide-based hydrogel in wound dressings.

Nanotechnology meets radiobiology: Fullerenols and Metallofullerenols as nano-shields in radiotherapy

Despite significant advances in the development of radioprotective measures, the clinical application of radioprotectors and radiomitigators remains limited due to insufficient efficacy and high toxicity of most agents. Additionally, in oncological radiotherapy, these compounds may interfere with the therapeutic effectiveness. Recent progress in nanotechnology highlights fullerenols (FulOHs) and metallofullerenols (Me@FulOHs) as promising candidates for next-generation radioprotectors. These nanostructures possess unique antioxidant properties, demonstrating greater efficacy in rediucing oxidative stress compared to conventional agents. Moreover, their potential to minimize pro-oxidative risks depends on the precise identification of cellular environments and irradiation conditions that optimize their radioprotective effects. In parallel, Me@FulOHs serve as powerful theranostic tools in oncology. Their strong imaging signals enable high-resolution PET and MRI, facilitating early detection and accurate localization of pathogenic alterations. This dual functionality positions Me@FulOHs as key components in advanced radiotherapy. By integrating these nanomaterials with modern theranostic approaches, it is possible to enhance the precision of treatment while minimizing side effects, addressing a critical need in contemporary oncology. This review emphasizes the importance of systematic evaluation of context-dependent effects of Me@FulOHs, particularly in pre- and post-irradiation scenarios, to optimize their clinical relevance. The dual role of Me@FulOHs as both radioprotectors and diagnostic agents distinguishes them from traditional compounds, paving the way for innovative practical applications. Their use in radiotherapy represents a significant step toward the development of safer and more effective strategies in radiation protection and cancer treatment. We also review ionizing radiation effects, classifications, cancer radiotherapy applications, and countermeasures.

Impact of Minimally Manipulated Cell Therapy on Immune Responses in Radiation-Induced Skin Wound Healing

The current treatment of radiation-induced skin wounds utilizes mainly conventional therapies, including topical steroids, creams, ointments, and hydrogel dressings, which do not take into account the immunologic changes that occur in the skin after radiation exposure. Therefore, it is relevant to consider alternative therapies and their impact on changes in the immune landscape of the skin. The aim of this study was to investigate the effect of allogeneic minimally manipulated keratinocytes and fibroblasts on rat skin repair and the development of immune responses. We found that the use of cell therapy compared to treatment with syntazone ointment and no treatment resulted in faster healing and a reduction in the size of radiation-induced skin wounds, area of inflammation, and edema. Additionally, in the group receiving the cell therapy application, there was an observed increase in the number of mast cells (MCs), activation of MC interaction with M2 macrophages, a reduction in the direct contact of MCs with the vascular bed, an increase in the content of collagen fibers due to the intensification of collagen fibrillogenesis, and a restoration of their histotopographic organization. Thus, the positive effect of cell therapy based on allogeneic minimally manipulated keratinocytes and fibroblasts on skin regeneration indicated that it can be used in clinical practice to improve the effectiveness of rehabilitation after radiation therapy.

Low-dose ionizing radiation and the exposure-lag response: protocol for a prospective cohort study on The Health Effects of Chongqing Occupational Radiation Workers

Introduction

Although the effects of ionizing radiation on radiation workers have been extensively studied in China, no prospective cohort study has been conducted in Chongqing. Furthermore, previous cohorts have not provided a broad-gauge assessment of the temporal relationship between low-dose occupational radiation exposure and the risk of health outcomes.

Methods

A prospective cohort study will be carried out focusing on radiation workers in Chongqing. Health examination outcomes and radiation dose monitoring data will be collected and analyzed using the distributed lag non-linear model (DLNM) combined with generalized additive model (GAM) or generalized linear model (GLM) to evaluate the exposure-lag response relationship.

Discussion

Our study will enhance our understanding of the exposure-lag response association between occupational radiation exposure and the health of radiation workers based on DLNM.

Clinical trial registration

Chinese Clinical Trials Registry, ChiCTR2400081804.

Role of radiation emergency medicine: historical view-a perspective on the past, present, and future

The more science progresses, the more life and society change. Medicine also changes with the times and the culture. This is also true for radiation emergency medicine, which includes dose-assessment leading to diagnosis, treatment, medical follow-up and prognosis of persons who have developed acute injury or illness due to radioactive contamination or radiation exposure. Before the report of X-rays by Roentgen, there was evidence that X-rays had been emitted from the electrically excited Crookes tube and that skin injury had been caused by the X-rays. Thus, the history of radiation and its exposure started before Roentgen. During the early stage of radiation use, people were simply exposed to radiation but were unaware of any danger. Radioactive materials were found soon after Roentgen's report, and contamination with these materials occurred. Together with the development of science and technology, sophisticated radiation devices were produced, and the use and application of radiation became much enhanced. New radionuclides were found one after another, leading to identification of different qualities of radiation. Development of nuclear physics allowed people to artificially produce radionuclides and to construct a nuclear reactor. After World War II, nuclear power plants were constructed, and related facilities such as nuclear fuel processing, reprocessing and spent fuel storage facilities were built. If radiation accidents or events occur at such facilities, radiation exposure with thermal or chemical burns could occur. Together with the expansion of globalism in the world and division in the society, there are now increasing concerns regarding the malicious usage of radiation by radiological dispersal devices (RDDs) including a dirty bomb. Upon detonation of RDDs, blast and thermal injuries with radiation exposure could be caused. In the present society, the natures of exposure to radiation and contamination with radioactive materials have become much more complicated. Not even mentioning the atomic bomb, the detonation of RDDs also necessitates scenarios of medical responses to complicated injuries and the involvement of numbers of people. This article looks back at the history of radiation and addresses the medical responses to radiation injuries that change with the times.

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.

Molecular biological mechanisms of radiotherapy-induced skin injury occurrence and treatment

Radiotherapy-Induced Skin Injury (RISI) is radiation damage to normal skin tissue that primarily occurs during tumor Radiotherapy and occupational exposure. The risk of RISI is high due to the fact that the skin is not only the first body organ that ionizing radiation comes into contact with, but it is also highly sensitive to it, especially the basal cell layer and capillaries. Typical clinical manifestations of RISI include erythema, dry desquamation, moist desquamation, and ulcers, which have been established to significantly impact patient care and cancer treatment. Notably, our current understanding of RISI's pathological mechanisms and signaling pathways is inadequate, and no standard treatments have been established. Radiation-induced oxidative stress, inflammatory responses, fibrosis, apoptosis, and cellular senescence are among the known mechanisms that interact and promote disease progression. Additionally, radiation can damage all cellular components and induce genetic and epigenetic changes, which play a crucial role in the occurrence and progression of skin injury. A deeper understanding of these mechanisms and pathways is crucial for exploring the potential therapeutic targets for RISI. Therefore, in this review, we summarize the key mechanisms and potential treatment methods for RISI, offering a reference for future research and development of treatment strategies.

Radiation dermatitis in the hairless mouse model mimics human radiation dermatitis

Over half of all people diagnosed with cancer receive radiation therapy. Moderate to severe radiation dermatitis occurs in most human radiation patients, causing pain, aesthetic distress, and a negative impact on tumor control. No effective prevention or treatment for radiation dermatitis exists. The lack of well-characterized, clinically relevant animal models of human radiation dermatitis contributes to the absence of strategies to mitigate radiation dermatitis. Here, we establish and characterize a hairless SKH-1 mouse model of human radiation dermatitis by correlating temporal stages of clinical and pathological skin injury. We demonstrate that a single ionizing radiation treatment of 30 Gy using 6 MeV electrons induces severe clinical grade 3 peak toxicity at 12 days, defined by marked erythema, desquamation and partial ulceration, with resolution occurring by 25 days. Histopathology reveals that radiation-induced skin injury features temporally unique inflammatory changes. Upregulation of epidermal and dermal TGF-ß1 and COX-2 protein expression occurs at peak dermatitis, with sustained epidermal TGF-ß1 expression beyond resolution. Specific histopathological variables that remain substantially high at peak toxicity and early clinical resolution, including epidermal thickening, hyperkeratosis and dermal fibroplasia/fibrosis, serve as specific measurable parameters for in vivo interventional preclinical studies that seek to mitigate radiation-induced skin injury.

Upregulation of PRRX2 by silencing Marveld3 as a protective mechanism against radiation-induced ferroptosis in skin cells

BACKGROUND

Radiation-induced skin injury (RISI) represents a significant complication in patients receiving radiotherapy and individuals exposed to nuclear accidents, characterized by a protracted wound-healing process relative to injuries from other etiologies. Current preventive and management approaches remain inadequate. Consequently, investigating efficacious intervention strategies that target the disease's progression characteristics holds significant practical importance.

METHODS

Small interfering RNA (siRNA) and overexpression plasmid were used to modulate the expression of Marvel domain containing 3 (Marveld3) and paired related homeobox 2 (PRRX2). Protein and mRNA levels were estimated by Western Blot and real-time PCR, respectively. Intracellular levels of Malondialdehyde (MDA), a terminal product of lipid peroxidation, were measured following the manufacturer's protocol for MDA assay kit. Similarly, intracellular levels of ferrous iron (Fe2+) and reactive oxygen species (ROS) were determined using their respective assay kits. Lipid peroxidation status within the cells was evaluated via BODIPY staining. Immunohistochemistry was conducted to ascertain the expression of PRRX2 in skin tissues collected at various time points following irradiation of rats. The H-score method was used to evaluate the percentage of positively stained cells and staining intensity. RNA sequencing, Gene Ontology (GO) analysis, and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analysis were conducted by OE Biotech Company.

RESULTS

In this study, our findings indicated that Marveld3 suppression could effectively inhibit lipid peroxidation levels in irradiated skin cells, concomitantly reducing intracellular Fe2+ content. Additionally, the silencing of Marveld3 effectively abrogated the impact of a ferroptosis agonist on cellular viability, resulting in the upregulation of 66 and 178 genes, as well as the downregulation of 188 and 31 genes in irradiated HaCaT and WS1 cells, respectively. Among the differentially expressed genes, the PRRX2 which was found to be involved in the process of ferroptosis, exhibited statistically significant upregulation. And the upregulation of PRRX2 expression may attenuate radiation-induced lipid peroxidation in skin cells, thereby functioning as a potential stress-responsive mechanism to counteract radiation effects.

CONCLUSIONS

This study elucidates the role of Marveld3 in radiation-induced ferroptosis in skin cells. Inhibition of Marveld3 led to the upregulation of PRRX2, which subsequently resulted in a reduction of Fe2+ and ROS levels, as well as the suppression of lipid peroxidation. These effects collectively mitigated the occurrence of ferroptosis.

A suprapubic refractory skin ulcer following keloid radiotherapy: from hyper-proliferation to hypo-proliferation

Radiation-induced skin ulcer following cancer and/or tumour is well-documented in the literature. However, radiation-induced skin ulcer following the excision of keloid is yet to be reported. Here, we report the case of a 33-year-old female patient with a suprapubic skin ulcer of five months' duration following keloid treatment with electron beam therapy at recommended dosage. Various examinations, including a skin biopsy, metagenomic sequencing, magnetic resonance imaging and immunochemistry, indicated that the skin ulcer was induced by radiotherapy. While postoperative radiotherapy has been recommended immediately following keloid excision to reduce the risk of recurrence, the present case highlights the risk of skin refractory ulcer following keloid radiotherapy.

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.

Expected role of photodynamic therapy to relieve skin damage in nuclear or radiological emergency: Review

Nuclear and radiological accidents can occur due to poor management, in transportation, radiation therapy and nuclear wards in hospitals, leading to extreme radiation exposure and serious consequences for human health. Additionally, in many of previous radiological accidents, skin damage was observed in patients and survivors due to the high radiation exposure. However, as part of a medical countermeasures in a nuclear/radiological emergency, it is critical to plan for the treatment of radiation-induced skin damage. Hence, the new, non-invasive technology of photodynamic therapy (PDT) is projected to be more effectively used for treating skin damage caused by high-dose radiation. PDT plays an important role in treating, repairing skin damage and promoting wound healing as evidenced by research. This review, highlighted and recommended potential impacts of PDT to repair and decrease radiation-induced skin tissue damage. Moreover, we have suggested some photosensitizer (PS) agent as radio-mitigator drugs to decrease radiobiological effects.

Skin Absorbed Dose Coefficients for Human Legs from Beta Radiation as a Function of Height

External exposure to skin from beta-emitter radionuclides following severe reactor accidents or nuclear testing can result in beta burning and other health complications. The skin absorbed dose coefficient (SADC) measures the energy deposition into the skin during such accidents. The U.S. Environmental Protection Agency has published several reports to measure the possible energy deposition into the skin in such accidents. However, the most recent SADC published by Federal Guidance Report (FGR) 12 was computed only at one meter above the contaminated surface. Therefore, it was necessary to develop a model to estimate the absorbed dose coefficients for skin at different heights. In this manuscript, Geant4, a Monte Carlo simulator toolkit, was used to estimate the absorbed dose coefficients from electron sources located on the soil surface with energies ranging from 0.1 to 4 MeV. The energy deposited from primary electrons, secondary electrons, and photons in a 50 µm thick layer of epidermis tissue (Basal Cells Layer) located at a depth of 50 µm from the skin surface was estimated at several discrete heights of human leg phantom. More than 40% of the total energy deposited comes from secondary electrons and photons in energy sources of 0.1 and 0.2 MeV on average, but for higher energies, this percentage is less than 1%, which indicates primary electrons are the main source of the deposited energy in the skin. Furthermore, the results showed the energy deposited into skin closer to the ground was 50–100% higher than the previously estimated doses for 1 m above the ground. The results from Geant4 showed a great correlation (R2 = 0.972) with the FGR 12 data at one meter height, and they were aligned with the published values from FGR 12, which validated the simulation results. Therefore, the calculated dose coefficients for different energy sources and different heights could be used in radiation protection measurements.

Cell Therapies for Acute Radiation Syndrome

The risks of severe ionizing radiation exposure are increasing due to the involvement of nuclear powers in combat operations, the increasing use of nuclear power, and the existence of terrorist threats. Exposure to a whole-body radiation dose above about 0.7 Gy results in H-ARS (hematopoietic acute radiation syndrome), which is characterized by damage to the hematopoietic system; higher doses result in further damage to the gastrointestinal and nervous systems. Only a few medical countermeasures for ARS are currently available and approved for use, although others are in development. Cell therapies (cells or products produced by cells) are complex therapeutics that show promise for the treatment of radiation injury and have been shown to reduce mortality and morbidity in animal models. Since clinical trials for ARS cannot be ethically conducted, animal testing is extremely important. Here, we describe cell therapies that have been tested in animal models. Both cells and cell products appear to promote survival and lessen tissue damage after whole-body irradiation, although the mechanisms are not clear. Because radiation exposure often occurs in conjunction with other traumatic injuries, animal models of combined injury involving radiation and future countermeasure testing for these complex medical problems are also discussed.

An Overview of Appropriate Medical Practice and Preparedness in Radiation Emergency Response

Radiation emergencies involving high doses of nuclear radiation pose significant risks from exposure to ionizing radiation in various scenarios. These situations include transportation accidents involving radioactive materials, occupational exposure, nuclear detonations, dirty bombs, and nuclear power plant accidents. In addition to the immediate risks of acute radiation syndrome (ARS) and related diseases, long-term exposure can increase the risk of other health issues such as cardiovascular disease and cancer. Vulnerable populations, including pregnant women and children, face particular concern due to potential impacts on their health and the health of unborn babies. The severity of ARS depends on several factors such as radiation dose, quality, dose rate, exposure uniformity, and individual biological responses. Bioindicators are biological responses or markers that help assess the severity and effects of radiation exposure on an individual. Bioindicators can include physical symptoms such as nausea, vomiting, and diarrhea, or laboratory tests such as changes in blood cell counts and gene expression that can help in assessing and treating exposed individuals. Additionally, early prodromal symptoms such as vomiting, diarrhea, and erythema can provide important clues for diagnosis and treatment. Developing a comprehensive plan for radiation emergencies is vital for safeguarding public health, infrastructure, and the environment. First responders play a critical role in establishing safety perimeters, triage, and coordination with various stakeholders. Education and training are essential for medical personnel and the public. This article provides general recommendations and identifies challenges to effective radiation emergency preparedness and response.

Radiation-induced gastrointestinal and cutaneous injuries: understanding models, pathologies, assessments, and clinically accepted practices

PURPOSE

A U. S. and European joint effort fostering the development of medical countermeasures (MCMs) operable in case of radiological or nuclear emergencies.

METHODS

Based on the joint engagement between the U.S. National Institute of Allergy and Infectious Diseases (NIAID) and the French Institut de Radioprotection et de Sûreté Nucléaire (IRSN), a Statement of Intent to Collaborate was signed in 2014 and a series of working group meeting were established. In December 2022, the NIAID and IRSN hosted a five-day, U.S./European meeting titled 'Radiation-Induced Cutaneous and Gastrointestinal Injuries: Advances in Understanding Pathologies, Assessment, and Clinically Accepted Practices' in Paris, France. The goals of the meeting were to bring together U.S. and European investigators to explore new research avenues for the medical management of skin and gastrointestinal injuries, including specific diagnostics for each organ system, animal models, and promising medical countermeasures (MCMs) to mitigate radiation damage. There was also an emphasis on exploring additional areas of medicine and response to understand best practices from other emergency scenarios, which could be leveraged to improve radiation preparedness, and the importance of accurate dosimetry in preclinical work.

RESULTS

Subsequent to the workshop, seven collaborative projects, funded by both organizations, were established on topics ranging from MCMs and predictive biomarkers, and using physical methods to assess cutaneous radiation injuries, to mechanistic studies to understand radiation-induced damage in multiple organ systems. The importance of accurate dosimetry in preclinical works was highlighted and two recently published U.S./European commentaries that focus on the need for dosimetry standardization in the reported literature had their origins in this meeting. This commentary summarizes the workshop and open discussions among academic investigators, industry researchers, and U.S. and IRSN program representatives.

CONCLUSIONS

Given the substantive progress made due to these interactions, both groups plan to expand out these meetings by incorporating high-level investigators from across the globe, while endeavoring to maintain the informal setting that was conducive to in-depth scientific discussion and enhanced the state of the science in radiation research.

3D skin bioprinting as promising therapeutic strategy for radiation-associated skin injuries

Both cutaneous radiation injury and radiation combined injury (RCI) could have serious skin traumas, which are collectively referred to as radiation-associated skin injuries in this paper. These two types of skin injuries require special managements of wounds, and the therapeutic effects still need to be further improved. Cutaneous radiation injuries are common in both radiotherapy patients and victims of radioactive source accidents, which could lead to skin necrosis and ulcers in serious conditions. At present, there are still many challenges in management of cutaneous radiation injuries including early diagnosis, lesion assessment, and treatment prognosis. Radiation combined injuries are special and important issues in severe nuclear accidents, which often accompanied by serious skin traumas. Mass victims of RCI would be the focus of public health concern. Three-dimensional (3D) bioprinting, as a versatile and favourable technique, offers effective approaches to fabricate biomimetic architectures with bioactivity, which provides potentials for resolve the challenges in treating radiation-associated skin injuries. Combining with the cutting-edge advances in 3D skin bioprinting, the authors analyse the damage characteristics of skin wounds in both cutaneous radiation injury and RCI and look forward to the potential value of 3D skin bioprinting for the treatments of radiation-associated skin injuries.

Health Effects of Ionizing Radiation on the Human Body

Radioactivity is a process in which the nuclei of unstable atoms spontaneously decay, producing other nuclei and releasing energy in the form of ionizing radiation in the form of alpha (α) and beta (β) particles as well as the emission of gamma (γ) electromagnetic waves. People may be exposed to radiation in various forms, as casualties of nuclear accidents, workers in power plants, or while working and using different radiation sources in medicine and health care. Acute radiation syndrome (ARS) occurs in subjects exposed to a very high dose of radiation in a very short period of time. Each form of radiation has a unique pathophysiological effect. Unfortunately, higher organisms-human beings-in the course of evolution have not acquired receptors for the direct "capture" of radiation energy, which is transferred at the level of DNA, cells, tissues, and organs. Radiation in biological systems depends on the amount of absorbed energy and its spatial distribution, particularly depending on the linear energy transfer (LET). Photon radiation with low LET leads to homogeneous energy deposition in the entire tissue volume. On the other hand, radiation with a high LET produces a fast Bragg peak, which generates a low input dose, whereby the penetration depth into the tissue increases with the radiation energy. The consequences are mutations, apoptosis, the development of cancer, and cell death. The most sensitive cells are those that divide intensively-bone marrow cells, digestive tract cells, reproductive cells, and skin cells. The health care system and the public should raise awareness of the consequences of ionizing radiation. Therefore, our aim is to identify the consequences of ARS taking into account radiation damage to the respiratory system, nervous system, hematopoietic system, gastrointestinal tract, and skin.

Advanced Technologies in Radiation Research

The U.S. Government is committed to maintaining a robust research program that supports a portfolio of scientific experts who are investigating the biological effects of radiation exposure. On August 17 and 18, 2023, the Radiation and Nuclear Countermeasures Program, within the National Institute of Allergy and Infectious Diseases, National Institutes of Health (NIH), partnered with the National Cancer Institute, NIH, the National Aeronautics and Space Administration, and the Radiation Injury Treatment Network to convene a workshop titled, Advanced Technologies in Radiation Research (ATRR), which focused on the use of advanced technologies under development or in current use to accelerate radiation research. This meeting report provides a comprehensive overview of the research presented at the workshop, which included an assembly of subject matter experts from government, industry, and academia. Topics discussed during the workshop included assessments of acute and delayed effects of radiation exposure using modalities such as clustered regularly interspaced short palindromic repeats (CRISPR) - based gene editing, tissue chips, advanced computing, artificial intelligence, and immersive imaging techniques. These approaches are being applied to develop products to diagnose and treat radiation injury to the bone marrow, skin, lung, and gastrointestinal tract, among other tissues. The overarching goal of the workshop was to provide an opportunity for the radiation research community to come together to assess the technological landscape through sharing of data, methodologies, and challenges, followed by a guided discussion with all participants. Ultimately, the organizers hope that the radiation research community will benefit from the workshop and seek solutions to scientific questions that remain unaddressed. Understanding existing research gaps and harnessing new or re-imagined tools and methods will allow for the design of studies to advance medical products along the critical path to U.S. Food and Drug Administration approval.

Cutaneous Radiation Injuries: REAC/TS Clinical Experience

The Radiation Emergency Assistance Center/Training Site (REAC/TS) is one of the US Department of Energy (DOE)/National Nuclear Security Administration (NNSA) Nuclear Emergency Response Team (NEST) assets and has been responding to radiological incidents since 1976. REAC/TS is in the Oak Ridge Institute for Science and Education (ORISE). A critical part of the REAC/TS mission is to provide emergency response, advice, and consultation on injuries and illnesses caused from ionizing radiation. Fortunately, radiation injuries are not frequent, but when they occur, they are more likely to be cutaneous radiation injuries (CRI) or internal contamination. In this paper, we will review selected cases from the REAC/TS experience in order to illustrate cutaneous patterns of injury and treatment options.

Effects of Radiation-Induced Skin Injury on Hyaluronan Degradation and Its Underlying Mechanisms

Radiation-induced skin injury (RISI) is a frequent and severe complication with a complex pathogenesis that often occurs during radiation therapy, nuclear incidents, and nuclear war, for which there is no effective treatment. Hyaluronan (HA) plays an overwhelming role in the skin, and it has been shown that UVB irradiation induces increased HA expression. Nevertheless, to the best of our knowledge, there has been no study regarding the biological correlation between RISI and HA degradation and its underlying mechanisms. Therefore, in our study, we investigated low-molecular-weight HA content using an enzyme-linked immunosorbent assay and changes in the expression of HA-related metabolic enzymes using real-time quantitative polymerase chain reaction and a Western blotting assay. The oxidative stress level of the RISI model was assessed using sodium dismutase, malondialdehyde, and reactive oxygen species assays. We demonstrated that low-molecular-weight HA content was significantly upregulated in skin tissues during the late phase of irradiation exposure in the RISI model and that HA-related metabolic enzymes, oxidative stress levels, the MEK5/ERK5 pathway, and inflammatory factors were consistent with changes in low-molecular-weight HA content. These findings prove that HA degradation is biologically relevant to RISI development and that the HA degradation mechanisms are related to HA-related metabolic enzymes, oxidative stress, and inflammatory factors. The MEK5/ERK5 pathway represents a potential mechanism of HA degradation. In conclusion, we aimed to investigate changes in HA content and preliminarily investigate the HA degradation mechanism in a RISI model under γ-ray irradiation, to consider HA as a new target for RISI and provide ideas for novel drug development.

Overlapping Science in Radiation and Sulfur Mustard Exposures of Skin and Lung: Consideration of Models, Mechanisms, Organ Systems, and Medical Countermeasures: Overlapping science in radiation and sulfur mustard injuries to lung and skin

PURPOSE

To summarize presentations and discussions from the 2022 trans-agency workshop titled "Overlapping science in radiation and sulfur mustard (SM) exposures of skin and lung: Consideration of models, mechanisms, organ systems, and medical countermeasures."

METHODS

Summary on topics includes: (1) an overview of the radiation and chemical countermeasure development programs and missions; (2) regulatory and industry perspectives for drugs and devices; 3) pathophysiology of skin and lung following radiation or SM exposure; 4) mechanisms of action/targets, biomarkers of injury; and 5) animal models that simulate anticipated clinical responses.

RESULTS

There are striking similarities between injuries caused by radiation and SM exposures. Primary outcomes from both types of exposure include acute injuries, while late complications comprise chronic inflammation, oxidative stress, and vascular dysfunction, which can culminate in fibrosis in both skin and lung organ systems. This workshop brought together academic and industrial researchers, medical practitioners, US Government program officials, and regulators to discuss lung-, and skin- specific animal models and biomarkers, novel pathways of injury and recovery, and paths to licensure for products to address radiation or SM injuries.

CONCLUSIONS

Regular communications between the radiological and chemical injury research communities can enhance the state-of-the-science, provide a unique perspective on novel therapeutic strategies, and improve overall US Government emergency preparedness.

Nano-Architecture of Persistent Focal DNA Damage Regions in the Minipig Epidermis Weeks after Acute γ-Irradiation

Exposure to high acute doses of ionizing radiation (IR) can induce cutaneous radiation syndrome. Weeks after such radiation insults, keratinocyte nuclei of the epidermis exhibit persisting genomic lesions that present as focal accumulations of DNA double-strand break (DSB) damage marker proteins. Knowledge about the nanostructure of these genomic lesions is scarce. Here, we compared the chromatin nano-architecture with respect to DNA damage response (DDR) factors in persistent genomic DNA damage regions and healthy chromatin in epidermis sections of two minipigs 28 days after lumbar irradiation with ~50 Gy γ-rays, using single-molecule localization microscopy (SMLM) combined with geometric and topological mathematical analyses. SMLM analysis of fluorochrome-stained paraffin sections revealed, within keratinocyte nuclei with perisitent DNA damage, the nano-arrangements of pATM, 53BP1 and Mre11 DDR proteins in γ-H2AX-positive focal chromatin areas (termed macro-foci). It was found that persistent macro-foci contained on average ~70% of 53BP1, ~23% of MRE11 and ~25% of pATM single molecule signals of a nucleus. MRE11 and pATM fluorescent tags were organized in focal nanoclusters peaking at about 40 nm diameter, while 53BP1 tags formed nanoclusters that made up super-foci of about 300 nm in size. Relative to undamaged nuclear chromatin, the enrichment of DDR protein signal tags in γ-H2AX macro-foci was on average 8.7-fold (±3) for 53BP1, 3.4-fold (±1.3) for MRE11 and 3.6-fold (±1.8) for pATM. The persistent macro-foci of minipig epidermis displayed a ~2-fold enrichment of DDR proteins, relative to DSB foci of lymphoblastoid control cells 30 min after 0.5 Gy X-ray exposure. A lasting accumulation of damage signaling and sensing molecules such as pATM and 53BP1, as well as the DSB end-processing protein MRE11 in the persistent macro-foci suggests the presence of diverse DNA damages which pose an insurmountable problem for DSB repair.

Employing High-Fidelity Simulation for the High-Risk, Low-Frequency Diagnosis and Management of Acute Radiation Syndrome (ARS)

Introduction

Acute radiation syndrome (ARS) is a high-risk, low-frequency diagnosis that can be fatal and is difficult to diagnose without an obvious history of ionizing radiation exposure.

Methods

Twenty-two emergency medicine residents and one pharmacy resident participated in an hour-long simulation session. To accommodate all learners, the simulation was conducted eight times over a block of scheduled time (two to four learners/session). Sessions included a prebriefing, pre/post questionnaires, the ARS case, and a debriefing. Learners evaluated and managed a 47-year-old male (manikin) with the hematopoietic and cutaneous subsyndromes of ARS who presented with hand pain/erythema/edema and underlying signs of infection 2 weeks after an unrecognized radiation exposure. Learners had to perform a history and physical, recognize/manage abnormal vitals, order/interpret labs, consult appropriate disciplines, and initiate supportive care.

Results

There was a mean reported increase in ability to recognize signs and symptoms of ARS (p < .001) and appropriately manage a patient with this condition (p = .03) even after controlling for baseline confidence in ability to make and manage uncommon diagnoses, respectively. Learners rated this simulation as a valuable learning experience, effective in teaching them how to diagnose and treat ARS, and one they would recommend to other health care professionals.

Discussion

This simulation aimed to teach the diagnosis and initial management of the hematopoietic and cutaneous subsyndromes of ARS. It should be used to increase awareness of the potential for ionizing radiation exposure under less obvious conditions and raise the index of suspicion for ARS in the undifferentiated patient.

The Therapeutic Application of Stem Cells and Their Derived Exosomes in the Treatment of Radiation-Induced Skin Injury

Radiation-induced skin injury (RISI) is a serious concern for nuclear accidents and cancer radiotherapy, which seriously affects the quality of life of patients. This injury differs from traditional wounds due to impaired healing and the propensity to recurrence and is divided into acute and chronic phases on the basis of the injury time. Unfortunately, there are few effective therapies for preventing or mitigating this injury. Over the last few decades, various studies have focused on the effects of stem cell-based therapies to address the tissue repair and regeneration of irradiated skin. These stem cells modulate inflammation and instigate tissue repair by differentiating into specific kinds of cells or releasing paracrine factors. Stem cell-based therapies, including bone marrow-derived stem cells (BMSCs), adipose-derived stem cells (ADSCs) and stromal vascular fraction (SVF), have been reported to facilitate wound healing after radiation exposure. Moreover, stem cell-derived exosomes have recently been suggested as an effective and cell-free approach to support skin regeneration, circumventing the concerns respecting direct application of stem cells. Based on the literature on stem cell-based therapies for radiation-induced skin injury, we summarize the characteristics of different stem cells and describe their latest animal and clinical applications, as well as potential mechanisms. The promise of stem-cell based therapies against radiation-induced skin injury contribute to our response to nuclear events and smooth progress of cancer radiotherapy.

Responding to radiation accidents: what more do we need to know?

A short review of the various types of radiation incidents and accidents that have occurred is used to provide a context for discussing the findings on medical management of the victims of such incidents and accidents reported in a recent Special Issue of the Journal of Radiological Protection. The review demonstrates that accidents and incidents giving rise to high radiation doses may involve over-exposure of a single individual, a few individuals, or very large numbers. In general, these exposures will be relatively short-term, ranging from a few seconds to a few days, but chronic situations resulting in high exposures can occur. Some of these exposures may be highly localised, whereas others may result in almost uniform whole-body irradiation. This diversity of situations means that it is not feasible to have a single protocol for the diagnosis and treatment of over-exposed individuals. If the over-exposures are limited to one or a few individuals, these can be addressed on a case-by-case basis. However, where large numbers have been exposed or may have been exposed, there is a need to implement a rapid and effective system of triage. Furthermore, this system is likely to have to be implemented by individuals who have little or no direct experience of radiation-induced injuries. For those individuals who may have been significantly exposed, the key consideration is not to determine the radiation dose that they have received, but to establish their present clinical status and how it is likely to develop with time. There is at most a very limited role for bone-marrow transplantation in the treatment of acute radiation syndrome, whereas there are good arguments for administering various treatments to boost bone marrow function together with other supportive interventions, e.g. in control of infections and handling both fluid loss and bleeding. However, there is concern that the focus to date has been only on the licencing of drugs related to the management of haematopoietic effects. Although a great deal is known about the diagnosis and treatment of injuries arising from high dose exposures, this knowledge is biased towards situations in which there is relatively uniform, external whole-body exposure. More attention needs to be given to assessing the implications of various inhomogeneous exposure regimes and to developing medical countermeasures optimised for addressing the complex, multi-organ effects likely to arise from such inhomogeneous exposures.