Cardiovascular Disease Risk Modeling for Astronauts: Making the Leap From Earth to Space

Radiation symptoms resemble laminopathies and the physical underlying cause may sit at the lamin A C-terminus

Ionizing radiation causes three divergent effects in the human body: On one side, tissue death (= deterministic effects) sets on, on the other side, mutations and cancer growth (= stochastic effects) can occur. In recent years, the additional phenomenon of accelerated aging has come to light. In the following, we argue that these seemingly contradictory radiation responses namely: (i) increased cancer growth, (ii) ablation of cancer tissue or (iii) deterministic senescence, share an underlying cause from damage at the lamin A C-terminus. In other words, besides the typically described genomic radiation impact, we propose an additional destabilization pathway via oxidation at the nuclear envelope. We propose five concrete hypotheses that draw a direct mechanistic model from radiation damage and cellular oxidative stress, to micronuclei and clinical symptoms. In conjunction with lamin B compensation, we might be able to explain why deterministic or stochastic responses dominate. If our model holds true, a novel target for radiotherapeutics and radiooncology arises, and a rationale to closer connect laminopathy and radioprotection research.

AOP report: Development of an adverse outcome pathway for deposition of energy leading to learning and memory impairment

Understanding radiation-induced non-cancer effects on the central nervous system (CNS) is essential for the risk assessment of medical (e.g., radiotherapy) and occupational (e.g., nuclear workers and astronauts) exposures. Herein, the adverse outcome pathway (AOP) approach was used to consolidate relevant studies in the area of cognitive decline for identification of research gaps, countermeasure development, and for eventual use in risk assessments. AOPs are an analytical construct describing critical events to an adverse outcome (AO) in a simplified form beginning with a molecular initiating event (MIE). An AOP was constructed utilizing mechanistic information to build empirical support for the key event relationships (KERs) between the MIE of deposition of energy to the AO of learning and memory impairment through multiple key events (KEs). The evidence for the AOP was acquired through a documented scoping review of the literature. In this AOP, the MIE is connected to the AO via six KEs: increased oxidative stress, increased deoxyribonucleic acid (DNA) strand breaks, altered stress response signaling, tissue resident cell activation, increased pro-inflammatory mediators, and abnormal neural remodeling that encompasses atypical structural and functional alterations of neural cells and surrounding environment. Deposition of energy directly leads to oxidative stress, increased DNA strand breaks, an increase of pro-inflammatory mediators and tissue resident cell activation. These KEs, which are themselves interconnected, can lead to abnormal neural remodeling impacting learning and memory processes. Identified knowledge gaps include improving quantitative understanding of the AOP across several KERs and additional testing of proposed modulating factors through experimental work. Broadly, it is envisioned that the outcome of these efforts could be extended to other cognitive disorders and complement ongoing work by international radiation governing bodies in their review of the system of radiological protection.

AOP report: Development of an adverse outcome pathway for deposition of energy leading to abnormal vascular remodeling

Cardiovascular diseases (CVDs) are complex, encompassing many types of heart pathophysiologies and associated etiologies. Radiotherapy studies have shown that fractionated radiation exposure at high doses (3-17 Gy) to the heart increases the incidence of CVD. However, the effects of low doses of radiation on the cardiovascular system or the effects from space travel, where radiation and microgravity are important contributors to damage, are not clearly understood. Herein, the adverse outcome pathway (AOP) framework was applied to develop an AOP to abnormal vascular remodeling from the deposition of energy. Following the creation of a preliminary pathway with the guidance of field experts and authoritative reviews, a scoping review was conducted that informed final key event (KE) selection and evaluation of the Bradford Hill criteria for the KE relationships (KERs). The AOP begins with a molecular initiating event of deposition of energy; ionization events increase oxidative stress, which when persistent concurrently causes the release of pro-inflammatory mediators, suppresses anti-inflammatory mechanisms and alters stress response signaling pathways. These KEs alter nitric oxide levels leading to endothelial dysfunction, and subsequent abnormal vascular remodeling (the adverse outcome). The work identifies evidence needed to strengthen understanding of the causal associations for the KERs, emphasizing where there are knowledge gaps and uncertainties in both qualitative and quantitative understanding. The AOP is anticipated to direct future research to better understand the effects of space on the human body and potentially develop countermeasures to better protect future space travelers.

Satellite-Based On-Orbit Printing of 3D Tumor Models

Space three dimension (3D） bioprinting provides a precise and bionic tumor model for evaluating the compound effect of the space environment on tumors, thereby providing insight into the progress of the disease and potential treatments. However, space 3D bioprinting faces several challenges, including prelaunch uncertainty, possible liquid leakage, long-term culture in space, automatic equipment control, data acquisition, and transmission. Here, a novel satellite-based 3D bioprinting device with high structural strength, small volume, and low weight (<6 kg) is developed. A microgel-based biphasic thermosensitive bioink and suspension medium that supports the on-orbit printing and in situ culture of complex tumor models is developed. An intelligent control algorithm that enables the automatic control of 3D printing, autofocusing, fluorescence imaging, and data transfer back to the ground is developed. To the authors' knowledge, this is the first time that on-orbit printing of tumor models is achieved in space with stable morphology and moderate viability via a satellite. It is found that 3D tumor models are more sensitive to antitumor drugs in space than on Earth. This study opens up a new avenue for 3D bioprinting in space and offers new possibilities for future research in space life science and medicine.

Considering clonal hematopoiesis of indeterminate potential in space radiation risk analysis for hematologic cancers and cardiovascular disease

BACKGROUND

Expanding human presence in space through long-duration exploration missions and commercial space operations warrants improvements in approaches for quantifying crew space radiation health risks. Currently, risk assessment models for radiogenic cancer and cardiovascular disease consider age, sex, and tobacco use, but do not incorporate other modifiable (e.g., body weight, physical activity, diet, environment) and non-modifiable individual risk factors (e.g., genetics, medical history, race/ethnicity, family history) that may greatly influence crew health both in-mission and long-term. For example, clonal hematopoiesis of indeterminate potential (CHIP) is a relatively common age-related condition that is an emerging risk factor for a variety of diseases including cardiovascular disease and cancer. CHIP carrier status may therefore exacerbate health risks associated with space radiation exposure.

METHODS

In the present study, published CHIP hazard ratios were used to modify background hazard rates for coronary heart disease, stroke, and hematologic cancers in the National Aeronautics and Space Administration space radiation risk assessment model. The risk of radiation exposure-induced death for these endpoints was projected for a future Mars exploration mission scenario.

RESULTS

Here we show appreciable increases in the lifetime risk of exposure-induced death for hematologic malignancies, coronary heart disease, and stroke, which are observed as a function of age after radiation exposure for male and female crew members that are directly attributable to the elevated health risks for CHIP carriers.

CONCLUSIONS

We discuss the importance of evaluating individual risk factors such as CHIP as part of a comprehensive space radiation risk assessment strategy aimed at effective risk communication and disease surveillance for astronauts embarking on future exploration missions.

Space research to explore novel biochemical insights on Earth

Travel to space has overcome unprecedent technological challenges and this has resulted in transfer of these technological results on Earth to better our lives. Health technology, medical devices, and research advancements in human biology are the first beneficiaries of this transfer. The real breakthrough came with the International Space Station, which endorsed multidisciplinary international scientific collaborations and boosted the research on pathophysiological adaptation of astronauts to life on space. These studies evidenced that life in space appeared to have exposed the astronauts to an accelerated aging-related pathophysiological dysregulation across multiple systems. In this review we emphasize the interaction between several biomarkers and their alteration in concentrations/expression/function by space stress factors. These altered interactions, suggest that different biochemical and hormonal factors, and cell signals, contribute to a complex network of pathophysiological mechanisms, orchestrating the homeostatic dysregulation of various organs/metabolic pathways. The main effects of space travel on altering cell organelles biology, ultrastructure, and cross-talk, have been observed in cell aging as well as in the disruption of metabolic pathways, which are also the causal factor of rare inherited metabolic disorders, one of the major pediatric health issue. The pathophysiologic breakthrough from space research could allow the development of precision health both on Earth and Space by promoting the validation of improved biomarker-based risk scores and the exploration of new pathophysiologic hypotheses and therapeutic targets. Nonstandard abbreviations: International Space Station (ISS), Artificial Intelligence (AI), European Space Agency (ESA), National Aeronautics and Space Agency (NASA), Low Earth Orbit (LEO), high sensitive troponin (hs-cTn), high sensitive troponin I (hs-cTn I), high sensitive troponin T, Brain Natriuretic Peptide (BNP), N terminal Brain Natriuretic Peptide (NT-BNP), cardiovascular disease (CVD), parathyroid hormone (PTH), urinary hydroxyproline (uHP), urinary C- and N-terminal telopeptides (uCTX and uNTX), pyridinoline (PYD), deoxypyridinoline (DPD), half-time (HF), serum Bone Alkaline Phosphatase (sBSAP), serum Alkaline Phosphatase (sAP), Carboxy-terminal Propeptide of Type 1 Procollagen (P1CP), serum Osteocalcin (sOC)), advanced glycation end products (AGEs), glycated hemoglobin A1c (HbA1c), Insulin-like growth factor 1 (IGF1), Growth Hormone (GH), amino acid (AA), β-hydroxy-β methyl butyrate (HMB), maple syrup urine disease (MSUD), non-communicable diseases (NCDs).

Comprehensive Analysis of Contaminants in Powdered Milk Samples Using an HPGe for γ Radiation

Aims: This study aimed to assess the activity concentrations and cancer risk assessments of 232Th and 40K in powdered milk samples collected from various suppliers in Pakistan, considering the increasing concern about cancer risks associated with environmental radiological effects related to food consumption. Subjects and Methods: Specific activity concentrations were determined using a high-resolution, high-purity germanium γ-spectroscopy system. Results: The specific activity levels of 40K and 232Th in the analyzed powdered milk samples were found to be 230.86 and 6.87 Bq/kg, respectively, well within the safe limits recommended by the United Nations Scientific Committee on the Effects of Atomic Radiation (UNSCEAR). The hazard index (0.074 Bq/kg) and radium equivalent (27.58 Bq/kg) were calculated as indicators of radiation hazard, along with absorbed dose (26.26 nGy/h), annual effective dose (0.13 nGy/h), and excess lifetime cancer risk (0.45). These parameters provide insights into the potential health risks associated with powdered milk consumption. Conclusions: The findings collectively affirm the radiological safety of the analyzed powdered milk samples, providing valuable insights into the potential health risks associated with their consumption.

Genetic diversity, clinical uses, and phytochemical and pharmacological properties of safflower (Carthamus tinctorius L.): an important medicinal plant

Safflower (Carthamus tinctorius L.), a member of the Asteraceae family, is widely used in traditional herbal medicine. This review summarized agronomic conditions, genetic diversity, clinical application, and phytochemicals and pharmacological properties of safflower. The genetic diversity of the plant is rich. Abundant in secondary metabolites like flavonoids, phenols, alkaloids, polysaccharides, fatty acids, polyacetylene, and other bioactive components, the medicinal plant is effective for treating cardiovascular diseases, neurodegenerative diseases, and respiratory diseases. Especially, Hydroxysafflor yellow A (HYSA) has a variety of pharmacological effects. In terms of treatment and prevention of some space sickness in space travel, safflower could be a potential therapeutic agent. Further studies are still required to support the development of safflower in medicine. Our review indicates that safflower is an important medicinal plant and research prospects regarding safflower are very broad and worthy of further investigation.

Cardiovascular Challenges Beyond Earth: Investigating the Impact of Space Travel on Astronauts' Cardiovascular Health

In the coming decades, as humanity aims to establish a presence on Mars, there is a growing significance in comprehending, monitoring, and controlling the diverse health challenges arising from space exploration. The extended exposure to microgravity during space missions leads to various physical alterations in astronauts, such as shifts in bodily fluids, reduced plasma volume, loss of bone density, muscle wasting, and cardiovascular deconditioning. These changes can ultimately lead to orthostatic intolerance, underscoring the increasing importance of addressing these health risks. Astronauts are exposed to cosmic radiation consisting of high-energy particles from various sources, including solar cosmic rays and galactic cosmic rays. These radiations can impact the electrical signals in the heart, potentially causing irregular heart rhythms. Understanding the risks to the heart and blood circulation brought on by exposure to space radiation and the overall stress of spaceflight is essential and this article reviews the cardiovascular effects of space travel on astronauts.

Public-private partnerships in fostering outer space innovations

As public and private institutions recognize the role of space exploration as a catalyst for economic growth, various areas of innovation are expected to emerge as drivers of the space economy. These include space transportation, in-space manufacturing, bioproduction, in-space agriculture, nuclear launch, and propulsion systems, as well as satellite services and their maintenance. However, the current nature of space as an open-access resource and global commons presents a systemic risk for exuberant competition for space goods and services, which may result in a "tragedy of the commons" dilemma. In the race among countries to capture the value of space exploration, NASA, American research universities, and private companies can avoid any coordination failures by collaborating in a public-private research and development partnership (PPRDP) structure. We present such a structure founded upon the principles of polycentric autonomous governance, which incorporate a decentralized autonomous organization framework and specialized research clusters. By advancing an alignment of incentives among the specified participatory members, PPRDPs can play a pivotal role in stimulating open-source research by creating positive knowledge spillover effects and agglomeration externalities as well as embracing the nonlinear decomposition paradigm that may blur the distinction between basic and applied research.

Noncancer Effects of Ionizing Radiation Exposure on the Eye, the Circulatory System and beyond: Developments made since the 2011 ICRP Statement on Tissue Reactions

For radiation protection purposes, noncancer effects with a threshold-type dose-response relationship have been classified as tissue reactions (formerly called nonstochastic or deterministic effects), and equivalent dose limits aim to prevent occurrence of such tissue reactions. Accumulating evidence demonstrates increased risks for several late occurring noncancer effects at doses and dose rates much lower than previously considered. In 2011, the International Commission on Radiological Protection (ICRP) issued a statement on tissue reactions to recommend a threshold of 0.5 Gy to the lens of the eye for cataracts and to the heart and brain for diseases of the circulatory system (DCS), independent of dose rate. Literature published thereafter continues to provide updated knowledge. Increased risks for cataracts below 0.5 Gy have been reported in several cohorts (e.g., including in those receiving protracted or chronic exposures). A dose threshold for cataracts is less evident with longer follow-up, with limited evidence available for risk of cataract removal surgery. There is emerging evidence for risk of normal-tension glaucoma and diabetic retinopathy, but the long-held tenet that the lens represents among the most radiosensitive tissues in the eye and in the body seems to remain unchanged. For DCS, increased risks have been reported in various cohorts, but the existence or otherwise of a dose threshold is unclear. The level of risk is less uncertain at lower dose and lower dose rate, with the possibility that risk per unit dose is greater at lower doses and dose rates. Target organs and tissues for DCS are also unknown, but may include heart, large blood vessels and kidneys. Identification of potential factors (e.g., sex, age, lifestyle factors, coexposures, comorbidities, genetics and epigenetics) that may modify radiation risk of cataracts and DCS would be important. Other noncancer effects on the radar include neurological effects (e.g., Parkinson's disease, Alzheimer's disease and dementia) of which elevated risk has increasingly been reported. These late occurring noncancer effects tend to deviate from the definition of tissue reactions, necessitating more scientific developments to reconsider the radiation effect classification system and risk management. This paper gives an overview of historical developments made in ICRP prior to the 2011 statement and an update on relevant developments made since the 2011 ICRP statement.

Cardiovascular Adaptations of Space Travel: A Systematic Review

INTRODUCTION

Space travel imposes significant gravitational and radiation stress on both cellular and systemic physiology, resulting in myriad cardiovascular changes that have not been fully characterized.

METHODS

We conducted a systematic review of the cellular and clinical adaptations of the cardiovascular system after exposure to real or simulated space travel in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. The PubMed and Cochrane databases were searched in June 2021 for all peer-reviewed articles published since 1950 related to the following search terms entered in separate pairs: "cardiology and space" and "cardiology and astronaut." Only cellular and clinical studies in English concerning the investigation of cardiology and space were included.

RESULTS

Eighteen studies were identified, comprising 14 clinical and 4 cellular investigations. On the genetic level, pluripotent stem cells in humans and cardiomyocytes in mice displayed increased beat irregularity, with clinical studies revealing a persistent increase in heart rate after space travel. Further cardiovascular adaptations included a higher frequency of orthostatic tachycardia but no evidence of orthostatic hypotension, after return to sea level. Hemoglobin concentration was also consistently decreased after return to Earth. No consistent change in systolic or diastolic blood pressure or any clinically significant arrhythmias were observed during or after space travel.

CONCLUSION

Changes in oxygen carrying capacity, blood pressure, and post-flight orthostatic tachycardia may serve as reasons to further screen for pre-existing anemic and hypotensive conditions among astronauts.