Editorial to the Special Issue: "Dysregulation of Human Molecular and Metabolic Mechanisms Resulting in Oxidative Stress and Damage Generation in the Space Environment".

Commercial space industries are emergent, bolstered by new exciting rocket systems, orbital and landing vehicles, the creation of multi-country orbital platforms, satellite technology, the renewed promise of low Earth orbit (LEO) business opportunities, as well as promised planetary exploration [...].

The Use of a Preoperative Mitral Valve Model to Guide Mitral Valve Repair.

BACKGROUND: Mitral valve repair is commonly used to address degenerative or functional changes to the mitral valve apparatus and surrounding ventricular anatomy. Preoperative transoesophageal echocardiogram (TOE) is routinely used to evaluate and identify the precise anatomic location of mitral valve pathology in order to guide repair. However, surgeons currently lack specific guidance regarding the approximate dimensions of the mitral valve they should aim for in order to achieve optimal valve function and avoid adverse outcomes. Therefore, through an observational study, we aimed to develop and test the accuracy of a preliminary mathematical model which represents the geometric relationship between various clinically relevant components of the mitral valve and its surrounding structures. METHODS: Using established trigonometric principles, the geometric relationship shared between several mitral valve components was represented in a two-dimensional (2D) model and described in a mathematical equation. The output variable of the model is the anteroposterior diameter of the mitral valve. To assess the accuracy of the mathematical model, we compared the model-predicted anteroposterior (AP) diameter against AP diameter measured by postoperative TOE in 42 cases. RESULTS: The root mean squared error (RMSE) of model predicted AP diameter compared to measured AP diameter was 0.43 cm. The mean absolute percentage error (MAPE) of the model was 17.7%. In 34 out of 42 cases, model-predicted AP diameters were within 25% of AP diameters measured by postoperative TOE. CONCLUSIONS: Preliminary testing of a simple mathematical model has shown its relative accuracy in representing the geometric relationship between several mitral valve variables. Further research and refinement of the model is required in order to improve its accuracy. We are encouraged that, with further improvement, the model has the potential for clinical application.

Oxidative Stress and Space Biology: An Organ-Based Approach.

The environment of space provides many challenges to the human physiology and therefore to extended habitation and exploration[...].

3D tissue-like assemblies: A novel approach to investigate virus-cell interactions.

Virus-host cell interactions are most commonly analyzed in cells maintained in vitro as two-dimensional tissue cultures. However, these in vitro conditions vary quite drastically from the tissues that are commonly infected in vivo. Over the years, a number of systems have been developed that allow the establishment of three-dimensional (3D) tissue structures that have properties similar to their in vivo 3D counterparts. These 3D systems have numerous applications including drug testing, maintenance of large tissue explants, monitoring migration of human lymphocytes in tissues, analysis of human organ tissue development and investigation of virus-host interactions including viral latency. Here, we describe the establishment of tissue-like assemblies for human lung and neuronal tissue that we infected with a variety of viruses including the respiratory pathogens human parainfluenza virus type 3 (PIV3), respiratory syncytial virus (RSV) and SARS corona virus (SARS-CoV) as well as the human neurotropic herpesvirus, varicella-zoster virus (VZV).

Novel Double-Hit Model of Radiation and Hyperoxia-Induced Oxidative Cell Damage Relevant to Space Travel.

Spaceflight occasionally requires multiple extravehicular activities (EVA) that potentially subject astronauts to repeated changes in ambient oxygen superimposed on those of space radiation exposure. We thus developed a novel in vitro model system to test lung cell damage following repeated exposure to radiation and hyperoxia. Non-tumorigenic murine alveolar type II epithelial cells (C10) were exposed to >95% O2 for 8 h only (O2), 0.25 Gy ionizing γ-radiation (IR) only, or a double-hit combination of both challenges (O2 + IR) followed by 16 h of normoxia (ambient air containing 21% O2 and 5% CO2) (1 cycle = 24 h, 2 cycles = 48 h). Cell survival, DNA damage, apoptosis, and indicators of oxidative stress were evaluated after 1 and 2 cycles of exposure. We observed a significant (p < 0.05) decrease in cell survival across all challenge conditions along with an increase in DNA damage, determined by Comet analysis and H2AX phosphorylation, and apoptosis, determined by Annexin-V staining, relative to cells unexposed to hyperoxia or radiation. DNA damage (GADD45α and cleaved-PARP), apoptotic (cleaved caspase-3 and BAX), and antioxidant (HO-1 and Nqo1) proteins were increased following radiation and hyperoxia exposure after 1 and 2 cycles of exposure. Importantly, exposure to combination challenge O2 + IR exacerbated cell death and DNA damage compared to individual exposures O2 or IR alone. Additionally levels of cell cycle proteins phospho-p53 and p21 were significantly increased, while levels of CDK1 and Cyclin B1 were decreased at both time points for all exposure groups. Similarly, proteins involved in cell cycle arrest was more profoundly changed with the combination challenges as compared to each stressor alone. These results correlate with a significant 4- to 6-fold increase in the ratio of cells in G2/G1 after 2 cycles of exposure to hyperoxic conditions. We have characterized a novel in vitro model of double-hit, low-level radiation and hyperoxia exposure that leads to oxidative lung cell injury, DNA damage, apoptosis, and cell cycle arrest.

Three-dimensional normal human neural progenitor tissue-like assemblies: a model of persistent varicella-zoster virus infection.

Varicella-zoster virus (VZV) is a neurotropic human alphaherpesvirus that causes varicella upon primary infection, establishes latency in multiple ganglionic neurons, and can reactivate to cause zoster. Live attenuated VZV vaccines are available; however, they can also establish latent infections and reactivate. Studies of VZV latency have been limited to the analyses of human ganglia removed at autopsy, as the virus is strictly a human pathogen. Recently, terminally differentiated human neurons have received much attention as a means to study the interaction between VZV and human neurons; however, the short life-span of these cells in culture has limited their application. Herein, we describe the construction of a model of normal human neural progenitor cells (NHNP) in tissue-like assemblies (TLAs), which can be successfully maintained for at least 180 days in three-dimensional (3D) culture, and exhibit an expression profile similar to that of human trigeminal ganglia. Infection of NHNP TLAs with cell-free VZV resulted in a persistent infection that was maintained for three months, during which the virus genome remained stable. Immediate-early, early and late VZV genes were transcribed, and low-levels of infectious VZV were recurrently detected in the culture supernatant. Our data suggest that NHNP TLAs are an effective system to investigate long-term interactions of VZV with complex assemblies of human neuronal cells.

From the bench to exploration medicine: NASA life sciences translational research for human exploration and habitation missions.

NASA's Space Biology and Human Research Program entities have recently spearheaded communications both internally and externally to coordinate the agency's translational research efforts. In this paper, we strongly advocate for translational research at NASA, provide recent examples of NASA sponsored early-stage translational research, and discuss options for a path forward. Our overall objective is to help in stimulating a collaborative research across multiple disciplines and entities that, working together, will more effectively and more rapidly achieve NASA's goals for human spaceflight.

Three-dimensional organotypic models of human colonic epithelium to study the early stages of enteric salmonellosis.

In vitro cell culture models used to study how Salmonella initiates disease at the intestinal epithelium would benefit from the recognition that organs and tissues function in a three-dimensional (3-D) environment and that this spatial context is necessary for development of cultures that more realistically resemble in vivo tissues/organs. Our aim was to establish and characterize biologically meaningful 3-D models of human colonic epithelium and apply them to study the early stages of enteric salmonellosis. The human colonic cell line HT-29 was cultured in 3-D and characterized by immunohistochemistry, histology, and scanning electron microscopy. Wild-type Salmonella typhimurium and an isogenic SPI-1 type three secretion system (TTSS) mutant derivative (invA) were used to compare the interactions with 3-D cells and monolayers in adherence/invasion, tissue pathology, and cytokine expression studies. The results showed that 3-D culture enhanced many characteristics normally associated with fully differentiated, functional intestinal epithelia in vivo, including better organization of junctional, extracellular matrix, and brush-border proteins, and highly localized mucin production. Wild-type Salmonella demonstrated increased adherence, but significantly lower invasion for 3-D cells. Interestingly, the SPI-I TTSS mutant showed wild-type ability to invade into the 3-D cells but did not cause significant structural changes to these cells. Moreover, 3-D cells produced less interleukin-8 before and after Salmonella infection. These results suggest that 3-D cultures of human colonic epithelium provide valuable alternative models to study human enteric salmonellosis with potential for novel insight into Salmonella pathogenesis.

Incorporation of omics analyses into artificial gravity research for space exploration countermeasure development.

The next major steps in human spaceflight include flyby, orbital, and landing missions to the Moon, Mars, and near earth asteroids. The first crewed deep space mission is expected to launch in 2022, which affords less than 7 years to address the complex question of whether and how to apply artificial gravity to counter the effects of prolonged weightlessness. Various phenotypic changes are demonstrated during artificial gravity experiments. However, the molecular dynamics (genotype and molecular phenotypes) that underlie these morphological, physiological, and behavioral phenotypes are far more complex than previously understood. Thus, targeted molecular assessment of subjects under various G conditions can be expected to miss important patterns of molecular variance that inform the more general phenotypes typically being measured. Use of omics methods can help detect changes across broad molecular networks, as various G-loading paradigms are applied. This will be useful in detecting off-target, or unanticipated effects of the different gravity paradigms applied to humans or animals. Insights gained from these approaches may eventually be used to inform countermeasure development or refine the deployment of existing countermeasures. This convergence of the omics and artificial gravity research communities may be critical if we are to develop the proper artificial gravity solutions under the severely compressed timelines currently established. Thus, the omics community may offer a unique ability to accelerate discovery, provide new insights, and benefit deep space missions in ways that have not been previously considered.

Synergistic interaction of hyperthermia and Gemcitabine in lung cancer.

Hyperthermia increases cytotoxicity of various antineoplastic agents. We investigated the cytotoxic effects of Gemcitabine and/or hyperthermia on BZR-T33 (human non-small-cell lung cancer cells) in vitro and in immune-suppressed athymic nude mice. Isobologram analysis of monolayer cell cultures for cytotoxicity demonstrates a synergistic interaction between hyperthermia and Gemcitabine. Clonogenic results show significant reductions in surviving fractions and colony size for both therapies; greatest reduction was for the combined therapy group. Using cell cycle analysis, hyperthermia enhanced Gemcitabine-induced G2-M arrest resulting in destruction of 3.5 log cells. Apoptotic studies (Annexin-V FITC staining) showed that hyperthermia augmented Gemcitabine-induced apoptosis. Transmission electron microscopy demonstrated pathology observed in cultures exposed to either therapy present in cultures exposed to both therapies. Studies in nude mice show that the combination therapy group had both an initial decrease in tumor size, and a significantly delayed rate of growth. Additionally, using tumor material harvested from nude mice two days after end to treatment reveals a significantly greater apoptotic index and significantly smaller mitotic index for the combined therapy group. Western blots of the same tumor material, showed that heat shock protein 70 was not significantly increased, however, caspase-3 activity of was significantly increased because of the combined therapy. In conclusion, the combined therapy is synergistic in effect because of hyperthermia enhancing Gemcitabine-induced apoptosis.

Personalized medicine in human space flight: using Omics based analyses to develop individualized countermeasures that enhance astronaut safety and performance.

Space flight is one of the most extreme conditions encountered by humans. Advances in Omics methodologies (genomics, transcriptomics, proteomics, and metabolomics) have revealed that unique differences exist between individuals. These differences can be amplified in extreme conditions, such as space flight. A better understanding of individual differences may allow us to develop personalized countermeasure packages that optimize the safety and performance of each astronaut. In this review, we explore the role of "Omics" in advancing our ability to: (1) more thoroughly describe the biological response of humans in space; (2) describe molecular attributes of individual astronauts that alter the risk profile prior to entering the space environment; (3) deploy Omics techniques in the development of personalized countermeasures; and (4) develop a comprehensive Omics-based assessment and countermeasure platform that will guide human space flight in the future. In this review, we advance the concept of personalized medicine in human space flight, with the goal of enhancing astronaut safety and performance. Because the field is vast, we explore selected examples where biochemical individuality might significantly impact countermeasure development. These include gene and small molecule variants associated with: (1) metabolism of therapeutic drugs used in space; (2) one carbon metabolism and DNA stability; (3) iron metabolism, oxidative stress and damage, and DNA stability; and (4) essential input (Mg and Zn) effects on DNA repair. From these examples, we advance the case that widespread Omics profiling should serve as the foundation for aerospace medicine and research, explore methodological considerations to advance the field, and suggest why personalized medicine may become the standard of care for humans in space.

Development of a three-dimensional model of lung cancer using cultured transformed lung cells.

Despite great strides in understanding cancer biology, the role cellular differentiation and three-dimensional (3-D) structural organization play in metastasis and malignancy remains unclear. Development of 3-D cultures may ultimately provide a model facilitating discovery and interpretation of more relevant information for the expression and role of antibodies in lung cellular pathobiology. The purpose was to develop traditional monolayer (ML) and 3-D cultures of a known transformed metastatic lung cell line and then determine similarities and differences between cultures in terms of differentiation, molecular marker expression and metastasis. A transformed lung cell line (BZR-T33) was initially transfected with green fluorescent protein (GFP) in ML culture. Nude mice were inoculated with BZR-T33 and observed for metastasis. BZR-T33 was grown as ML and 3-D cultures under identical conditions. Immunohistochemical comparison for degree of antibody expression between cultures and control tissue were studied. Electron microscopy (EM) for identification of ultra structures was done and compared between cultures. A 3-D co-culture containing GFP-transformed cells over an immortalized lung-cell line was developed. The GFP-transfected cell line formed tumors and metastasized in mice. EM identified significant mitochondrial and granular endoplasmic reticular pathology in ML not seen in 3-D. Degree of differentiation shows ultra structures and antibody expressions were more representative of control tissue in 3-D than ML. The co-culture experiment in 3-D demonstrates the ability of transformed cells to penetrate the sub-layer of immortalized cells. Development of 3-D cultures will provide a new and powerful tool to study lung biology and pathobiology.

Cellular differentiation in three-dimensional lung cell cultures.

INTRODUCTION: Aspects of human biology that are not sufficiently addressed by current cell culture models are cellular differentiation and three-dimensional (3-D) structural organization. A model that more closely associates the presence and biology of organelles to molecular expressions relevant to these organelles may provide evidence of cellular differentiation and the beginning steps in the construction of a 3-D architecture. The development of a new model--3-D cell cultures--may ultimately provide a better understanding of lung biology and pathobiology. PURPOSE: The purpose of this study was to develop both traditional monolayer and 3-D cell cultures of a known and well documented normal lung cell line and then to determine similarities and differences between these cultures in terms of differentiation and molecular marker expression. RESULTS: Electron microscopy identified presence of lipid inclusion, microvilli, extra cellular matrix, and tight junctions in the 3-D cultures; differentiation not seen in ML cultures. The degree of differentiation determined by immunohistochemistry when the cell line was grown as ML or 3-D cultures shows that ultra-structure and marker expressions were more representative of control tissue than when cells were grown in 3-D than as MLs. METHODS: An immortalized cell line was grown as a traditional monolayer (ML) in culture flasks and as 3-D cultures in rotating walled vessels and incubated under identical conditions. Comparison for presence of differentiation and marker expression between these cultures and control tissue collected from surgical patient specimens was studied. Electron microscopy for identification of ultra structures, and immunohistochemistry (ZO-1, EMA, ICAM-1, villin, tubulin, CK 18, VWF, Collagen IV and human mucin) for phenotypic comparisons between cells in ML and 3-D cell cultures was conducted. SUMMARY: The development of 3-D cell cultures will provide for a new and more powerful tool in the study of lung biology and pathobiology.

Three-dimensional co-culture models to study prostate cancer growth, progression, and metastasis to bone.

Cancer-stromal interaction results in the co-evolution of both the cancer cells and the surrounding host stromal cells. As a consequence of this interaction, cancer cells acquire increased malignant potential and stromal cells become more inductive. In this review we suggest that cancer-stromal interaction can best be investigated by three-dimensional (3D) co-culture models with the results validated by clinical specimens. We showed that 3D culture promoted bone formation in vitro, and explored for the first time, with the help of the astronauts of the Space Shuttle Columbia, the co-culture of human prostate cancer and bone cells to further understand the interactions between these cells. Continued exploration of cancer growth under 3D conditions will rapidly lead to new discoveries and ultimately to improvements in the treatment of men with hormonal refractory prostate cancer.