Microbiology of human spaceflight: microbial responses to mechanical forces that impact health and habitat sustainability.

SUMMARYUnderstanding the dynamic adaptive plasticity of microorganisms has been advanced by studying their responses to extreme environments. Spaceflight research platforms provide a unique opportunity to study microbial characteristics in new extreme adaptational modes, including sustained exposure to reduced forces of gravity and associated low fluid shear force conditions. Under these conditions, unexpected microbial responses occur, including alterations in virulence, antibiotic and stress resistance, biofilm formation, metabolism, motility, and gene expression, which are not observed using conventional experimental approaches.

Promoting Tech Transfer Between Space and Global Mental Health.

Numerous issues in mental health benefit from technological innovation. An example involves the mental health challenges of long-duration spaceflight (such as a Mars mission), including prolonged confinement, microgravity, and different sunlight exposure lengths. Persisting on Earth are global mental health challenges stemming from disease burdens, limited interview-based diagnostic systems, trial-and-error treatment approaches, and suboptimal access.

A three-dimensional tissue culture model of bone formation utilizing rotational co-culture of human adult osteoblasts and osteoclasts.

Living bone is a complex, three-dimensional composite material consisting of numerous cell types spatially organized within a mineralized extracellular matrix. To date, mechanistic investigation of the complex cellular level cross-talk between the major bone-forming cells involved in the response of bone to mechanical and biochemical stimuli has been hindered by the lack of a suitable in vitro model that captures the "coupled" nature of this response. Using a novel rotational co-culture approach, we have generated large (>4mm diameter), three-dimensional mineralized tissue constructs from a mixture of normal human primary osteoblast and osteoclast precursor cells without the need for any exogenous osteoconductive scaffolding material that might interfere with such cell-cell interactions.

Cellular and genetic adaptation in low-gravity environments.

Genetic response suites in human lymphocytes in response to microgravity are important to identify and study further to augment physiological adaptation to new milieus. Human peripheral blood from normal donors was used to isolate peripheral blood mononuclear cells. Blood traverses through most organs and hence is a suitable overall physiological predictor.

Proteomic analysis of mouse hypothalamus under simulated microgravity.

Exposure to altered microgravity during space travel induces changes in the brain and these are reflected in many of the physical behavior seen in the astronauts. The vulnerability of the brain to microgravity stress has been reviewed and reported. Identifying microgravity-induced changes in the brain proteome may aid in understanding the impact of the microgravity environment on brain function.

Melanoma growth and tumorigenicity in models of microgravity.

Introduction: Spaceflight involves numerous biological stressors that could affect long-term cancer incidence and tumor behavior. Ground-based models of microgravity can be used to investigate in vitro and in vivo tumor growth as a preparation for later work in space. The incidence of tumor growth and carcinogenesis in microgravity is as yet unknown.

Gene expression alterations in activated human T-cells induced by modeled microgravity.

Studies conducted in real Space and in ground-based microgravity analog systems (MAS) have demonstrated changes in numerous lymphocyte functions. In this investigation we explored whether the observed functional changes in lymphocytes in MAS are associated with changes in gene expression. NASA-developed Rotating Wall Vessel (RWV) bioreactor was utilized as a MAS.

Activation of activator protein-1 in mouse brain regions exposed to simulated microgravity.

Microgravity induces stress, and the brain is one of the targets that is more influenced in this environment. Alteration in transcription factors can have enormous effect because of discrepancy in the signaling process of the cells. Activator protein-1 (AP-1) is a stress-regulated transcription factor and is involved in the regulation of physiological and pathological stimuli that include cytokines, growth factors, and stress signals.

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.

Proteomic analysis of mice hippocampus in simulated microgravity environment.

Space travel induces many deleterious effects on the flight crew due to the '0' g environment. The brain experiences a tremendous fluid shift, which is responsible for many of the detrimental changes in physical behavior seen in astronauts. It therefore indicates that the brain may undergo major changes in its protein levels in a '0' g environment to counteract the stress.

Countermeasure for space flight effects on immune system: nutritional nucleotides.

Microgravity and its environment have adverse effects on the immune system. Abnormal immune responses observed in microgravity may pose serious consequences, especially for the recent directions of NASA for long-term space missions to Moon, Mars and deep Space exploration. The study of space flight immunology is limited due to relative inaccessibility, difficulty of performing experiments in space, and inadequate provisions in this area in the United States and Russian space programs (Taylor 1993).

Activation of nuclear transcription factor-kappaB in mouse brain induced by a simulated microgravity environment.

Microgravity induces inflammatory responses and modulates immune functions that may increase oxidative stress. Exposure to a microgravity environment induces adverse neurological effects; however, there is little research exploring the etiology of these effects resulting from exposure to such an environment. It is also known that spaceflight is associated with increase in oxidative stress; however, this phenomenon has not been reproduced in land-based simulated microgravity models.

Recent NASA research accomplishments aboard the ISS.

The activation of the US Laboratory Module "Destiny" on the International Space Station (ISS) in February 2001 launched a new era in microgravity research. Destiny provides the environment to conduct long-term microgravity research utilizing human intervention to assess, report, and modify experiments real time. As the only available pressurized space platform, ISS maximizes today's scientific resources and substantially increases the opportunity to obtain much longed-for answers on the effects of microgravity and long-term exposure to space.

Altered cytokine expression in tissues of mice subjected to simulated microgravity.

Space flight is known to induce microgravity-associated immune dysfunction in humans, non-human primates and rodents. To understand the mechanism underlying these defects, several studies in rodents have been conducted in a ground-based antiorthostatic suspension (AOS) model that would mimic the effects of microgravity. In all these in vivo studies that showed the effects on cytokine profiles actually investigated the ex vivo production from culturing the cells isolated from whole organism that was exposed to space flight and/or microgravity.

Modeled microgravity-induced protein kinase C isoform expression in human lymphocytes.

In long-term space travel, the crew is exposed to microgravity and radiation that invoke potential hazards to the immune system. T cell activation is a critical step in the immune response. Receptor-mediated signaling is inhibited in both microgravity and modeled microgravity (MMG) as reflected by diminished DNA synthesis in peripheral blood lymphocytes and their locomotion through gelled type I collagen.

A countermeasure to ameliorate immune dysfunction in in vitro simulated microgravity environment: role of cellularnucleotide nutrition.

Considerable evidence suggests that space travelers are immunosuppressed, presumably by microgravity environmental stresses, putting them at risk for adverse effects, such as opportunistic infections, poor wound healing, and cancer. The purpose of this study was to examine the role and mechanisms of nucleotide (NT) supplementation as a countermeasure to obviate immunosuppression during space travel. The in vitro rotary cell culture system, a bioreactor (BIO), was used to simulate the effect of microgravity and to isolate the neuroendocrine effects inherent to in vitro models.

Nutrition beyond nutrition: plausibility of immunotrophic nutrition for space travel.

Background And Aims: Microgravity has adverse effects on the immune system. We examined the effects of supplemental dietary nucleotides on immune function in ground-based in vivo anti-orthostatic tail-suspended (AOS) mice and in vitro (bioreactor-BIO) analogs of microgravity.

Methods: BALB/c mice were divided into the following three groups: group housed, single isolation, and AOS.

Dietary nucleotides prevent decrease in cellular immunity in ground-based microgravity analog.

Microgravity and stress of spaceflights result in immune dysfunction. The role of nutrition, especially nucleotide supplementation, has become an area of intensive research and significant interest in immunomodulation for maintenance of cellular immune responses. The studies presented here evaluate the plausibility of administering nucleotides to obviate immune dysfunction in an Earth-based in vivo analog of microgravity as studied in anti-orthostatic tail suspension (AOS) of mice.

Loss of signal transduction and inhibition of lymphocyte locomotion in a ground-based model of microgravity.

Inflammatory adherence to, and locomotion through the interstitium is an important component of the immune response. Conditions such as microgravity and modeled microgravity (MMG) severely inhibit lymphocyte locomotion in vitro through gelled type I collagen. We used the NASA rotating wall vessel bioreactor or slow-turning lateral vessel as a prototype for MMG in ground-based experiments.

Cultures of human liver cells in simulated microgravity environment.

We used microgravity-simulated bioreactors that create the unique environment of low shear force and high-mass transfer to establish long-term cultures of primary human liver cells (HLC). To assess the feasibility of establishing HLC cultures, human liver cells obtained either from cells dissociated by collagenase perfusion or minced tissues were cultured in rotating vessels. Formation of multidimensional tissue-like spheroids (up to 1.

Microgravity cultivation of cells and tissues.

In vitro studies of cells and tissues in microgravity, either simulated by cultivation conditions on earth or actual, during spaceflight, are expected to help identify mechanisms underlying gravity sensing and transduction in biological organisms. In this paper, we review rotating bioreactor studies of engineered skeletal and cardiovascular tissues carried out in unit gravity, a four month long cartilage tissue engineering study carried out aboard the Mir Space Station, and the ongoing laboratory development and testing of a system for cell and tissue cultivation aboard the International Space Station.

Locomotion of lymphocytes towards melanoma cells treated with tumor necrosis factor in a syngeneic in vitro model.

Tumor necrosis factor (TNF) causes cell necrosis in vivo by damaging the endothelium of the neovasculature. However, its mechanism of action is not well understood. We hypothesized that TNF affects the tumor microenvironment even before neovascularization occurs, thereby increasing lymphocyte locomotion through the peritumoral matrix, a crucial step in tumor cell killing.

Characteristics of human dendritic cells generated in a microgravity analog culture system.

Generation of an effective immune response requires that antigens be processed and presented to T lymphocytes by antigen-presenting cells, the most efficient of which are dendritic cells (DC). Because of their influence on both the innate and the acquired arms of immunity, a defect in DC would be expected to result in a broad impairment of immune function, not unlike that observed in astronauts during or after space flight. In the study reported here, we investigated whether DC generation and function are altered in a culture environment that models microgravity, i.

Microarray analysis of genes differentially expressed in HepG2 cells cultured in simulated microgravity: preliminary report.

Developed at NASA, the rotary cell culture system (RCCS) allows the creation of unique microgravity environment of low shear force, high-mass transfer, and enables three-dimensional (3D) cell culture of dissimilar cell types. Recently we demonstrated that a simulated microgravity is conducive for maintaining long-term cultures of functional hepatocytes and promote 3D cell assembly. Using deoxyribonucleic acid (DNA) microarray technology, it is now possible to measure the levels of thousands of different messenger ribonucleic acids (mRNAs) in a single hybridization step.