FLUMIAS - live-cell imaging fluorescence microscopy on a centrifuge for research on gravity-sensitive cellular dynamics on-board the ISS

Since the dawn of space-research microgravity was one of the most important environmental factors affecting biological systems in space from humans and plants to single cells. Several biological research questions can be targeted on platforms providing short-duration microgravity conditions such as parabolic flights or sounding rockets. For a multitude of questions, prolonged time frames are necessary to observe processes such as cellular differentiation, maturation, tissue development or gravity adaptation. The ISS provides constant high quality microgravity and is therefore an excellent platform for gravity-related research. FLUMIAS-ISS will implement the first fluorescent live-cell microscope to grant true insight into dynamic changes or adaptive processes on a cellular level and induced by controlled changes between 1g and microgravity (0g). Identifying gravity-sensitive signaling pathways will further enhance the development of countermeasures for health risks of manned space fligh

Hypergravity attenuates Reactivity in Primary Murine Astrocytes

Neuronal activity is the key modulator of nearly every aspect of behavior, affecting cognition, learning and memory as well as motion. Alterations or even disruptions of the transmission of synaptic signals are the main cause of many neurological disorders. Lesions to nervous tissues are associated with phenotypic changes mediated by astrocytes becoming reactive. Reactive astrocytes form the basis of astrogliosis and glial scar formation. Astrocyte reactivity is often targeted to inhibit axon dystrophy and thus promote neuronal regeneration. Here, we use increased gravitational (mechanical) loading induced by hypergravity to identify a potential method to modify key features of astrocyte reactivity. We exposed primary murine astrocytes as a model system closely resembling the reactivity phenotype in vivo on custom-built centrifuges for cultivation as well as for livecell imaging under hypergravity conditions in a physiological range (2g and 10g). This resulted in significant changes to astrocyte morphology, behavior and reactivity phenotypes, with the ultimate goal being to enhance neuronal regeneration for novel therapeutic approaches

Hypergravity attenuates Reactivity in Primary Murine Astrocytes

Neuronal activity is the key modulator of nearly every aspect of behavior, affecting cognition, learning, and memory as well as motion. Hence, disturbances of the transmission of synaptic signals are the main cause of many neurological disorders. Lesions to nervous tissues are associated with phenotypic changes mediated by astrocytes becoming reactive. Reactive astrocytes form the basis of astrogliosis and glial scar formation. Astrocyte reactivity is often targeted to inhibit axon dystrophy and thus promote neuronal regeneration. Here, we aim to understand the impact of gravitational loading induced by hypergravity to potentially modify key features of astrocyte reactivity. We exposed primary murine astrocytes as a model system closely resembling the in vivo reactivity phenotype on custom-built centrifuges for cultivation as well as for live-cell imaging under hypergravity conditions in a physiological range (2g and 10g). We revealed spreading rates, migration velocities, and stellation to be diminished under 2g hypergravity. In contrast, proliferation and apoptosis rates were not affected. In particular, hypergravity attenuated reactivity induction. We observed cytoskeletal remodeling of actin filaments and microtubules under hypergravity. Hence, the reorganization of these key elements of cell structure demonstrates that fundamental mechanisms on shape and mobility of astrocytes are affected due to altered gravity conditions. In future experiments, potential target molecules for pharmacological interventions that attenuate astrocytic reactivity will be investigated. The ultimate goal is to enhance neuronal regeneration for novel therapeutic approache

Wound Healing Capacity of Adult Human Fibroblasts Derived from the AGBRESA Bed Rest and Artificial Gravity Study Subjects

During spaceflight, the microgravity-environment induces physiological adaptations in the human body. Of particular interest for this thesis was the impairment of the wound healing process during long-term exposure to weightlessness. The underlying molecular and cellular mechanisms of wound healing alterations in skin tissue in microgravity are unknown. However, with attenuated wound healing, the chance for infections increases, possibly threatening missions in space and the health of astronauts. A well-established model to mimic physiological deconditioning in response to weightlessness is HeadDown Tilt (HDT) bed rest on Earth. HDT bed rest was evaluated as a model system for wound healing. Further, 30 minutes of Artificial Gravity (AG) were applied daily as a potential countermeasure either continuously (cAG) or in 5 minute intervals (iAG). During the Artificial Gravity Bed Rest Study with European Space Agency (AGBRESA), a new method to isolate primary adult human fibroblasts from skin biopsy tissue has been established to evaluate wound healing in bed rest subjects. A prolonged closure time in the scratch assays for cAG and bed rest group was indicated, while this trend was alleviated for iAG. Thermography was a well tolerated method for monitoring of the biopsy site and revealed a significantly increasing wound temperature in both AG groups over the course of the HDT phase. Analysis of the blood serum-based inflammation markers CRP, IL-6 and leukocytes ensured that no infections, inducing a deteriorated healing process, were occurring. Investigating the effects of AG in HDT bed rest subjects, it was found that AG is able to change the effects of bed rest on humans and thus might result in possible positive effects on the impaired wound healing process in weightlessness. In general, HDT bed rest induces changes in wound healing that still remain to be evaluated, especially regarding their comparability to spaceflight-induced alterations in wound healing