Engineering topics

Steffy Tabares Ruiz

Publications and source records attributed to Steffy Tabares Ruiz.

8 records

NASA NTRS2024

Long-term effects of acute irradiation and isolation on crew age-matched mice

The future of space missions beyond low-Earth orbit presents exciting opportunities but may come with formidable health challenges. Astronauts face a unique combination of space stressors capable of exerting effects on the central nervous system (CNS) with possible sex-dependent differences. The interaction of these combined spaceflight stressors may induce oxidative stress, thereby altering brain integrity and behavioral performance. Understanding these changes is critical for safeguarding astronaut health and enabling successful exploration. By understanding the physiological responses to the combined effects of ionizing radiation (IR) and social isolation in the brain through immunohistochemistry (IHC), proteomics and cytokine expression analyses, we aim to identify CNS pathways ripe for countermeasure development to mitigate adverse brain changes with future deep space exploration. Here, we study the combined effects of simulated 5-ion galactic cosmic radiation (GCRsim) at acute dosage (5, 15, and 50 cGy) and social isolation on crew age-matched male and female mice at 124 days post-irradiation. We conducted analyses of hippocampal cytokine biomarkers and proteomic profiling on hippocampal lysates. Our findings reveal sex-specific regulation of hippocampal cytokines and proteomic profiles. Ongoing immunohistochemistry findings on the hippocampus will provide qualitative information regarding key protein expression and cellular changes such as microglial activation, blood brain barrier integrity, and neuroinflammation. With future plans for long-duration space missions, such as Mars exploration, understanding CNS changes over extended periods in mice can provide insights into potential long-term health impacts on astronauts. This project will provide us with valuable insights into sex-differences in neurobiological processes and disease mechanisms impacting men and women in space.

space radiation↗

NASA NTRS2021

The Effects of Simulated Microgravity and PLacental-EXpanded (PLX-PAD) Stromal Cell Treatment on The Behavior and Correlation with Cytokine Profiles in Female Mice

Spacelight can lead to altered immune responses and inflammation (Crucian et al. 2014) and elevated levels of inflammation are connected to anxiety and depression. A recent study on the International Space Station showed that mice exhibited a novel circling behavior during spaceflight (Ronca 2019). However, there is still a gap in knowledge on how microgravity impacts behavior. In this current study, we performed 30 days of hindlimb unloading (HU) on four-month old female mice and analyzed select behavior from video image capture. We also determined the effects of PLacental-eXpanded stromal cells dervided from the maternal placenta (PLX-PAD), alone and in combination with HU and isolation, on behavior. We have previoulst shown that PLX-PAD mitigated select inflammatory responses and changes in cytokine expression causes by HU. In-cage behaviors were analyzed in HU or control female mice treated with 2 injections of PlasmaLyte (Sham) or PLX-PAD (n=7/group). We found that PLX-PAD decreased exploratory behaviors compared to Sham treated mice at night. Normally loaded (NL) PLX mice slept less than NL Sham mice during the day, and HU animals had signficantly higher involuntary movement during sleep compared to NL animals, suggesting sleep distruption. Overall, we show that both HU and PLX affect important behavioral factors., This experiment is the first to study the effects of PLX-PAD on behavior. Additional studies are needed to define the behavioral changes in spaceflight and test possible countermeasures. Funding for this project was provided through the 2019 Ames Research Innovation Award (ARIA) provided by NASA Ames Research Center.

Stromal cell treatment↗

NASA NTRSDate not supplied

The Effects of Placental-expanded (PLX-PAD) Stromal Cell Treatment, Hindlimb Unloading, and Isolation on the Behavior of Female Mice

Spaceflight can lead to altered immune responses and inflammation (Crucian et al. 2014) and elevated levels of inflammation are connected to anxiety and depression. A recent study on the International Space Station showed that mice exhibited a novel circling behavior during spaceflight (Ronca et al. 2019). However, there is still a gap in knowledge on how microgravity impacts behavior. In this current study, we performed 30 days of hindlimb unloading (HU) on four-month old female mice and analyzed select behavior from video image capture. We also determined the effects of PLacental-eXpanded stromal cells derived from the maternal placenta (PLX-PAD), alone and in combination with HU and isolation, on behavior. We have previously shown that PLX-PAD mitigates select inflammatory responses and changes in cytokine expression caused by HU. In-cage behaviors were analyzed in HU or control female mice treated with 2 injections of PlasmaLyte (Sham) or PLX-PAD (n=7/group). We found that PLX-PAD decreased exploratory behaviors compared to Sham-treated mice at night. Normally loaded (NL) PLX mice slept less than NL Sham mice during the day, and HU animals had significantly higher involuntary movement during sleep compared to NL animals, suggesting sleep disruption. Overall, we show that both HU and PLX affect important behavioral factors. This experiment is the first to study the effects of PLX-PAD on behavior. Additional studies are needed to define the behavioral changes in spaceflight and test possible countermeasures.

PLacental-EXpanded stromal cells, behavior, microg↗

NASA NTRSDate not supplied

Human placenta-derived stromal cells mitigate select immune responses to simulated weightlessness

Space flight presents unique risks to human health. Microgravity and social isolation are important space flight stressors which have vast impact on multiple systems such as the musculoskeletal, immune and central nervous system (CNS). To explore candidate countermeasures against tissue decrements caused by spaceflight, we performed a pilot study with PLacental-eXpanded stromal (PLX) cells. PLX cells secrete factors that modulate the immune system, but do not trigger host immune responses, enabling treatment in subjects that have intact immune systems. These cells had previous success in treating critical limb ischemia and acute radiation syndrome in murine models. In this study, 4-month-old female mice underwent 30 days of hindlimb unloading (HU) in single housing conditions to simulate long-term weightlessness and isolation. HU and normally ambulating controls were administered with PLX cells or sham-injected with Plasmalyte. We hypothesized that administration of PLX cells will mitigate some of the effects caused by prolonged HU. We found that treatment with PLX cells was well tolerated as indicated by body weights, circulating corticosterone levels and immune organ response to injection of the cells. HU led to the expected decreases in soleus muscle weights and bone loss. We did not observe any protective properties of the PLX cells in the musculoskeletal system but found that the cell treatment partially protected from a subset of HU-induced immune and CNS changes. In the hippocampus, protein levels of 9 of 44 cytokines were downregulated by HU. PLX administration mitigated changes in expression of 8 of these cytokines, including IL-2, IL-6 and MCP-1. To our knowledge, this is the first report on the protective effects of PLX-PAD against HU-induced changes in the cytokine milieu of the CNS. Our findings warrant further studies, which includes testing in actual spaceflight.

Microgravity↗

NASA NTRSDate not supplied

Behavioral consequences of low dose radiation and sex differences in MCAT mouse model

Our study used 1-year old C57BL/6NJ male and female mice (astronaut-relevant age) that underwent exposure to 0.5 gray of gamma radiation and were euthanized 12 weeks after. In this study, we used an MCAT mouse model for mitochondrial ROS quenching, which overexpress human catalase. MCAT mice were shown to live longer and age better. Hence, in this study we determined whether quenching ROS in the mitochondria will mitigate the adverse effects of ionizing radiation exposure on spaceflight-relevant tissues. As part of the analysis, we have completed 5 different behavioral tests which focus on memory, physical stance, stress, anxiety, and other mission relevant behaviors. In the Neuro-score battery, performed after both 1and 8 weeks post IR we saw that all female groups had significantly higher scores compared to males. When comparing the baseline vs 8 weeks of radiation, we saw that all the male groups (including the sham) had lower neuro-score, pointing out to aging effect in addition to IR. In the female groups only the female IR group had lower neuro-score and the MCAT group was protected from this effect. In the Nestlet building test we saw similarly that only females were affected by radiation, having lower scores and this effect was mitigated in the MCAT animals as well. In the Catwalk test we saw that females were faster, had higher swing speed and stride length in all four paws. Males had higher stand, step cycle and max contact area. Aging is associated with slowing of gait speed, swing speed and shortening of stride length which we see in males, this is consistent with physical appearance where males look markedly older. In the Light-Dark Box test we saw that females were more frequently present in the light side and altered zones more frequently, pointing out to a more exploratory and less anxious pattern of behavior. Similarly, to what was detected in the Nest building and Neuro-score test, in the Barnes maze test, during the acquisition phase (learning) we saw that IR affected more the females who did not do better in the maze after 4 days. On the other hand, during the probe phase of the test (spatial memory) the females visited the target hole and the box quadrant more often, but also had more errors vs males, which points out to possible serial escape vs spatial escape strategy. Overall, we see that older females look physically better are faster and perform better almost in all behavioral tests compared to their male counterparts. On the other hand, they are more sensitive to low dose radiation in many cases, in some cases this effect was mitigated in the MCAT model pointing out to the importance of ROS in these stressors. In the near future we will focus on corelating these behavioral tests with molecular findings such as for example brain IHC, plasma and hippocampal cytokines in order to find specific biomarkers for behavioral deficits.

radiation↗

NASA NTRSDate not supplied

Cardiovascular Responses to Simulated Spaceflight: Molecular Signatures and Surrogate Outputs to Measure CVD Risk

During extended space missions beyond low Earth orbit, astronauts will encounter prolonged periods of weightlessness and low dose space radiation. Previous studies have shown that exposure to small doses of high LET radiation (< 50 cGy) can lead to both short-term and long-term alterations in heart function, structure and underlying molecular mechanisms. In this study, we aim to identify the molecular signature associated with the cardiovascular response to simulated galactic cosmic radiation (5-ion GCR) alone or in combination with simulated weightlessness at time intervals relevant to mission length and recovery. Additionally, we aim to determine whether sex impacts cardiovascular responses to these spaceflight factors. Our overarching goal is to enhance our understanding of the cardiovascular risks associated with extended space missions and the clinical endpoints they suggest. We hypothesize that exposure to simulated space radiation leads to enduring alterations in the transcriptome, redox signaling and cytokine environment of cardiovascular tissue, some which have known links with reduced cardiovascular performance, aging, and increased risk of cardiovascular disease (CVD). Furthermore, we posit that simulated space radiation exposure in combination with simulated microgravity exacerbates cardiovascular deficits compared to single factor exposure. Female and male C57BL/6J mice, aged 23-24 weeks, were exposed to a single dose of 5, 15, or 50 cGy of 5-ion GCR, or sham-treated (0 cGy). Euthanasia was performed at 14 days and ~4 months post-irradiation. Hearts, aorta and blood plasma were collected shortly thereafter. RNA-sequencing of left ventricles at ~4 months post-GCR exposure revealed sex differences in the heart transcriptome with a few genes showing radiation-dependent changes in expression levels. Notably, some of the differentially expressed genes in 15 and 50 cGy GCR groups are known to play roles in the development of CVD. Analysis of protein levels of a subset of inflammatory cytokines in the heart indicated sex differences but no differences between sham and 50 cGy groups. Results also showed correlations among differentially expressed genes and a subset of inflammatory cytokines, with some correlations altered by GCR exposure. These findings suggest that GCR exposure can modify protein and gene networks linked to inflammation and CVD progression. In the aorta, telomere lengths were comparable across treatment groups sexes. Mitochondrial copy number is a biomarker for mitochondrial function with decreased copy numbers associated with cardiometabolic disease traits. Mitochondrial copy numbers of aorta also showed no sex nor dose differences. In a second study, mice underwent one week of simulated microgravity by hindlimb unloading (HU) and then exposed to a single dose of 15 cGy of 5-ion GCR. HU was conducted for an additional two weeks following GCR exposure. Single factor exposure groups (HU or GCR only) also were included in the study. Euthanasia was then performed and the same tissues were collected. Protein levels of select inflammatory cytokines in the heart showed sex-dependent differences in expression. In the aorta, telomere lengths and mitochondrial copy number also showed sex differences. In summary, our results indicate differences between sexes in biomarkers related to cardiovascular health. Exposure to 5-ion GCR or HU, alone or in combination, did not result in changes in most of the cardiovascular biomarkers that were examined. However, in the heart, simulated space radiation at doses of 15 and 50 cGy led to long-term alterations in the expression levels of a small group of genes known to be associated with the progression of CVD. The long-term transcriptomic changes resulting from exposure to simulated space radiation should be carefully investigated to mitigate adverse cardiovascular events during and after deep space missions. Our results also highlight the importance of sex-specific strategies in monitoring and maintaining cardiovascular health during and after deep space missions.

cardiovascular↗

NASA NTRSDate not supplied

Neurobiological Outcomes of Mice Exposed to Combined Spaceflight Stressors

As NASA plans for exploration beyond Low-Earth Orbit, it is imperative to understand how deep spaceflight stressors impact human physiology. Deep space exposes crew members to multiple NASA-defined risks, including altered gravity, ionizing radiation, and social isolation. While the effects of individual stressors have been studied, there are still gaps in our understanding of their combined effects. In this study, we utilized the simulated five-ion galactic cosmic radiation (GCR) and isolation to assess the combinatorial effects of space stressors on the central nervous system (CNS) in mice. Our study captures sexually dimorphic responses by quantifying CNS outcomes in crewage-matched male and female mice. We assessed CNS responses in mice exposed to four days of isolation, followed by three different dosage of acute radiation exposure (5 cGy, 15 cGy, and 50 cGy 5-ion GCRsim). Comprehensive hippocampal cytokine biomarker analyses were conducted in both males and females at two weeks post-irradiation (intermediate cohort) and 124 days post-irradiation (delayed cohort). Proteomics on hippocampal lysates were conducted in the delayed cohort. Our results provide evidence for sex-specific differentially regulated hippocampal cytokines and proteomic profiles. Immunohistochemical analysis of the mice brain from intermediate and delayed cohorts is currently underway for multiple protein markers, including microglial activation, astrocytes, and dopaminergic neuronal population, among others. This project closely aligns with NASA’s efforts to characterize sex-specific risks associated with deep space exploration. We anticipate the results from this project will aid in our understanding of spaceflight stressors to ensure crew health and performance.

spaceflight↗

NASA NTRSDate not supplied

Impact of the ISS Environment on CNS in Drosophila Melanogaster

Altered gravity and elevated carbon dioxide (CO 2 ) levels as experienced on the ISS can adversely affect human health across various organ systems, especially the Central Nervous System (CNS). Investigating these changes is essential for understanding the long-term effects of spaceflight on human physiology to ensure crew health. Ground-based analogs provide an efficient method to evaluate alterations induced by chronic spaceflight on a larger scale. This study focuses on CNS changes in response to hypergravity (HG) and elevated CO 2 levels via a ground-based analog using the well-established model organism, Drosophila melanogaster. We hypothesize behavior and physiological changes immediately post exposure to HG+CO 2 , along with chronic effects up to 25 days post-exposure. Adult male and female flies were exposed to varying gravity loads (1g, 1.2g, and 3g) and elevated CO 2 levels (~4000 ppm, mimicking CO 2 levels on the ISS) for 15 days and were assessed immediately and at 5-, 10-, and 25-days post-exposure, mirroring astronauts’ post-return profiling. The flies were assessed for neurobehavioral changes, including longevity and negative geotaxis; brain morphological changes, such as dopaminergic neuron count, apoptosis, and glial cell density; and bioenergetic changes in the brain, including mitochondrial abundance and membrane potential. Longevity remained unchanged under hypergravity, even with the addition of elevated CO 2 as a stressor. However, despite the stable lifespan, quality of life appeared to be affected, as shown by negative geotaxis and neuroanatomical changes. Negative geotaxis testing revealed a reduction in motor ability at R0 across all conditions, which correlated with a decrease in dopaminergic (DA) neuron count. Additional observations suggested further systemic alterations, including a decrease in glial cell count, an increase in apoptosis, and notable bioenergetic changes. Collectively, these findings contribute to our understanding of the long-term effects of spaceflight on the CNS.

spaceflight↗