An organoid is a 3D organization of cells that can recapitulate some of the structure and function of native tissue. Recent work has seen organoids gain prominence as a valuable model for studying ...tissue development, drug discovery, and potential clinical applications. The requirements for the successful culture of organoids in vitro differ significantly from those of traditional monolayer cell cultures. The generation and maturation of high-fidelity organoids entails developing and optimizing environmental conditions to provide the optimal cues for growth and 3D maturation, such as oxygenation, mechanical and fluidic activation, nutrition gradients, etc. To this end, we discuss the four main categories of bioreactors used for organoid culture: stirred bioreactors (SBR), microfluidic bioreactors (MFB), rotating wall vessels (RWV), and electrically stimulating (ES) bioreactors. We aim to lay out the state-of-the-art of both commercial and in-house developed bioreactor systems, their benefits to the culture of organoids derived from various cells and tissues, and the limitations of bioreactor technology, including sterilization, accessibility, and suitability and ease of use for long-term culture. Finally, we discuss future directions for improvements to existing bioreactor technology and how they may be used to enhance organoid culture for specific applications.
The Michigan State University Narrow Channel Apparatus (MSU-NCA) was used to investigate opposed flow flame spread over samples of thermally thick Polymethylmethacrylate (PMMA). Three different fuel ...thicknesses were tested for mean airflow velocities 8-58 cm/s. The sample thicknesses were 6.6 mm, 12.1 mm and 24.5 mm, respectively. The measured flame position versus time determined the spread rate. Flame spread rates ranged between 0.02 - 0.07 mm/s depending on fuel thickness and mean opposed flow. Complete sample burnout occurred for the 6.6 mm and 12.1 mm samples at the critical flow velocity of 30 cm/s ± 5 cm/s and higher. The flame spread results appeared to be independent of flow velocities for this range (>30 cm/s): this plateau regime is identified as the regressive burning regime. The 24.5 mm thick samples never completely burned through, but they entered the regressive burning regime at 41.4 cm/s flow velocity. The nature of surface regression and its influence on the spread mechanism in this regime at high flow velocities was discussed for completely burned through samples (6.6 mm and 12.1 mm) and partially burned through samples (24.5 mm). For 12.1 mm thick samples, the flame spread results were compared with the same material (PMMA) and similar thickness (12.7 mm) results from the 1981 Fernandez-Pello et al. study. Their tests used a wind tunnel having a different length and cross-section than the MSU-NCA. The comparison was favorable when employing the stretch rate theory of flame spread incorporating the appropriate numerically computed stretch rate. Since buoyancy was an important factor in the 1981 study, when the buoyant stretch was also included, excellent agreement was obtained between the Fernandez-Pello et al. data and the current NCA data. The results demonstrated the effectiveness of the stretch rate theory for markedly different experimental configurations.
Microgravity is a novel strategy that may serve as a complementary tool to develop future cancer therapies. In lung cancer, the influence of microgravity on cellular processes and the migratory ...capacity of cells is well addressed. However, its effect on the mechanisms that drive lung cancer progression remains in their infancy. In this study, 13 differentially expressed genes were shown to be associated with the prognosis of lung cancer under simulated microgravity (SMG). Using gene set enrichment analysis, these genes are enriched in humoral immunity pathways. In lieu, alveolar basal-epithelial (A549) cells were exposed to SMG via a 2D clinostat system in vitro. In addition to morphology change and decrease in proliferation rate, SMG reverted the epithelial-to-mesenchymal transition (EMT) phenotype of A549, a key mechanism in cancer progression. This was evidenced by increased epithelial E-cadherin expression and decreased mesenchymal N-cadherin expression, hence exhibiting a less metastatic state. Interestingly, we observed increased expression of
,
,
,
, and
and their correlation to EMT under SMG, rendering them potential tumor suppressor biomarkers. Together, these findings reveal new opportunities to establish novel therapeutic strategies for lung cancer treatment.
The past few decades have seen an increasing number of both space travels and studies aimed at investigating the effects induced by space flights and the environment on humans. One of the main ...features of these conditions is the presence of altered gravity, mostly represented by microgravity experienced by astronauts. Microgravity is well known to induce deleterious effects at cellular, organ and systemic levels, including alterations in the male and female reproductive systems. In the present study, we investigated the effect of simulated microgravity on the metabolic activity of male germ cells using TCam-2 line as a cell model. These cells were cultured in the Random Positioning Machine that simulated microgravity conditions, and were grown as 2D monolayers or 3D spheroids to assay the effects on single cells or on organ-like structures. After a 24 hour-exposure to simulated microgravity, TCam-2 monolayers showed: (1) a decreased proliferation rate and a delay in cell cycle progression; (2) increased anaerobic metabolism; (3) increased levels of reactive oxygen species and superoxide anion; (4) modifications in mitochondrial morphology. After the same 24 hour-exposure, TCam-2 spheroids showed: (1) an increased anaerobic and aerobic activity in 40% and 26% of samples, respectively; (2) alterations in the redox balance with a decrease in catalase activity in about 65% of cell samples, and therefore, a deficit in the cellular antioxidant capacity; (3) increases in oxidative damage to proteins and lipids in more than 50% of cell samples. In conclusion, these data demonstrated a clear inference of simulated microgravity on the metabolic activity of TCam-2 cells, which is expressed through the activation of an oxidative stress state, that, if not compensated for, could be deleted over time.
The extracellular matrix (ECM) is the principal structure of bone tissue. Long-term spaceflights lead to osteopenia, which may be a result of the changes in composition as well as remodeling of the ...ECM by osteogenic cells. To elucidate the cellular effects of microgravity, human mesenchymal stromal cells (MSCs) and their osteocommitted progeny were exposed to simulated microgravity (SMG) for 10 days using random positioning machine (RPM). After RPM exposure, an imbalance of MSC collagen/non-collagen ratio at the expense of a decreased level of collagenous proteins was detected. At the same time, the secretion of proteases (cathepsin A, cathepsin D, MMP3) was increased. No significant effects of SMG on the expression of stromal markers and cell adhesion molecules on the MSC surface were noted. Upregulation of COL11A1, CTNND1, TIMP3, and TNC and downregulation of HAS1, ITGA3, ITGB1, LAMA3, MMP1, and MMP11 were detected in RPM exposed MSCs. ECM-associated transcriptomic changes were more pronounced in osteocommitted progeny. Thus, 10 days of SMG provokes a decrease in the collagenous components of ECM, probably due to the decrease in collagen synthesis and activation of proteases. The presented data demonstrate that ECM-associated molecules of both native and osteocommitted MSCs may be involved in bone matrix reorganization during spaceflight.
In previous studies, it has been proved that repetitive transcranial magnetic stimulation (rTMS) improves dyskinesia induced by conditions such as spinal cord injury, Parkinson diseases and cerebral ...ischemia. However, it is still unknown whether it can be used as a countermeasure for gait disorders in astronauts during space flight. In this study, we evaluated the effects of rTMS on the rat gait function under simulated microgravity (SM) conditions. The SM procedure continued for consecutive 21 days in male Wistar rats. Meanwhile, the high-frequency rTMS (10 Hz) was applied for 14 days from the eighth day of SM procedure. The behavioral results showed that SM could cause gait disorders such as decreased walking ability and contralateral limb imbalance in rats, which could be reversed by rTMS. Furthermore, rTMS affected the neural oscillations of motor cortex, enhancing in δ (2-4 Hz) band, suppressing in θ (4-7 Hz), and α (7-12 Hz) bands. Additionally, rTMS could activate mTOR in the motor cortex. These data suggests that the improvement effects of rTMS on gait disorders in rats under SM conditions might be associated with its regulation on neural oscillations in the cerebral motor cortex and the expression of some motor-related proteins which may enhance the control of nervous system on muscle function. Based on our results, rTMS can be used as an potential effective supplement in the field of clinical and rehabilitation research to reduce gait disorders caused by the space environment.
Metal corrosion caused by Aspergillus sp. was shown to be significantly enhanced on a space station, but its mechanism is still unknown. To simulate this on earth, the corrosion capability of A. ...carbonarius on five metal sheets was investigated under simulated microgravity. Also, the effect of metal ions on growth and organic acid production was determined. Results showed that
could corrode all five types of metal, including Ti alloy, aluminum alloy, iron, and aluminum and copper sheet, and the corrosion was intensified under simulated microgravity. Energy dispersive X-ray spectrometry (EDS) analysis showed that metal ions enriched on
spores, especially iron, aluminum ions, and copper ions, indicating that
can use these metal ions. In particular, the content of oxalic acid was significantly increased after
cocultured with five metal materials under simulated microgravity. Al
, Fe
, and Cu
at the concentration of 0.3 mg/mL and Mg
at 0.8 mg/mL significantly promoted the growth and oxalic acid and citric acid production of
and A. niger under normal gravity and simulated microgravity. Comparing the impact of metal ions and metal sheets on the production of organic acids, it can be inferred that oxalic acid may dominate in the corrosion process of
. In summary, molds promoted metal corrosion by producing organic acids, and the released metal ions will further promote the growth of mold and the accumulation of organic acids. This may be an important reason for the intensification of mold corrosion under microgravity.
The space station and other long-term manned spacecrafts will experience the risk of microbial corrosion, especially mold, which will be harmful to the platform system and astronauts. Aspergillus sp. has been widely reported to produce organic acids that corrode and destroy materials, and the ability of these crafts to fly through space can be significantly affected. Research on the mechanism that causes enhanced corrosion ability of fungi in space stations is important to control their growth. Our research focuses on the interaction between mold and metals. In particular, it is found that metal ions promote mold growth and produce organic acids, thus accelerating mold corrosion of metals. Our results provide a new perspective for the control of fungal corrosion under simulated microgravity.
Microgravity is a major environmental factor of space flight that triggers dysregulation of the immune system and increases clinical risks for deep-space-exploration crews. However, systematic ...studies and molecular mechanisms of the adverse effects of microgravity on the immune system in animal models are limited. Here, we establish a ground-based zebrafish disease model of microgravity for the research of space immunology. RNA sequencing analysis demonstrates that the retinoic-acid-inducible gene (RIG)-I-like receptor (RLR) and the Toll-like receptor (TLR) signaling pathways are significantly compromised by simulated microgravity (Sμg). TRIM25, an essential E3 for RLR signaling, is inhibited under Sμg, hampering the K63-linked ubiquitination of RIG-I and the following function-induction positive feedback loop of antiviral immune response. These mechanisms provide insights into better understanding of the effects and principles of microgravity on host antiviral immunity and present broad potential implications for developing strategies that can prevent and control viral diseases during space flight.
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•Simulated microgravity attenuates the antiviral innate immune responses•Simulated microgravity hampers TRIM25-mediated K63-linked ubiquitination of RIG-I•TRIM25 function-induction positive feedback loop is essential in antiviral immunity•Reduced TRIM25 expression under simulated microgravity interferes with the feedback loop
Using a ground-based zebrafish model, Zhu et al. show that simulated microgravity suppresses TRIM25-mediated K63-linked ubiquitination of RIG-I and the subsequent function-induced positive feedback loop of the immune response. These findings reveal the effects of microgravity on immunity and highlight potential directions for disease control during space flight.
In our study, Bacillus subtilis was disposed to a simulated microgravity (SMG) environment in high-aspect ratio rotating-wall vessel bioreactors for 14 days, while the control group was disposed to ...the same bioreactors in a normal gravity (NG) environment for 14 days. The B. subtilis strain exposed to the SMG (labeled BSS) showed an enhanced growth ability, increased biofilm formation ability, increased sensitivity to ampicillin sulbactam and cefotaxime, and some metabolic alterations compared with the B. subtilis strain under NG conditions (labeled BSN) and the original strain of B. subtilis (labeled BSO). The DEPs associated with an increased growth rate, such as DNA strand exchange activity, oxidoreductase activity, proton-transporting ATP synthase complex, and biosynthetic process, were significantly upregulated in BSS. The enhanced biofilm formation ability may be related with the DEPs of spore germination and protein processing in BSS, and DEGs involved in protein localization, peptide secretion were also significantly enriched. The results revealed that SMG may increase the level of related functional proteins by upregulating or downregulating affiliated genes to change physiological characteristics and modulate growth ability, biofilm formation ability (epsB, epsC, epsN), antibiotic sensitivity (penP) and metabolism. Our experiment may gives new ideas for the study of space microbiology.
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