Jayashree Sahana

Changes in Morphology, Gene Expression and Protein Content in Chondrocytes Cultured on a Random Positioning Machine

Tissue engineering of chondrocytes on a Random Positioning Machine (RPM) is a new strategy for cartilage regeneration. Using a three-dimensional RPM, a device designed to simulate microgravity on Earth, we investigated the early effects of RPM exposure on human chondrocytes of six different donors after 30 min, 2 h, 4 h, 16 h, and 24 h and compared the results with the corresponding static controls cultured under normal gravity conditions. As little as 30 min of RPM exposure resulted in increased expression of several genes responsible for cell motility, structure and integrity (beta-actin); control of cell growth, cell proliferation, cell differentiation and apoptosis (TGF-β1, osteopontin); and cytoskeletal components such as microtubules (beta-tubulin) and intermediate filaments (vimentin). After 4 hours of RPM exposure disruptions in the vimentin network were detected. These changes were less dramatic after 16 hours on the RPM, when human chondrocytes appeared to reorganize their cytoskeleton. However, the gene expression and protein content of TGF-β1 was enhanced during RPM culture for 24 h. Taking these results together, we suggest that chondrocytes exposed to the RPM seem to change their extracellular matrix production behaviour while they rearrange their cytoskeletal proteins prior to forming three-dimensional aggregates.

Moderate alterations of the cytoskeleton in human chondrocytes after short-term microgravity produced by parabolic flight maneuvers could be prevented by up-regulation of BMP-2 and SOX-9

Real and simulated microgravity induce a variety of changes in human cells. Most importantly, changes in the cytoskeleton have been noted, and studies on microtubules have shown that they are gravisensitive. This study focuses on the effects of short‐term real microgravity on gene expression, protein content, and cytoskeletal structure of human chondrocytes. We cultivated human chondrocytes, took them along a parabolic flight during the 24th Deutsches Zentrum für Luft‐ und Raumfahrt Parabolic (DLR) Flight Campaign, and fixed them after the 1st and the 31st parabola. Immunofluorescence microscopy revealed no changes after the 1st parabola, but disruptions of β‐tubulin, vimentin, and cytokeratin networks after the 31st parabola. No F‐actin stress fibers were detected even after 31 parabolas. Furthermore, mRNA and protein quantifications after the 31st parabola showed a clear up‐regulation of cytoskeletal genes and proteins. The mRNAs were significantly up‐regulated as follows: TUBB, 2‐fold; VIM, 1.3‐fold; KRT8, 1.8‐fold; ACTB, 1.9‐fold; ICAM1, 4.8‐fold; OPN, 7‐fold; ITGA10, 1.5‐fold; ITGB1, 1.2‐fold; TGFB1, 1.5‐fold; CAV1, 2.6‐fold; SOX9, 1.7‐fold; BMP‐2, 5.3‐fold. However, SOX5 (‐25%) and SOX6 (‐28%) gene expression was decreased. Contrary, no significant changes in gene expression levels were observed during vibration and hypergravity experiments. These data suggest that short‐term microgravity affects the gene expression of distinct proteins. In contrast to poorly differentiated follicular thyroid cancer cells or human endothelial cells, chondrocytes only exert moderate cytoskeletal alterations. The up‐regulation of BMP‐2, TGF‐β1, and SOX9 in chondrocytes may play a key role in preventing cytoskeletal alterations.—Aleshcheva, G., Wehland, M., Sahana, J., Bauer, J., Corydon, T. J., Hemmersbach, R., Frett, T., Egli, M., Infanger, M., Grosse, J., Grimm, D. Moderate alterations of the cytoskeleton in human chondrocytes after short‐term microgravity produced by parabolic flight maneuvers could be prevented by up‐regulation of BMP‐2 and SOX‐9. FASEB J. 29, 2303‐2314 (2015). www.fasebj.org

Common Effects on Cancer Cells Exerted by a Random Positioning Machine and a 2D Clinostat.

In this study we focused on gravity-sensitive proteins of two human thyroid cancer cell lines (ML-1; RO82-W-1), which were exposed to a 2D clinostat (CLINO), a random positioning machine (RPM) and to normal 1g-conditions. After a three (3d)- or seven-day-culture (7d) on the two devices, we found both cell types growing three-dimensionally within multicellular spheroids (MCS) and also cells remaining adherent (AD) to the culture flask, while 1g-control cultures only formed adherent monolayers, unless the bottom of the culture dish was covered by agarose. In this case, the cytokines IL-6 and IL-8 facilitated the formation of MCS in both cell lines using the liquid-overlay technique at 1g. ML-1 cells grown on the RPM or the CLINO released amounts of IL-6 and MCP-1 into the supernatant, which were significantly elevated as compared to 1g-controls. Release of IL-4, IL-7, IL-8, IL-17, eotaxin-1 and VEGF increased time-dependently, but was not significantly influenced by the gravity conditions. After 3d on the RPM or the CLINO, an accumulation of F-actin around the cellular membrane was detectable in AD cells of both cell lines. IL-6 and IL-8 stimulation of ML-1 cells for 3d and 7d influenced the protein contents of ß1-integrin, talin-1, Ki-67, and beta-actin dose-dependently in adherent cells. The ß1-integrin content was significantly decreased in AD and MCS samples compared with 1g, while talin-1 was higher expressed in MCS than AD populations. The proliferation marker Ki-67 was elevated in AD samples compared with 1g and MCS samples. The ß-actin content of R082-W-1 cells remained unchanged. ML-1 cells exhibited no change in ß-actin in RPM cultures, but a reduction in CLINO samples. Thus, we concluded that simulated microgravity influences the release of cytokines in follicular thyroid cancer cells, and the production of ß1-integrin and talin-1 and predicts an identical effect under real microgravity conditions.

Identifications of novel mechanisms in breast cancer cells involving duct-like multicellular spheroid formation after exposure to the Random Positioning Machine

Many cell types form three-dimensional aggregates (MCS; multicellular spheroids), when they are cultured under microgravity. MCS often resemble the organ, from which the cells have been derived. In this study we investigated human MCF-7 breast cancer cells after a 2 h-, 4 h-, 16 h-, 24 h- and 5d-exposure to a Random Positioning Machine (RPM) simulating microgravity. At 24 h few small compact MCS were detectable, whereas after 5d many MCS were floating in the supernatant above the cells, remaining adherently (AD). The MCS resembled the ducts formed in vivo by human epithelial breast cells. In order to clarify the underlying mechanisms, we harvested MCS and AD cells separately from each RPM-culture and measured the expression of 29 selected genes with a known involvement in MCS formation. qPCR analyses indicated that cytoskeletal genes were unaltered in short-term samples. IL8, VEGFA, and FLT1 were upregulated in 2 h/4 h AD-cultures. The ACTB, TUBB, EZR, RDX, FN1, VEGFA, FLK1 Casp9, Casp3, PRKCA mRNAs were downregulated in 5d-MCS-samples. ESR1 was upregulated in AD, and PGR1 in both phenotypes after 5d. A pathway analysis revealed that the corresponding gene products are involved in organization and regulation of the cell shape, in cell tip formation and membrane to membrane docking.

Reduced Expression of Cytoskeletal and Extracellular Matrix Genes in Human Adult Retinal Pigment Epithelium Cells Exposed to Simulated Microgravity

Background/Aims: Microgravity (µg) has adverse effects on the eye of humans in space. The risk of visual impairment is therefore one of the leading health concerns for NASA. The impact of µg on human adult retinal epithelium (ARPE-19) cells is unknown. Methods: In this study we investigated the influence of simulated µg (s-µg; 5 and 10 days (d)), using a Random Positioning Machine (RPM), on ARPE-19 cells. We performed phase-contrast/fluorescent microscopy, qRT-PCR, Western blotting and pathway analysis. Results: Following RPM-exposure a subset of ARPE-19 cells formed multicellular spheroids (MCS), whereas the majority of the cells remained adherent (AD). After 5d, alterations of F-actin and fibronectin were observed which reverted after 10d-exposure, suggesting a time-dependent adaptation to s-µg. Gene expression analysis of 12 genes involved in cell structure, shape, adhesion, migration, and angiogenesis suggested significant changes after a 10d-RPM-exposure. 11 genes were down-regulated in AD and MCS 10d-RPM-samples compared to 1g, whereas FLK1 was up-regulated in 5d- and 10d-RPM-MCS-samples. Similarly, TIMP1 was up-regulated in 5d-RPM-samples, whereas the remaining genes were down-regulated in 5d-RPM-samples. Western blotting revealed similar changes in VEGF, β-actin, laminin and fibronectin of 5d-RPM-samples compared to 10d, whereas different alterations of β-tubulin and vimentin were observed. The pathway analysis showed complementing effects of VEGF and integrin β-1. Conclusions: These findings clearly show that s-µg induces significant alterations in the F-actin-cytoskeleton and cytoskeleton-related proteins of ARPE-19, in addition to changes in cell growth behavior and gene expression patterns involved in cell structure, growth, shape, migration, adhesion and angiogenesis.

Proteome Analysis of Human Follicular Thyroid Cancer Cells Exposed to the Random Positioning Machine

Several years ago, we detected the formation of multicellular spheroids in experiments with human thyroid cancer cells cultured on the Random Positioning Machine (RPM), a ground-based model to simulate microgravity by continuously changing the orientation of samples. Since then, we have studied cellular mechanisms triggering the cells to leave a monolayer and aggregate to spheroids. Our work focused on spheroid-related changes in gene expression patterns, in protein concentrations, and in factors secreted to the culture supernatant during the period when growth is altered. We detected that factors inducing angiogenesis, the composition of integrins, the density of the cell monolayer exposed to microgravity, the enhanced production of caveolin-1, and the nuclear factor kappa B p65 could play a role during spheroid formation in thyroid cancer cells. In this study, we performed a deep proteome analysis on FTC-133 thyroid cancer cells cultured under conditions designed to encourage or discourage spheroid formation. The experiments revealed more than 5900 proteins. Their evaluation confirmed and explained the observations mentioned above. In addition, we learned that FTC-133 cells growing in monolayers or in spheroids after RPM-exposure incorporate vinculin, paxillin, focal adhesion kinase 1, and adenine diphosphate (ADP)-ribosylation factor 6 in different ways into the focal adhesion complex.

The role of NFκB in spheroid formation of human breast cancer cells cultured on the Random Positioning Machine

Human MCF-7 breast cancer cells were exposed to a Random Positioning Machine (RPM). After 24 hours (h) the cells grew either adherently within a monolayer (AD) or within multicellular spheroids (MCS). AD and MCS populations were separately harvested, their cellular differences were determined performing qPCR on genes, which were differently expressed in AD and MCS cells. Gene array technology was applied to detect RPM-sensitive genes in MCF-7 cells after 24 h. Furthermore, the capability to form multicellular spheroids in vitro was compared with the intracellular distribution of NF-kappaB (NFκB) p65. NFκB was equally distributed in static control cells, but predominantly localized in the cytoplasm in AD cells and nucleus in MCS cells exposed to the RPM. Gene array analyses revealed a more than 2-fold change of only 23 genes including some whose products are affected by oxygen levels or regulate glycolysis. Significant upregulations of the mRNAs of enzymes degrading heme, of ANXA1, ANXA2, CTGF, CAV2 and ICAM1, as well as of FAS, Casp8, BAX, p53, CYC1 and PARP1 were observed in MCS cells as compared with 1g-control and AD cells. An interaction analysis of 47 investigated genes suggested that HMOX-1 and NFκB variants are activated, when multicellular spheroids are formed.

Key Proteins Involved in Spheroid Formation and Angiogenesis in Endothelial Cells After Long-Term Exposure to Simulated Microgravity

Background/Aims: Cardiovascular complications are common in astronauts returning from a prolonged spaceflight. These health problems might be driven by complex modulations of gene expression and protein synthesis in endothelial cells (ECs). Studies on the influence of microgravity on phenotype, growth pattern and biological processes of ECs can help to understand these complications. Methods: We exposed ECs (EA.hy926) to a Random Positioning Machine (RPM). Proteins associated with cell structure, angiogenesis and endothelial dysfunction were investigated in distinct pools of multicellular spheroids (MCS), adherent cells (AD) and tubular structures (TS) formed after a 35-day RPM-exposure. Results: Combining morphological and molecular approaches, we found AD, MCS and TS with changes in the synthesis and release of proteins involved in three-dimensional growth. Fibronectin and monocyte chemoattractant protein-1 (MCP-1) mRNAs and protein contents were elevated along with an increased secretion of vascular endothelial growth factor (VEGF), interleukin (IL)-6, IL-8, MCP-1, intercellular adhesion molecule 1 (ICAM-1), vascular cell adhesion molecule 1 (VCAM-1), neutrophil gelatinase-associated lipocalin (NGAL) and regulated on activation, normal T cell expressed and secreted (RANTES) proteins in the culture supernatant as determined by multianalyte profiling technology. Together they form a network of interaction. Conclusions: These results show that a prolonged RPM-exposure of ECs induced TS and MCS formation. The factors VEGF, NGAL, IL-6, IL-8, MCP-1, VCAM-1, ICAM-1, fibronectin and RANTES seem to be affected when gravity is omitted.

Decreased E-Cadherin in MCF7 Human Breast Cancer Cells Forming Multicellular Spheroids Exposed to Simulated Microgravity

MCF7 human breast cancer cells were cultured under normal gravity (1 g) and on a random positioning machine (RPM) preventing sedimentation. After 2 weeks, adherent 1 g‐control and adherent RPM cells (AD) as well as multicellular spheroids (MCS) were harvested. AD and MCS had been exposed to the RPM in the same culture flask. In a subsequent proteome analysis, the majority of the proteins detected showed similar label‐free quantification (LFQ) scores in each of the respective subpopulations, but in both AD or MCS cultures, proteins were also found whose LFQs deviated at least twofold from their counterparts in the 1 g‐control cells. They included the cell junction protein E‐cadherin, which was diminished in MCS cells, where proteins of the E‐cadherin autodegradation pathway were enhanced and c‐Src (proto‐oncogene tyrosine‐protein kinase c‐Src) was detected. Spheroid formation was prevented by inhibition of c‐Src but promoted by antibodies blocking E‐cadherin activity. An interaction analysis of the detected proteins that are involved in forming and regulating junctions or adhesion complexes and in E‐cadherin autodegradation indicated connections between the two protein groups. This suggests that the balance of proteins that up‐ or downregulate E‐cadherin mediates the tendency of MCF7 cells to form MCS during RPM exposure.

Pathway Analysis Hints Towards Beneficial Effects of Long-Term Vibration on Human Chondrocytes

Background/Aims: Spaceflight negatively influences the function of cartilage tissue in vivo. In vitro human chondrocytes exhibit an altered gene expression of inflammation markers after a two-hour exposure to vibration. Little is known about the impact of long-term vibration on chondrocytes. Methods: Human cartilage cells were exposed for up to 24 h (VIB) on a specialised vibration platform (Vibraplex) simulating the vibration profile which occurs during parabolic flights and compared to static control conditions (CON). Afterwards, they were investigated by phase-contrast microscopy, rhodamine phalloidin staining, microarray analysis, qPCR and western blot analysis. Results: Morphological investigations revealed no changes between CON and VIB chondrocytes. F-Actin staining showed no alterations of the cytoskeleton in VIB compared with CON cells. DAPI and TUNEL staining did not identify apoptotic cells. ICAM-1 was elevated and vimentin, beta-tubulin and osteopontin proteins were significantly reduced in VIB compared to CON cells. qPCR of cytoskeletal genes, ITGB1, SOX3, SOX5, SOX9 did not reveal differential regulations. Microarray analysis detected 13 differentially expressed genes, mostly indicating unspecific stimulations. Pathway analyses demonstrated interactions of PSMD4 and CNOT7 with ICAM. Conclusions: Long-term vibration did not damage human chondrocytes in vitro. The reduction of osteopontin protein and the down-regulation of PSMD4 and TBX15 gene expression suggest that in vitro long-term vibration might even positively influence cultured chondrocytes.