Project description:Mammalian cells were grown as multicellular aggregates (spheroids) in an effort to determine the signaling events required for two cellular transformations states; primary foreskin fibroblasts (HFF-2) and glioblastoma cancer (T98G) cells, to survive at room temperature under oxygen and nutrient-deprived conditions for extended periods of time (2 weeks) and subsequently grown out from the arrested state as adherent monolayers. HFF-2 cells were cultured in DMEM supplemented with 15% fetal bovine serum and 5% carbon dioxide humidified air at 37 degrees C. T98G cells were cultured in EMEM with 10% FBS, 5% non-essential amino acids and 5% carbon dioxide humidified air at 37 degreesC. Monolayers were grown in T-185 flasks to 60% confluency then split into T-185 flasks coated with a 1% agarose mix in a 2:1 media/water ratio. Cells were suspended in 30 ml of supplemented media and grown for 4 days in order to form multicellular spheroids as described previously by our group (J. Cell. Physiol., 206 [2006] 526-536; see GSE1364 and GSE1455 for similar experiments with HEK293 cells). The suspension was removed from the flasks and centrifuged (1500 x g, 2 min) and the media removed. The pellet was returned to the flasks and then placed in vacuum bags (Dri-shield 2000 moisture barrier bag from Surmount Inc., USA; Cat. number 70068), which were sealed immediately under vacuum (Deni Magic Vac, Champion model; Keystone Manufacturing, USA). Vacuum-sealed flasks were stored for 2 weeks (in the dark) at room temperature. Recovery was initiated by removing the flask from the bag and resuspending the spheroids in supplemented media and placing the flasks in a 5% CO2/humidified air incubator maintained at 37 degreesC. Timepoints for transcriptional analysis were monolayer (control), 4 day growth spheroids, 2 week stored spheroids and 7 day growth back to monolayers. There were 67 HFF-2 and 50 T98G genes that exhibited at least a 10-fold change in expression during the course of arrest and recovery. Eleven of these genes were common to both cell lines. While the trends were the same between the two cell lines for genes that were in common, the timing of the responses were clearly different. The primary fibroblasts showed significant gene expression changes during spheroid formation and returned to their initial monolayer state after the two week arrest, whereas the glioblastoma cells exhibited major changes in gene expression during the recovery process. Furthermore, the T98G cells never returned to the monolayer expression levels during the time course of the recovery phase (7 days growth under monolayer conditions). Major differences in the transcriptional data were also found between the cell lines with regards to the putative cellular location of the encoded proteins. Of the genes with significant fold changes (+/- 10-fold) for which location information is available, the primary fibroblasts were significantly enriched in genes encoding extracellular (32%) and membrane-associated (26%) proteins. The glioblastoma cells, on the other hand, had only 17% extracellular and 13% membrane-associated. The expression level trends for all genes above the 10-fold cutoff were as observed for the "in common" genes; HFF-2 genes had returned to monolayer expression levels after 7 days of recovery whereas the T98G line was still exhibiting expression values much different from that of the monolayer control. Keywords = human foreskin fibroblasts, desiccation, rehydration, monolayer, spheroid, stabilization, ambient temperature Keywords: other

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Long-Term Storage of Human Cells at Ambient Temperature

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