Raman Microscopy of Human Embryonic Stem Cells Exposed to Heat and Cold Stress
Human embryonic stem cells (hESCs) have large nucleus-to-cytoplasm ratios and nucleic acid spectral bands are prominent in their characteristic Raman signatures. Under normal conditions, the major variations in these signatures are due to changes in glycogen content, but how these signatures
vary in response to different external conditions is largely unknown. In this study we investigated the influences of temperature variations on hESC Raman signatures. At 32 °C, compared to the 37 °C control condition, cell proliferation rates were markedly reduced and glycogen Raman
band intensities were elevated. In addition, at both temperatures, an inverse relationship between cell proliferation rates (i.e., onset of exponential growth phase vs. end of exponential phase) and glycogen Raman band intensities was observed. This relationship suggested a role for glycogen
in the energy metabolism of hESC self-renewal. Protein and lipid spectral variations were small and co-varied with those of nucleic acids, suggesting that they were related to changes in cellular dimensions occurring during the cell cycle. When the temperature was elevated to 39 °C, increased
glycogen band intensities, compared to controls, were also observed. In addition, spectral evidence of differentiation emerged that was supported by reduced SSEA-3 expression. Taken together, these results demonstrated that heat and cold stress had quite different effects on the characteristic
Raman signatures of hESCs. Thus, Raman spectroscopy can be used to detect deviation from optimal culturing temperatures and therefore it could be of considerable value in the routine and noninvasive determination of hESC culture quality.
Human embryonic stem cells;
Document Type: Research Article
Michael Smith Laboratories, The University of British Columbia, 2185 East Mall, Vancouver, BC, Canada, V6T 1Z4
Department of Pathology and Laboratory Medicine, The University of British Columbia, BC Cancer Research Centre, 675 West 10th Avenue, Vancouver, BC, Canada, V5Z 1L3
Department of Chemistry, The University of British Columbia, 2036 Main Mall, Vancouver, BC, Canada, V6T 1Z1
Department of Electrical and Computer Engineering, The University of British Columbia, 2332 Main Mall, Vancouver, BC, Canada, V6T
Publication date: December 1, 2011
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