Visualizing Cell State Transition Using Raman Spectroscopy

Abstract

System level understanding of the cell requires detailed description of the cell state, which is often characterized by the expression levels of proteins. However, understanding the cell state requires comprehensive information of the cell, which is usually obtained from a large number of cells and their disruption. In this study, we used Raman spectroscopy, which can report changes in the cell state without introducing any label, as a non-invasive method with single cell capability. Significant differences in Raman spectra were observed at the levels of both the cytosol and nucleus in different cell-lines from mouse, indicating that Raman spectra reflect differences in the cell state. Difference in cell state was observed before and after the induction of differentiation in neuroblastoma and adipocytes, showing that Raman spectra can detect subtle changes in the cell state. Cell state transitions during embryonic stem cell (ESC) differentiation were visualized when Raman spectroscopy was coupled with principal component analysis (PCA), which showed gradual transition in the cell states during differentiation. Detailed analysis showed that the diversity between cells are large in undifferentiated ESC and in mesenchymal stem cells compared with terminally differentiated cells, implying that the cell state in stem cells stochastically fluctuates during the self-renewal process. The present study strongly indicates that Raman spectral morphology, in combination with PCA, can be used to establish cells' fingerprints, which can be useful for distinguishing and identifying different cellular states.

Probing differentiation in cancer cell lines by single-cell micro-Raman spectroscopy

“…This might be indicative of the cells probed in our experiments primarily undergoing differentiation rather than proliferation. Raman experiments by Ichimura et al 26 also offered indications that differences in the state of neuroblastoma and adipocyte cells could be visualized before and after differentiation. In the case of N2a and 3T3L1 cell lines, differentiation gave rise to increases in peak intensity attributable to cytochrome C in the cytosol and lipids.…”

Principles and applications of Raman spectroscopy in pharmaceutical drug discovery and development

“…Raman spectroscopy can be used in biomedicine to understand the dynamics of cell nucleic acids [104,105]. Ichimura et al utilized Raman spectroscopy for studying various cell-state transitions [106]. Chen et al used laser tweezer Raman spectroscopy to study cellular processes [107].…”

Non-label immune cell state prediction using Raman spectroscopy

“…When implemented as a microscopy tool, Raman spectroscopy enables label-free, noninvasive analytical imaging of cells with single-cell sensitivity and resolution. In recent years, many groups, including ours, have reported the biological/biomedical applications of Raman scattering microscopy in cancer diagnosis12, cytochrome dynamics in apoptosis3, discrimination of normal and abnormal human sperm4, and in discrimination of cellular state upon differentiation5678. Thus, Raman scattering microscopy has been revealed as an optional analytical tool in life sciences9.…”