Detecting viability transitions of umbilical cord mesenchymal stem cells by Raman micro-spectroscopy

Recent research suggests that human umbilical cord derived mesenchymal stem cells (hUC-MSCs) can be promising candidates for cell-based therapy. Since large population and high viability are generally required, detecting viability transitions of these cells is crucial for their population expansion and quality control. Here, as a non-invasive method, Raman micro-spectroscopy is applied to examine hUC-MSCs with different viability. Using peak fitting and statistic t-test, the Raman peaks with obvious differences between the cells with high viability (> 90%) and low viability (< 20%) are extracted. It is found that the C=O out of plane bending in thymine at 744 cm -1 , symmetric stretching of C–C in lipids at 877 cm -1 and CH deformation in proteins at 1342 cm -1 show the most significant changes ( p < 0.001). When the cell viability decreases, the intensities of the former two peaks are both about doubled while that of the latter peak reduces by about 30%. Based on these results, we propose that the viability of hUC-MSCs can be characterized by these three peaks. And their intensity changes can be understood from the model of excessive reactive oxygen species interacting with the bio-macromolecules.