Two sides of the same coin? Unraveling subtle differences between human embryonic and induced pluripotent stem cells by Raman spectroscopy

Elvira Parrotta,Stefania De Vitis,Stefania Scalise,Mariagrazia Paonessa,Gerardo Perozziello,Giovanni Cuda,Maria Teresa De Angelis,Patrizio Candeloro,Antonella Sgura,Maria Laura Coluccio,Enzo Mario Di Fabrizio,Vincenzo Mollace,Elisa Coluzzi,Gianluca Santamaria

doi:10.1186/s13287-017-0720-1

Abstract

BackgroundHuman pluripotent stem cells, including embryonic stem cells and induced pluripotent stem cells, hold enormous promise for many biomedical applications, such as regenerative medicine, drug testing, and disease modeling. Although induced pluripotent stem cells resemble embryonic stem cells both morphologically and functionally, the extent to which these cell lines are truly equivalent, from a molecular point of view, remains controversial.MethodsPrincipal component analysis and K-means cluster analysis of collected Raman spectroscopy data were used for a comparative study of the biochemical fingerprint of human induced pluripotent stem cells and human embryonic stem cells. The Raman spectra analysis results were further validated by conventional biological assays.ResultsRaman spectra analysis revealed that the major difference between human embryonic stem cells and induced pluripotent stem cells is due to the nucleic acid content, as shown by the strong positive peaks at 785, 1098, 1334, 1371, 1484, and 1575 cm–1, which is enriched in human induced pluripotent stem cells.ConclusionsHere, we report a nonbiological approach to discriminate human induced pluripotent stem cells from their native embryonic stem cell counterparts.

Highlights

Human pluripotent stem cells, including embryonic stem cells and induced pluripotent stem cells, hold enormous promise for many biomedical applications, such as regenerative medicine, drug testing, and disease modeling
The first six principal components (PCs), which comprised more than 98% of the total variance, were used to perform K-means cluster analysis (KCA), imposing six clusters to be addressed inside the cells
It is immediately evident that the human induced pluripotent stem cells (iPSCs) (hiPSC) exhibits a more intense Raman signal corresponding to nucleic acids and that this overexpression is localized in welldefined regions inside the cell

Summary

Introduction

Human pluripotent stem cells, including embryonic stem cells and induced pluripotent stem cells, hold enormous promise for many biomedical applications, such as regenerative medicine, drug testing, and disease modeling. Induced pluripotent stem cells resemble embryonic stem cells both morphologically and functionally, the extent to which these cell lines are truly equivalent, from a molecular point of view, remains controversial. Human pluripotent stem cells (hPSCs) include embryonic stem cells (ESCs), derived from the inner cell mass of the blastocyst [1], and induced pluripotent stem cells (iPSCs), generated from adult somatic cells by forced expression of Parrotta et al Stem Cell Research & Therapy (2017) 8:271. We use Raman spectroscopy to perform a comparative analysis of a human iPSC (hiPSC) line reprogrammed from skin fibroblasts and the commercially available hESC line H9 in order to identify specific biochemical signatures capable of discriminating between reprogrammed and native pluripotent stem cells. The results of Raman analysis performed on human reprogrammed and ESC lines indicate that the overall spectral behavior is very similar for both cell lines, the hiPSC spectra still exhibit distinctive Raman features which allow for their discrimination from the native counterpart

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Conclusion