Open AccessFourier Transform Infrared Microspectroscopy Identifies Symmetric PO 2 − Modifications as a Marker of the Putative Stem Cell Region of Human Intestinal Crypts
Author(s) -
Walsh Michael J.,
Fellous Tariq G.,
Hammiche Azzedine,
Lin WeyRan,
Fullwood Nigel J.,
Grude Olaug,
Bahrami Fariba,
Nicholson James M.,
Cotte Marine,
Susini Jean,
Pollock Hubert M.,
Brittan Mairi,
MartinHirsch Pierre L.,
Alison Malcolm R.,
Martin Francis L.
Publication year - 2008
Publication title -
stem cells
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.159
H-Index - 229
eISSN - 1549-4918
pISSN - 1066-5099
DOI - 10.1634/stemcells.2007-0196
Subject(s) - biology , infrared , fourier transform infrared spectroscopy , fourier transform , stem cell , optics , biophysics , microbiology and biotechnology , physics , quantum mechanics
Complex biomolecules absorb in the mid‐infrared (λ = 2–20 μm), giving vibrational spectra associated with structure and function. We used Fourier transform infrared (FTIR) microspectroscopy to “fingerprint” locations along the length of human small and large intestinal crypts. Paraffin‐embedded slices of normal human gut were sectioned (10 μm thick) and mounted to facilitate infrared (IR) spectral analyses. IR spectra were collected using globar (15 μm × 15 μm aperture) FTIR microspectroscopy in reflection mode, synchrotron (≤10 μm × 10 μm aperture) FTIR microspectroscopy in transmission mode or near‐field photothermal microspectroscopy. Dependent on the location of crypt interrogation, clear differences in spectral characteristics were noted. Epithelial‐cell IR spectra were subjected to principal component analysis to determine whether wavenumber‐absorbance relationships expressed as single points in “hyperspace” might on the basis of multivariate distance reveal biophysical differences along the length of gut crypts. Following spectroscopic analysis, plotted clusters and their loadings plots pointed toward symmetric (ν s )PO 2 − (1,080 cm −1 ) vibrations as a discriminating factor for the putative stem cell region; this proved to be a more robust marker than other phenotypic markers, such as β‐catenin or CD133. This pattern was subsequently confirmed by image mapping and points to a novel approach of nondestructively identifying a tissue's stem cell location. ν s PO 2 − , probably associated with DNA conformational alterations, might facilitate a means of identifying stem cells, which may have utility in other tissues where the location of stem cells is unclear. Disclosure of potential conflicts of interest is found at the end of this article.