Novel methods to track and identify the stem cell niche

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Pharmacological tools to mobilize mesenchymal stromal cells into the blood promote bone formation after surgery

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Tracking the cell hierarchy in the human intestine using biochemical signatures derived by mid-infrared microspectroscopy.

Markers of gastrointestinal (GI) stem cells remain elusive. We employed synchrotron Fourier-transform infrared (FTIR) microspectroscopy to derive mid-infrared (IR) spectra along the length of human GI crypts. Tissue sections (10-μm thick) were floated onto BaF2 windows and image maps were acquired of small intestine and large bowel crypts in transmission mode with an aperture of ≤ 10 μm × 10 μm. Counting upwards in a step-size (≤ 10 μm) fashion from the crypt base, IR spectra were extracted from the image maps and each spectrum corresponding to a particular location was identified. Spectra were analyzed using principal component analysis plus linear discriminant analysis. Compared to putative crypt base columnar/Paneth cells, those assigned as label-retaining cells were chemically more similar to putative large bowel stem cells and, the small intestine transit-amplifying cells were closest to large bowel transit-amplifying cells; interestingly, the base of small intestine crypts was the most chemically-distinct. This study suggests that in the complex cell lineage of human GI crypts, chemical similarities as revealed by FTIR microspectroscopy between regions putatively assigned as stem cell, transit-amplifying and terminally-differentiated facilitates identification of cell function

FTIR micro-spectroscopy identifies symmetric PO2- modifications as a marker of the putative stem cell region of human intestinal crypts.

Complex biomolecules absorb in the mid-infrared ( = 2-20 m) giving vibrational spectra associated with structure and function. We employed Fourier transform infrared (FTIR) micro-spectroscopy to “fingerprint” locations along the length of human small and large intestinal crypts. Paraffin-embedded slices of normal human gut were sectioned (10-m thick) and mounted to facilitate infrared (IR) spectral analyses. IR spectra were collected employing globar (15 m 15 m aperture) FTIR micro-spectroscopy in reflection mode, synchrotron (10 m 10 m aperture) FTIR micro-spectroscopy in transmission mode, or near-field photothermal micro-spectroscopy (PTMS). 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 between cells in situ along the length of gut crypts. Following spectroscopic analysis, plotted clusters and their loadings plots pointed towards symmetric (s) PO2- (1080 cm-1) vibrations as a discriminating factor for the putative stem cell region of crypts. This was subsequently confirmed by image mapping and points to a novel approach of deriving an integrated biochemical fingerprint of a tissue’s stem cell niche and identifying its spatial location in a non-destructive fashion. These results suggest that DNA conformational alterations associated with cells residing in the putative stem cell region of crypts can be used as a means of identification, which may have utility in other tissues where the location of the niche is unclear