Nature Communications (Sep 2024)

Label-free 3D molecular imaging of living tissues using Raman spectral projection tomography

  • Elzbieta Stepula,
  • Anders R. Walther,
  • Magnus Jensen,
  • Dev R. Mehrotra,
  • Mu H. Yuan,
  • Simon V. Pedersen,
  • Vishal Kumar,
  • Eileen Gentleman,
  • Michael B. Albro,
  • Martin A. B. Hedegaard,
  • Mads S. Bergholt

DOI
https://doi.org/10.1038/s41467-024-51616-y
Journal volume & issue
Vol. 15, no. 1
pp. 1 – 11

Abstract

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Abstract The ability to image tissues in three dimensions (3D) with label-free molecular contrast at the mesoscale would be a valuable capability in biology and biomedicine. Here, we introduce Raman spectral projection tomography (RSPT) for volumetric molecular imaging with optical sub-millimeter spatial resolution. We have developed a RSPT imaging instrument capable of providing 3D molecular contrast in transparent and semi-transparent samples. We also created a computational pipeline for multivariate reconstruction to extract label-free spatial molecular information from Raman projection data. Using these tools, we demonstrate imaging and visualization of phantoms of various complex shapes with label-free molecular contrast. Finally, we apply RSPT as a tool for imaging of molecular gradients and extracellular matrix heterogeneities in fixed and living tissue-engineered constructs and explanted native cartilage tissues. We show that there exists a favorable balance wherein employing Raman spectroscopy, with its advantages in live cell imaging and label-free molecular contrast, outweighs the reduction in imaging resolution and blurring caused by diffuse photon propagation. Thus, RSPT imaging opens new possibilities for label-free molecular monitoring of tissues.