We have developed a prototype multiplexed fiber-optic system that enables real-time monitoring of hypoxia-sensing fluorophores in beating isolated rat hearts, providing dynamic data useful for the assessment of cardiac metabolism, with potential for cross-correlation and biological validation using parallel MR spectroscopy and PET or SPECT imaging. The system has been designed to suppress background and increase light efficiency. We have established a data analysis pipeline using nonnegative least-squares curve fitting allowing unmixing of overlapped fluorescence spectra and fluorophore quantification. In this first phase of our work, we demonstrate simultaneous detection of a mixture of fluorophores in isolated perfused hearts.
Tissue engineering (TE) constructs are an attractive alternative therapy for patients with e.g., degenerated cartilage. The positive patient outcome relies on the quality of the TE constructs as they should mimic the native tissue in its molecular, chemical, and physical properties. Most quality assessment techniques of TE constructs are destructive to the sample. Therefore, there is an urgent need for a novel non-destructive method to control the in vitro cultivating process. Here, we present Raman Projection Tomography (RPT) which enables live label-free 3D molecular imaging. RPT was employed for the non-destructive quality control of cartilage TE constructs.
Rheumatoid arthritis (RA) is a chronic inflammatory autoimmune disorder characterized by synovial inflammation and pannus formation leading to destruction of local articular structure, bone erosion and functional disabilities. Common research models of inflammatory arthritis in rodents e.g. collagen antibody-induced arthritis (CAIA) in mice are associated with pain, discomfort, and distress.
Here we demonstrate in vivo assessment of CAIA mice using a transflection Raman setup. Mice with induced arthritis and controls were clinically and spectroscopically assessed for 14 days. Raman measurements of tibiotarsal joint bone density correlated well with volumetric bone mineral density (vBMD) in mice exhibiting clinical symptoms of arthritis.
We have developed a forward-scattered high-resolution Raman-Computed Tomography (R-CT) technique that relies on true CT principles rather than diffuse tomography. The in-house built optical system rotates around the sample while Raman spectra are measured from different angles by multiplexing on the 2D CCD. Forward scattered photons are largely in the far-field to reject diffuse photons. We show that R-CT provides both, spatial and molecular information in diffusely scattering phantoms. Data reconstruction is performed using backprojection and multivariate regression analysis to provide a 3D chemical contrast. We finally present preliminary results on rodent limbs.
The R-CT technique developed offers a potential technique to improve the characterisation of tissues and drug efficiency in rodent limbs at the molecular level as it offers morphological information that is not available in conventional transmission Raman spectroscopy.
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