Biology subjects

Bergholt, M. S.

Publications and source records attributed to Bergholt, M. S..

3 recordsLinked to original sources

bioRxiv2023

Label-free 3-D molecular imaging of living tissues using Raman Spectral Projection Tomography

The ability to image tissues in three-dimensions (3-D) with label-free molecular contrast at mesoscale would be a valuable capability in biology and biomedicine. Here, we introduce Raman spectral projection tomography (RSPT) for volumetric molecular imaging with sub-millimeter spatial resolution. We have developed a RSPT imaging instrument capable of providing 3-D molecular contrast in transparent and semi-transparent samples. A computational pipeline for multivariate reconstruction was established to extract label-free spatial molecular information from Raman projection data. We demonstrate imaging and visualization of phantoms of various complex shapes with label-free molecular contrast. Finally, we apply RSPT as a novel tool for imaging of molecular gradients and extracellular matrix heterogeneities in fixed and live tissue-engineered constructs and explanted native tissues. RSPT imaging opens new possibilities for label-free molecular monitoring of tissues.

bioengineering↗

bioRxiv2023

Opto-lipidomics of tissues

Lipid metabolism and signalling play pivotal functions in biology and disease development. Despite this, there is currently no optical technique available that can directly visualise the lipidome in tissues. In this study, we introduce opto-lipidomics, a new approach to optical molecular tissue imaging. We expand the capability of vibrational Raman spectroscopy to identify individual lipids in complex tissue matrices through correlation with desorption electrospray ionisation (DESI) - mass spectrometry imaging in an integrated instrument. A computational pipeline of inter-modality regression analysis is established to extract lipidomic information from optical vibrational spectra. Opto-lipidomic imaging of transient cerebral ischemia-reperfusion injury in a murine model of ischemic stroke demonstrates the visualisation and identification of lipids in disease with unprecedented molecular specificity using light. Furthermore, we deploy opto-lipidomics in a handheld fiber-optic Raman probe and demonstrate real-time classification of bulk brain tissues based on specific lipid abundances. Opto-lipidomics opens a host of opportunities to study lipid biomarkers for diagnostics, prognostics, and novel therapeutic targets.

bioengineering↗

bioRxiv2021

Raman Needle Arthroscopy for In Vivo Molecular Assessment of Cartilage

The development of treatments for osteoarthritis (OA) is burdened by the lack of standardized biomarkers of cartilage health that can be applied in clinical trials. We present a novel arthroscopic Raman probe that can "optically biopsy" cartilage and quantify key ECM biomarkers for determining cartilage composition, structure, and material properties in health and disease. Technological and analytical innovations to optimize Raman analysis include: 1) multivariate decomposition of cartilage Raman spectra into ECM-constituent-specific biomarkers (glycosaminoglycan [GAG], collagen [COL], water [H2O] scores), and 2) multiplexed polarized Raman spectroscopy to quantify superficial zone collagen anisotropy via a PLS-DA-derived Raman collagen alignment factor (RCAF). Raman measurements were performed on a series of ex vivo cartilage models: 1) chemically GAG-depleted bovine cartilage explants (n=40), 2) mechanically abraded bovine cartilage explants (n=30), 3) aging human cartilage explants (n=14), and 4) anatomical-site-varied ovine osteochondral explants (n=6). Derived Raman GAG score biomarkers predicted 95%, 66%, and 96% of the variation in GAG content of GAG-depleted bovine explants, human explants, and ovine explants, respectively (p<0.001). RCAF values were significantly different for explants with abrasion-induced superficial zone collagen loss (p<0.001). The multivariate linear regression of Raman-derived ECM biomarkers (GAG and H2O scores) predicted 94% of the variation in elastic modulus of ovine explants (p<0.001). Finally, we demonstrated the first in vivo Raman arthroscopy assessment of an ovine femoral condyle through intraarticular entry into the synovial capsule. This work advances Raman arthroscopy towards a transformative low cost, minimally invasive diagnostic platform for objective monitoring of treatment outcomes from emerging OA therapies.

bioengineering↗