Label-free photoacoustic tomography of whole mouse brain structures ex vivo

Recent studies of cerebral hypoxia-ischemia (HI) have highlighted slowly progressive neurodegeneration whose mechanisms remain elusive, but if blocked, could considerably improve long-term neurological function. We previously established that the cytokine transforming growth factor (TGF)β1 is highly elevated following HI and that delivering an antagonist for TGFβ receptor activin-like kinase 5 (ALK5)—SB505124—three days after injury in a rat model of moderate pre-term HI significantly preserved the structural integrity of the thalamus and hippocampus as well as neurological functions associated with those brain structures. To elucidate the mechanism whereby ALK5 inhibition reduces cell death, we assessed levels of autophagy markers in neurons and found that SB505124 increased numbers of autophagosomes and levels of lipidated light chain 3 (LC3), a key protein known to mediate autophagy. However, those studies did not determine whether (1) SB was acting directly on the CNS and (2) whether directly inducing autophagy could decrease cell death and improve outcome. Here we show that administering an ALK5 antagonist three days after HI reduced actively apoptotic cells by ~90% when assessed one week after injury. Ex vivo studies using the lysosomal inhibitor chloroquine confirmed that SB505124 enhanced autophagy flux in the injured hemisphere, with a significant accumulation of the autophagic proteins LC3 and p62 in SB505124 + chloroquine treated brain slices. We independently activated autophagy using the stimulatory peptide Tat-Beclin1 to determine if enhanced autophagy is directly responsible for improved outcomes. Administering Tat-Beclin1 starting three days after injury preserved the structural integrity of the hippocampus and thalamus with improved sensorimotor function. These data support the conclusion that intervening at this phase of injury represents a window of opportunity where stimulating autophagy is beneficial.

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1700 nm optical coherence microscopy enables minimally invasive, label-free, in vivo optical biopsy deep in the mouse brain

Light Science & Applications ◽

10.1038/s41377-021-00586-7 ◽

2021 ◽

Vol 10 (1) ◽

Author(s):

Jun Zhu ◽

Hercules Rezende Freitas ◽

Izumi Maezawa ◽

Lee-way Jin ◽

Vivek J. Srinivasan

Keyword(s):

Minimally Invasive ◽

Mouse Brain ◽

Numerical Aperture ◽

Optical Biopsy ◽

Optical Coherence ◽

Label Free ◽

Optical Coherence Microscopy ◽

Minimal Invasiveness ◽

Cortical Regions

AbstractIn vivo, minimally invasive microscopy in deep cortical and sub-cortical regions of the mouse brain has been challenging. To address this challenge, we present an in vivo high numerical aperture optical coherence microscopy (OCM) approach that fully utilizes the water absorption window around 1700 nm, where ballistic attenuation in the brain is minimized. Key issues, including detector noise, excess light source noise, chromatic dispersion, and the resolution-speckle tradeoff, are analyzed and optimized. Imaging through a thinned-skull preparation that preserves intracranial space, we present volumetric imaging of cytoarchitecture and myeloarchitecture across the entire depth of the mouse neocortex, and some sub-cortical regions. In an Alzheimer’s disease model, we report that findings in superficial and deep cortical layers diverge, highlighting the importance of deep optical biopsy. Compared to other microscopic techniques, our 1700 nm OCM approach achieves a unique combination of intrinsic contrast, minimal invasiveness, and high resolution for deep brain imaging.

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Optical Biomarkers for the Diagnosis of Osteoarthritis through Raman Spectroscopy: Radiological and Biochemical Validation Using Ex Vivo Human Cartilage Samples

Diagnostics ◽

10.3390/diagnostics11030546 ◽

2021 ◽

Vol 11 (3) ◽

pp. 546

Author(s):

Paula Casal-Beiroa ◽

Vanesa Balboa-Barreiro ◽

Natividad Oreiro ◽

Sonia Pértega-Díaz ◽

Francisco J. Blanco ◽

...

Keyword(s):

Raman Spectroscopy ◽

Articular Cartilage ◽

Ex Vivo ◽

Cartilage Degradation ◽

Calcium Pyrophosphate ◽

Calcium Pyrophosphate Dihydrate ◽

Label Free ◽

Molecular Fingerprint ◽

Human Cartilage ◽

Biochemical Validation

Osteoarthritis (OA) is the most common rheumatic disease, characterized by progressive articular cartilage degradation. Raman spectroscopy (RS) has been recently proposed as a label-free tool to detect molecular changes in musculoskeletal tissues. We used cartilage samples derived from human femoral heads to perform an ex vivo study of different Raman signals and ratios, related to major and minor molecular components of articular cartilage, hereby proposed as candidate optical biomarkers for OA. Validation was performed against the radiological Kellgren–Lawrence (K-L) grading system, as a gold standard, and cross-validated against sulfated glycosaminoglycans (sGAGs) and total collagens (Hyp) biochemical contents. Our results showed a significant decrease in sGAGs (SGAGs, A1063 cm−1/A1004 cm−1) and proteoglycans (PGs, A1375 cm−1/A1004 cm−1) and a significant increase in collagen disorganization (ColD/F, A1245 cm−1/A1270 cm−1), with OA severity. These were correlated with sGAGs or Hyp contents, respectively. Moreover, the SGAGs/HA ratio (A1063 cm−1/A960 cm−1), representing a functional matrix, rich in proteoglycans, to a mineralized matrix-hydroxyapatite (HA), was significantly lower in OA cartilage (K-L I vs. III–IV, p < 0.05), whilst the mineralized to collagenous matrix ratio (HA/Col, A960 cm−1/A920 cm−1) increased, being correlated with K-L. OA samples showed signs of tissue mineralization, supported by the presence of calcium crystals-related signals, such as phosphate, carbonate, and calcium pyrophosphate dihydrate (MGP, A960 cm−1/A1004 cm−1, MGC, A1070 cm−1/A1004 cm−1 and A1050 cm−1/A1004 cm−1). Finally, we observed an increase in lipids ratio (IL, A1450 cm−1/A1670 cm−1) with OA severity. As a conclusion, we have described the molecular fingerprint of hip cartilage, validating a panel of optical biomarkers and the potential of RS as a complementary diagnostic tool for OA.

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Applications of Vibrational Spectroscopy for Analysis of Connective Tissues

Molecules ◽

10.3390/molecules26040922 ◽

2021 ◽

Vol 26 (4) ◽

pp. 922

Author(s):

William Querido ◽

Shital Kandel ◽

Nancy Pleshko

Keyword(s):

Raman Spectroscopy ◽

Vibrational Spectroscopy ◽

Near Infrared ◽

Ex Vivo ◽

Biological Tissues ◽

Label Free ◽

Connective Tissues ◽

Bone Properties ◽

Composition And Structure

Advances in vibrational spectroscopy have propelled new insights into the molecular composition and structure of biological tissues. In this review, we discuss common modalities and techniques of vibrational spectroscopy, and present key examples to illustrate how they have been applied to enrich the assessment of connective tissues. In particular, we focus on applications of Fourier transform infrared (FTIR), near infrared (NIR) and Raman spectroscopy to assess cartilage and bone properties. We present strengths and limitations of each approach and discuss how the combination of spectrometers with microscopes (hyperspectral imaging) and fiber optic probes have greatly advanced their biomedical applications. We show how these modalities may be used to evaluate virtually any type of sample (ex vivo, in situ or in vivo) and how “spectral fingerprints” can be interpreted to quantify outcomes related to tissue composition and quality. We highlight the unparalleled advantage of vibrational spectroscopy as a label-free and often nondestructive approach to assess properties of the extracellular matrix (ECM) associated with normal, developing, aging, pathological and treated tissues. We believe this review will assist readers not only in better understanding applications of FTIR, NIR and Raman spectroscopy, but also in implementing these approaches for their own research projects.

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A Novel Method for Ex-Vivo Latex Angiography of the Mouse Brain

Journal of Neuroscience Methods ◽

10.1016/j.jneumeth.2021.109342 ◽

2021 ◽

pp. 109342

Author(s):

Keyan Peterson ◽

Stephanie Coffman ◽

Stacey Wolfe ◽

Zhidan Xiang

Keyword(s):

Mouse Brain ◽

Ex Vivo ◽

Novel Method

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Photoacoustic tomography of ex vivo mouse hearts with myocardial infarction

Journal of Biomedical Optics ◽

10.1117/1.3556720 ◽

2011 ◽

Vol 16 (3) ◽

pp. 036007 ◽

Cited By ~ 6

Author(s):

Markus Holotta ◽

Harald Grossauer ◽

Christian Kremser ◽

Pavle Torbica ◽

Jakob Völkl ◽

...

Keyword(s):

Myocardial Infarction ◽

Ex Vivo ◽

Photoacoustic Tomography

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Flexible annotation atlas of the mouse brain: combining and dividing brain structures of the Allen Brain Atlas while maintaining anatomical hierarchy

Scientific Reports ◽

10.1038/s41598-021-85807-0 ◽

2021 ◽

Vol 11 (1) ◽

Author(s):

Norio Takata ◽

Nobuhiko Sato ◽

Yuji Komaki ◽

Hideyuki Okano ◽

Kenji F. Tanaka

Keyword(s):

Mouse Brain ◽

Brain Structures ◽

Brain Atlas ◽

Resting State Functional Connectivity ◽

Brain Science ◽

Step Procedure ◽

Public Resources ◽

Large Brain ◽

Magnetic Resonance Imaging Mri ◽

And Function

AbstractA brain atlas is necessary for analyzing structure and function in neuroimaging research. Although various annotation volumes (AVs) for the mouse brain have been proposed, it is common in magnetic resonance imaging (MRI) of the mouse brain that regions-of-interest (ROIs) for brain structures (nodes) are created arbitrarily according to each researcher’s necessity, leading to inconsistent ROIs among studies. One reason for such a situation is the fact that earlier AVs were fixed, i.e. combination and division of nodes were not implemented. This report presents a pipeline for constructing a flexible annotation atlas (FAA) of the mouse brain by leveraging public resources of the Allen Institute for Brain Science on brain structure, gene expression, and axonal projection. A mere two-step procedure with user-specified, text-based information and Python codes constructs FAA with nodes which can be combined or divided objectively while maintaining anatomical hierarchy of brain structures. Four FAAs with total node count of 4, 101, 866, and 1381 were demonstrated. Unique characteristics of FAA realized analysis of resting-state functional connectivity (FC) across the anatomical hierarchy and among cortical layers, which were thin but large brain structures. FAA can improve the consistency of whole brain ROI definition among laboratories by fulfilling various requests from researchers with its flexibility and reproducibility.

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