Correlation of optical attenuation coefficient estimated using optical coherence tomography with changes in astrocytes and neurons in a chronic photothrombosis stroke model

Abstract

The optical attenuation coefficient (OAC) estimated using optical coherence tomography (OAC-OCT) offers a label-free 3D mapping of tissue infarction, but the physiological origin of the OAC contrast remains unclear. For effectively suppressing OAC fluctuations, we propose a hybrid (wavelength/angle) division multiplexing (HDM) method, which improved the OAC contrast by 70.7% in tissue phantoms. To test the feasibility of OAC-based infarction detection, triphenyltetrazolium chloride (TTC) staining was performed on fresh ex vivo brain slices, and the TTC-defined infarction was used as the ground truth. Sharp OAC contrast was observed between the TTC-defined infarction (1.09 mm −1 ) and normal tissue (0.79 mm −1 ). The OAC infarction spatially matched well with the TTC-defined infarction. To further explore the physiological origin of OAC contrast in ischemic stroke at the cellular level, the dynamic changes in OAC were measured in the rat cortex in vivo over 3 weeks after photothrombosis (PT) occlusion and found significantly correlated with the changes in astrocytes and neurons acquired with ex vivo hematoxylin and eosin (HE), glial fibrillary acidic protein (GFAP), and NeuN staining. These results suggest that OAC imaging enables non-invasive infarction detection and its contrast might originate from the changes in astrocytes and neurons in the chronic PT stroke model. The cellular responses revealed by in vivo OAC imaging would be essential for evaluating treatments and even developing novel therapies.

Determination of significant parameters in remote ischemic postconditioning for ischemic stroke in experimental models: A systematic review and meta‐analysis study

“…Based on infarct size, testing within 48–72 h showed better effects compared with that done at hyperacute stage and 4–7 days. On the other hand, previous studies by our group have revealed that loss of blood flow and nervous tissue damage to the ischemic area increased and reached the most at about 3 days after stroke in the rat models, then gradually recovered with recanalization and collateral revascularization 42,47 . The almost coincidence of the two time points indicates that RIPostC has a much prominent efficacy on severe injuries, more importantly, the measurement based on infarct size should be done in the early acute stage to more realistically reflect the therapeutic outcome.…”

“…reached the most at about 3 days after stroke in the rat models, then gradually recovered with recanalization and collateral revascularization. 42,47 The almost coincidence of the two time points…”

Target ischemic stroke model creation method using photoacoustic microscopy with simultaneous vessel monitoring and dynamic photothrombosis induction

“…These neuroimaging techniques are widely used in clinical settings to diagnose ischemia, but the static nature in both modalities, low sensitivity of CT, and long acquisition time in MRI might affect continuous monitoring of animal ischemic stroke model [23] , [24] , [25] . To overcome these shortcomings, optical coherence tomography has been implemented as a non-invasive method for the dynamic imaging of photothrombotic models [26] , [27] . However, it only provides morphology-based structural details, which is insufficient to obtain blood vessel-based dynamic information.…”