Intravital imaging in spontaneously hypertensive stroke-prone rats-a pilot study

Abstract

BackgroundThere is growing evidence that endothelial failure and subsequent blood brain barrier (BBB) breakdown initiate cerebral small vessel disease (CSVD) pathology. In spontaneously hypertensive stroke-prone rats (SHRSP) endothelial damage is indicated by intraluminal accumulations of erythrocytes (erythrocyte thrombi) that are not observed with current magnetic resonance imaging techniques. Two-photon microscopy (2 PM) offers the potential for real-time direct detection of the small vasculature. Thus, within this pilot study we investigated the sensitivity of 2 PM to detect erythrocyte thrombi expressing initiating CSVD phenomena in vivo.MethodsEight SHRSP and 13 Wistar controls were used for in vivo imaging and subsequent histology with haematoxylin-eosin (HE). For 2 PM, cerebral blood vessels were labeled by fluorescent Dextran (70 kDa) applied intraorbitally. The correlation between vascular erythrocyte thrombi observed by 2 PM and HE-staining was assessed. Artificial surgical damage and parenchymal Dextran distribution were analyzed postmortem.ResultsDextran was distributed within the small vessel walls and co-localized with IgG.Artificial surgical damage was comparable between SHRSP and Wistar controls and mainly affected the small vasculature. In fewer than 20% of animals there was correlation between erythrocyte thrombi as observed with 2 PM and histologically with HE.ConclusionsContrary to our initial expectations, there was little agreement between intravital 2 PM imaging and histology for the detection of erythrocyte thrombi. Two-photon microscopy is a valuable technique that complements but does not replace the value of conventional histology.

Copolymer-1 Promotes Neurogenesis and Improves Functional Recovery after Acute Ischemic Stroke in Rats

“…Another recent study also called into question the effect of GA on the outcome of ischemic stroke. The publication by Kraft el al, also used a murine model (C57Bl/6) of 60 min tMCAo[ 15 ]. This study concluded that GA failed to protect from acute ischemic stroke.…”

“…This strategy has already shown to improve neurological recovery and decrease infarct volume 7 days after stroke in a rat model of transient middle cerebral artery occlusion (tMCAo) [ 4 ]. Although, it has recently been suggested that there is no benefit to using this therapy [ 14 , 15 ].…”

“…Our previous study observed a substantial benefit to treatment with Cop-1 after tMCAo in rats [ 4 ]. However, two separate studies have suggested that GA (Copaxone) is ineffective in treating murine models of MCAo [ 14 , 15 ]. This discrepancy in findings may be due to short follow-up period duration.…”

Gliovascular Disruption and Cognitive Deficits in a Mouse Model with Features of Small Vessel Disease

“…[12][13][14][15] Blood-brain barrier breakdown, evident by the leakage of immunoglobulin G and dextran, as well as the aggregation of platelets in the vicinity of vascular stases has also been observed. 16,17 Furthermore, ultrastructural changes to astrocytic endfeet in the spontaneously hypertensive stroke prone rat model are indicative of changes in the gliovasculature. 18 Models of chronic cerebral hypoperfusion reproduce diffuse white matter damage and behavioral impairments relevant to SVD.…”

Multiparametric Imaging of Organ System Interfaces

“…Intravital two-photon imaging of blood vessels using fluorescent dextran has visualized endothelial integrity after stroke 75–77 . The microscope’s lasers have also been applied to the rat cortex to occlude one specific vascular lumen in the presence of a circulating photosensitizer, thereby illustrating how single microinfarcts in a cortical column can cause debilitated performance on a whiskers-based behavioral task 78 .…”