An exploratory investigation of brain collateral circulation plasticity after cerebral ischemia in two experimental C57BL/6 mouse models

Abstract

Brain collateral circulation is an essential compensatory mechanism in response to acute brain ischemia. To study the temporal evolution of brain macro and microcollateral recruitment and their reciprocal interactions in response to different ischemic conditions, we applied a combination of complementary techniques (T2-weighted magnetic resonance imaging [MRI], time of flight [TOF] angiography [MRA], cerebral blood flow [CBF] imaging and histology) in two different mouse models. Hypoperfusion was either induced by permanent bilateral common carotid artery stenosis (BCCAS) or 60-min transient unilateral middle cerebral artery occlusion (MCAO). In both models, collateralization is a very dynamic phenomenon with a global effect affecting both hemispheres. Patency of ipsilateral posterior communicating artery (PcomA) represents the main variable survival mechanism and the main determinant of stroke lesion volume and recovery in MCAO, whereas the promptness of external carotid artery retrograde flow recruitment together with PcomA patency, critically influence survival, brain ischemic lesion volume and retinopathy in BCCAS mice. Finally, different ischemic gradients shape microcollateral density and size.

Investigating APOE, APP-Aβ metabolism genes and Alzheimer’s disease GWAS hits in brain small vessel ischemic disease

“…22 male C57BL/6 J mice, purchased at 8 weeks of age, Charles River, Germany, were housed in a temperature (22 ± 2 °C), humidity (55 ± 10%), and light (12/12-hour light/dark cycle) controlled environment. As previously described 31 , the animals underwent hypoperfusion between 9 and 13 weeks of age. Hypoperfusion was achieved by bilateral common carotid artery stenosis (BCCAS).…”

“…To study APP-Aβ metabolism and LOAD GWAS genes during brain acute and subacute hypoperfusion, we used a mouse model of vascular dementia, where brain hypoperfusion is achieved through the placement of microcoils around both common carotid arteries leading to a ≈ 70% stenosis (bilateral common carotid stenosis [BCCAS] mouse model) 32 . The main features of the model during severe acute and subacute hypoperfusion have been already described 31 .…”

“…The staining protocol for the mouse brain histological sections has been already described 31 . Briefly, for the 20 mice subjected to gene-expression study (8 BCCAS mice, 8 Sham mice and 4 naive mice) one hemisphere was used for RNA sequencing and the contralateral for histology.…”

“…Exome-enriched libraries were PCR-amplified, and then DNA hybridized to paired-end flow cells using a cBot (Illumina, Inc.) cluster generation system. Samples were sequenced on the Illumina HiSeq ™ 3000/4000 using 2×76 paired end reads cycles.We used exome sequencing data to identify common (minor allele frequency [MAF] > 3%), rare (MAF < 3%), and very rare (MAF < 1%) coding variants in 31…”

A Semiquantitative Non-invasive Measurement of PcomA Patency in C57BL/6 Mice Explains Variance in Ischemic Brain Damage in Filament MCAo

“…For Evans Blue perfusion and vessel fixation, mice were deeply anaesthetized with ketamine and xylazine at the conclusion of the experiment and perfused through the heart with physiological saline followed by 4% paraformaldehyde, Termofisher, W32465, 3% Gelatin (Sigma-Aldrich, G1890), 1% low melting agarose (Sigma Aldrich A4018) and 0.1% Evans Blue (Sigma Aldrich E2129) as described previously (Foddis et al, 2019).…”