Non-invasive near-infrared fluorescence imaging of the neutrophil response in a mouse model of transient cerebral ischaemia

Vaas, Markus; Enzmann, Gaby; Perinat, Therese; Siler, Ulrich; Reichenbach, Janine; Licha, Kai; Kipar, Anja; Rudin, Markus; Engelhardt, Britta; Klohs, Jan

doi:10.1177/0271678x16676825

Cited by 18 publications

(19 citation statements)

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“…Neutrophils were isolated from the bone marrow of C57BL/6 mice and labeled for nearinfrared fluorescence (NIRF) imaging as previously described [29,30]. Isolated neutrophils were incubated in HBSS (0.2x10 6…”

Section: Adoptive Transfer Of Fluorescent-labeled Neutrophilsmentioning

confidence: 99%

“…We first asked if absence of ICAM-1 reduced the accumulation of CD45 + /Ly6G + neutrophils following tMCAO and reperfusion. We have previously shown that near-infrared fluorescence (NIRF) imaging provides a versatile tool to non-invasively study dynamics of neutrophil accumulation into the mouse brain after experimental cerebral ischemia [30]. Taking (Fig.…”

Section: Absence Of Icam-1 Does Not Affect Neutrophil Accumulation Inmentioning

confidence: 99%

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ICAM-1null C57BL/6 Mice Are Not Protected from Experimental Ischemic Stroke

Enzmann

Pavlidou

Vaas

et al. 2018

Transl. Stroke Res.

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Accumulation of neutrophils in the brain is a hallmark of cerebral ischemia and considered central in exacerbating tissue injury. Intercellular adhesion molecule (ICAM)-1 is upregulated on brain endothelial cells after ischemic stroke and considered pivotal in neutrophil recruitment as ICAM-1-deficient mouse lines were found protected from experimental stroke. Translation of therapeutic inhibition of ICAM-1 into the clinic however failed. This prompted us to investigate stroke pathogenesis in Icam1 C57BL/6 mutants, a true ICAM-1 mouse line. Performing transient middle cerebral artery occlusion, we found that absence of ICAM-1 did not ameliorate stroke pathology at acute time points after reperfusion. Near-infrared imaging showed comparable accumulation of neutrophils in the ischemic hemispheres of ICAM-1 and wild type C57BL/6 mice. We also isolated equal numbers of neutrophils from the ischemic brains of ICAM-1 and wild type C57BL/6 mice. Immunostaining of the brains showed neutrophils to equally accumulate in the leptomeninges and brain parenchymal vessels of ICAM-1 and wild type C57BL/6 mice. In addition, the lesion size was comparable in ICAM-1 and wild type mice. Our study demonstrates that absence of ICAM-1 neither inhibits cerebral ischemia-induced accumulation of neutrophils in the brain nor provides protection from ischemic stroke.

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Section: Adoptive Transfer Of Fluorescent-labeled Neutrophilsmentioning

confidence: 99%

Section: Absence Of Icam-1 Does Not Affect Neutrophil Accumulation Inmentioning

confidence: 99%

ICAM-1null C57BL/6 Mice Are Not Protected from Experimental Ischemic Stroke

Enzmann

Pavlidou

Vaas

et al. 2018

Transl. Stroke Res.

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“…For granulocyte labeling, nanoparticles must have appropriate physicochemical properties in relation to size, coating, zeta potential, concentration and stability; these proprieties contribute to efficient internalization, maintaining the cell viability of the granulocytes [75][76][77]. Efficient labeling with the contrast agent is important in granulocyte detection by different imaging techniques supporting various clinical applications, such as immune response, diagnosis and therapies [51,[78][79][80][81].…”

Section: Discussionmentioning

confidence: 99%

Methods of Granulocyte Isolation from Human Blood and Labeling with Multimodal Superparamagnetic Iron Oxide Nanoparticles

et al. 2020

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This in vitro study aimed to find the best method of granulocyte isolation for subsequent labeling with multimodal nanoparticles (magnetic and fluorescent properties) to enable detection by optical and magnetic resonance imaging (MRI) techniques. The granulocytes were obtained from venous blood samples from 12 healthy volunteers. To achieve high purity and yield, four different methods of granulocyte isolation were evaluated. The isolated granulocytes were labeled with multimodal superparamagnetic iron oxide nanoparticles (M-SPIONs) coated with dextran, and the iron load was evaluated qualitatively and quantitatively by MRI, near-infrared fluorescence (NIRF) and inductively coupled plasma mass spectrometry (ICP-MS). The best method of granulocyte isolation was Percoll with Ficoll, which showed 95.92% purity and 94% viability. After labeling with M-SPIONs, the granulocytes showed 98.0% purity with a yield of 3.5 × 10 6 cells/mL and more than 98.6% viability. The iron-loading value in the labeled granulocytes, as obtained by MRI, was 6.40 ± 0.18 pg/cell. Similar values were found with the ICP-MS and NIRF imaging techniques. Therefore, our study shows that it is possible to isolate granulocytes with high purity and yield and labeling with M-SPIONs provides a high internalized iron load and low toxicity to cells. Therefore, these M-SPION-labeled granulocytes could be a promising candidate for future use in inflammation/infection detection by optical and MRI techniques.Hard-to-reach or occult inflammation and infection processes are clinically challenging. Their clinical diagnoses involve biochemical and radiological examinations, but these methods can produce false negatives [11][12][13][14][15]. To determine the localization, extent and severity of inflammation, imaging techniques such as computed tomography (CT) and magnetic resonance imaging (MRI) can be performed but have limitations in the early stages of the disease, as they are dependent on morphological changes [16][17][18]. Accurate and early diagnosis of inflammation and infection helps reduce mortality and morbidity and increase drug treatment success [19][20][21].Proinflammatory effects help leukocytes migrate from the blood vessel to the site of injury, due to increased vascular permeability through stimulation by cytokines and interleukins. There is an initial accumulation of granulocytes, mainly neutrophils, in the inflamed area and later of lymphocytes and macrophages [22][23][24]. Granulocytes are the most abundant subset of leukocytes [25] and are produced in the bone marrow, originating from myeloid precursor cells and undergoing a maturing process before they are able to perform their functions, mainly phagocytosis [25,26]. They differ from other cells in that they have granules with proteolytic enzymes that fight microorganisms or other inflammatory agents [25,27]. Granulocytes are considered frontline cells in inflammation and infection processes [28]. In many cases, to detect inflammation/infection, it is necessary to label isolated granulocyte...

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“…However, this view has been challenged by a number of other studies 5 , 6 , 10 , 21 and later, also, a partly revised view of the original authors appeared. 7 …”

Section: Role Of Polymorphonuclear Neutrophils For Ischemic Reperfusimentioning

confidence: 99%

“…Postischemic neuroinflammation comprises the early (within minutes to hours poststroke) infiltration of the injured brain by polymorphonuclear neutrophils (PMNs) and monocytes/macrophages. 5 – 7 This is accompanied by the activation of microglia and expression of proinflammatory cytokines, adhesion molecules and integrins, which are supposed to contribute to ischemic reperfusion injury. 5 , 8 , 9 Massive infiltration of PMNs into ischemic brain tissue has recently been documented in human stroke patients.…”

Section: Introductionmentioning

confidence: 99%

Role of polymorphonuclear neutrophils in the reperfused ischemic brain: insights from cell-type-specific immunodepletion and fluorescence microscopy studies

Hermann

Kleinschnitz

Gunzer

2018

Ther Adv Neurol Disord

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Polymorphonuclear neutrophil granulocytes (PMNs) are part of the early post-ischemic immune response that orchestrates the removal of infarcted brain tissue. PMNs contribute to secondary brain injury in experimental stroke models. In human patients, high PMN-to-lymphocyte ratios in peripheral blood are predictive of poor stroke outcome. Following earlier studies indicating that the cerebral microvasculature forms an efficient barrier that impedes PMN brain entry even under conditions of ischemia, more recent studies combining intravital two-photon microscopy and ex vivo immunohistochemistry unequivocally demonstrated the accumulation of PMNs in the ischemic brain parenchyma. In the meantime, transgenic mouse lines, such as mice expressing Cre-recombinase and the red fluorescent reporter protein tdTomato under the highly granulocyte-specific locus for the gene Ly6G (so-called Catchup mice), have become available that allow study of dynamic interactions of PMNs with brain parenchymal cells. These mice will further help us understand how PMNs promote brain injury and disturb brain remodeling and plasticity.

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Non-invasive near-infrared fluorescence imaging of the neutrophil response in a mouse model of transient cerebral ischaemia

Cited by 18 publications

References 53 publications

ICAM-1null C57BL/6 Mice Are Not Protected from Experimental Ischemic Stroke

ICAM-1null C57BL/6 Mice Are Not Protected from Experimental Ischemic Stroke

Methods of Granulocyte Isolation from Human Blood and Labeling with Multimodal Superparamagnetic Iron Oxide Nanoparticles

Role of polymorphonuclear neutrophils in the reperfused ischemic brain: insights from cell-type-specific immunodepletion and fluorescence microscopy studies

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