Microclots and Neutrophil Activation as Potential Indicators for Stroke Risk and Reperfusion Failure

Official title

Micro-clots and Neutrophil Activation as Potential Indicators for Stroke Risk and Reperfusion Failure The CLOTSAFE - Study (Micro-CLOTs, Stroke Risk, Activated Neutrophils, Reperfusion FailurE)

Overview

Stroke remains a major health burden worldwide. Many patients are severely disabled and stay in need of care. Mechanical thrombectomy has dramatically improved outcomes for stroke patients with large vessel occlusions, yet 40-50% of patients with successful recanalization remain severely disabled despite successful recanalization, a scenario called "futile recanalization". One of the causes for this lack of treatment effect is capillary obstruction, or "no reflow", potentially resulting from activated neutrophils and micrometer-sized blood clots. To address this issue, we employ digital holotomographic and atomic force microscopy to investigate the structural and chemical characteristics of blood and clot material in stroke patients and individuals at high risk of developing a stroke. Our study elucidates the association of activated neutrophils and microclots with stroke risk, and may be associated with clinical outcome, stroke ethology and reperfusion failure in patients with stroke. Leveraging label-free microscopy tools, could potentially lead to the discovery of new biomarkers for individualized stroke treatment and prevention, ultimately offering rapid identification of at risk patients and improving clinical outcomes

Detailed description

Background:

Stroke remains a major health burden worldwide. Many patients are severely disabled and stay in need of care. Since introducing mechanical thrombectomy as a therapeutic option, clinical outcome has drastically improved over the last few years. However, despite successful macrovascular reperfusion (recanalization), patients with stroke still have a significant risk (about 40-50%) of remaining severely disabled, a scenario called "futile recanalization". One of the causes for this lack of treatment effect is capillary obstruction, or "no reflow", potentially resulting from activated neutrophils and micrometer-sized blood clots. Previous work in rodent stroke models demonstrated that removal of these capillary stalls indeed improves reperfusion and recovery after stroke. However, there is a lack of knowledge regarding the role of neutrophils or microclots in patients with stroke, and their potential to indicate reperfusion failure.

Aim:

The goal of our study is to search for activated neutrophils and microclots in peripheral blood samples from patients with stroke. We anticipate that neutrophil and microclot characteristics such as size, shape, or surface structure may indicate stroke risk, and may be associated with clinical outcome, stroke ethology and reperfusion failure in patients with stroke. Our goal is to improve the prediction of stroke risk and treatment success.

Methodology:

We plan to prospectively include 500 patients with acute and chronic stroke, as well as a control group. We have teamed up with biophysicists from the Swiss Federal Laboratories for Materials Science (EMPA) using the novel microscopic tools 3D rotational digital tomography (DHTM) to achieve an unprecedented resolution of less than 10 μm for detection of altered neutrophil phenotypes and microclots in peripheral blood samples. Furthermore, in patients undergoing mechanical thrombectomy, retrieved clots will be analyzed with high-density micro-computertomography (micro-CT). Quantity, mechanical and structural properties of microclots and neutrophils will be correlated with risk of reperfusion failure, stroke recurrence and clinical recovery. Analyses of clots from patients with large vessel occlusion will be used to derive risk of reperfusion failure along with most likely source of the clot, and thus, most likely stroke etiology.

Potential Significance:

Current diagnostic tools are insufficient to predict response to treatment, clot source or stroke recurrence risk. Our project has the potential to discover new, clinically applicable biomarkers identifying patients at risk within a few hours, enabling individualized stroke treatment and prevention.

Interventions

• Diagnostic test 3D rotational digital tomography
  DHTM is label-free and records the phase shift of low-energy light passing through the specimen on a transparent surface with minimal perturbation. DHTM measures the refractive index (RI) and computes the refractive index gradient (RIG), unveiling optical heterogeneity in cells. We will analyze blood samples for the detection of altered neutrophil phenotypes and microclots.
• Diagnostic test Atomic Force Microscopy
  The atomic force microscope (AFM) is widely used in materials science and has found many applications in biological sciences but has been limited in use in vision science. The AFM can be used to image the topography of soft biological materials in their native environments. We will analyze blood samples for the detection of altered neutrophil phenotypes and microclots
• Diagnostic test Micro-Computertomography
  Micro-CT is a 3D imaging technique utilizing X-rays to see inside an object, slice by slice. Micro-CT, also called microtomography or micro computed tomography, is similar to hospital CT or "CAT" scan imaging but on a small scale with greatly increased resolution. Samples can be imaged with pixel sizes as small as 100 nanometers and objects can be scanned as large as 200 millimeters in diameter. We will use micro-CT to analyze blood clots from patients with large vessel occlusion.

Primary outcome measures

• Quantification and characterization of microclots [Time frame: First Visit/Admission and patients with acute stroke after 24 hours, 3 months and 1 year]
• Quantification and characterization of neutrophils [Time frame: First Visit/Admission and patients with acute stroke after 24 hours, 3 months and 1 year]
• Evaluation of reperfusion failure in patients with large vessel occlusion and mechanical thrombectomy [Time frame: <24 hours in patients with mechanical thrombectomy]

Secondary outcome measures (5)

• Change in National Institute of Health Score Scale (NIHSS) [Time frame: First Visit/Admission and patients with acute stroke after 24 hours, 3 months and 1 year]
• Degree of disability or dependence assessed by the modified ranking scale (mRS) [Time frame: First Visit/Admission and patients with acute stroke after 24 hours, 3 months and 1 year]
• Assessment Quality of Life using European Quality of Life 5 Dimensions 5 Level Version (EQ-5D-5L) [Time frame: 365 days]
• Incidence of new cardiovascular disease [Time frame: 365 days]
• All-cause mortality [Time frame: 365 days]

Eligibility criteria

Inclusion criteria

Patients without acute stroke CS or CSG

• No previous stroke or previous stroke ≥ 1 year ago
• Signed informed consent

Patients with acute stroke (AS-noTx, AS-IVT, AS-MT):

• Patients admitted with high suspicion of acute ischemic stroke
• Time of onset of stroke symptoms ≤ 12 hours
• Consent according to the regulations of research in an emergency situation
• Ischemic stroke later confirmed

Exclusion criteria

All groups:

• Pregnancy
• Age under 18 years

Acute Stroke no Therapy

• Acute treatment with IVT or with MT

Acute Stroke IVT-Group • Acute treatment with MT or without IVT

Acute Stroke MT-Group

• Acute treatment without MT

Criteria are shown verbatim from the registry (in English). Final eligibility is always assessed by the study center.

Healthy volunteers: Yes

Study design

Observational model

Cohort

Study locations

Switzerland · 1 center

• University Hospital Zurich — Zurich

Identifiers

NCT: NCT06530927 · 2024-01353

Primary sources (government registries)

• ClinicalTrials.gov (US NIH)

View this study on ClinicalTrials.gov ↗