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Group de Kleijn

Cardiovascular disease, extracellular vesicles and the immune system

Cardiovascular disease presents itself in many forms and gradations of pain, and proper and timely diagnosis can be challenging. Paradoxically, treatments and interventions to restore blood flow can also result in additional cardiac damage and complications. We focus on extracellular vesicles as a clinically beneficial factor for diagnosis and prognosis of cardiovascular disease. In addition, we’re establishing several large animal models that closely mimic human cardiovascular/atherosclerotic conditions in order to accelerate translation of our scientific findings into the clinic.  
 

From garbage bins to therapy

Extracellular vesicles were formerly thought of as the garbage bins of the cell, sequestering waste and expelling it from the cell. We now have reason to think the complete opposite, that these versatile pouches may contain proteins involved in cellular communication and thus, in many cellular processes.
 
Before returning to Utrecht in June 2016, I worked for four years in Singapore and investigated the use of extracellular vesicles for therapy and as a biomarker source. We discovered that mesenchymal stem cells produce extracellular vesicles with proteins that may reduce ischemic reperfusion injury. We’re now using the conditioned medium from these cells in pig models in Utrecht in order to validate and translate our findings in a preclinical setting.
 
We also set up a biobank where we collected patient blood samples and clinical data in both Utrecht and Singapore. Because extracellular vesicles are present in the plasma of blood, we’re researching whether these vesicles can be used as biomarkers for diagnosis and prognosis of patients with cardiovascular disease.
 

Diagnosis from a drop of blood

With an eye to therapy, we’ve conducted a study to figure out how to differentiate between patients with stable and unstable angina (chest pain); unstable angina is usually unexpected, severe and should be treated as an emergency. Currently, about 50% of patients who are sent home after a hospital visit, return within a year because of unstable angina that was undetected during their first visit.
 
We’ve collected blood samples and clinical data from a Stable and Unstable Angina patient cohorts and conducted a proteomics analysis on the extracellular vesicles in the blood samples. To our surprise, we discovered that we could diagnose stable or unstable angina based on a drop of blood. In addition, we could also discriminate the negative subset of patients – patients who could be sent home without intervention.
 
Interestingly, we did not look at markers of ischemic damage but rather at markers that indicated an coagulation and immune response. We saw markers of inflammation and coagulation and determined that the extracellular vesicles were the source of these markers. For patients with unstable angina, this could be detected within hours of the onset of symptoms. We will further investigate this our 2 large cohorts in order to be able to diagnose these patients early for stable or unstable angina. This is done in collaboration with a 3rd large AMC cohort in our CVON funded program.
 

Developing more human-like models for heart disease

A few years ago, we established the pig model of myocardial infarction (heart attack). Because pigs develop human-like atherosclerosis and plaques, we’re working on setting up transgenic pig models as well. Transgenic pigs are missing a particular gene that is important for example, in controlling cholesterol levels. We’d like to also use these pig models to improve the implementation of endovascular device therapy. Testing an intervention on a healthy blood vessel is a good start, but it’s much different when the vessel is partially blocked by plaque. And finally, we’re interested in developing more human-like carotid and aortic aneurysm models in the pig.
 

AtheroExpress Biobank

We have the largest carotid artery plaque biobank in the word with over 3000 samples. My group focuses on patients with severe atherosclerosis, most of whom have had a cardiovascular event either in the brain, heart or elsewhere in the body, like the legs. Next to atherosclerotic plaques, we’re analyzing extracellular vesicles to see if we can predict which patients are at risk of a particular type of event. This biobank is a wealth of information, and we’re just beginning to extract data that can help us refine our research questions. For example, we’re seeing that in the general population, cardiovascular events are decreasing however, not for diabetic patients. Why is this, what other factors are involved and can we use extracellular vesicles to advance our understanding?

Principal Investigator:

Dominique de Kleijn PhD

Intervention cardiologist:  

Leo Timmers MD PhD   
 

Research technician:

Joelle van Bennekom MSc 

PhD students:

Mirthe Dekker MD
Constance van Laar MD
Max Silvis MD
Nathalie Timmerman MD
Farahnaz Waissi MD