A major breakthrough in stroke research

“ We have developed a new contrast agent that allows us to reveal the presence of microthrombi in magnetic resonance imaging ,” explains Dr. Thomas Bonnard, INSERM at the Blood and Brain Institute ( PhIND laboratory, INSERM U-1237 ).

Thrombi are clots that obstruct blood vessels , block blood flow to the brain, and cause a stroke .

stroke patient is brought to the hospital by emergency services, doctors will try to obtain brain imaging as quickly as possible using a CT scan or magnetic resonance imaging ( MRI ). With current technologies, it is possible to observe the brain's blood vessels and thus understand where the blockage is located, which is already extremely useful for choosing the best intervention. It is also possible to identify the larger thrombi responsible for these blockages. However, in some cases, there are small fragments of thrombi scattered throughout the patient's brain, called microthrombi, which are impossible to observe, even with the latest imaging technologies .

This is where the contrast agent invented by Dr. Charlène Jacqmarcq and Dr. Thomas Bonnard . They developed magnetic microparticles designed to be injected into the bloodstream and capable of binding to microthrombi. The magnetic properties of these microparticles produce a signal on MRI , thus enabling their diagnosis. With this new contrast agent, called PHySIOMIC, microthrombi can be visualized on MRI .

The challenge was complex, and the synthesis of this contrast agent required several years of development and advanced expertise in chemistry and materials engineering. It notably includes an innovative organic material that uses dopamine as a raw material. Dopamine is a neurotransmitter that influences our brain. Here, this same molecule is used in a test tube to create a material called polydopamine. This material has a black, jelly-like consistency, is completely biodegradable, and possesses unique properties in terms of its interaction with metals. The research of Dr. Charlène Jacqmarcq and Dr. Thomas Bonnard established that this polydopamine has a specific affinity for microthrombi. To synthesize their contrast agent PHySIOMIC, they combined this polydopamine with magnetic materials that exhibit a signal in MRI .

All the work published here was covered by public funding administered by the French National Research Agency (ANR), including the PHySIOMIC young researcher funding.

Dr. Maxime Gauberti of Caen Normandy University Hospital, author of the study, designed some of the radiology experiments as part of his clinical research year at INSERM -Bettencourt. A contract has also been signed with CSL-Behring, Australia's largest pharmaceutical company.

“Today, the next steps in this project are on hold until the patent is filed,” explains Dr. Bonnard, who has just returned from a year-long placement as part of a collaboration with an Australian laboratory.