Cardiovascular diseases at the early stages typically include alterations of the aorta, which is the largest artery connected to the heart and carries oxygenated blood towards the whole body. Indeed, each heartbeat generates mechanical stress and elevated pressures on the aortic wall that can be amplified by highly prevalent conditions such as hypertension, diabetes or obesity, and modify aortic geometry but also related wall elasticity and inner blood flow hemodynamics. However, to date, diagnosis, severity assessment and surgery decision-making in patients with aortic disease such as aneurysm are based on a simple geometrical measurement of aortic diameter from 2D medical images only, while rupture can still occur below recommended diameter thresholds. Our hypothesis is that exhaustive overview of aortic changes: function, wall tissue and blood flow hemodynamics, beyond and complementarily to geometry, would provide personalized and more accurate risk prediction, and thus better suited, individual patient management. In that setting, MRI is a unique opportunity to manage patients who can inherit such disease from their youngest age and require frequent follow-up: MRI provides non-invasive, radiation- and contrast agent-free evaluation of anatomy, function, tissue composition and hemodynamics, simultaneously within a 3D volume. However, MRI is associated with lengthy exams, high costs and long waiting lists. On the other hand, reading of the large and complex MRI image datasets can be challenging and tedious. The present proposal builds on our aim to accelerate aortic MRI, in terms of both image acquisition and analysis, in order to improve patient comfort as well as optimize radiologist and technologist time. More specifically, the objectives of MAGNOLIA are: 1) to design a software providing automated, reproducible, comprehensive and fast measurement of quantitative biomarkers of thoracic aortic 3D morphology, wall stiffness, hemodynamics and tissue characterization from MRI images, 2) to test recently available novel MRI techniques providing superior image quality or new information compared to current imaging methods. Our methodology will be trained on images acquired within the ongoing SEQUOIA protocol in healthy volunteers, and we will setup a prospective study, again in healthy volunteers, in order to evaluate feasibility and performances of the aforementioned latest MRI techniques. In the long term, such research will define the best compromise between scan and analysis time, and MRI diagnostic and prognostic value in aortic disease. MAGNOLIA will be led in Paris (Laboratory of Biomedical Imaging, Sorbonne University and Pitié-Salpêtrière hospital) by a young researcher who will collaborate with her coworkers to bring together complementary skills in MRI, image processing, artificial intelligence, software development and clinical expertise in radiology and cardiology. MAGNOLIA open-source, free software as well as tested and optimized MRI techniques will be used in future local MRI research studies, but also at the European and international levels through sharing with scientific community in order to favor MRI multicentric efforts and standardization. Findings will be reported in specialized journals and conferences, but communication with society is also planned.

Intraosseous blood circulation is thought to have a key role in bone growth and remodeling, in fracture healing and in the development of bone disorders. However it is rarely considered in the clinical practice because of the absence of a suitable technique for its in vivo evaluation in humans. Inadequate bone vascularity has been associated with bone disorders (e.g. osteoporosis, osteonecrosis) in animal models, most often with invasive techniques. However evidence in humans is very sparse. There exists no gold standard method for the measurement of intraosseous blood flow in humans. Magnetic resonance imaging (MRI) has been proposed to assess the perfusion of marrow only. Positron emission tomography (PET) and near-infrared optical methods have poor spatial resolution; therefore they do not allow the clear distinction between blood flow in cortical bone, in marrow and in soft tissues surrounding bone. On the other hand, ultrasonography offers higher spatial resolution and has the potential to investigate deeper tissues compared to optical techniques. We hypothesize that the development of intraosseous functional ultrasonography will enable the non-invasive characterization of intraosseous blood circulation, i.e. blood flow in the cortical bone tissue and in the bone marrow. Our project is organized in four tasks. A first task will be to develop and validate transmission pulsing schemes and methods of image reconstruction in order to relax two major assumptions made in conventional ultrasonography, namely the speed of sound in the human body is assumed to be uniform and the multiple reflections experienced by ultrasound waves in the human body are neglected. The reconstruction of an anatomical image of bone will be performed by an adaptation of time-tested seismic imaging methods and an adaptation of automatic sound speed selection methods developed for ultrasonography in soft tissues or seismic imaging. Ultrasound images of the forearm of healthy volunteers will be validated with gold standard anatomy obtained by high-resolution x-ray computed tomography (CT). Capitalizing on the results of task 1, a second task will aim to develop transmission pulsing schemes and signal processing for intraosseous functional ultrasonography by adapting recent advances in ultrafast ultrasonic assessment of blood flow in soft tissues. The sensitivity of those methods to characterize intraosseous blood flow will be tested in healthy volunteers. The third task will study the added value of using an ultrasound contrast agent (routinely used for conventional contrast-enhanced ultrasound imaging) by developing specific transmission pulsing schemes and signal processing. An injection of contrast agent enhances the echogenicity of blood since contrast agent microbubbles reflect ultrasound much more efficiently than red blood cells. The contrast agent signal can then be used as a surrogate for the blood signal. In this way, we hope to improve the sensitivity of the methods developed in task 2. The goal of the fourth task will be to evaluate the sensitivity of intraosseous functional ultrasonography to physiological variations of intraosseous blood flow in the tibia of healthy volunteers that change position (sitting - head-down tilt), and in patients with bone fracture at the radius or at the tibia. This scientific project aims to develop and validate a non-invasive and relatively inexpensive way of assessing intraosseous blood circulation in vivo in humans, which is currently unavailable. The success of this work will help to better understand bone physiopathology. It may provide in the long term a clinical tool that misses today, and help in the early diagnosis of bone diseases or the monitoring of bone healing. Besides it will broaden the range of clinical uses of ultrasonography, which fails to image bone so far.

Heart failure (HF) is a major life-threatening disease affecting more than 1 million people in France and is associated with a high mortality rate. While the etiology of HF is diverse (coronary artery disease, myocardial infarction, hypertension, aging, etc.), they are all associated with aberrant myocardial tissue remodeling and cardiac fibrosis. The principal feature of cardiac fibrosis is an excessive accumulation of extracellular matrix (ECM) which reduces tissue compliance, increases myocardial stiffness, leads to mechanical and electrical dysfunction and eventually to heart failure. However, there is currently no effective anti-fibrotic therapeutic strategy that could complement the current therapies for HF. To achieve an anti-fibrotic therapy, a better understanding of the mechanisms contributing to cardiac fibrosis is needed. Activated cardiac fibroblasts are essential for the production of ECM proteins however, recent studies have established that cardiac fibroblasts represent a very heterogeneous cell population. The exact nature of activated fibroblasts and consequently the sources of cardiac fibrosis remains poorly understood. In this research project, we propose to evaluate the role in cardiac fibrosis of a novel population of cardiac cells that reside in the myocardium and that we have demonstrated recently to be fibrogenic in response to an ischemic injury. This population has been identified based upon the expression of the pan-stem cell marker, Pw1/Peg3 (referred hereafter as PW1). In normal hearts, PW1 is expressed in the interstitial cells of the heart and is not expressed in cardiac myocytes. Cardiac PW1+ cells were isolated and displayed both colony forming capacity and cell fate plasticity in vitro to form mesenchymal-lineage cells (adipocytes, osteoblasts, chondrocytes), as well as fibroblasts and smooth muscle cells but not cardiomyocytes. In ischemic hearts, the number of PW1+ cells markedly increased and we demonstrated that a significant proportion (~22%) of fibroblasts were derived from PW1 expressing cells. Based on this first study and on additional preliminary results, we propose that cardiac PW1+ cells contribute to cardiac fibrosis (i) by directly giving rise to fibroblasts thus representing a source of additional ECM and (ii) by orchestrating a microenvironment that further favors resident fibroblasts activation. We therefore propose to further elucidate the role of cardiac PW1+ cells in myocardial fibrogenesis in two different models of cardiac diseases (cardiac ischemia and pharmacologically-induced pressure overload) in genetically-modified mice. We will use high field MRI to non-invasively detect and quantify diffuse interstitial fibrosis processes. The project will be organized in 4 specific tasks with the following aims: (1) to study whether genetic ablation of cardiac PW1+ cells limits fibrotic scar tissue and improves cardiac function, (2) to develop an innovative anti-fibrotic strategy targeting ?V-containing integrins expressed at the surface of cardiac PW1+ cells (3) to define the molecular pathways underlying the fibrogenic cell fate potential of cardiac PW1+ cells and (4) to characterize the cardiac PW1+ cells microenvironment and cellular interactions with fibroblasts. The consortium includes two different partners with complementary skills and expertise: one partner has extensive expertise in cardiac diseases, biology and pharmacology of heart failure, and stem cell biology and has primarily described PW1/Peg3 cells and developed unique tools to investigate the biological function of these cells; one partner has expertise in cardiac imaging with high-field MRI and has developed innovative computing tools to image and quantify myocardial dense vs. interstitial fibrosis. This project has a great potential for fundamental and translational discovery and brings promising and innovative perspectives for the treatment of cardiac fibrosis.

Stroke is one of the main causes of chronic disability in the world. Patients recover spontaneously, but most often retain after-effects that can be reduced by rapid implementation of appropriate rehabilitation. Optimizing rehabilitation to maximize autonomy is therefore a major public health issue. One of the means is to develop devices allowing an optimal and early rehabilitation. The objective of iSMRehab is to develop and validate medical devices allowing an early sensorimotor rehabilitation to (re)activate the sensorimotor neural networks and recover the altered motor functions. Functional recovery depends on the ability of the central nervous system to adapt and reorganize itself after an injury (neuroplasticity). The Vibramoov system proposes an innovative sensorimotor rehabilitation, unique in the world, based on muscle-tendon vibration programs whose frequency, amplitude and sequence make it possible to reproduce the sensory inputs during complex intentional movements such as walking, to activate the corresponding sensorimotor networks and to produce an illusion of this movement. However, the level of evidence for the efficacy of Vibramoov, like all currently recommended rehabilitative practices (manual or instrumented), is overall low due to the lack of randomized controlled trials and because neuroplasticity is not evaluated. Objective 1 is to provide experimental evidence (electrophysiology, neuroimaging) of neuroplasticity by Vibramoov and its neuroprotective effect in post-stroke patients in the sub-acute phase i.e., when recovery is optimal. Experimental data will be correlated with clinically assessed motor performances (neurological assessment, functional tests and scales) and their modifications during rehabilitation. Objective 2 is to bring technological developments to the current Vibramoov system by synchronizing functional vibrations with stimulations of other sensory modalities (touch, vision and hearing) in virtual reality. Multisensory immersion in an enriched environment is indeed known to improve post-stroke functional recovery but no device exists to date despite the potential interest of immersing patients with no or little ability, to move in a virtual environment t. Finally, objective 3 is to implement a proof-of-concept study on naive and expert participants to evaluate the new device (acceptability, appetence, usability). We will take advantage of this study to also evaluate brain activity with ecological electrophysiological recordings in order to compare the effectiveness of the current device and the new device on brain integrative processes. The expected results are objective evidence of the neuroplasticity and neuroprotective effect of the Vibramoov and of a new, even more innovative therapeutic device, addressing early rehabilitation needs. The project is focused on gait disorders after a stroke because i) gait recovery is a major issue in rehabilitation as stroke sequelae greatly limit autonomy and socio-professional links and ii) stroke is the main cause of chronic disability. However, the devices will allow to generate programs mimicking other movements involving the lower and/or upper limbs. Moreover, the therapy can be proposed to all patients presenting a motor handicap, whether it is linked to neurological lesions of traumatic, vascular, neurodegenerative or viral origin (COVID), or consecutive to an orthopedic trauma requiring immobilization; patients for whom a sensorimotor rehabilitation is required for the recovery and/or the maintenance of the motor functions.

Since the 1990’s, recombinant tissue plasminogen activator (rt-PA) has been the most effective and sole clinically approved drug to induce vessel recanalization in acute thrombotic events such as ischemic stroke. However, due to its short half-life, high doses of rt-PA have to be injected which generate a cascade of events in the circulation leading to serious side effects such as bleeding complications, modulation of the permeability of the blood-brain-barrier and intracranial hemorrhages. The number of patients that could benefit from rt-PA based treatment is significantly limited due to all of these safety-related restrictions. It is estimated that less than 5% of the patients receive a rt-PA treatment and, out of them, 60% either suffer permanent disabilities or die in the case of acute ischemic strokes. So, there is still a dire need for safe and noninvasive treatments. The development of new formulation of thrombolytics gains more and more interest to open new perspectives for clinical thrombolytic therapy with the aim to reduce the dose and, therefore, hemorrhagic side effects. In addition to the development of new fibrinolytic agents, a promising strategy based on Nanomedicine is propose here. The aim of FightClot is to develop innovative medical devices for the visualization and the targeted treatment of thrombotic diseases and particularly for stroke. Partner 1 (INSERM U1148) has previously demonstrated that fucoidan, an abundant and cost-effective marine polysaccharide with sulfated chains, exhibits a high affinity for P-selectin in vitro and in vivo which is overexpressed at the surface of endothelial cells and activated platelets during thrombotic diseases. The Laboratory developed micro- and nano-carriers functionalized with fucoidan and loaded with rt-PA to achieved the molecular diagnosis and targeted therapy in vitro and in vivo of cardiovascular diseases. To promote the targeted treatment of thrombotic diseases, Partner 1 will synthesize, thanks to these preliminary data, echogenic functionalized polymer microbubbles loaded with the new fibrinolytic drug produced by Partner 2 and able to be visualized and destroyed (sonoporation) by the ultrafast ultrasound sequences developed by Partner 3 (UMR 7371). To answer the safety-related restrictions of the clinical use of rt-PA, Partner 2 (INSERM U1237) will develop new fibrinolytic drugs with the production of an original double mutant of human tissue plasminogen activators displaying a fibrinolytic activity similar to that of the wilt type t-PA but without neurotoxicity which will be loaded onto microbubbles. To enhance thrombolysis Partner 3, which has a huge experience in high resolved, functional and vascular imaging using ultrafast ultrasound apparatus, along with ultrasonic drug-delivery, has developed two techniques to highlight microbubbles i) flowing microbubbles can be separated from tissue with spatio-temporal filters, a technique that is used for ultrasound localization microscopy of the brain, ii) stationary or targeted microbubbles can be separated using ultrafast radial modulation imaging. Finally, to validate the thrombolysis efficacy of the echogenic functionalized microbubbles, Partner 2 will use two preclinical stroke models in mice with in situ clot formation which mimic the main etiologies of the ischemic stroke in clinic. One done by local application of FeCl3 to induce platelets rich and tPA-resistant clots, and the other by local infusion of thrombin to generate fibrin rich and tPA–sensitive clots. FightClot is a disruptive project on ultrasound molecular diagnosis and targeted therapy of thrombotic diseases to answer the unmet medical need of acute clinical events treatment. By starting with preliminary results achieved by the Partners, FightClot project should succeed in to reach the endpoints proposed at ANR.