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Introduction: RNA-based therapies of the myocardium offer a range of therapeutic opportunities for conditions in which gene transfer needs to be highly effective but transient, such as cardiac regeneration and cardiac gene editing. MicroRNA and mRNA gene transfer can be achieved by intramyocardial injection of lipofectamine-based products, but these are not amenable to clinical translation. In contrast, lipid nanoparticles (LNPs) have already reached clinical approval for siRNA administration with patisiran in 2018 and for mRNA delivery with the COVID-19 vaccines by Pfizer-BioNTech and Moderna in 2020. Objective(s): We wanted to develop Stable Nucleic Acid Lipid nanoParticles (SNALPs) for the effective myocardial delivery of microRNAs and mRNAs. Material(s) and Method(s): We generated various SNALP formulations via ethanol injection method, carrying the pro-regenerative microRNA-199a-3p or GFP mRNA and assessed their transfection efficiency by high-content microscopy (stimulation of EdU incorporation and GFP fluorescence respectively) in neonatal rat and mouse cardiomyocytes and upon intramyocardial injection in mice. Result(s): We started by investigating the inclusion of different ionisable lipids, helper lipids and PEG-lipids in the nanoparticle shell. Then, we systematically tested the effect of varying the molar ratios of each of the constituents to improve transfection. After optimising the formulations in vitro, we tested the same in mice through direct intramyocardial injection. Conclusion(s): The results obtained highlight the applicability of the LNP technology for efficient delivery of mRNA and microRNA into cardiomyocytes. Copyright © 2022
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BACKGROUND AND PURPOSE: Ischaemic stroke has been described in association with COVID-19. Several pathophysiological mechanisms have been suggested, i.e. prothrombotic state, cardiac injury etc. It was sought to assess the potential association between ischaemic stroke associated with SARS-CoV-2 infection and underlying atherosclerotic lesions. METHODS: A retrospective analysis of stroke related to large vessel occlusion was conducted amongst patients with SARS-CoV-2 infection and underlying mild atherosclerotic disease, between 19 March and 19 April 2020 in six different stroke centers in the Île-de France area, France. RESULTS: The median age was 52 years, median body mass index was 29.5 kg/m2 . All patients displayed previous vascular risk factors such as high blood pressure, diabetes, dyslipidemia or body mass index > 25. The delay between the first respiratory symptoms of COVID-19 and stroke was 11.5 days. At baseline, all had tandem occlusions, i.e. intracerebral and extracerebral thrombus assessed with computed tomography or magnetic resonance imaging. Cases displayed a large thrombus in the cervical carotid artery with underlying mild non-stenosing atheroma, after an etiological workup based on angio-computed tomography or magnetic resonance imaging and/or cervical echography. CONCLUSION: Our study should alert clinicians to scrutinize any new onset of ischaemic stroke during COVID-19 infection, mainly in patients with vascular risk factors or underlying atherosclerotic lesions.