Genetically Engineered MRI-Trackable Extracellular Vesicles as SARS-CoV-2 Mimetics for Mapping ACE2 Binding In Vivo

Abstract

The elucidation of viral-receptor interactions and an understanding of virus-spreading mechanisms are of great importance, particularly in the era of a pandemic. Indeed, advances in computational chemistry, synthetic biology, and protein engineering have allowed precise prediction and characterization of such interactions. Nevertheless, the hazards of the infectiousness of viruses, their rapid mutagenesis, and the need to study viral-receptor interactions in a complex in vivo setup call for further developments. Here, we show the development of biocompatible genetically engineered extracellular vesicles (EVs) that display the receptor binding domain (RBD) of SARS-CoV-2 on their surface as coronavirus mimetics (EVs RBD ). Loading EVs RBD with iron oxide nanoparticles makes them MRI-visible and, thus, allows mapping of the binding of RBD to ACE2 receptors noninvasively in live subjects. Moreover, we show that EVs RBD can be modified to display mutants of the RBD of SARS-CoV-2, allowing rapid screening of currently raised or predicted variants of the virus. The proposed platform thus shows relevance and cruciality in the examination of quickly evolving pathogenic viruses in an adjustable, fast, and safe manner. Relying on MRI for visualization, the presented approach could be considered in the future to map ligand-receptor binding events in deep tissues, which are not accessible to luminescence-based imaging.

Theranostic extracellular vesicles: a concise review of current imaging technologies and labeling strategies

“…This strategy has been used in a few studies and gained some success [ 103 , 104 ] . Recently, this method was utilized for the MRI detection of the binding of receptor binding domain (RBD) of SARS-CoV-2 to ACE2 receptors using SPION-loaded genetically engineered EVs that display the receptor binding domain (RBD) of SARS-CoV-2 on their surface as coronavirus mimetics (EVsRBD) [ 105 ] . The inherent drawback of this approach is the low labeling efficiency.…”

“…In a later study by Busato [102] , the parental cells were first incubated with adipose stem cells (ASCs) to include SPIONs, and the secreted ASC-EVs were subsequently collected, in which a portion of EVs contained SPIONs. This strategy has been used in a few studies and gained some success [103,104] . Recently, this method was utilized for the MRI detection of the binding of receptor binding domain (RBD) of SARS-CoV-2 to ACE2 receptors using SPION-loaded genetically engineered EVs that display the receptor binding domain (RBD) of SARS-CoV-2 on their surface as coronavirus mimetics (EVsRBD) [105] .…”

Proteolytic Vesicles Derived from Salmonella enterica Serovar Typhimurium-Infected Macrophages: Enhancing MMP-9-Mediated Invasion and EV Accumulation

“…After 24 h the mice were perfused and fixed in 4% PFA, and their brains, lungs, hearts, livers, spleens, kidneys, and intestines were excised. Fluorescent intensity was measured using IVIS imaging and analyzed using the Aura Imaging Software v4.0.8, as previously demonstrated [83]. To control for background fluorescence, mice were injected with PBS.…”

Genomic communication via circulating extracellular vesicles and long-term health consequences of COVID-19

“…For example, engineered EVs loaded with the receptor- binding domain (RBD) of the S protein accumulate specifically in the tissues enriched with the ACE2 receptor, including lungs, and delivered anti-viral siRNAs to suppress infection in vivo [ 99 ]. Engineered EVs decorated with the RBD of viral S protein, and labelled with an imageable molecule is an attractive method to monitor the in vivo biodistribution, and the binding affinities of different viral variants to inform therapeutic strategy [ 100 ].…”