Extracellular vesicles provide a capsid‐free vector for oncolytic adenoviral DNA delivery

Abstract

Extracellular vesicles (EVs) have been showcased as auspicious candidates for delivering therapeutic cargo, including oncolytic viruses for cancer treatment. Delivery of oncolytic viruses in EVs could provide considerable advantages, hiding the viruses from the immune system and providing alternative entry pathways into cancer cells. Here we describe the formation and viral cargo of EVs secreted by cancer cells infected with an oncolytic adenovirus (IEVs, infected cell-derived EVs) as a function of time after infection. IEVs were secreted already before the lytic release of virions and their structure resembled normally secreted EVs, suggesting that they were not just apoptotic fragments of infected cells. IEVs were able to carry the viral genome and induce infection in other cancer cells. As such, the role of EVs in the life cycle of adenoviruses may be an important part of a successful infection and may also be harnessed for cancer-and gene therapy.

Extracellular Vesicles: Roles in Human Viral Infections, Immune-Diagnostic, and Therapeutic Applications

“…Notably, these vesicles are similar in size to many typical retroviruses, such as human immunodeficiency virus (HIV). This could potentially explain why studies on the EV–HIV relationship have revealed key similarities in the pathways involved in their intracellular formation [ 2 , 7 ]. Moreover, EVs such as exosomes, have been shown to play critical roles in disease pathogenesis for a number of viruses, including HIV [ 8 ], human adenovirus (HAdv) [ 9 ], and coronavirus (CoV) [ 10 ].…”

Development of New Strategies Using Extracellular Vesicles Loaded with Exogenous Nucleic Acid

“…By combining the desirable features of both exosomes and the AAV vector system, ongoing research is aimed at understanding the role of the exosomes-enveloped viral vector (exo-AAV or vexosomes), where viral capsid has been coated with a surrounding, host-derived membrane, allowing enveloping of the protein viral vector to coordinate cellular tropism by binding to cell-surface molecules [79]. Exo-AAV can be achieved by transfecting the AAV vectors into human embryonic kidney cell line 293 (HEK-293T), and conditioned media containing the EVs associated with AAV vectors are isolated by density gradient centrifugation using iodixanol [80]. The initial characterization of this viral envelope by transmission electron microscopy exhibited an AAV/EVs association with the size range of~50 to 200 nm [80].…”

“…Exo-AAV can be achieved by transfecting the AAV vectors into human embryonic kidney cell line 293 (HEK-293T), and conditioned media containing the EVs associated with AAV vectors are isolated by density gradient centrifugation using iodixanol [80]. The initial characterization of this viral envelope by transmission electron microscopy exhibited an AAV/EVs association with the size range of~50 to 200 nm [80]. Exo-AAV can also be engineered to display targeting peptides on their surfaces to enable enhanced deliveries to the target tissues.…”

Use of exosomes as vectors to carry advanced therapies

“…Several groups documented a subpopulation of EV particles that could be employed as a carrier system to deliver oncolytic adenoviruses to human tumors. 69,70 Moreover, several studies have tested the ability of a subpopulation of adenoassociated virus (AAV) vectors interacting with exosomes to deliver genes. 71 Those exosomes loaded with adenoassociated virus (exo-AAV), contained AAV vectors encoding the gene of interest as well as vector encoded proteins.…”