Update on Extracellular Vesicle-Based Vaccines and Therapeutics to Combat COVID-19.

The COVID-19 pandemic has had a deep impact on people worldwide since late 2019 when SARS-CoV-2 was first identified in Wuhan, China. In addition to its effect on public health, it has affected humans in various aspects of life, including social, economic, cultural, and political. It is also true that researchers have made vigorous efforts to overcome COVID-19 throughout the world, but they still have a long way to go. Accordingly, innumerable therapeutics and vaccine candidates have been studied for their efficacies and have been tried clinically in a very short span of time. For example, the versatility of extracellular vesicles, which are membrane-bound particles released from all types of cells, have recently been highlighted in terms of their effectiveness, biocompatibility, and safety in the fight against COVID-19. Thus, here, we tried to explain the use of extracellular vesicles as therapeutics and for the development of vaccines against COVID-19. Along with the mechanisms and a comprehensive background of their application in trapping the coronavirus or controlling the cytokine storm, we also discuss the obstacles to the clinical use of extracellular vesicles and how these could be resolved in the future.

Possibility of exosome­based coronavirus disease 2019 vaccine (Review).

Coronavirus disease 2019 (COVID­19) is a global pandemic that can have a long­lasting impact on public health if not properly managed. Ongoing vaccine development trials involve classical molecular strategies based on inactivated or attenuated viruses, single peptides or viral vectors. However, there are multiple issues, such as the risk of reversion to virulence, inability to provide long­lasting protection and limited protective immunity. To overcome the aforementioned drawbacks of currently available COVID­19 vaccines, an alternative strategy is required to produce safe and efficacious vaccines that impart long­term immunity. Exosomes (key intercellular communicators characterized by low immunogenicity, high biocompatibility and innate cargo­loading capacity) offer a novel approach for effective COVID­19 vaccine development. An engineered exosome­based vaccine displaying the four primary structural proteins of SARS­CoV­2 (spike, membrane, nucleocapside and envelope proteins) induces humoral and cell mediated immunity and triggers long­lasting immunity. The present review investigated the prospective use of exosomes in the development of COVID­19 vaccines; moreover, exosome­based vaccines may be key to control the COVID­19 pandemic by providing enhanced protection compared with existing vaccines.