Bioprocess Development for the Large Scale Production of Extracellular Vesicles From Adult Stem Cells

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Stem cells exist in very small numbers in almost all tissues within the body. For example, mesenchymal stem cells (MSCs) are a type of adult stem cell that can be found in bone marrow and fat. There is huge interest in MSCs because their implantation into a damaged tissue often leads to some degree of functional recovery. Despite there being significant barriers (e.g. regulatory issues, cost) to the widespread clinical use of MSCs, hundreds of clinical trials have been undertaken to investigate how MSCs can be used to treat medical conditions such as heart disease, stroke and type I diabetes. Evidence now suggests that many of the positive outcomes observed after MSC implantation are due to the products they secrete. Of particular interest are extracellular vesicles (EVs), small spherical structures secreted by MSCs that contain cargo composed of bioactive molecules. EVs have been observed to migrate from the cell where they were produced and deliver their cargo to target cells, causing the target cells to perform a desired action, such as initiating a repair process. Thus, MSC derived EVs (MSC-EVs) have the potential to be administered clinically as effective therapeutic agents, an approach with fewer barriers compared to MSC implantation. Moreover, EVs are now known to be naturally produced in all of us, from the time we are embryos to the time that we die. They are believed to serve as a complex communication system between cells and are implicated in the processes of tissue development, function and aging. Thus, researchers can use EVs to learn more about these processes in healthy individuals and understand how changes in these processes can lead to birth defects, tissue degeneration and disease. The field of EVs is currently in its infancy and primed for explosive growth. A huge challenge hampering progress is a lack of defined EVs with which researchers can work. Because they can't be easily obtained directly from tissues, researchers collect EVs made by MSCs that are grown outside the body in vessels which contain a liquid medium made up of ingredients that encourage isolated MSCs to divide and secrete EVs. Standard large-scale EV production methods do not yet exist, and current methods to collect EVs from the medium are laborious, time consuming and have low recoveries. We have an established biomanufacturing research program in which we have previously developed robust technologies to scale-up stem cell production in large, controlled vessels called bioreactors. Here we propose to extend our program, and over the next 5 years, (i) engineer standard methods for the large-scale production of defined, functional MSC-EV populations in bioreactors, and (ii) design a novel device capable of rapidly collecting EVs from medium. Outcomes of this work will be the creation of novel technologies that support EV production, study and application development, and the training of individuals qualified to work in this rapidly emerging new field.