Mesenchymal stem cell-derived extracellular vesicles as a cell-free therapy for ARDS.

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Acute Respiratory Distress Syndrome (ARDS) is a severe clinical syndrom that affects 20% of all critically ill patients in intensive care. Unfortunately, around 30-50% of these people will die from the condition and the quality of life of the survivers can be seriously reduced due to the consequent chronic lung problems.There is no effective treatments for this condition at this time and therefore new medicines are urgently needed. ARDS is characterised by an excessive and disregulated inflammation in the lung that leads to inappropriate infiltration of immune cells, lungs fill with water and fail to maintain its main function - breathing. In order to breath these patients require mechanical ventilation.Recently more and more clinicians and basic scientists attention is drawn to cell-based therapies. One of the most promising candidate for a cell based therapy are cells termed Mesenchymal Stem Cells (MSCs), which represent one kind of adult stem cells (can be easily isolated from tissues of adult patients or healthy volunteers), because of this, there is no ethical issues. MSCs could easily be propagated and manipulated under laboratory conditions and have capacity to produce multiple mediators with immuno-modulatory properties. However, concerns regarding safety of long-term effects of MSC administration (e.g. development of tumors) as well as logistical challenges may limit their successful clinical translation. Accumulating evidence now suggests that MSCs act primarily through secretion of different biologically active mediators. Therefore researchers are increasingly considering MSC cell products (which can not replicate and therefore form tumors) as an alternative to the whole cell therapy.In this project we will investigate the therapeutic potential of small membrane wrapped "exracellular vesicles" released by MSCs. These vesicles represent the key component of MSCs secretome and are relatively easy to isolate from MSC conditioned medium by high speed centrifugation. Previously we and others had demonstrated that these vesicles were capable to recapitulate therapeutic effects of MSCs in various pre-clinical models of ARDS. Furthemore, in our recent work we had found that these vesicles contain organelles responsible for maintaining cell bioenergetics (mitochondria). This is very exciting finding as it is known that mitochondrial function is impaired in acute inflammatory conditions such as ARDS.In this project we will use small animal model of ARDS to investigate the therapeutic potential of these vesicles, optimise best route and strategy of administration, gain isights into their bio-distribution in the tissues and also investigate whether or not functionally active mitochondria are important for the therapeutic effect and which tissues are major recipients of the mitochondria transferred in the EVs. These studies will be further complemented by the investigation of the EV mitochndrial transfer to primary human lung cells in vitro. These data are an essential requirement by regulatory bodies such as UK Medicines and Healthcare Products Regulatory Agency and European Medicines Agency for clincal translation of new therapies. The principle anticipated output of this project will be the establishment of a defined strategy for clinical development and knowledge of the specific mechanism of action (based on mitochondrial transfer) of the MSC derived extracellular vesicles. More immediately these data will inform further pre-clinical studies in larger animal models of ARDS required to obtain neccessary data on safety, efficacy and mechanism of action of MSCs EVs. Collectively data in small and large animal models will inform early phase clinical trials for MSC extracellular vesicles in patients with ARDS.