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Using biomaterials to investigate how ageing affects the anti-inflammatory properties of MSCs and their EVs

Primary Supervisor: Dr Ewan Ross, Life & Health Sciences

Secondary supervisor: Professor Andrew Devitt

PhD project title: Using biomaterials to investigate how ageing affects the anti-inflammatory properties of MSCs and their EVs.

University of Registration: Aston University

Project outline:

Cell based therapies have become an increasingly effective clinical approach for complex inflammatory conditions, due to their ability to both suppress the local immune response as well as promoting tissue regeneration. Mesenchymal stromal cells (MSCs) are a key cell type used for this cell therapy; these multipotent tissue progenitors can be isolated, expanded in the laboratory and infused into patients to exert both anti-inflammatory and regenerative effects with out the harmful side effects of immunosuppressive drug treatments[1,2]. MSCs use a number of strategies to modulate an inflammatory environment, including release of soluble factors, cross-talk mediated by surface proteins as well as the release of extracellular vesicles (EVs). Immunomodulation by EVs is an exciting and novel mechanism by which the immune system may be modulated for therapeutic benefit. Importantly, it highlights that EVs, rather than the MSC alone, have therapeutic potential and this would greatly reduce the number of cells required for therapeutic efficacy.

Producing sufficient MSCs for therapy in the laboratory is challenging. MSCs spontaneously differentiate in culture over time, losing their naïve, immuno-modulatory abilities, instead committing to differentiate to mature stromal lineages[3]. Therefore, the ability to grow large numbers of undifferentiated, naïve MSCs remains a key goal for research. We have recently described a new functional link between metabolism, cell adhesion and immuno-modulatory function in MSCs[4]. In this work, we reveal that altering an MSCs growth surface by using distinct biomaterials modulates their metabolism, resulting in the maintenance of their naïve phenotype and prolonging their capacity to direct immune cell function. This has provided a new reliable approach for the culture of naïve MSCs and this new study will look to use the potential of this system to explore how this affects EVs functionality.

This PhD will develop a new area of research, specifically investigating how maintaining MSCs in a naive state with biomaterials affects the anti-inflammatory potential of their EVs. You will optimise the culture of naïve MSCs on polymer based growth systems (through collaboration with the University of Glasgow). These allow delivery of both an adhesive and soluble factor signal to the MSCs, allowing “tuning” of the growth conditions. Changes to MSC physiology and phenotype will be assessed as well as immuno-suppressive function on T cell proliferation. Once optimal conditions have been established, EVs will be collected, characterised, phenotyped and their cargo contents examined using established techniques at Aston. Effects of MSCs derived EVs on macrophage biology as well as T cell function will inform about the therapeutic potential of these cell products.

Importantly, this approach will allow the evaluation on the effects of donor age on MSC expansion and EVs biology in culture. Older donors often have MSCs which are less potent compared to those from younger donors. As patients with chronic inflammatory conditions are often in the older population, a better understanding of how aged cells react to expansion in culture compared to younger donors may reveal new methods for restoring full functionality back to aged MSCs and their EVs products. Therefore, a key component of this work will be to directly compare the functional effects of new culture conditions on young versus old donor MSCs and EVs.

This exciting project will provide you with practical working experience of progenitor biology, biomaterials and EVs. You will apply these skills in the areas of immunology, ageing and inflammation research. Using this multidisciplinary approach, you will gain experience in several areas of cutting edge research allowing further development and exploration of this project as you make it your own.

References:

  1. Tissue regeneration: The crosstalk between mesenchymal stem cells and immune response. Qi et al., J Cellular Immunology 2018. https://doi.org/10.1016/j.cellimm.2017.11.010
  2. Challenges in clinical development of mesenchymal stromal/stem cells. Mastrolla et al., Stem Cells Trans Med 2019. https://doi.org/10.1002/sctm.19-0044
  3. Bone marrow-derived mesenchymal stem cells change phenotype following in vitro culture: implications for basic research and the clinic. Bara et al., Stem Cells 2014. https://doi.org/10.1002/stem.1649
  4. Nanotopography reveals metabolites that maintain the immunosuppressive phenotype of mesenchymal stem cells. Ross et al., 2019. https://doi.org/10.1101/603332

BBSRC Strategic Research Priority: Understanding the Rules of Life: Immunology & Stem Cells. Integrated Understanding of Health: Ageing

Techniques that will be undertaken during the project:

MSCs from young or old donors will be grown on tuneable biomaterial surfaces using standard tissue culture techniques. Effects on MSCs immuno-modulation will be assessed by suppression of T cell proliferation (via flow cytometry), regulatory T cell maturation (in vitro suppression assay) and MSC characterisation (PCR, Western Blot, in vitro differentiation assay). Effects on metabolism will be revealed in real time using the Seahorse platform as well as by flow cytometry. Release of soluble factors by cultured MSCs will be quantified (by ELISA). EVs will be collected, characterised, phenotyped and their contents examined using established methods and technical expertise at Aston University. The immunomodulatory potential of purified EVs will be assessed using in vitro assays of T cell proliferation as well as assessing changes to specific subsets of T cells and B cells (by flow cytometry). EVs will also be used to assess effects on macrophage function (via horizontal and vertical chemotaxis assays), polarisation (via flow cytometry) and activation (by ELISA) in vitro.

Contact: Dr Ewan Ross, Aston University