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

With a progressively ageing population and increasing prevalence of chronic diseases, remaining healthier for longer has become a heightened challenge. As we age our immune system changes causing an increase in inflammatory responses, making us more prone to disease and injury; this process is termed inflammaging. New treatment strategies which contribute towards healthier ageing need to be pursued.
Using mesenchymal stem cells (MSC), which are found throughout the body and aid with normal tissue function, are being trialled as a cell based therapy for treating age-related diseases. Importantly, MSCs can both modulate the immune system, reducing inflammation as well as promoting tissue regeneration. MSCs manipulate the immune system using cell-cell interactions, secretion of anti-inflammatory enzymes and soluble factors, as well as particles derived from the MSC, termed extracellular vesicles (EV). EVs contain similar proteins, DNA and lipids to their parent MSC allowing them to also manipulate cells of the immune system. Undifferentiated, naïve MSCs have been shown to be most effective for therapy as they have the strongest anti-inflammatory properties. However, MSCs are a rare population of cells in the body, so expansion is in the laboratory is required as large numbers of these cells are used for effective therapy. Unfortunately, culture conditions affect MSCs resulting in loss of their anti-inflammatory and tissue regenerative properties resulting in differentiation into mature stromal cells over time, losing their therapeutic efficacy. This change in function is affected by multiple factors such as their surrounding environment and the surfaces they are grown on. For example, MSCs cultured on engineered growth surfaces can influence MSC metabolism and maintain their functional anti-inflammatory properties for longer periods during culture. Additionally, donor age and tissue source all affect MSC functional properties; younger donor MSCs have more potent functional therapeutic properties compared to older donor cells when transfused into patients. Thus there is a reliance on younger donor MSCs, reducing the number of potential patients who can be treated with this effective therapy. The ageing population would benefit more from alternative sources of MSCs for cell therapy, and finding new ways of expanding functional, clinically effective anti-inflammatory naïve MSCs in the laboratory remains a key challenge for research, reducing the reliance on younger donors.
The aim of this project is to investigate if altering MSC metabolism through modulating mitochondrial function can aid the rejuvenation of older donor MSCs during expansion in the laboratory. Energy production is closely linked to MSC function, and this study will investigate how mitochondrial function and distribution is altered between older and younger donor MSCs during different culture conditions. Specifically, how this is linked to MSC and secreted EV anti-inflammatory properties and ageing. To evaluate effects on anti-inflammatory properties MSCs and EVs suppression of immune cells activity will be measured. The effects of ageing on mitochondria function during expansion will be investigated using characterised markers of cellular ageing. Effects on mitochondrial activity will also be assessed when MSCs are expanded on specific biomaterials growth substrates to look at how the interaction of the cell with its growth surface can modulate cell metabolism to promote rejuvenation in older donor MSCs. All experiments will be repeated with multiple donors due to known variability issues with MSCs functional properties.
A deeper understanding of how ageing impacts cellular processes will contribute towards better growth conditions for expanding MSCs for cell-based therapies.