Poster Presentation Australia and New Zealand Society for Extracellular Vesicles Conference 2023

Enhancing Exosome Secretion in MSCs by Modulating Substrate Stiffness and Dimensionality

Exosomes are cell-secreted lipid bilayer membrane nanoparticles containing cytokines, chemokines, growth factors, ECM proteins, RNA, DNA, etc. These are of emerging therapeutic interest as they possess immunomodulatory, anti-inflammatory and wound healing properties and present a novel acellular therapeutic potential in the field of nanomedicine. However, improving the yield of MSC-Exosomes remains a challenge due to paucity of knowledge of how ECM cues like stiffness and dimensionality of culture substrate activate MSC phenotype.

Herein, we present a novel 3D macroporous granular scaffold of tunable mechanical properties which activates MSCs to secrete higher amount of exosomes. We seeded MSCs on 3D microgels of stiffness similar to healthy native tissues (0.3 to 16 KPa) and found more exosomes secreted as compared to those on plastic substrate. Microgels with a stiffness of ~10 and ~13 KPa stand out with the highest amount of secreted exosomes ranging from 16-19x as compared to plastic substrates. Proteomic analysis demonstrates the presence of 1506 proteins including ECM proteins, integrin binding, growth factors, cytokines, exosomal surface markers and many more necessary for regenerative medicine. These results provide a potential bioreactor cell culture substrate to improve exosomes secretion while maintaining their functionality.  

Figure 1a. Morphology of MSCs in GelMA microgel suspension under confocal microscopy, b. Presence of MSCs in the macro porosity of the GelMA microgel scaffold, c. Cryo-EM of MSC-Exosomes and d. Fold increase in exosome secretion between GelMA bulk and microgel suspensions