Gautrot, J. E. | bioRxiv Science

bioRxiv2022

Growth of Mesenchymal Stem Cells at the Surface of Silicone, Mineral and Plant-Based Oils

Bioemulsions are attractive platforms for the expansion of adherent cells in bioreactors. Their design relies on the self-assembly of protein nanosheets at liquid-liquid interfaces, displaying strong interfacial mechanical properties and promoting integrin-mediated cell adhesion. However, most systems developed to date have focused on fluorinated oils, which are unlikely to be accepted for direct implantation of resulting cell products for regenerative medicine, and protein nanosheets self-assembly at other interfaces has not been investigated. In this report, the composition of aliphatic pro-surfactants palmitoyl chloride and sebacoyl chloride, on the assembly kinetics of poly(L-lysine) at silicone oil interfaces and characterisation of ultimate interfacial shear mechanics and viscoelasticity is presented. The impact of the resulting nanosheets on the adhesion of mesenchymal stem cells (MSCs) is investigated via immunostaining and fluorescence microscopy, demonstrating the engagement of the classic focal adhesion-actin cytoskeleton machinery. The ability of MSCs to proliferate at the corresponding interfaces is quantified. In addition, expansion of MSCs at other non-fluorinated oil interfaces, based on mineral and plant-based oils is investigated. Finally, the proof-of-concept of such non-fluorinated oil systems for the formulation of bioemulsions supporting stem cell adhesion and expansion is demonstrated.

bioengineering↗

bioRxiv2022

Mesenchymal Stem Cells Sense the Toughness of Nanomaterials and Interfaces

Stem cells are known to sense and respond to a broad range of physical stimuli arising from their extra-cellular environment. In particular, the role of the mechanical properties (Youngs or shear modulus, viscoelasticity) of biomaterials has extensively been shown to have a significant impact on the adhesion, spreading, expansion and differentiation of stem cells. In turn, cells exert forces on their environment that can lead to striking changes in shape, size and contraction of associated tissues, and may result in mechanical disruption and functional failure. However, no study has so far correlated stem cell phenotype and biomaterials toughness. Indeed, disentangling toughness-mediated cell response from other mechanosensing processes has remained elusive as it is particularly challenging to uncouple Youngs or shear moduli from toughness, within a range relevant to cell-generated forces. In this report, we show how the design of macromolecular architecture of polymer nanosheets regulates interfacial toughness, independently to interfacial shear storage modulus, and how this, in turn, controls the expansion of mesenchymal stem cells at liquid interfaces.

bioengineering↗