Characterization of Mechanics Driven Heterogeneity in Mesenchymal Stromal Cells

Abstract

Mesenchymal stromal or stem cells (MSC) are one of the most promising candidates for a myriad of cell therapy applications because of their multipotency, trophic properties and immunomodulatory properties. Despite showing promises in numerous preclinical and clinical studies, MSC based therapy is not yet a reality for regenerative medicine due their suboptimal outcome at the clinical endpoint. Suboptimal function of MSC is often attributed to the monolayer expansion process on plastic which is a necessary condition to reach the therapeutically relevant number, and also to their response to a fibrotic environment post transplantation. In both scenarios of plastic culture and fibrotic conditions, the mechanical environment experienced by the MSC is completely different from the natural mechanical niche of the MSC. Accordingly, the role of mechanical environment has been shown to be a critical determinant of MSC gene expression and function. In this study we report that human bone marrow derived primary MSC population becomes phenotypically heterogenous when they experience an abnormal mechanical environment, compared to their native environment. Using a newly developed technique to quantify the heterogeneity, we provide the evidence of phenotypical heterogeneity of MSC through high resolution imaging and image analysis. Additionally, we provide mechanistic insight of the origin of such substrate mechanics driven heterogeneity, which is further determined by the cell-cell mechanical communication through the substrate. The outcome of this study might provide mechanism driven design principles to the molecular, cellular and tissue engineering researchers for rational design of MSC culture condition and biomaterials, thus improving their functional outcome.