Influence of Biophysical Parameters on Maintaining the Mesenchymal Stem Cell Phenotype

The maintenance of the mesenchymal stem cell (MSC) phenotype in vivo is influenced by the precise orchestration of biochemical and biophysical signals in the stem cell "niche". However, when MSCs are removed from the body and expanded in vitro, there is a loss of multipotency. Here, we employ micropatterned hydrogels to explore how biophysical cues influence the retention of MSC multipotency marker expression. At the single-cell level, soft substrates and patterns that restrict spreading and cytoskeletal tension help maintain the expression of MSC markers. When MSCs are patterned in multicellular geometries, both high cell density and regions of low tension within the pattern are shown to assist the maintenance of multipotency. Combining experiment and simulation along with cytoskeleton disrupting agents reveals spatial patterns of cytoskeletal tension in multicellular architectures that guides the expression of markers associated with MSC multipotency. These findings uncover a relationship between multiple biophysical parameters in maintaining the MSC phenotype, which may shed light on the structure of the MSC "niche" and prove useful in guiding the selection of in vitro expansion materials for regenerative therapies.