Novel surfactant self-assembly process generates multi-scale surface topographies for stem cell growth and differentiation

Topographical features on a substrate can greatly influence stem cell fate through contact guidance. While the response of stem cells to topography at the nano-, micro-, and meso-scale has been studied extensively, little is known about the interplay of surface features acting simultaneously across multiple length scales. A limiting factor has been the availability of high throughput methods for probing the potentially unlimited parameter space. Herein we describe a facile method for rapidly generating a hierarchy of multi-scaled topographical features on polymer substrates via the self-assembly of surfactants at the monomer/water interface. Having previously assembled polydimethylsiloxane-diacrylate (PDMS-DA) into surfaces resembling multiple tissue morphologies, the current study refines this method to produce biocompatible substrates. To manage the large parameter space, we limit the scope of this study to surface features spanning nanometer (< 1 µm) and micrometer (1-50 µm) length scales, which arise both individually and in combination. Adipose-derived stem cells were plated onto five surface types and their morphology, proliferation, and osteogenic differentiation were assessed after non-inductive and osteogenic culture. We observed statistically significant differences in cellular responses to each surface. Among our observations, the increased osteogenesis of cells on surfaces with nano-scaled features superimposed over micro-scaled features suggests that such hierarchical surface structure mediates the osteogenic properties of a surface.