Biomaterial arrays with defined adhesion ligand densities and matrix stiffness identify distinct phenotypes for tumorigenic and non-tumorigenic human mesenchymal cell types

Here, we aimed to investigate migration of a model tumor cell line (HT-1080 fibrosarcoma cells, HT-1080s) using synthetic biomaterials to systematically vary peptide ligand density and substrate stiffness. A range of substrate elastic moduli were investigated by using poly(ethylene glycol) (PEG) hydrogel arrays (0.34-17 kPa) and self-assembled monolayer (SAM) arrays (similar to 0.1-1 GPa), while cell adhesion was tuned by varying the presentation of Arg-Gly-Asp (RGD)-containing peptides. HT-1080 motility was insensitive to cell adhesion ligand density on RGD-SAMs, as they migrated with similar speed and directionality for a wide range of RGD densities (0.2-5% mol fraction RGD). Similarly, HT-1080 migration speed was weakly dependent on adhesion on 0.34 kPa PEG surfaces. On 13 kPa surfaces, a sharp initial increase in cell speed was observed at low RGD concentration, with no further changes observed as RGD concentration was increased further. An increase in cell speed similar to two-fold for the 13 kPa relative to the 0.34 kPa PEG surface suggested an important role for substrate stiffness in mediating motility, which was confirmed for HT-1080s migrating on variable modulus PEG hydrogels with constant RGD concentration. Notably, despite similar to two-fold changes in cell speed over a wide range of moduli, HT-1080s adopted rounded morphologies on all surfaces investigated, which contrasted with well spread primary human mesenchymal stem cells (hMSCs). Taken together, our results demonstrate that HT-1080s are morphologically distinct from primary mesenchymal cells (hMSCs) and migrate with minimal dependence on cell adhesion for surfaces within a wide range of moduli, whereas motility is strongly influenced by matrix mechanical properties.