Effects of biophysical and biochemical cues on human corneal epithelial cell behavior

Recent advances in the design of biomaterials aim at mimicking the natural biophysical and biochemical components found in a tissue's extracellular environment (ECM). Of particular interest in this work is mimicking the specialized ECM of the human corneal epithelium called the basement membrane (BM) and understanding how corneal epithelial cells (HCECs) respond to biophysical and biochemical cues. To this end, well defined topographic features with dimension of the BM (20 to 200 nm) were fabricated to support controlled cell interactions with biochemical motifs (e.g., adhesive peptide ligands) found in the BM. Here, features of 30 to 70 nm that represent the smallest features found in the BM were used to demonstrate that the smallest features that HCECs can recognize are 30 and 45 nm, depending on the soluble environment. In addition, HCECs demonstrate contact guidance on the smallest BM features (30 to 70 nm) and on the largest BM features (200 nm), but differs from contact guidance on micron-scale features, suggesting that BM scale topography scale is an influential factor in regulating HCEC behavior. To study the simultaneous presentation of biophysical and biochemical cues, topographic features are coated with thin films using a layer-by-layer deposition of covalently reacting polymers, poly(ethylene imine) and poly(2-vinyl-4,4-dimethylazlactone (PEI/PVDMA). The films are functionalized with the bioactive peptide argenine-glycine-aspartic acid (RGD) to control cell-substrate interactions. We demonstrate that PEI/PVDMA films can be functionalized with monotonically increasing densities of ROD to control HCEC attachment and proliferation. In addition PEI/PVDMA films functionalized with RGD were used to demonstrate that HCEC response to topographic cues is dependent on the scale of the topography, the surface chemical composition and the soluble environment. Results from these studies will advance the understanding of how BM-relevant biophysical and biochemical cues regulate HCEC behaviors in order to design better synthetic implants and in vitro cell culture environments.