Topographic effect on human induced pluripotent stem cells differentiation towards neuronal lineage.

Pluripotent stem cells have the potential to develop into all cell types of the adult body. Besides chemical and mechanical cues, topographical effect of surfaces could also contribute to the development of new therapies in regenerative medicine. In the present study, we tested the effects of nanograting substrates with different widths (width:350 nm/2 μm/5 μm, height: 300 nm) on human induced pluripotent stem cells (hiPSCs), in particular regarding the commitment of stem cell differentiation to desired phenotypes. We found that nuclei of hiPSCs could align and elongate in the direction of the nano/microstructure, whereas they distributed randomly on flat surfaces. The contact guidance significantly increased when the cells were cultured on the surface with smaller pitch. Gene expression profiling by real-time PCR and immunostaining showed significant up-regulation of neuronal markers on nanostructured substrates either with solely topographical cues or combined with pre-neuronal induction. A width of 350 nm, in particular, induced highest neuronal marker expression. This study demonstrates the significance of topography, especially regarding the width of the structures, in directing differentiation of hiPSCs towards the neuronal lineage. Our study suggests the potential applications of surface topography in clinical regenerative medicine for nerve injury repair.