Designing nanotopographical density of extracellular matrix for controlled morphology and function of human mesenchymal stem cells.

Inspired by ultrastructural analysis of ex vivo human tissues as well as the physiological importance of structural density, we fabricated nanogrooves with 1:1, 1:3, and 1:5 spacing ratio (width:spacing, width = 550 nm). In response to the nanotopographical density, the adhesion, migration, and differentiation of human mesenchymal stem cells (hMSCs) were sensitively controlled, but the proliferation showed no significant difference. In particular, the osteo- or neurogenesis of hMSCs were enhanced at the 1:3 spacing ratio rather than 1:1 or 1:5 spacing ratio, implying an existence of potentially optimized nanotopographical density for stem cell function. Furthermore, such cellular behaviors were positively correlated with several cell morphological indexes as well as the expression of integrin β1 or N-cadherin. Our findings propose that nanotopographical density may be a key parameter for the design and manipulation of functional scaffolds for stem cell-based tissue engineering and regenerative medicine.