Endothelial and stem cell interactions on dielectrophoretically aligned fibrous silk fibroin-chitosan scaffolds

Regenerative tissue engineering requires biomaterials that would mimic structure and composition of the extracellular matrix to facilitate cell infiltration, differentiation, and vascularization. Engineered scaffolds composed of natural biomaterials silk fibroin (SF) and chitosan (CS) blend were fabricated to achieve fibrillar nano-structures aligned in three-dimensions using the technique of dielectrophoresis. The effect of scaffold properties on adhesion and migration of human adipose-derived stem cells (hASC) and endothelial cells (HUVEC) was studied on SFCS (micro-structure, unaligned) and engineered SFCS (E-SFCS; nano-structure, aligned). E-SFCS constituted of a nano-featured fibrillar sheets, whereas SFCS sheets had a smooth morphology with unaligned micro-fibrillar extensions at the ends. Adhesion of hASC to either scaffolds occurred within 30 min and was higher than HUVEC adhesion. The percentage of moving cells and average speed was highest for hASC on SFCS scaffold as compared to hASC cocultured with HUVEC. HUVEC interactions with hASC appeared to slow the speed of hASC migration (in coculture) on both scaffolds. It is concluded that the guidance of cells for regenerative tissue engineering using SFCS scaffolds requires a fine balance between cell-cell interactions that affect the migration speed of cells and the surface characteristics that affects the overall adhesion and direction of migration.