Effects of aligned and random fibers with different diameter on cell behaviors.

Tissue-engineered vascular grafts show promise as a treatment for patients with diseased or damaged arteries. The formation of a confluent endothelium lumen on scaffold is one of the key issues in vascular tissue engineering. The endothelial layer is composed of endothelial cells (ECs) aligned along the long axis of the vessel. The contact guidance effect is believed to fundamentally impact cell morphology, alignment, and behavior. By tuning the scaffold topography where the EC cells reside, the cell adhesion, shape, and other behaviors might be regulated. To this end, poly(ε-caprolactone) was electrospun to obtain different topographies by varying fiber diameter and orientation. The morphology and alignment of EC cells were investigated by analyzing fluorescence staining images. The results show that nano-sized fibers significantly enhance cell adhesion and proliferation due to the comparable geometric feature size of the fiber diameter. ECs align along the fiber oriented direction for both microfibers and nanofibers. It shows a better alignment of ECs on micro-aligned fibers than on nano-aligned fibers, which is due to the active size range of the contact guidance effect. These results indicate that scaffolds with ordered topographies might favor the formation of a confluent endothelium for vascular tissue engineering.